Wood Stoves
Part Two

Making Wood Stoves

By Ole Wik

Photographs by Manya Wik

Contents

Chapter 12. Techniques Versus Attitudes

You can do more than you may think.

Chapter 13. How to Build the Three-Way Oil-Barrel Stove

Step-by-step instructions on how to build a stove out of a single oil drum.

Chapter 14. About Efficiency

A complicated concept. Definition: Efficiency of combustion, efficiency of heat transfer, overall efficiency. Experiments on relative and absolute efficiency.

Chapter 15. Elements of Design

The design process. Function. Placement. Shape. Materials. Size. Seams. Doors. Hinges. Latches. Stovepipe collars Baffles. Ovens. Smoke by-passes. Cleanouts. Draft systems: controls; primary and secondary drafts. Hot-air systems. Hot-water systems. Shcives. Legs. Firebrick. Grates. Ash pans and ash doors. Fastenings. Budget. Flowchart.

Chapter 16. Oil-Barrel Stoves

Types of drums. How to reseal a drum after installing a baffle. Whole-barrel stoves (horizontal; vertical). Two-thirds-barrel stoves (vertical; vertical with oven; horizontal round; horizontal squared). One-third-barrel stoves (square; round; oval). Half-cylinder stoves. Half-cylinder with cast-iron stove top. Welded stoves of oil-barrel steel.

Chapter 17. Sheet-Metal Stoves

Stovepipe-steel stove. Sheet-steel stove with cast-iron top. The Ideal Stove. The Super Yukon. The Larry Gay Stove. The Dual-Fire Range.

Chapter 18. Tin-Can Stoves and Emergency Stoves

Five-gallon-can stoves (round and square; horizontal and vertical). Twenty-five-gallon-can camp stove. Nesting stovepipes. Tin-can pipeless stove. Tin-can stove with tin-can pipe. Outboard-tank stove.

Chapter 19. Coking Stoves

Definition. Principle of operation. The draft problem. Ted Ledger's Two-Barrel Stove. Ted Ledger's Coking Stove. Hypothetical coking stove design. The rotary grate. Stove with separate coking compartment.

Chapter 20. Stove-Top and Stovepipe Ovens

Stove-top single can. Double can, insulated. Stovepipe oven principle of operation. Tin can and sheet steel. Round, square, octagonal. Cleaning device.

Chapter 21. Making Stovepipe, Dampers and Adapters

Making stovepipe. How to form crimping. How to make dampers (flat; curved; sleeve). How to make dripless adapters. Tin-can adapters.

Chapter 22. Hot-Water Systems

Stove-top can. How to mend a leaky hot-water can. Built-in reservoir. Firebox coils. Self circulating baseboard heater. Stovepipe or chimney coils. Chip heater. Oil-barrel laundry heater.

Chapter 23. Epilogue

An invitation for feedback.

Bibliography

Chapter 12

Techniques versus Attitudes

In Part II we'll explore the world of homemade wood stoves. First we'll go through the construction of one stove in complete detail. After reading this account - which is a mini-book in itself - I think you'll agree that space doesn't permit complete step-by-step instructions for other stoves.

Instead, I'll describe a number of ways to build the various parts of homemade stoves. These elements of design can then be combined by the builder to produce a variety of stoves, just as the letters of the alphabet can be combined to form an almost limitless number of words. I believe that if a person has the interest, the materials, the tools and the manual skill to put a stove together, he or she will be able to work from a general sketch of a particular stove and do the designing and dimensioning without further help.

But the first thing I want to talk about is not tools, or materials, or techniques, but attitudes. The tendency in a modern industrial society is for the division of labor to be so complete that individuals rely on specialists for almost all of their goods and services. We have come so far from the days of pioneer self-sufficiency that we speak of the "do-it-yourself" movement as if it were some sort of curiosity or fad rather than an expression of man's innate desire for independence.

The trouble is that by depending on specialists - be they plumbers, bakers, or tailors - we rob ourselves of the opportunity to probe the limits of our own abilities. A person who never handles tools cannot know what skill might lie hidden in those magnificent hands. As a result, one who has had no experience with using tools and building things may easily come to consider himself or herself incapable of using tools and building things. Such an attitude - unseen and unrecognized - can cripple a potential artisan as surely as the loss of a hand.

I fell into this trap myself, and might never have gotten out of it had I not settled in the Alaskan bush, where self-sufficiency is still a way of life. My crippling self-image was exposed before I'd been in the valley a month. One day I asked a village craftsman if it was possible to fashion a homemade adapter that would reduce a 6-inch stovepipe down to 5 inches. "Of course it's possible," he answered. "The only question is how to do it."

All of a sudden, I realized that I had been on the verge of giving in to the specialists by ordering an adapter from a faraway hardware store. My friend, by contrast, was already looking through his supply of scrap metal in order to decide which of many possible approaches might be the best. Ever since that time, I've operated on the assumption that if other human beings can do a certain thing, then I can at least give it a try.

Figure 12.1 shows an oil-barrel stove made by elementary school children in a small Eskimo village. Though a seasoned craftsman could suggest a few improvements, there's no doubt that this is a functional stove, capable of heating a trapper's cabin in any weather.

If school kids can build a successful stove, why not you and I? Dig right in, with an attitude of optimistic confidence. If you become discouraged, keep right on going. Remind yourself that you're not trying to build a concert violin or an artificial heart - you're only making a simple container for burning wood.

Figure 12.1 - One-third-barrel stove made by Eskimo school children.

Chapter 13

How To Build the Three-Way Oil-Barrel Stove

Ah, the oil barrel! Tens of thousands, perhaps hundreds of thousands of the 55-gallon steel drums have made the trip to Alaska over the years. World War II and the early oil exploration programs resulted in so many abandoned drums that they came to be called "tundra daisies."

But one man's pollution is another man's solution, and the drums have been a genuine boon to people in the bush. Here was a source of cheap, easily worked sheet steel that could be made into such useful things as rain-water catchments, roofing, dog-food cookers, laundry tubs, gutter pipes, sleds, fish smokers, and - above all - wood stoves. Anybody who has traveled much in the Alaskan bush has seen dozens of different designs of homemade oil-barrel stoves, and indeed one wonders what the villagers would have used for heating had no old oil drums been available.

I was already fascinated with oil-barrel stoves by the time I decided to settle in the bush, but it didn't occur to me that circumstances would quickly force me to make one of my own. As I mentioned in Chapter 1, winter was pressing in when I learned that I couldn't get a commercial stove for my new cabin from Outside suppliers, and consequently had no choice but to go ahead and start cutting steel.

The first problem was to pick a design that would fit my rather pinched circumstances. My cabin was tiny - 8 by 11 feet - so the stove had to be compact. It had to be good for both cooking and heating. It had to be made from a single oil drum, with no other metal besides the fastenings. And it had to be simple enough that I could build it under primitive conditions, working on the ground and using nothing but ordinary hand tools - no welding or power equipment. I settled on a little rectangular design, went to work, and was more than a little surprised when I ended up with quite a satisfactory little stove.

Partly out of nostalgia and partly to have a spare tent stove, I recently built another one on the same basic pattern. If you decide that this type of stove meets your needs, I can guarantee that by the time you've finished you'll have a good feeling for oil-barrel steel and what it can do; it really is a friendly medium. Should you choose a different design, it might still help to read through these instructions, since you may pick up some ideas and techniques that will be helpful in building your own stove.

The Three-Way Stove is basically a rectangular box with a baffle that forces flames up against the cooking surface. The design is such that the stove can be used with either cooking surface up; a special baffle sealer closes off the opening between the baffle and the stove bottom in either position. The stove can also be used as a heater, in the upright position, by removing the baffle sealer altogether (Figure 13.2).

Figure 13.2 - Three-Way Stove seen in each of its possible positions. A removable baffle sealer closes off the bottom of the baffle for the horizontal positions.

First, the oil barrel: There are two kinds of 55-gallon drums. The older kind has a round rim and is made of fairly heavy- gauge steel. The newer kind has a square rim and is made of lighter gauge metal. The older, heavier drums make more durable stoves, but the metal is far harder to work. For a first stove, I recommend the square-rimmed variety. Your stove will still be substantial.

Obtain a reasonably sound drum (I always hold out for a leaker - they're cheaper) and assemble your tools. Here is what I used (Figure 13.3):

Figure 13.3 - Tools required.

• 1. Cutting tools (old snowmobile spring, file, ax to hammer with)
• 2. Tin snips
• 3. Anvil
• 4. Punch
• 5. Cold chisel
• 6. Hammer
• 7. Vise-grip pliers
• 8. C clamps
• 9. Drill and bits
• 10. Gloves
• 11. Ear protectors
• 12. Large screwdriver
• 13. Slip-joint pliers
• 14. Steel measuring tape
• 15. Felt-tipped pen
• 16. Carpenter's square
• 17. Hacksaw (not pictured)

Note that I include ear protectors on the list. There's no way you can make an oil-barrel stove without an awful lot of pounding, and no way you can do all that pounding without damaging your hearing - unless you wear ear protection of some sort.

I find that the earmuff type is the handiest, because it goes on and comes off so easily. There are several other types that are worn inside the ear. Of these, my favorite is the kind made of sponge rubber. Sponge rubber ear protectors are rolled into tight little cylinders and inserted into the ears, where they expand to form a perfect fit. Next I would choose the swimmer's type of earplug, designed to keep water out of the ears. I have also tried the various sonic-valve shooter's plugs, but I find that they hurt my ears. In a pinch, even a wad of cotton will help quite a bit.

Once you have your drum, flush out any explosive fuels that may remain inside. Study the perspective drawing (Figure 13.4), the plans (Figure 13.5) and cutting diagram (Figure 13.6), and budget your materials carefully. Make sure you thoroughly understand every step, then proceed as follows:

Figure 13.4 - Perspective drawing of the Three-Way Stove.

Figure 13.5 - Three-Way Stove, front, side and plan views.

1. Draw reference lines. Draw two lines around the circumference of the drum, 4 inches from each rim. These aid in keeping the work square later.

2. Open the drum. Mark a line along the crest of one of the ribs that divide the barrel into thirds, measuring from the rim to keep it even. Cut along this line to divide the barrel into two parts.

How does one cut a barrel? Lacking anything more sophisticated, I made a barrel-opening tool from_an old snowmobile spring by filing an edge on one corner (Figure 13.7). With this and an ax I could cut the top off my drum in just under 15 minutes (Figure 13.8). If you have access to an electric handsaw, you can make a faster, cleaner job of it either by using a special metal-cutting blade or by turning an old wood-cutting blade around backwards.

If you have access to an oxyacetylene cutting torch, flush your drum with hot, soapy water, then fill it with more soapy water within 1 inch of the top. This will virtually eliminate the danger of explosion. Cut the top off according to Step 3, spill the water out, and cut along the rib as described above.

Figure 13.6 - Cutting diagram.

Figure 13.7 (above) - Snowmobile spring filed to make barrel-cutting tool.

Figure 13.8 - Cutting the drum with homemade tool and ax.

3. Remove the top and bottom of the drum. Mark and cut around the side of the drum V2 inch below the top and bottom rims. (The rims stay with the top and bottom.)

4. Form the stove body. The one-third barrel will be your stove body. Hammer off the rough edges and file or cut away uneven or jagged projections. Form into a rectangle as shown in Figure 13.9: Mark a line parallel to the barrel seam and 2 inches away from it. This is your first corner. From this line measure clockwise around the drum 36 inches and make a mark. Then measure 36 inches the other way from your first corner and make a second mark. A point centered between these two marks establishes the location of the diagonally opposite corner; draw the line. Measure 16 inches around the drum from one of these corners, and then 16 inches in the same direction from the other to locate the remaining two corners. Draw the lines.

Figure 13.9 - Marking the corners of the one-third barrel to form into a rectangle.

Transfer the four corner lines to the inside of the barrel, and score lightly with the cold chisel. Be very careful not to score too deeply, or the metal may break when you bend it. Now give the barrel a bear hug to begin squaring it up, and finish off by pounding on a squared log or other timber (Figure 13.10). Spare no effort in getting the body as square as you can, especially at the corners.

Figure 13.10 - Forming the stove body on a squared iog.

What residual roundness you can't get out at this stage will be removed in the next step.

5. Form the body flanges. Fold a 1/2-inch flange outward at the top and bottom of the stove body. Since your first cuts (Steps 2 and 3) are no doubt a bit wavy, use the reference lines drawn in Step 1 as a guide in marking a fold line that averages 1/2 inch from the top and bottom edges. Then cut inward along the corner lines from the top and bottom until you just intersect the fold lines.

Now comes a careful operation, in which you form the flanges while simultaneously eliminating any residual roundness from the body. Using the pliers, fold one flange outward along the line. On this first pass, bend only about 15 degrees. The bend will stiffen the side somewhat, but not so much that you can't push the side of the body inward wherever it is still bowed out with the original barrel curve. When you push inward to straighten the side, your flange will buckle, forming a wave. Bend this wave back down while holding the side in.

This will lock the metal in the newly straightened position. When you have worked all along the length of the flange and it is as straight as you can get it, make another pass with the pliers, folding another 15 degrees or so. After this pass, you will be able to do more straightening. Continue in this way until you have bent the flange a full 90 degrees, and then treat the other flanges similarly. You'll be amazed at how straight and boxlike the sides have become.

Figure 13.11 - Cutting and scoring oil-barrel steel requires a solid anvil.

6. Cut out the stove bottom. Now return to the other two-thirds of your barrel and cut it along the seam. This can be done easily with a cold chisel and a hammer (Figure 13.11), working from the inside of the drum and pounding against a good, solid anvil of some kind (any heavy slab of metal will do). Measure the length of your stove body, without the flanges, and add 3 inches to determine the length of the bottom.

Draw a line this distance from the cut you just made, and parallel to it. Transfer the line to the inside of the barrel (which is still in the round), cut out the sheet, and flatten it by pounding and tromping. This sheet will be the proper length for the stove bottom, but it will have excess material at the sides, giving you a chance to cut off the ragged edges left from the barrel-opening operation.

To determine the width of the bottom, measure the width of the stove body, without the flanges, and add 3 inches. Lay off the appropriate lines on the sheet and cut off the excess. By cutting close to one of the original edges, you should have enough metal at the other to form the stove handle.

The bottom sheet will be 1-1/2 inches larger all around than your stove body. This allows you to fold a 3/4-inch flap all the way around the bottom to grasp the 1/2-inch flange on the stove body, leaving an extra 1/4 inch to allow for irregularities in the flange and any curve that may remain in the stove walls.

Now cut notches in the corners of the stove bottom, as shown in Figure 13.12. With the pliers, fold up flanges at a right angle, as if you were making a cookie sheet with 3/4-inch sides. Work slowly; make about six passes to complete each edge.

Figure 13.12 - Cutting notches at corners of stove bottom.

Repeat this whole process to form the stove top. Set both pieces aside for now. The sheet of metal remaining from the two-thirds barrel will provide almost all of the material you'll need for the rest of the stove components, with the balance coming from one end of the drum.

7. Form the stovepipe collar. There are at least five ways to fasten a collar to a stove body without welding, as shown in Figure 13.13. In every case you form the collar first, since it is far easier to cut a hole to fit an existing collar than it is to make a collar to fit an existing hole. Then you cut a hole in the stove body, somewhat smaller than the collar, and turn up its edge to form a shallow, volcano-like rim. Part of the collar metal grasps the inside of this rim, and part grasps the outside - so that the finished collar can't slip either in or out - or else the collar is riveted to the rim.

For purposes of illustration, I've used three different collar systems in this stove. You may wish to follow the directions and gain experience with all three methods, or you may wish to select one method and make all three collars the same way. Whatever method you choose, always form your stovepipe collar so that the crimped end of the pipe fits inside.

Figure 13.13 - Five ways of attaching a collar to a sheet.

To build the stovepipe collar by the method shown in Figure 13.13, Drawing A, use a section of 5-inch or 6-inch stovepipe as a form and shape a 2-1/2-inch-wide strip of metal around the crimped end, allowing a 1/2-inch overlap. For the best fit, arrange the overlap to nest with the seam of the pipe. Mark the strip and rivet twice through the overlap to tie the collar together. A six- or eight-penny nail with most of the shank removed makes a fine rivet.

Center the collar on one of the short sides of the stove body (Figure 13.5, Drawing B). Trace a line on the stove side around the inside of the collar. Before moving anything, make a mark on the circle where the collar seam is, so that you can align the two parts later. Make a second circle 3/16 inch inside the first, and cut out the inner circle of metal. This will leave enough metal to bend up a Winch rim all around.

Bend the edge of the circular hole outward with the pliers to form the little volcano-like rim, sloping upward about 45 degrees. Slip the collar inside the rim with the seam marks lined up and tap the rim against the collar to close any gaps (but don't deform the collar). Now tap the collar down further so that 1/2 inch sticks inside the rim and mark a line around the collar at the top of the rim.

Remove the collar and cut from the near edge to this line to form a series of tabs about 1/2-inch wide. Fold every other tab outward to match the flare of the rim. Slip the collar inside the rim. Pound the inside tabs down against the inside of the rim, then pound the outside tabs down (Figure 13.14). Keep the collar pressed tightly against the stove body while pounding the tabs over.

Figure 13.14 - Stovepipe collar after mounting, inside view.

Although this is the quickest and easiest way to attach a collar to the stove body, it is also the least airtight and the most likely to drip when condensate runs down the pipe. Unless you're pressed for time, I'd suggest one of the other methods shown in Figure 13.13.

8. Form and mount the stokehole collar. Here we'll use the method shown in Figure 13.13, Drawing B. This type of collar is the most airtight, the tidiest, and to my mind, the most elegant of the bunch. Cut a strip of metal 23-1/2 by 5 inches. Draw a line along the length of the strip on the painted side, 2-3/8 inches from one edge. Score lightly and fold over to form a doubled strip. Carefully form this into a circle, leaving the shorter side of the fold out.

(This collar should be as nearly circular as you can possibly make it, since the stokehole cover should be able to fit over the collar in three different positions, depending on which side of the stove is up. You might consider making a circular wooden form 7-1/2 inches in diameter for shaping your collar. If your collar is too far out of round, you'll have to make a second stokehole cover, for use when the stove is in the other horizontal position. Either cover will then work for the vertical position.)

Butt the two ends of the collar together and insert a 2- by 2-inch piece of metal between the two layers to span the junction. Rivet the insert in place, fastening the ends of the collar together. Be sure that the insert lies well up inside the inner and outer sleeves of the collar so that it will not interfere with the lower edges when you fasten them to the stove-body rim.

Lay the collar on the front of the stove, positioned as shown in Figure 13.5, Drawing A, and trace a circle inside the collar on the stove. Cut the hole a bit smaller and form the rim, just as for the stovepipe port (Step 7). Now pry up a slight lip on the shorter, outer sleeve of the collar, using a large screwdriver. Make an index mark across the screwdriver 3/8 inch from the tip as a depth guide for inserting the blade. Taking very small bites, bend a small angle at each pass and work all around the collar evenly (Figure 13.15).

Figure 13.15.- Stokehole collar prior to mounting. Note volcano-like rim on stove body.

Slip the collar into the ho;e and bend the lip of the collar and the rim of the hole until the lip fits nicely against the rim. When satisfied with the fit, pound the longer, inner sleeve of the collar over the inside of the rim, making sure that the collar is pressed firmly into position (Figure 13.16). Then tap the collar lip down against the outside of the rim to complete the seal.

Figure 13.16 - Stokehole collar after mounting, inside view. (The gap at the bottom was caused by an error.)

9. Mount the stove bottom. Now fold over further one of the right-angle flanges on the long side of the stove bottom until it is almost flat. Slide the body of the stove into position so that this flap grasps the body flange nearest the stokehole. (The stokehole collar will interfere with the flattening of this one flange, so that is why we prefold it most of the way.)

Hammer the other stove-bottom flaps over to clasp the stove-body flanges, working all sides down evenly and gradually. When the flanges are folded over enough to holdthe body in position, turn the stovs upside down so that you can kneel on the bottom to press it down firmly against the flanges. Pound the flaps over from underneath (Figure 13.17) and finish them off on the anvil.

Figure 13.17 - Mounting the stove bottom.

Your stove body may now have a crazy warp to it, but don't worry - it will come out later, when you install the stove top.

10. Make and install the baffle. Measure the width and depth of your stove at a point 12-1/2 inches from the end opposite the stovepipe port. Cut a piece of metal 12 by 18 inches and fold it, as shown in Figure 13.18. Install in the position indicated in Figure

Figure 13.18 - Baffle pattern.

13.5, Drawings A and C, leaving 1-1/4 inches of clearance between the top and bottom of the stove. Rivet four times to the sides. Figure 13.19 shows how the stove should look at this stage.

Figure 13.19 - Stove with bottom, baffle and both collars installed.

11. Install the stove top. Repeat Step 9.

12. Rivet the stove top and bottom to the body flanges. To prevent the stove sides from buckling and pulling the seams apart under the stresses of repeated heating and cooling, rivet through the top and bottom and the body flanges as shown in Figure 13.20.

Figure 13.20 - Riveting system for stove top and bottom.

Allow 3 rivets for each long side and 2 for each short side, evenly spaced - 20 in all. Resist the temptation to omit these rivets; your stove really will cave in without them.

13. Make the stokehole cover collar. (See Figure 13.21). Measure around the outside of the stokehole collar to get the length of the strip you need, allowing 1/2 inch for overlap. Cut the strip 2-1/4 inches wide and mold it to the stokehole collar so that it slides on and off with a smooth, gentle friction fit. A collar that is too tight makes it hard to get the cover on and off, and one that is too loose admits too much air for best control of the fire. Rivet it twice through the overlap.

Make a mark on both collars so that you can always line them up in the same way. With the stokehole cover collar in place on the stokehole collar, bend a V4-inch flange outward on the cover collar, working slowly so as not to distort it. When finished, hammer the collar as necessary to correct the fit.

Figure 13.21 - Stokehole cover and draft system.

14. Make the stokehole cover faceplate. Lay the flanged stokehole cover collar on your oil drum top, with the flanges against the painted side. Trace a circle around the flanges to establish the fold line. Draw another circle 1/4 inch outside this line to establish the edge line. Before moving the collar, make marks on it and on the drum top so that you can always align the two pieces the same way. Cut along the edge line, file off rough edges and pound the plate out flat.

15. Form the draft hole collar. The draft system is also shown in Figure 13.21. A tin can, with air holes cut as shown, slides inside a small collar in the stokehole cover faceplate to admit varying amounts of air to the firebox. This collar is constructed according to the method shown in Figure 13.13, Drawing C. First, obtain a soup or tomato sauce can to use as a form in rolling the strips. Carefully measure the circumference of your can and cut a sheet of metal just a shade longer and 3 inches wide. You want the sheet to go all the way around the can and just butt up edge to edge, with a gently snug fit.

Mold this sheet to fit around the can, thus forming the inner sleeve of the collar. Now cut another sheet of metal a shade longer than the inner sleeve and 1/2 inch narrower. Form it around the inner sleeve, with the seams offset 180 degrees. Take care to get both sleeves as round as possible, and check the fit against your can. Clamp the sleeves together so that 1/4 inch of the inner sleeve protrudes at each end of the outer sleeve and rivet twice on each side of each seam - eight rivets in all.

Fold the top of the longer, inner sleeve outward over the lip of the shorter, outer sleeve. Then, using the techniques in Step 8, cut the draft hole in the faceplate, 1 inch from the bottom edge, and mount the collar onto it (Figures 13.22 and 13.23).

Figure 13.22 (left) - Faceplate and draft-hole collar. Figure 13.23 (right) - Mounting the draft-hole collar.

Alternative: A simpler way to form the draft is to cut the stokehole cover faceplate (Step 14) in such a way that the large bung hole of the drum falls where you want the draft hole to be. With the bung in place, your stove is shut down all the way, and with the bung out, the stove is wide open. For intermediate settings, get two tomato paste (not sauce) cans.

Flatten the open end of one to make it easier to hold, and slide the closed end into the draft hole; the loose fit gives a low intermediate setting. Cut a 1/2-inch-square hole in the bottom of the other can, flatten the open end, and stick it into the draft hole for a high intermediate setting. These four positions, combined with the stovepipe damper, will give you the full range of stove control.

16. Cut the draft can. After removing one end and the rim, cut the draft can to the pattern shown in Figure 13.21. Pushing the can all the way into the draft hole collar closes the draft completely; pulling it out various distances gives varying amounts of air to the fire; removing it from the collar completely allows a strong blast of air to rush through the tube onto the coals. A simple handle can be riveted onto the bottom of the can to aid in manipulating it.

17. Mount the stokehole cover faceplate. With the pliers, slowly fold down a flange around the faceplate, following the fold line. When you have completed a right-angle bend, cut shallow grooves into the outside of this flange with a hacksaw at 1/4-inch intervals. Cut only about halfway to the bend through the metal. Cutting these kerfs removes enough material that the remaining metal can compress easily as you fold the flange over the rest of the way.

Place the stokehole cover collar from Step 13 onto the faceplate, being certain to line up the marks so that the draft hole will be at the bottom of the faceplate when the completed cover is mounted onto the stokehole collar. Hammer the faceplate flange over, so that it grips the flange on the collar. When finished, slip the whole assembly onto the stokehole collar and pound as necessary to correct the fit.

18. Mount the handle. Cut and mark the handle strip according to Figure 13.24. Drill the holes at each end, then fold along the dashed lines until you have right-angle flanges tapering toward the ends. Starting at the center, pound the flanges over nearly flat - just enough so that the handle is pleasant to the touch. Then fold the handle on the dotted lines to the shape shown. Position the handle on the faceplate high enough to clear the draft system, and rivet twice at both ends through the drilled holes. File any rough edges smooth. Figure 13.25 shows the completed unit.

Figure 13.24 {above)-How to fold the handle.

Figure 13.25 - Stokehole cover and draft system, with handle.

19. Form the baffle sealer. Cut a strip 5 inches wide and 1/4 inch shorter than the width of your stove body and fold according to Figure 13.26.

Figure 13.26-Baffle sealer.

20. Paint the stove. If you wish, you can add a coat or two of stove enamel to improve looks and retard rust. Be sure to remove the original barrel paint completely first, since it is not designed for high-temperature use and will flake off after the first few fires, taking your stove enamel with it. Your first fire will drive the volatiles from the enamel, causing an odor, so make sure you have adequate ventilation, or else make your first setup outdoors.

21. Make a trivet. Take the circle you cut from the stove body to form the stokehole, and cut four tabs in it at 90-degree intervals, 1 inch wide and 3/4 inch deep. Bend the tabs over at right angles to form legs, adjusting the angle of the bend so that the trivet sits flat on the stove top. The trivet will keep pots up off the cooking surface when they need gentle heat (see Figure 5.1).

Your stove is now complete. Make your first fire a gentle one, both to give the metal a chance to adjust to its new configuration and to complete the cure of the enamel. And make your first fire a time for ceremony. Invite some friends over for the stove warming, and put the kettle on. I think you'll be warmed in two ways - by the heat of the burning wood, and by the satisfaction that always comes when you've made something really nice with your hands.

Figuire 13.27 - The author and his son light up the Three-Way Stove for the first time. Note how a tin can has been used as an elbow adapter for the stovepipe.

Chapter 14

About Efficiency

Before going into other details of building wood stoves, let's consider the problem of efficiency. Any old metal box with a draft hole and a flue will deliver some useful heat, but it takes a certain amount of thought to design a stove that can be called efficient. In the following chapter we'll discuss the various design elements that, in combination, make a stove. Right now we'll consider the relationship between certain of those elements and the efficiency which may be expected from the finished unit.

The concept of efficiency, as applied to wood stoves, is unexpectedly complicated. Any meaningful measurement of the absolute efficiency of a particular stove requires, first, an agreement as to the definition of the term, followed by standardization of the wood used in the test (as to species, moisture content, size, condition), determination of the wood's actual energy content, careful weighing of the wood burned in the course of the experiment, and - most difficult of all - some measurements that would relate the heat actually released by the stove into a standardized enclosure to the amount of wood burned over a period of time.

In spite of all these difficulties, stove manufacturers are not at all shy about praising the "efficiency" of their offerings. Some manufacturers state, for example, that their products deliver "complete combustion" of the wood, basing their claims on the fact that, after a fire, the ash pan contains only powdery ash, not charcoal. Left unsaid is the important fact that a major portion of the energy in the wood is held in the form of volatile substances. Some estimates say that half or more of the energy chemically bound up in a stick of wood can leave the stove unburned, in the smoke. Further, even stoves that deliver reasonably complete combustion may be constructed in such a way that the resulting hot gases rush up the flue without contributing more than a fraction of their heat to the room.

Buyer's Guide to Woodstoves, an excellent booklet published by the Vermont Woodstove Company, defines the efficiency of combustion (Ec) as the percentage of heat released by the wood to the stove. The efficiency of heat transfer (Eh) is the percentage of heat released by the stove to the house. The goal, of course, is to get heat out of the wood and into the house. This overall efficiency (Eo) is the product of EcxEh. The booklet continues:

For example, in a good woodstove Ec and Eh might both be 80%. [Figure 14.1, Drawing A). Then Eo will be 80% x 80% = 64%. This is saying that 64% of the potential heat value of the wood winds up in the house and the other 36% goes up the chimney. This may seem horribly wasteful but it is about comparable to the average oil heat system.

In a poorer stove Ec and Eh might both be 50% [Figure 14.1, Drawing B]. Then Eo will be 50% x 50% = 25%. In this example only 25% of the heat winds up in the house and 75% goes up the chimney, which is a sinful waste.

Figure 14.1 - Hypothetical efficiency diagrams of a good and a poor wood stove (from Buyers Guide to Woodstoves).

In designing wood stoves it is important to remember that the completeness of combustion will be determined largely by the arrangement of the draft system. Efficiency demands two drafts - one to feed primary air to the coals for maintaining the basic fire, and another to admit secondary air to the region above the coals for the combustion of unburned volatile substances in the smoke. Ideally, both primary and secondary air should be preheated before entering the firebox, and both draft systems should be either independently adjustable or else preproportioned, so that the proper ratio of primary to secondary air can be maintained.

We should also remember that heat-transfer efficiency is increased by forcing the smoke to pass closer to the stove's surface on the way to the flue or by forcing it to take a longer path. Baffles, cooling fins, heat-exchange chambers, convection tubes and forced-air plenums are all worth considering when the stove is being designed. Often a fairly simple structural modification can result in a significant increase in heat-transfer efficiency.

The Jøtul company has published some interesting data on the comparative performance of wood stoves with and without these efficiency-promoting features. In an experiment conducted independently in Canada, two cast-iron stoves were installed in identical camp buildings 1-1/2 miles apart. One of the test units was a conventional box stove with neither baffle nor provision for secondary air (Figure 14.2). Airflow from the draft to the flue is

Figure 14.2 - Cross-section of a typical unbaffled cast-iron box stove. Airflow from the draft to the flue is direct, and there is no provision for secondary combustion of the smoke.

direct, and smoke may rush up the stovepipe unburned. The other was the Jøtul No. 118. The Jøtul incorporates a horizontal baffle that forces the smoke to travel toward the front of the stove and then through a top-mounted heat-exchange box before reaching the stovepipe (Figure 14.3). It also features a hollow door with asingle draft control on the outside and two ports on the inner surface. The air is preheated in the door cavity and then passes into the firebox through a primary draft near the coals and a proportionately-sized secondary draft higher up. This design is intended to promote complete combustion of the smoke just as it enters the heat-exchange box.

Figure 14.3 - Cross-section of the Jøtul No. 118 wood stove, distributed in the U.S. by Kristia Associates. Incoming air is preheated within the hollow door and divided into primary and secondary streams. Wood burns from front to back. Secondary combustion takes place as smoke is entering upper chamber.

Throughout the experiment, office clerks in both camp buildings kept careful records of indoor and outdoor temperatures and of the amounts and types of wood used. Although both buildings were maintained at essentially the same temperature and burned about the same proportions of hardwood and softwood, the standard box stove consumed 8.53 cubic feet of wood per day, compared to 4.25 cubic feet per day for the Jøtul No. 118. In other words, the conventional stove required about two cords of wood to produce the useful heat that the baffled stove squeezed out of one cord. And there was another notable difference:

The conventional stove was usually dead by 2:00 a.m., so that indoor temperatures often fell into the 20's by morning, while the Jøtul always held enough coals to start dry wood in the morning, and the indoor temperatures on corresponding days never dropped below 40. Anybody with a little training can pick out some unfortunate flaws in the design of this experiment, but on the basis of experience with both baffled and unbaffled stoves, I find these results entirely believable.

The above experiment was comparative only - it measured the relative efficiencies of the two stoves. The Jøtul company's engineering department has conducted other tests that shed some light on the interesting problem of absolute efficiency. Figure 14.4 shows the results of tests conducted on the same model stove used in the Canadian experiment. Notice that the overall efficiency starts relatively low, rises to a peak of 76 percent, and then declines as the firing rate is progressively increased.

I would guess that the efficiency is low at low firing rates because the stove is relatively cool, so that the smoke is below its kindjing temperature by the time it reaches the zone of secondary combustion, and leaves the stove unburned. At somewhat higher firing rates, everything works as it should, and the gases are more completely burned. When the stove is opened up still further, airflow through the unit is probably so rapid that the hot gases escape to the flue before they have had time to yield their heat to the metal, so that efficiency once more falls off. At the maximum firing rate, the overall efficiency is a shade under 55 percent.

This experiment demonstrates that the efficiency of a wood stove cannot be expressed as a single number, because it dependsso much on how the unit is used. In the previous experiment we learned that efficiency also depends heavily on how the stove is built. In the next chapter we'll plunge into stove design. If you are especially interested in efficiency, you might pay particular attention to the sections on drafts, baffles, and heat-transfer systems.

Figure 14.4 - Graph illustrating manufacturer's test results on Jøtul No. 118 shows the absolute efficiency. Overall efficiency starts low, rises to a peak of 76 percent and then declines as the firing rate increases.

Chapter 15

Elements of Design

The process of design consists largely of making decisions. From a multitude of different possibilities, the designer gradually selects certain elements and rejects others, until at last the final outlines of the object are fixed. In the case of wood-stove design, I break the process down into two parts - the general and the specific. The general phase goes something like this:

FUNCTION.

First of all it is necessary to know the purpose of the stove. If it is to be strictly a heater, the possibilities are almost unlimited. But if the stove is to be used for any serious cooking, then its top will have to be at least partially flat, and the firebox will have to be relatively shallow, so that live flames can lick the underside of the cooking surface.

PLACEMENT.

It is helpful to know exactly where the stove will sit when completed. This will help determine the general location of such features as the stovepipe port, door, hinges and draft controls.

SHAPE.

Will the stove be round or rectangular? Horizontal or vertical? A decision on shape significantly restricts the choice in other categories, and helps to determine the precise locations of the various openings and controls.

MATERIALS.

What sort of metal will the stove be made of? Oil barrels can be worked into either round or rectangular stoves with simple hand tools. Sheet steel generally requires welding, and may not lend itself to round shapes without special rolling equipment.

In considering materials, don't overlook the advantages of using ready-made components. It is entirely possible to build a stove from scratch, but pleasing results (and time savings) can also be had by using commercial stove tops, draft sliders, oven and firebox doors, legs and grates - either salvaged from old stoves or purchased new.

So far, we've decided what the stove is going to do, where it is going to be, and what it is going to be made of. Next we have to decide what it is going to be like and how it is going to be put together - in sum, the specifics:

SIZE.

This is important. A given stove may be able to heat either a small house or a large one, but the efficiency may be markedly different in the two cases. For example, Figure 15.1 shows the results of another efficiency test run on the Jøtul No. 118 wood stove by company engineers. In this chart, actual heat output in BTU per hour (a BTU or British Thermal Unit is the amount of heat required to raise the temperature of 1 pound of water 1°F) is shown in relation to wood consumption.

Naturally, the heat output rises as the firing rate increases. But in Figure 14.4 we saw that this particular stove is most efficient at a firing rate of 3.1 pounds of wood per hour. The chart in Figure 15.1 shows that in order todouble the heat put out at that most efficient firing rate, the firing rate must be more than tripled. The implication is that, other things being equal, a large stove operating at a moderate setting may heat a given space more efficiently than a small one burning wide open most of the time.

Figure 15.1 - Efficiency test run by manufacturer on Jøtul No. 118 shows actual heat output in BTU per hour in relation to wood consumption. In order to double heat output at the most efficient firing rate, the firing rate must be more than tripled.

On the other hand, a stove that is too large for its surroundings may operate at such a low setting that the smoke is too cool either to burn off in secondary combustion or to keep the chimney warm enough to prevent condensation. I speak from experience on this, since I designed my present stove to be just the right size for our cabin after the building is enlarged by about half. For now, the stove loafs almost all the time. The wood smolders in the firebox, wasting much of the energy contained in the volatiles, and the stovepipe oven soots up amazingly fast.

There are no hard-and-fast rules for sizing stoves, because so much depends on the climate and on the insulation and tighthess of the building to be heated, not to mention the efficiency of the stove itself. One approach is to determine the best size for the firebox by comparison with the one in the stove presently heating the house, adjusting up or down according to how the old unit performs. For a new house, one might check out the neighbors' stoves and then adjust for differences in space, insulation and tighthess. Either way, it's an educated guess.

If the stove is to be used for cooking, I'd recommend that the stovetop be no more than 9 inches above the ashes. As for length, a longer firebox naturally saves time at the sawbuck, but logs cut to that maximum length may prove hard to split.

SEAMS.

In all but the very simplest stoves, the builder will have to fasten various sheets of metal together. Welding and seam-making are practically synonymous, and I will only mention the fact for those with the proper torch that oil-barrel steel can be welded without using welding rod (Figure 15.2). Non-welders have a number of different types of seams to choose from, as illustrated in Figure 15.3.

Figure 15.2 (left) - Welding oil-barrel steel without using welding rod. The metal parts are clamped together and tacked at intervals to hold them securely. The edges of the plates are then simply fused together.

Figure 15.3 - Four types of non-welded seams. Any of these seams can be sealed with asbestos wicking before being pounded closed and riveted.

DOORS.

A door can make or break a wood stove, since this is a major source of the air leakage which can destroy your control of the unit. Air leakage around a door can be minimized by making the door as small as possible; on the other hand, a larger door increases the range of firewood sizes that can be slipped into the firebox. As a rule of thumb, I recommend that the door be no smaller than 6 inches in either dimension, and no larger than one-half the cross-sectional area of the firebox, measured in the same plane as the door.

Placement of the door involves another trade-off. Raising the door opening lessens the chance of coals falling out onto the floor, but increases the likelihood that smoke will escape into the room when the door is opened. If the door is to be on the stove top rather than on a side, it should be placed close to the edge from which the stove will be fed. This will make it possible to fill the firebox to capacity with a minimum of jiggling.

The simplest kind of door is formed from the piece of metal cut out to make the door opening (Figure 15.4, Drawing A). A good trick is to cut the hinge line first, and then mount the hinges before cutting the other three sides of the door opening; this way there will be no problem in getting the spaces around the door to come out evenly.

It is a good idea to install backing strips around the door to seal the cracks and to give the door something solid to close against. The strips can be mounted either on the inside of the stove, on the outside of the door, or both (Figure 15.4, Drawing B). Remember that strips on the inside of the stove will reduce theeffective size of the door opening, so be sure to allow for them when dimensioning the door.

Figure 15.4 - Simple cut-out door.

This type of door is adaptable either to flat or curved stock.

There may be a tendency for the metal to warp, with resulting air leakage, but a good solid latch should press the door against the backing strips with enough force to overcome the problem. In severe cases, a warped door can be unhinged and pounded back into shape.

Another simple door is the overlapping type. For this, a sheet of metal somewhat larger than the door opening is mounted so as to overlap the edges all around. This is an especially handy door for an oven, since an airtight seal isn't as critical there as it would be on the firebox itself. The metal can be stiffened by turning out a lip all around. (See Figures 15.5 and 16.7.)

Figure 15.5 - Overlap doors may be either flat or curved.

The cover-and-collar type of door (used on the Three-Way Stove, Chapter 13) is more complicated to build than simple hinged doors, but usually provides a more complete seal. This is especially so on round stoves, since curved doors are harder to seal than flat ones.

Several ways of forming collars are shown in Figure 13.13. The cover collar can be sized to fit either outside or inside the stokehole collar (Figure 15.6, Drawings A and B). I always place mine on the outside, because an inside collar is more likely to leak air, and can be jammed by a firewood stick long enough to extend inside the stokehole collar. On the other hand, an inside-fitting cover can be used with an easily made turned-in stokehole collar to give a flush fit (Figure 15.6, Drawing C).

A box-type door (Figure 15.7) is formed by folding two sheets of metal into a shallow, closed box. The resulting structure is fairly rigid, and hence resists warping. The door opening is cut somewhat smaller than the mating part of the door, so that flaps can be foldedinward and bent one way or another until they grip the door with the desired amount of force. This eliminates the need for a latch.

Figure 15.6 (above) - Three cover-and-collar door systems.

Figure 15.7 - Four types of box door.

Like the overlapping door, the box door is especially suitable for use on an oven. The door cavity can even be filled with insulation to help retain heat. The door may be hinged either at one side or along the bottom, or - because of the gripping flaps all around the door opening - it can be left hingeless so that it is entirely removable, as in the cover-and-collar door system. If the door is to be used on the firebox, where it will be subject to intense heat, its lifetime can be increased by placing the draft away from the door opening and by installing a heat shield, like the one in Figure 15.15, on the inner face of the door.

HINGES.

The quickest, easiest way to hang a door on a stove is to use ready-made hinges from the hardware store. A few of the many different types c&n the market are shown in Figure 15.8. Hinges can be attached with stove bolts or rivets, or by welding. (For welding, use plain iron hinges, so that there can be no chance that the weld will be fouled by metallic elements in the plating.)

Figure 15.8 - Types of hinges readily available in the hardware store.

Functional hinges can also be made from scratch, as shown in Figure 15.9. Drawing A shows a simple hinge made of strips of metal folded around some sort of pin. Drawing B shows a pipe-and-pin hinge which requires welding, and is suitable mainly forheavier stoves. Drawing C shows a kind of swing-away hinge that is especially suitable for box-type doors.

Figure 15.9 - Three types of homemade hinges.

In most applications, hinges are mounted with the pins directly over the crack between the two parts to be joined. For a firebox door on a wood stove, however, it may be advantageous to set the hinge line back from the crack by about 1/2 inch (Figure 15.10). This way a foil closure pad will seal the entire door opening when the fire is banked for the night. Even a leaky door can be sealed very nicely in this way, and the operation of the hinge is not affected at all.

Figure 15.10 - Normal and set-back hinge lines.

LATCHES.

Certain ready-made doors and those of the cover-and-collar and box types are self-latching, and require no additional fittings to keep them closed. Others require a latch of some kind. In principle all latches are much the same, but in detail probably no other component of the stove shows so much craftsmanship, individuality and ingenuity.

Some simple types of latches are illustrated in Figure 15.11. Drawings A and B show two easily made latches which require only a few strips of metal and some fastenings. Drawing C shows a more elaborate latch incorporating a ramp. When the handle is twisted, the plate rides up the ramp and forces the door shut. Drawing D shows an internal catch that grasps the stove body. (The hinge pins have to be loose enough to allow the door to be lifted slightly to disengage the catch.) Drawing E shows a latch consisting of a pipe or tube attached to the stove body, and a gripper made out of a bent piece of metal.

Figure 15.11 - Homemade stove door latches.

STOVEPIPE COLLARS.

Please reread the section in Chapter 4 about the desirability of placing the crimped end of the stovepipe down. In making the stovepipe collar, form the strip of metal around the crimped end of a joint of pipe of the proper diameter. Once the collar is fastened together and checked for fit, there is no reason why it has to remain round; often a flattened, oval collar will give more usable space on the stove top. Round or oval, trace the outline of the collar on the stove metal as a guide in cutting out the hole. (I urge you not to reverse the order of these steps, because the fit may suffer.)

A stovepipe collar need not be more than 1-1/2 inches high, since this is as far as the crimped end of the stovepipe will go in anyway. It can be welded or brazed to the stove body, or attached according to any of the methods pictured in Figure 13.13. Collars usually protrude from the stove, but occasionally it is desirable to place the collar on the inside - for example, on a stove that is to be used for camping and transported by sled, horse or boat.

Figure 15.12 shows a simple way to form an inside collar. In a very primitive stove it is possible to omit the collar entirely by simplyplacing the stovepipe into a hole in the stove top, but the hole should be cut very carefully in order to avoid the possibility that the pipe will separate and slip down into the firebox.

Figure 15.12 - How to make an internal stovepipe collar.

What diameter stovepipe is best? This depends, among other things, on the purpose of the stove, its size, the dwelling in which it will be placed, the chimney to which it will be connected, and the climate. Six-inch pipe seems to be more or less standard; I have never seen anything larger attached to a homemade stove, although there is no reason why this couldn't be done if it seemed desirable.

I have used 5-inch pipe on many uncomplicated stoves, with good results; but if the unit has either an integral or stovepipe oven, I would recommend going an inch larger. Four-inch pipe draws well enough on some small stoves, but the smoke flow may be rapid enough to carry live sparks right out of the pipe and onto the roof.

Should the stovepipe collar be placed on the top of the stove or on a side? A collar on the stove top takes up some room that might otherwise be available for cooking, but offers a compensating advantage: Creosote and carbon chips fall back into the stove, rather than leaking out of an elbow or plugging it up. One way to avoid problems with an elbow in side-mounted stovepipe collars is to fit the stovepipe with a creosote trap, as shown in Figure 15.13.

Figure 15.13 - Creosote trap. Sooty condensate and carbon chips falling down the pipe are caught in the No. 10 can and periodically discarded.

BAFFLES

A simple baffle can improve the performance of many stoves by forcing the smoke and flames into closer contact with the top or sides of the stove before entering the flue. I've added baffles to commercial stoves on occasion (Figure 15.14), and would never build a homemade stove without a baffle.

Figure 15.14 - Improving the performance of a small Yukon stove by adding a baffle.

A baffle, being a flame concentrator, takes a lot of heat itself, and should always be reinforced in some way. Angle-iron supports, either ready-made or fashioned from the same metal as the stove, can be attached to the surface of the baffle away from the firebox, or the baffle can be made of two-ply metal or of metal heavier than the rest of the stove. At the very least, the working edges of the baffle ought to be folded over double, or even triple (see Figure 13.18).

How much clearance should there be between the top of the baffle and the stove top? This is another one of those trade-offs. If the space is relatively small, the stove top will get hotter and cook better, but will burn out sooner. If it is relatively large, the metal will last longer, but peak cooking temperatures will be lower.

I always decide on a baffle space by first calculating the cross-sectional area of the stovepipe, and then dividing that number by the baffle length. The result represents a spacing that leaves a smokeway over the baffle with the same area as the cross section of the stovepipe. This seems like a reasonable starting point. I may then adjust the spacing up or down, depending on the characteristics of the stove and its intended function.

OVENS.

In the next chapters we'll see many different ways of incorporating an integral oven into the design of a wood stove. Remember, though, that it may be better to omit the oven in a very small stove, since the space may be more valuable as part of the firebox. Occasional baking can always be done in a stove-top or stovepipe oven (Chapter 20).

One side of an integral oven usually gets hotter than the other, so that the pans have to be rotated halfway through the baking process. One way to equalize the heat on the two sides of the oven is to mount a heat shield on the hot side, using stove or machine bolts and an extra nut as: a spacer (Figure 15.15).

Figure 15.15 - Heat shield for hot side of oven.

Supports for the shelves should be installed before the oven is fixed in position. They should be planned for versatility, so that the oven can hold, for example, two shelves with two loaves of bread each, three shelves with a muffin tin each, or four shelves with a cookie sheet each. Grate-like shelves from some old refrigerators can be cut down to make oven racks, and custom grates can be made from welding rod of appropriate thicknesses.

SMOKE BY-PASSES.

In stoves with baffles or integral ovens, the smoke may tend to pour from the stokehole each time the door is opened unless the design provides for a by-pass through which smoke may reach the flue directly. Various types of by-pass systems are shown with particular stoves in Chapters 16 and 17.

CLEANOUTS.

Stoves that have special passages to conduct the smoke around baffles or under ovens should also have cleanouts, so that accumulations of carbon chips and ashes can be removed from time to time. If possible, a cleanout should be located where several different interior surfaces can be reached for scraping.

Figure 15.16 - Simple cleanout door.

Figure 15.16 shows a simple cleanout with metal tabs folded out around the opening to hold a sliding door. A cleanout can also be left open to act as a spoiler when the fire is banked for the night, as described in Chapter 7.

DRAFT SYSTEMS.

It is no trouble at all to provide a wood stove with a draft system that will encourage a good hot fire; all that this requires is an opening of some kind near the coals. But controllability demands a system that can be shut down tight, and efficiency demands one that will encourage complete combustion of the smoke (meaning a double system, as described in Chapter 14).

A common mistake is to make the draft hole too large. A stove properly sized for its environment and connected to a stovepipe with a reasonable draft should only require full draft when the fire is being brought quickly to life. Most of the time the primary draft will be partially or fully closed, so tight seal is most important. Several types of draft controls are shown in Figure 15.17.

If the primary draft is located on the door, any leakage it may have can be stopped by a foil closure pad placed over the door opening when the fire is banked for the night. If the draft opening is to be below the door or to one side, it should be placed fairly close to the top of the ash bed, since its function is to maintain a robust bed of coals. In this portion it can oft2n be sealed with a layer of ashes from inside the st: ve.

In the hot-blast type of draft system, the air reaches the fire through a pipe which is either mounted on the outside of the stove or within the firebox (Figure 15.18). The pre-heated air does notcool the coals or the smoke as much as an unheated stream does, so efficiency of combustion is increased.

Figure 15.17 (left) - Types of draft controls. Figure 15.18 (below) - Hot-blast draft systems.

Figure 15.19 shows some secondary draft systems. In Drawing A the air pipe runs through the flame zone; the perforations can be concentrated on the main pipe or on the extension across the faceof the baffle, or else spread evenly along both. In Drawing B the pipe is lower, in the zone of the coals or underneath the ashes.

Secondary air passes through the pipe to a hollow baffle, and emerges through holes along the top. Drawing C shows a simpler system, consisting merely of a covered hole near the top of the baffle. Drawing D shows an opening like the ones found on certain airtight heaters. Sometimes you can look through this sort of opening and see the bluish flames that indicate complete combustion is taking place.

Figure 15.19 - Secondary draft systems.

Many secondary drafts are located so that the smoke burns off just before entering the flue. One might wonder whether the secondary draft is worth including, since most of the heat drawn from the smoke appears to go right up the chimney. Still, the alternative is to let the heat go up the flue anyway, bound as chemical energy in the unburned smoke. Secondary combustion results in at least a partial transfer of this energy to the room, and the rest will keep the chimney a bit warmer, discouraging creosote formation. The flue gases will also contain far less of the substances that form creosote in the first place.

The secondary draft can also be used to provide "maintenance" air to the fire, with the primary draft shut down tight. Primary air, directed at the coal bed (or even passing through it, in the case of grated stoves), is pretty well stripped of oxygen by the time it reaches the area of secondary combustion above the coals. But if the maintenance air enters through the secondary system, the region above the coals will be richer in oxygen, and combustion will be more complete. Depending on the layout of the stove, the fire may also tend to burn more evenly across the firebox, instead of burning out first in the region nearest the primary draft opening.

Theory aside, many simple stoves will have only one draft system. The opening should be placed somewhere between the coal bed and the top of the flame zone, so that the air can perform both primary and secondary functions. Place the draft in the lower portion of this range to encourage responsiveness, or toward the top to favor controllability.

HOT-AIR SYSTEMS.

One shortcoming of a wood-stove heating system is that warm air tends to rise and hang near the ceiling, while cooler air collects near the floor. This thermal stratification can be mild or severe, depending on the climate and the house. Cold air near the floor encourages mildew or even frost in places where circulation is impaired (under beds, behind couches), and is especially annoying if the household includes infants who like to play on the rug.

Many commercial wood stoves have places for electric blowers that circulate warmed air to break up this layering, and the same feature can be included in the designs of many homemade stoves. In addition, there are several ways to get the air to circulate by itself, merely by building some sort of air chamber into or onto the stove. Cool air enters the chamber near the bottom, and heated air rises through outlets near the top.

Several hot-air systems are illustrated in Figure 15.20.

Drawing A shows a simple metal enclosure more or less wrapped around the stove. It is open at the front, and additional openings can be provided at the sides and rear. This simple system, while not the most efficient, can easily be added to many existing stoves. My neighbor made one by wrapping oil-barrel metal around his bigairtight heater, and gained not only an air circulator but also a fence to guard his toddlers from burns.

Figure 15.20 - Hot-air heating systems.

Drawing B shows a chamber built into the back of a stove. (It could surround the sides as well.) Cool air enters the chamber through a series of openings at floor level. Drawing C shows the same system with an opening connected by piping to the crawl space beneath the house (or to a basement or room on the next lower level). In this case, the new air brought into the room from below must be balanced by air leaving through vents and through the stove, via the draft. Some say that leakage around doors and windows can be reversed by the use of this type of system; instead of cold air leaking in around a door, for example, warm air leaks out. There would be fewer cold drafts in the room, and it would be more comfortable.

Drawing D shows a similar system. Registers in the floor permit cool air to sink into the crawl space, making room for the rising warm air. The registers will be most effective if placed against outside walls or near doors, where the floor air is likely to be the coolest. This system is practical only if the crawl space is reasonably well sealed against the wind; otherwise, cold air may blow right up through the registers.

Drawing E shows the chamber connected by pipe to an adjacent room, storm shed or garage. The connection could conceivably be made to the great outdoors, in which case the pipe should be screened against insects and provided with a positive-seal damper for days when wind would interfere with proper operation.

There will be time's when the hot-air system should be shut off - for example, when the stove is fired up for cooking and the room is already warm enough. The chamber can be fitted with a hinged or removable cap to cover the top, or with movable flaps to cover the inlets.

Drawing F shows a simple hot-air system that can be incorporated into many designs with little additional work. Pipes used as legs extend through the stove at the corners. Air enters openings near the bottoms of the legs and emerges at the top of the stove through the open ends of the pipes.

Another way to increase the heat-transfer efficiency of a wood stove is to attach cooling fins to the sides. I used this system on my current stove, thereby increasing the surface area of the sides by 155%. An air chamber will also be more efficient if partitioned with a series of cooling fins.

HOT-WATER SYSTEMS.

Chapter 22 is devoted entirely to wood-stove hot-water systems. All that needs to be said here is that the design process should take into account the need to install either built-in hot-water reservoirs or firebox coils. Stove-top systems can be added at any time.

SHELVES.

Many stoves can be fitted with permanent or removable shelves - either at the same level as the stove top (Figures 16.8 and 17.6) or at a higher level, like the warming racks found on some commercial stoves.

LEGS.

Most of the homemade wood stoves I've seen don't have legs at all; they rest on various non-combustible supports or else stand directly on the stove pad. But the little oil-barrel stove in Figure 16.17 has legs scrounged from an old wood cookstove, and similar legs can easily be formed from sheet steel.

Figure 15.21 - A stove leg made from pipe.

My own preference is for legs made from pipe screwed into threaded couplings welded to the corners of the stove (Figure 15.21). Floor flanges at the lower end of the pipes provide nonscratch footings that can be screwed right to the floor. With this system, the pipe can be screwed into or out of the couplings and flanges to level the stove very accurately. Also, the legs can be removed when the stove is transported, or a shorter set can be installed in winter so that the stove will sit closer to the floor and break up the cold-air layer that forms there. I find that 1-inch pipe is entirely adequate for legs 12 inches long, and possibly longer.

FIREBRICK.

Many commercial wood stoves feature firebrick lining in the firebox. Since firebrick is a poor conductor of heat, the lining protects the metal from burning out, and also maintains the coals at a high temperature, thus helping to get new wood started and ensuring that the charcoal stays hot enough to burn to powder before going out. Firebrick can also be put into the firebox in the summertime to insulate the sides of the stove and raise a smaller fire close to the stove top, so that one can cook without heating up the house too much.

Stove manufacturers like to claim that the firebrick lining forms a kind of heat sink that continues to give off warmth even after the fire has died down. But if you do some calculating, it turns out that the amount of heat conserved is really not all that large. If I lined the lower half of my firebox with firebrick 2 inches thick and heated it to incipient red heat (1.000° F), the amount of heat held by the bricks would just about equal the amount held by 5 gallons of 200° F water on the stove top.

GRATES.

Wood ranges and many circulating heaters are fitted with cast-iron or stainless-steel grates to support the burning wood. Use of a grate permits the introduction of primary air below the coals, where it can do the most good. Curiously enough, I've never seen a homemade stove that employed a grate, probably because a fire on a grate is harder to bank than one which rests on ashes. In our climate, a stove has to be able to hold a fire overnight, and a grate would make that more difficult. Besides, a primary draft placed near, rather than under, the coals provides all the air the fire needs anyway.

Nevertheless, other builders with other needs and different ideas may well find use for a grate in their stoves. If you want a grate, it may be worth noting that environmental regulations have forced the shutdown of many foundries in the United States, so that cast-iron parts now commonly come from other countries, such as South Korea. Some of this cast iron is porous and inferior to the old American kind, so it may be better to hold out for a grate salvaged from an old stove than to buy a brand-new part. If you do choose to buy a new one, you should inquire as to the origin and quality of the iron before making a purchase.

ASH PANS AND ASH DOORS.

Stoves with grates generally require a pan, or at least an enclosure, below the grate to catch the ashes. The door through which the ashes are removed must be built carefully, since, if you want to bank the fire for the night, leakage at this point admits air at the worst possible place: beneath the coals. That's why I prefer to do away with grates, ash pans and ash doors entirely.

FASTENINGS.

Stove parts that are not held together by welding or by their own seams have to be secured with stove bolts or rivets. Stove bolts come in either flat- or round-head styles, and in standard sizes from 1/8 to 3/8-inch diameter. For metal light enough to be fabricated into a stove without welding, the 3/16 or 1/4-inch sizes are sufficient. I generally use a lock washer behind the nut for those places that are inaccessible after the stove is completed.

Once you get used to rivets, stove bolts seem gross and inelegant. A well-done riveting job certainly is less conspicuous than the same thing done with stove bolts. But if there is any doubt as to the kind of metal the rivet is made of - or more exactly, the metal's melting point - stove bolts are safer. I remember watching a friend's new stove slowly go to pieces as the rivets melted away and lost their grip, one by one.

In Chapter 13 we saw that a fine rivet can easily be made by cutting off the head of an ordinary nail retaining whatever length of shaft is required.

Pop rivets are also suitable for use on stoves where they will not be subjected to the direct heat of the coals. A pop rivet consists of a malleable head loosely mounted on a shaft (Figure 15.22). The pointed end of the shaft is placed in a special hand-held rivet gun and the other end is placed through the hole; when the lever on the gun is squeezed, the shaft pulls in, squashes the head, and then breaks off, leaving a neat, washer-like rivet head on the surface toward the gun (Figure 21.9).

A pop riveter is fast, and can be used from outside the stove without the need for holding a bucking dolly inside. Again, it is vital to use the right kind of rivet, since many are made of aluminum and simply will not stand up to the high temperatures produced in stoves.

Figure 15.22 - Pop rivets.

Sheet-metal screws are specially hardened so that they cut a thread in sheet metal without stripping their own threads. They are useful in making lightweight stoves and sheet-steel stovepipe, and also in connecting two or more joints of stovepipe together so that they won't separate.

BUDGET.

If you have limited stock available for completion of your project, it pays to make a scale diagram showing the amount of material available and the way it can be cut to yield the needed parts with a minimum of waste. For example, the Three-Way Stove was constructed from a single oil drum, and it would have been most unwise to begin cutting without first preparing a complete cutting diagram, as shown in Figure 13.6.

FLOW CHART.

Finally, take time to work out a flow chart showing all of the major phases of the project in sequence. Many operations can be done in interchangeable order, but some will interfere with other steps if done too soon. This is particularly true of welded stoves, where certain internal welds are more easily accomplished if one side or the top or bottom is left till last; but the same thing applies to almost any stove. In the Three-Way Stove, it would have been difficult to mount the stovepipe and stokehole collars after the top and bottom of the stove had been assembled.

Chapter 16

Oil-Barrel Stoves

In Chapter 13 I discussed one possible way of making a stove from a castoff oil barrel, and indicated that there were dozens more. In this chapter we'll take a look at a number of other designs. Any of these stoves can be made from the standard 55-gallon drum or from the smaller 30-gallon type. Remember that the older 55-gallon drums (identifiable by their large, round rims) are made of metal considerably thicker than that of the newer, square-rimmed variety and are a good deal harder to work. Reread the section on page 90 about flushing out explosive fuels, especially if you contemplate doing any cutting with an oxyacetylene torch. It may also be useful to review some of the other techniques discussed in Chapter 13, especially on the use of reference lines (Step 1), opening a drum (Step 2), and forming collars (Steps 7 and 8).

In this chapter and in those to follow, there are photographs or drawings of almost every type of homemade stove discussed. As indicated in Chapter 12, the precise dimensions and details of homemade stoves depend so much on personal taste that I will have to omit them. I trust that the stove builder will fill in the blanks when the time comes.

Many of the oil-barrel stoves illustrated in this chapter feature baffles, for reasons outlined elsewhere. Installation of a baffle may involve removing the end of the drum and then replacing it, so let's go over a few ways of doing this before we begin our discussion of individual stoves.

First of all, decide which end of the drum to cut off - the solid one or the one with the bung openings. For horizontal stoves, the large bung makes a handy opening for the primary draft, especially since it is threaded to accept standard pipe. This suggests removing the solid end. On vertical designs, however, I prefer to have the barrel upside down, so that the solid end becomes the stove top. Consequently, I would remove the end with the bung openings. The seam would be near the floor, which would eliminate any possibility of smoke leakage.

Figure 16.1, Drawing A, shows the simplest way of reattaching the end of the drum. A cut is made so that 2 to 3 inches of metal remain with the end. This metal is pounded and stretched enough to fit over the main part of the drum like a cap, and then fastened in place. This method is suitable for use even when the barrel has been opened with a crude tool, since the metal can be pounded as much as necessary to complete the fit.

Drawing B shows a somewhat neater method, suitable for use when the barrel is opened cleanly with a power saw or, if you have the patience, with a hacksaw blade. First, a backing strip is attached to either section of the drum. The two halves are then rejoined, with the barrel seam lined up, and the second half is fastened to the backing strip with rivets. A small section of the drum makes an ideal backing strip, since it already has the proper curvature.

Either of these methods can also be used to shorten a drum for two-thirds- and one-third-barrel stoves. Figure 16.1,

Drawing C, shows another way. The drum is cut just beneath one of the ribs, and cut again right next to the rim. The rib is folded out far enough to accept the bottom of the drum, and then clinched over again.

Drawing D shows a somewhat similar method. Here the folded-out rib grasps a flange folded over on the other portion of the stove body.

Figure 16.1 {above and below) - How to open and reseal a drum for installation of internal parts.

Drawing E in Figure 16.1 shows a way of making the entire stove top from flattened barrel metal. The drum is cut along the crest of a rib, the metal is folded outward to form a flange, and the new top is installed using a flanged seam. The body can also be cut at some other point than the crest of a rib, and a flange formed by bending the side of the stove outward. Thus the technique can also be used to replace a burned-out top. This kind of top, being rimless, may be able to accommodate a few more kettles and pots than the original barrel end, since they can stick over the edge a bit.

And now, on to the stoves:

WHOLE-BARREL STOVE, HORIZONTAL.

The most elementary oil-barrel stove I ever saw was a drum with a stokehole punched in one end and a stovepipe port cut at the top near the other. The crude horizontal heater needed no legs, since it sat right on the sand floor of a sod hut. I used it for a time, and found that it threw out plenty of heat - though control was definitely a problem.

The next-easiest horizontal whole-barrel stove to build is one made with a commercial kit (Figure 16.2). The same result can beachieved from scratch by using a homemade door, draft system, legs and stovepipe collar.

Figure 16.2 - Horizontal whole-barrel stove made with a barrel-stove kit from Fatsco. Note how a No. 10 can fits perfectly over the stovepipe collar at the rear. Made by Howard Kanther.

Figure 16.3 shows two types of baffles suitable for use in horizontal drum stoves. The handiest material for making them might be the top of another drum of the same size. A baffle shortens the firebox somewhat, making it necessary to cut shorter firewood, but the increased efficiency makes the effort worthwhile.

WHOLE-BARREL STOVE, VERTICAL.

An oil barrel placed in an upright position provides just as much stove as a horizontal drum, but takes up a lot less space. The stovepipe collar can be placed either on the top or on the side of the drum, although a topmount in an unbaffled stove may allow the hot gases to escape up the stovepipe without giving up much heat to the room. In that case, a heat exchanger or stovepipe oven in the pipe will help quite a bit.

Figure 16.3 - Baffles for horizontal drum stoves.

Figure 16.4 shows the vertical drum heater in our local church. The elbow is placed well down the side because a heavy cast-iron plate has been mounted inside as a baffle. Drawing A in Figure 16.5 shows a cross-sectional diagram of this stove, and Drawings B through F show other possible baffle arrangements. Figure 16.6 shows a stove that uses the baffle system shown in Drawing B.

TWO-THIRDS-BARREL STOVE, VERTICAL.

A wood stove made from a whole barrel may be more appropriate for a shop, church, meeting hall, schoolhouse or barn than for a dwelling. A two-thirds-barrel stove, on the other hand, gets down to family scale and fits nicely into a cabin of moderate size.

Since the drum has to be cut open anyway, when removing a third of it, there is no reason whatever to build this kind of stove without a baffle. Most of the baffling systems shown in Figure 16.5 work in these smaller stoves also.

Figure 16.4 (left) - Vertical whole-barrel stove. The stovepipe collar is located well down one side of the stove because there is a baffle inside the firebox. Made by Tommy Douglas.

Figure 16.5 - Various baffle arrangements for vertical drum stoves.

Figure 16.6 - Vertical whole-barrel stove with the baffle arrangement shown in 16.5, Drawing B.

TWO-THIRDS-BARREL STOVE, VERTICAL, WITH OVEN.

This type of stove is very popular in our area, and for good reason: It is good for cooking, heating and baking. It also gets good marks for efficiency, due to the long smoke path. Two examples are shown in Figures 16.7 and 16.8. Although a good deal different in detail and construction, both stoves are laid out according to the same basic plan, as illustrated in Figure 16.9.

Figure 16.7 (left) - Vertical two-thirds-barrel stove, with oven. The firebox is in the upper half, the oven below. Made by Isaac Douglas.

Figure 16.8 (right) - Another vertical two-thirds-barrel stove, with oven. Made by Oliver Cameron.

The firebox is in the upper chamber. Smoke passes over the baffle, down around and under the oven, and finally up along the other side of the oven before reaching the stovepipe. The firebox floor and the top of the oven atffe one and the same; the depth of the ash layer determines how much heat reaches the oven from above.

Constructing this type of stove requires two drums. I am told that in the stove shown in Figure 16.7, the entire baffle and oven assembly can be prefabricated and then slipped into the stove from one end. (This may require some tamping with a pole.) In the stove shown in Figure 16.8, the oven is made separately and slipped into the stove from the front.

Figure 16.9 - Cross section of a two-thirds-barrel stove, with oven.

Since a stove like this has a long and somewhat unnatural smoke path, it should be connected to a stovepipe with a good draft so that smoke won't pour out of the stokehole door every time the fire is fed. I recommend using pipe not less than 6 inches in diameter.

A two-thirds-barrel vertical stove can also be made square, like the Three-Way Stove. This may simplify installation of an oven or some other special feature, but otherwise there seems to be little reason for doing the additional work.

TWO-THIRDS-BARREL STOVE, HORIZONTAL, ROUND.

Any of the horizontal whole-barrel stoves described earlier can be shortened to make it fit more easily into a smaller dwelling. Figure 16.10 shows a fireplace built on this principle, offered by Washington Stove Works.

Figure 16.10 - The Drummer, a freestanding fireplace by Washington Stove Works. A round two-thirds-barrel stove could be made on the same pattern. The company will sell legs, stovepipe collar and feeder door separately.

TWO-THIRDS-BARREL STOVE, HORIZONTAL, SQUARED.

Figure 16.11 shows an entirely different way of forming a stove from two-thirds of a barrel. The body is squared asin the Three-Way Stove, but the barrel is rotated so that the openings are at the ends rather than at the top and bottom. The end panels are installed using inset seaming (see Figure 15.3).

Figure 16.11 - How to form a squared, horizontal two-thirds-barrel stove.

Figure 16.12 shows an old stove constructed on this principle. In this case, the builder reduced the size of the stove by slitting the two-thirds barrel lengthwise, removing a strip of metal, andresealing with a flanged seam (visible at the front of the stove top).

Figure 16.13 shows a cross-section of this type of stove. Drawing A shows how the baffle confines the fire so that the smokeway under the oven doesn't get plugged with ashes and charcoal. Drawing B shows a simple smoke flap that allows the user to proportion the amount of smoke going directly to the flue to the amount traveling around and under the oven.

Figure 16.12 - Squared two-thirds-barrel camp stove, with oven. Made by Nelson Griest.

Figure 16.13-barrel stove.

If the oven is omitted, the baffle can be placed closer to the stovepipe port, giving a larger firebox. The door can also be shifted to the end of the stove, as shown in Figure 16.14. (Note the slanting baffle, designed as a spark trap.)

Figure 16.14 - Cross-section of another type of squared, horizontal two-thirds-barrel stove.

ONE-THIRD-BARREL STOVE.

The Three Way Stove was made from one-third of a barrel, squared up in such a way that the body was open at top and bottom. Figure 16.15 shows another one-third-barrel stove squared in such a way that the body is more elongated. The stokehole is at the end, and the baffle arrangementis like that shown in Figure 16.14. This little stove is good for cooking and is small enough to take camping.

Figure 16.15 - Squared one-third-barrel stove. Note tin-can damper in pipe, and small area of pipe retaining original galvanized luster just above the damper slit. Made by Oliver Cameron.

Figure 16.16 - Cross-section of a simple round one-third-barrel stove.

A somewhat quicker stove can be made by simply leaving the one-third-barrel in the round, as shown in Figure 16.16. If the draft is placed in the stokehole cover and the baffle stops short of the bottom, the result will be a Two-Way Stove that can be used with either end up. If there is no need to turn the stove over, the draft can be located around the stove body from the door, opposite the stovepipe port. This gives the longest airflow through the stove. Figure 16.17 shows a one-third-barrel stove fitted with three legs taken from an old wood cookstove.

Figure 16.17 (left) - Round one-third-barrel stove, with legs. Made by George Melton.

Figure 16.18 (right) - Oval one-third-barrel camp stove (note carrying handle at rear top edge of stove top). Made by Arthur Skin.

Figure 16.18 shows yet another type of one-third-barrel stove. Here the builder has formed the body into an oval shape to increase the length of the firebox. The carrying handle near the rear shows that this is a portable model intended for camping.

A particularly compact one-third-barrel stove is shown in Figure 16.19. Drawing A illustrates how the stove body is cut from the drum; the original curved surfaces are retained, still attached to the bottom of the drum, at front and back. The long sides are fashioned from straightened barrel metal still attached to one of the curved stove surfaces. This eliminates the need to fasten two of the four vertical seams, as shown in Drawing B. Note that since the long sides now follow a straight line instead of the original barrel curvature, they reach the curved end of the stove with enough extra length to form flaps for attachment.

Figure 16.19 - Avery compact, modified one-third-barrel stove.

Drawing C shows how the barrel end is cut, leaving flaps that are folded up to seal the joint between the stove bottom and the sides. The basic body is completed by fashioning a top from the other two-thirds of the barrel, and fastening it to a flange formed from the original rib that circles the barrel one-third of the way from the bottom. Such details as the door, baffle and stovepipe collar can be handled in many different ways, depending on the builder's preference.

HALF-CYLINDER STOVES.

Another fairly simple stove can be made by splitting a drum in half lengthwise and making the body from one half, the stove top from the other. Figure 16.20 shows such a stove, made from a full-length barrel. Note that the large bung opening can be left at the bottom of the front panel to form the draft. The large, flat top will be hot enough for cooking, especially if a baffle is installed as shown. A large washtub will fit nicely on the stove top on laundry day.

Figure 16.20 - Full-length half-cylinder barrel stove.

This same design can be used with two-thirds of a barrel, or the barrel can be split in some other way than straight down the middle. Figure 16.21 shows a stove of much fuller cut, made from a 30-gallondrum.

Figure 16.21 - Flat-topped horizontal 30-gallon-drum stove. Collection of Pete MacManus.

Figure 16.22-Stove built around a salvaged cast-iron stove top. The old top was shoner than the barrel, so the builder added an oven at the back.

The drum can also be cut to fit a cast-iron stove top, even if the top is shorter than the drum. Figure 16.22 shows a stove built around a salvaged stove tc p that is only about two-thirds as long as the drum itself. In the remaining third of the barrel the builder has installed an oven, separated from the firebox by a perforated baffle. A second baffle, with a hole at the bottom, surrounds the oven. Smoke flow to the oven is controlled by the damper in the pipe which comes out of the cast-iron stove top.

A stove of similar shape is shown in Figure 16.23. Here the builder formed a one-piece stove top and vertical riser out of heavy sheet steel. When the original 30-gallon drum burns out, the stove top can easily be mounted on a fresh one.

Before leaving oil-barrel stoves, we should consider units in which the barrel serves only as a source of steel. Figure 16.24 shows a small tent stove made from welded plates of flattened oil-barrel steel. My impression is that the flattening process produces stresses in the metal which cause it to buckle when it is heated up for welding. My own inclination is to form oil-barrel stoves with as few welded seams as possible, and to save the acetylene for use with proper sheet steel. We'll dig into sheet-metal stoves in the next chapter.

Figure 16.23 - Full-cut semi-cylinder whole-barrel stove with steel-plate stove top. Note the double-door stovepipe oven and the inclined hot-blast tube draft. Made by Shorty Schmidt for Jack Hebert.

Figure 16.24 - Tent stove with oven, consisting of plates of oil-barrel steel welded together. The lever at the upper left-hand corner of the front panel controls the smoke by-pass that sends smoke either over or under the oven. Made by Don Bucknell.

Chapter 17

Sheet-Metal Stoves

We've just seen that many different kinds of stoves can be built from oil barrels, even though the metal is curved and ribbed and only comes in a few sizes and gauges. By drawing on other sources of sheet steel, the stove designer frees him- or herself to think in entirely new ways and to create stoves that are impractical or impossible to build from oil drums.

But like many another liberty, the freedom from dimension or shape restrictions puts a burden on the builder. By virtue of that very freedom, the designer is forced to make additional decisions, which in turn demand a rationale. That's why I find it so interesting to study homemade sheet-steel stoves. They always express something of the builder's personality and way of thinking.

Figure 17.1 - Lightweight camp stove made of galvanized stovepipe by Oliver Cameron.

As an example, consider the little stove in Figure 17.1. In this case, the bu:lder wanted a stove that would be large enough to cook a meal and heat a small tent in weather well below freezing, and yet light enough to be carried in a simple camping outfit pulled on a small sled by one dog. He took two sections of heavy-gauge galvanized stovepipe, joined them together by their self-locking seams to form a single tube, squared the tube to form the stove body, and then installed end panels made from the same gauge metal (Figure 17.2).

Figure 17.2 - Forming Oliver Cameron's stovepipe stove body. Two sections of stovepipe are snapped together to form a single tube and then squared. End panels are installed using inset seams (see Figure 15.3).

Figure 17.3 shows a stove made in a regular sheet-metal shop for the retail trade. The builder used a commercial cast-iron stove top and feeder door (thus side-stepping all the really demanding design decisions and construction steps) and then fabricated the simple, rounded body and the legs from flat stock. The rationale in this case was to turn out a stove with a minimum of labor in a way that would make maximum use of the metal-working equipment and skills available in the shop.

Closer to home, I've already described the tough time I had with a certain cast-iron box stove one winter near Fairbanks. Prodded as much by necessity as by interest - and unable to find a commercial stove that was good for both cooking and heating - I sat down to design my own Ideal Stove.

Figure 17.3 (/e/t) - Sheet-steel stove with cast-iron stove top and feeder door. Collection of Pete MacManus.

Figure 17.4 (right) - The Ideal Stove. The lever on the left side of the front panel controls the smoke flap. Made by A. J. Klistoff Sr., from a design by the author.

The result is shown in Figure 17.4. This stove has a unique baffling system (Figure 17.5) that ensures good cooking temperatures and encourages heat-transfer efficiency without shortening the firebox. The smoke flap serves another function besides by-passing the baffling: When I place it in the open position and rap on the stovepipe, the dislodged carbon chips fall onto the flap and slide back into the firebox for disposal.

The Ideal Stove gave us four winters of very good service, and we still use it at spring camp every year When we built the new cabin, I designed a new stove that is basically the same, except that it is larger and heavier and has cooling fins on the sides and a removable shelf at the back (Figure 17.6). With even less modesty, I dubbed this one the Super Yukon - a name that should be reasonably appropriate once I remove the inefficient draft slider and replace it with primary and secondary drafts.

Figure 17.7 shows the result of another individual's search for an ultimate stove. This one was made by Larry Gay, author of The Complete Book of Heating with Wood (excellent reading, by the way). The stove is patterned after the famous Jotul No. 118, except that it is bigger and cheaper and is made of welded steel rather than cast iron.

It features a hollow door, which serves as a preheating chamber for the incoming air, and independent controls for primary and secondary drafts. Recognizing that this stove fills a blank spot in the wood-stove market, Mr. Gay has gone into commercial production (see the list of manufacturers in the Appendix).

Figure 17.5 (above) - Cross-section of the Ideal Stove. Smoke passes over vertical baffle, down through notches in horizontal baffle, toward rear of stove and up through stovepipe collar. When door is opened for refueling, a lever is turned to open flap so that smoke goes directly up the flue.

Figure 17.6 - The Super Yukon, featuring the baffling system shown in Figure 17.5. Note also the heavy square stovepipe oven. Made by A. J. Klistoff Sr., from a design by the author.

Figure 17.7 - Larry Gay's stove, patterned after the J0tul No. 118 and now available commercially.

One trouble with building a really good wood stove is that it lasts too long. A true stove tinkerer always has another design just over the horizon, and often the new stove has to wait until the old one starts showing its age. Figure 17.8 shows the next major stove I hope to build, when old Super Yukon finally gives up the ghost.

Figure 17.8 - Hypothetical Dual-Fire Range.

This Dual-Fire Range has a welded steel body dimensioned to fit a commercial cast-iron stove top (hopefully salvaged). Its most unusual feature is that it has two fireboxes: a large one for heavy-duty heating, and a smaller one for baking and for summertime use. (It can be hot above the Arctic Circle in the summer months.) If the two fires are burning at the same time, the smoke from the lower firebox will be completely consumed in passing through the fire in the upper one.

It will be possible to transfer charred wood (with most of the volatiles gone) to the upper firebox with the tongs just before refilling the lower one, and so to have a nearly smokeless fire. Each firebox is fitted with primary and secondary drafts, the secondary draft for the lower firebox doubling as the primary draft for the upper one. A hot-air system draws cool air from floor level.

Sheet steel is such a supremely versatile medium that an almost endless variety of stoves can be fashioned from it. I wish I could offer more examples, but this is not sheet-steel country up here. If you have a design, I'd be glad to hear from you.

Chapter 18

Tin-Can Stoves and Emergency Stoves

TIN-CAN STOVES.

Like castoff oil drums, large tin cans may be fashioned into quite acceptable stoves. They are usually free for the asking, extremely light, and so easy to work that a child can make a stove from one.

Take the stove in Figure 18.1 as an example: Seth Kanther was ten years old when he made it. His family depended on the littleheater when they camped in the Brooks Range one snowy April. Seth's dad told me that the stove was "a little slow at boiling water for coffee," but otherwise worked very well.

Figure 18.1 - Seth Kanther, age 10, with the stove he built from a 5-gallon can.

Figure 18.2 shows a horizontal stove formed from a square 5-gallon can, with a smaller can in the bung opening for the draft system and an old pot lid in the stove top for the stokehole door. The stovepipe is made of metal from the same kind of can, as described in Chapter 21.

Figure 18.2 (left) - Simple 5-gallon-can stove. Note the homemade pipe. The draft is in the bung opening. Made by Oliver Cameron.

Figure 18.3 (right) - Simple 5-gallon stove that doubles as a smudge to keep bugs away. Collection of Pete MacManus.

In Figure 18.3 we see a little round stove of the most basic form, consisting of firebox, door and flue. The twist latch attached by a bent nail, the leaky door, and the carrying handle at the top suggest that the little unit was built quickly. No doubt it doubled as a smudge to keep the mosquitoes away from people working outside or to keep flies away from the fish on the drying racks.

Figure 18.4 shows a more carefully made version of the same sort of stove. This time the feed door is in the top, and there is a sealable draft located opposite the stovepipe collar. Emptied of ashes and rinsed with river water, the stove doubles as a bucket for carrying odds and ends down to the boat and on to the next camp.

One spring I made a somewhat larger stove from an old military storage can (Figure 18.5). The original can had two ribs on it, like an oil drum. I cut off the upper third of the can at the rib, installed a baffle, sealed the stove by attaching the lid to the rib (just as it had been attached to the original rim), and turned the works upside down so that the airtight bottom of the can became the top of the stove.

This stove heated the tent, kettle and many pots of marrow bones, and kept us comfortable in spite of a constant north wind that shook the tent and kept the pipe ring in perpetual motion up and down the stovepipe. Unfortunately, it disappeared under mysterious circumstances the following summer, so I got another can of the same type and made a new stove for our next spring camp.

Figure 18.4 - Vertical 5-gallon-can heater. Made by Oliver Cameron.

Figure 18.5 - Vertical camp stove made from a 25-gallon storage can. The baffle is the type shown in Figure 16.5, Drawing A. Made by the author.

This time I used the whole can, placed horizontally, and fashioned a flat top that extended back to a stovepipe gallery (Figure 18.6). With this shape, I was able to mount a baffle that didn't shorten the firebox at all, and yet forced the flames to lick theback of the stove before exiting through the stovepipe (Figure 18.7, Drawing A). The entire stove was fastened with pop rivets; in especially hot locations, they were protected from direct contact with the flames by special flaps of metal (Figure 18.7, Drawing B).

Fiqure 18.6 - Horizontal stove made from a 25-gallon storage can, with a flat top that extends back to a stovepipe gallery. Made by the author.

Figure 18.7 - Cross-section of the stove in Figure 18.6, showing the horizontal baffle and pop rivets protected from direct contact with the flames by a simple fold of metal.

Since this stove was to be carried on the dog sled with the rest of our snow-camping outfit, I made a tapered, nesting stovepipe for it. Using old 5-inch stovepipe sections that were sound except for the seams (which I cut off), I made the first joint 4 inches in diameter at the bottom and 4-1/3 inches at the top. The next joint tapered from 4-1/3 to 4-2/3 inches, and the next from 4-2/3 to 5 inches. Two lengths of standard 5-inch pipe completed the setup. (All of the custom-made joints were fashioned according to the method described in Chapter 21.)

When not in use, the three custom joints of stovepipe nested one inside the other, and the set, in turn, fit inside one of the 5-inch lengths. That bundle, plus the other 5-inch length, can be stored inside the firebox, along with a poker fashioned from the handle of an old bucket, a set of legs made from old corrugated iron roofing, a damper made from a piece of tin can metal, and a piece of aluminum foil for setting an overnight fire. Like all of the stoves in this chapter, I like to think of it as a fairly nice example of doing more with less.

EMERGENCY STOVES.

The word "emergency" may be too strong. I mean to describe a few stoves that people put together on the spur of the moment, from whatever materials were at hand. Perhaps they had been stranded without a stove under weather conditions that made some sort of heating system necessary, or maybe they had just decided to brew up a quick mug of tea.

One blustery day, just before freeze up, Manya and I were kayaking downriver to our ukiuvik (wintering place), when we came upon an Eskimo hunting camp. More than ready for a warmup, we accepted the invitation waved from shore, nosed the kayak in beside the other boats, and went up to the small tent. Smoke was billowing out of its open flaps, and the kettle was heating on the simplest stove I'd ever seen.

One of the hunters had taken an empty 5-gallon can and simply cut two holes in it with his knife: a large one in one side (the stove top) that was just a shade smaller than the kettle, and a small one in the upper part of one end to serve as a smoke exit (Figure 18.8). The bung opening, in the lower part of the other end, served as the draft hole. To load the stove, his wife simply lifted the kettle, stuffed dry grass into the "firebox," and put the kettle back in place.

Figure 18.8 - The simplest stove I've ever seen.

Then there was the time the local pilot flew over to the hot springs, neglecting to take a stove. In spite of the warm water and the almost continual spring daylight, evenings in the tent were uncomfortably cool. So he cut a door opening in one end of a 5-gallon can and attached a stovepipe made from a series of tin cans, one on top of another (Figure 18.9). Simple as it was, the little stove took the chill off the tent very nicely, making it much easier to leave the springs after a good soak.

Figure 18.9 - A tin-can emergency stove with a tin-can pipe. Designed by Dan Denslow and Tommy Lee.

Another stove, that Manya noticed in the village, speaks of an ocean storm that pinned a family down in a hasty camp on the Arctic Coast. Faced with the prospect of several days of discomfort, the craftsman sacrificed one of his 6 gallon portable outboard fuel tanks in order to make a tent heater that would make use of the tangled skeins of driftwood lining the beach (Figure 18.10). The stokehole has a proper collar, cover and draft system, and the far end is fitted with a stovepipe collar. Because of its durability and handy flat cooking top, this little stove outlived the emergency and became a prized all-around boating stove.

Figure 18.10 - Camp stove made from an outboard fuel tank. The handle came off the tank, and the stoke-hole cover was once the reservoir of a gasoline lantern. Made by Nelson Griest.

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Chapter 19

Coking Stoves

A coking or downdraft stove is one in which the smoke must pass through the coals before reaching the flue. The high temperature of the coal bed encourages complete combustion, thus making available the 50 percent or so of the wood's energy that can (and often does) pass out through the chimney in the form of smoke. New fuel is first coked (distilled), and then gradually settles down into the zone of active combustion to provide heat for the next charge. Properly operating, such a stove should be smokeless and free of creosote.

The main challenge in building a coking stove is to get the smoke to go downward rather than upward. Larry Gay, in The Complete Book of Heating with Wood, gives an interesting account of how Benjamin Franklin conceived, designed and successfully operated a downdraft stove. Franklin stressed the necessity of connecting his creation to a chimney with a strong draft, and the same requirement holds for any downdraft stove we might build. Today, a builder may be able to compensate for insufficient draft by installing a small booster fan in the stovepipe.

A downdraft stove consists of an inner wood magazine (or coking oven) where the wood is distilled, and an outer box through which the flames and hot gases travel on the way to the flue. Complete combustion occurs near the junction of the inner and outer chambers, and it is here that secondary air should be introduced. When the unit is operating in the downdraft mode, primary air enters the coking oven and travels down toward the coal bed, carrying the smoke and distillation products with it.

As this mixture passes through the coals, the oxygen is consumed in maintaining the fire, while the volatiles are either burned, broken down into simpler compounds, or simply heated. Any flammable substances that manage to leave the coal bed are immediately consumed in the secondary combustion process, providing heat to continue the wood volatilization and to warm the room.

Larry Gay writes that "true downdraft stoves and furnaces have appeared on the American market from time to time, but none has survived because of the same difficulties that Franklin experienced" - chiefly inadequate draft, which allowed smoke to puff into the room when the feed door was opened. Perhaps the reason these units failed the test of the marketplace is that too few people were willing to maintain a stove that required understanding, skill and determination to operate. In our present era of fuel shortages, however, we may expect renewed interest in efficiency and economy, and downdraft stoves may find increasing favor. Very likely much of the developmental work will have to be done by amateur stove builders. ?

Figure 19.1 - Ted Ledger's two-barrel coking stove. For proper operation, all seams and the ash and feed doors must he airtight, so that the fire can get air only through the primary draft. The sand on top of the stove seals the feed door (the fit should be checked each time the fire is stoked).

The only information I have been able to find on homemade coking stoves is one article in the May, 1974 issue of Alternative Sources of Energy. The author, Ted Ledger, gives a simple design for constructing a downdraft stove from two drums, one inside the other (Figure 19.1). Like all downdraft stoves, it operates in the updraft mode at first, with primary air admitted through the ash door. When the coal bed is established and the stove and flue are warm enough to provide adequate draft, the ash door is closed and the unit switches over to the downdraft mode.

Mr. Ledger has been kind enough to provide me with a description of another coking stove, which he built a number of years ago. He had seen a drawing of a commercial stove in a Swedish technical publication some years previously, and built his own version from memory (Figure 19.2). The heater, as it turned out, was so powerful that it was not suitable for use in the small cabin for which it was built.

Figure 19.2 - Another type of coking stove by Ted Ledger. The triangular stiffener doubles as a heat exchanger.

This brings up another characteristic of downdraft stoves. Complete combustion means live flames, and live flames mean fairly high temperatures. A stove that is getting nearly all the energy out of the wood is going to be a potent heater. It stands to reason that such a stove should be somewhat smaller than a less efficient unit.

Figure 19.3 - Author's hypothetical coking stove designed with a tall coking chamber and a small active flame zone.

My inclination would be to try a stove with a tall coking chamber and a small active flame zone, as shown in Figure 19.3. In this design, the coking chamber is open only at the front edge, facing the ash door. The accumulated ashes in the fuel magazine will naturally slope toward this opening, and consequently the coals will always tend to roll down to the place where they will do the most good.

The size of the flame way is adjustable, merely by varying the quantity of ashes left in the bottom of the stove. Note that the primary air enters through a control on the side, so that the air travels more sideways than downward. Secondary air enters through a hot-blast perforated pipe along the upper edge of the flame way, where it will no doubt perform some primary draft function as well, keeping the charcoal bed glowing.

While we're thinking about complete combustion, we should perhaps consider other ways of burning the smoke besides forcing it to go down through the coals. Larry Gay mentions another Benjamin Franklin invention - the rotary grate. After wood was added, this grate was closed and turned over, so that the coals rested on top of the fresh wood. The smoke rose upward and passed through the coals, where it was completely consumed. On a much smaller scale, it is possible in some stoves to shove the coals to one side of the firebox, lay a stick of new wood on the ashes, and cover it over again with the active coals. Try it once for a very convincing demonstration of smokeless, complete combustion.

Another approach to the coking problem is to have an entirely separate coking compartment for the new wood, connected by pipe to the main firebox { Figure 19.4). The idea is that the heat of the main fire will distill the wood in the coking chamber, and thatthe combustible distillation products will enter the firebox underneath the coals. The stove always operates in the standard updraft fashion, whether or not the coking feature is in use.

Figure 19.4 - Hypothetical charcoal-burning, smokeless, complete combustion updraft stove with separate firebox and coking oven.

Unfortunately, the wood must be handled twice - once to stoke the coking chamber, and again to transfer the devolatilized fuel to the main firebox. But this could be accomplished fairly easily with a pair of sturdy tongs, especially if the feed doors were placed close together. The extra effort would be paid for in increased efficiency and fuel savings.

With this brief description of coking stoves, I turn it over to you. If you are thinking of building one, know that you are in the vanguard of wood-stove research. If you have already built one, I'd certainly be interested in knowing what it's like and how it has worked for you.

Chapter 20

Stove-Top and Stovepipe Ovens

STOVE-TOP OVENS.

When Manya and I first set up housekeeping, our "house" was a 7- by 9-foot wall tent on the bank of a river. During that summer we slowly accumulated materials from the forest for building our cabin. In August, when the blueberries ripened, we'd spend some time every day up on the tundra gathering the fruit, and then bake something special when we got back to camp.

Our outfit was pretty slim, so Manya's first stove-top oven was nothing more than a 5-gallon kerosene can with one side cut out (Figure 20.1). She'd set the baking pan on a metal stand or "lifter"

Figure 20.1 - A simple tin-can stove-top oven.

(made of metal from another can) in order to get it up into the hottest air and also to keep the bottom from burning. I also made a heat spreader out of the panel cut from the side of the can that became the oven. The spreader went on top of the lifter when Manya used the oven on the wood stove, and underneath the lifter when she used it on the gasoline camp stove.

The next-generation stove-top oven was built on the same pattern, except that it consisted of two cans - one inside the other (Figure 20.2). The outer can is just the same as the can in the original design, except that a little extra metal remains around the opening to form retaining flaps for the lining.

The inner can is cut across all four upper corners and pinched along the edges in order to make it small enough to slide inside the outer can. It is then covered with a layer of fiberglass or asbestos insulation, slipped in place, and secured with the retaining flaps of the outer can. The resulting oven has a shade less capacity than the single-can model, but it bakes more quickly and more evenly due to the insulation (Figure 20.3).

Figure 20.2 - Oat crunch toasting under an insulated double-walled 5-gallon-can stove-top oven. Designed by Dan Denslow and made by the author.

A third-generation stove-top oven undoubtedly would have been made of light-gauge sheet metal, with insulated walls and perhaps a door and shelves. But I never got that far - I was sidetracked by stovepipe ovens.

STOVEPIPE OVENS.

The great advantage of a stovepipe oven is that one can be added to almost any existing stove; the only requirement is that there be enough physical space (clearance from the wall, and vertical distance between the stovepipe collar and the chimney inlet or ceiling). It is tempting to add that a stovepipe oven operates entirely on waste heat, but this may not be the case. Wefind it necessary to build a special baking fire that sends much more heat up the stovepipe than we would otherwise tolerate.

Figure 20.3 - Construction of the double-walled insulated tin-can stove-top oven.

Most stovepipe ovens are similar in construction to the one shown in Figure 20.4. The round oven chamber is encased in a larger round shell, with a smokeway between the walls. The back of the oven chamber may touch the back of the outer shell, or there may be a space between them for the passage of smoke. For versatility, the shelving is made in such a way that the oven can be used with either end up.

Figure 20.4 - Typical stovepipe oven. Note that the shelf can be turned upside down if the oven should be inverted in the next installation. Collection of Pete MacManus.

Figure 16.23 shows a homemade unit that differs from most in having a door at either end. When both doors are open, the oven functions as an efficient heat exchanger.

The raw materials for making a simple round stovepipe oven of this type are two cans of appropriate sizes, and metal for making the door, hinge, latch, shelving and collars. Most of the critical dimensions will be determined by the sizes of the cans. The most important measurement is the annular space (smokeway) between the walls. If the space is too big, the oven may not heat well; if it is too small, the smokeway may soot up quickly, impairing the draft and creating the possibility of stack fires. (I notice that the Louisville Tin & Stove Company unit uses a 1-1/2-inch annular spacing. This gives a smokeway with an area about one and a half times the cross-sectional area of the stovepipe - a useful rule of thumb.)

I have never been able to locate two cans of the right relative diameters to make a round stovepipe oven, so I designed one requiring only flat stock (set? Figure 17.6). In this unit the incoming smoke is deflected by a flame spreader and then passes around and behind the oven chamber.

Figure 20.5 - Welded plate octagonal stovepipe oven. This shape should solve the problem of accumulation of carbon chips on flat-plate surfaces.

I made two critical mistakes in designing this oven, and both of them relate to the creosote problem. First, the annular space of 1 inch that I allowed is simply too small, and poor draft is a chronic problem. Secondly, dislodged carbon chips collect on the flat surfaces, blocking the draft even further. Eventually, the draft is so weak that it isn't even possible to get the oven hot enough to start a stack fire to burn off the clogging debris, and then the back of the oven has to be removed and all the accumulated junk laboriously scraped out - a 45-minute job.

Still, I like the idea of a welded, flat-plate stovepipe oven, because heavy steel lasts longer and heats more evenly than tin cans do. Next time I'll make the unit in an octagonal shape, with the lower portion designed in such a way that stovepipe debris can funnel back down into the stove (Figure 20.5). There will also be an internal cleaning device that will eliminate the need for a removable back (with its potential for dripping creosote) and manual scraping. Believe me, scraping soot from a stovepipe oven gets tiresome after the first few times.

Chapter 21

Making Stovepipe, and Adapters

Commercial stovepipe is durable, dependable, uniform and reasonably inexpensive. Considering the disastrous consequences that could follow a stovepipe failure, I have always favored using the ready-made variety. But there are situations where it is desirable or necessary to make stovepipe, and there are several ways of doing so. The main points to remember are:

1. Make the pipe safe. The seams must be secure so that individual joints cannot open up, and the various joints must be held securely together so that they can't accidentally separate.

2. Make the pipe uniform so that the sections don't have to be assembled in any special order. An exception is pipe that is intentionally tapered in order to nest one section inside the other.

Commercial stovepipe has a self-locking seam, crimping (to reduce one end enough to fit inside the uncrimped end of the next section) and a swedge (the swelling above the crimping that prevents one section from sliding too far into the next). Homemade pipe will have to include elements that duplicate or substitute for these features.

Perhaps the easiest way to make stovepipe is to roll each end of a sheet of flat stock around the crimped end of a joint of commercial stovepipe to form a uniform tube, both ends of which have the same diameter. Crimping can be added by twisting with a pair of needle-nose pliers, as shown in Figure 21.1, and a stop can be made by installing a sheet-metal screw about 2 inches from the uncrimped end. The seam can be secured either with pop rivets or sheet-metal screws.

A seam that requires no fasteners is shown in Figure 21.2. Two small flaps along the edges of the metal are mated and then pounded flat. The metal along one edge of the resulting four-ply seam is then flattened in such a way that the two halves can't pull apart again.

Many a stove in this part of Alaska is fitted with a simple damper made from a sheet of tin-can metal with a few folds at the end for a handle. The simplest kind is merely a flat sheet that slides in and out of a horizontal slit in the stovepipe (Figures 16.15 and 21.3, Drawing A). A somewhat more sophisticated type consists of a curved sheet riding in a slit that curves slightly downward (Figure 21.3, Drawing B). Instead of just sliding in and out, this type of damper also pivots about the end points of the slit.

Figure 21.1 (above) - How to form crimping on homemade pipe.

Figure 21.2 (below) - A. pipe seam that requires no fasteners. Designed by Oliver Cameron.

With either style of damper, the inner end of the sheet is cut into a circular shape to match the curvature of the pipe. There should be some space for smoke to escape around the flat sides, so that the damper can be closed all the way without making the stove smoke. (That way, the stove can be shut down in one quick motion, without a lot of tiresome fine-tuning.) If the edge spaces don't provide enough by-pass when the damper is fully closed, a hole of appropriate size can be cut into the middle of the sheet.

Figure 21.3 - Flat and curved tin-can dampers. Designed by Keith Jones.

Ted Ledger has published a drawing of an entirely different sort of damper (Figure 21.4). Rather than controlling the fire by limiting the smoke flow from the stove, this sleeve damper spoils the draft by admitting air from the room into the pipe, much like the draft corrector described in Chapter 4.

Figure 21.4 - Ted Ledger's sleeve damper. The sleeve is rotated to expose or cover a hole in the stovepipe (from Alternative Sources of Energy, No. 14, May, 1974, p. 35).

A sleeve damper mounted just below a stovepipe oven would double as a secondary draft. When the stove is fired up for baking, the stack gases are bound to be hot enough for complete combustion to take place, but they may be somewhat deficient in oxygen. Secondary air entering the pipe just below the oven would encourage complete combustion of the smoke at the very point where the heat would do the most good.

You may go a long time without needing to make your own stovepipes or dampers, but chances are you will eventually run across a situation in which you'll need to make an adapter. We generally think of using adapters to connect one pipe to another of a different diameter, but, in practice, I've more often made adapters to satisfy my insistence that the crimped end of the stovepipe be placed down so that sooty condensate won't dribble out at every junction. In other words, I have often had to build a special adapter just to connect a 6-inch stovepipe to a 6-inch collar.

My neighbor recently encountered a situation that provides a good example. His range had a 7-inch stovepipe collar, sized for use with the crimped end up (the messy way), and his roof jack was sized for 6-inch pipe. Thus, he had two problems: first, to reduce the pipe from 7 to 6 inches, and second, to invert the whole thing so it wouldn't drip.

He bought a commercial adapter, and was able to put the stove into service. But since the adapter was also crimped the wrong way, so much condensate dribbled out of the joints in the pipe that a tarry deposit began to build up at the base of the pipe (Figure 21.5). It looked bad, smelled worse, and even caught fire a few times.

Figure 21.5 - Build-up of creosote at the base of my neighbor's stovepipe, due to the use of an adapter with the crimped end up.

Next he pounded the^ crimps out of the adapter and inverted the pipe; now the pipe didn't streak, but all of the creosote leaked out where the adapter joined the stove. In his next attempt to solve the problem, he slit the adapter to try to make it fit inside the stovepipe collar, but that didn't work either.

Figure 21.6 - This homemade dripless adapter, fashioned by the author from a joint of 8"inch pipe, simultaneously inverts the stovepipe and reduces it from 7 to 6 inches.

Finally we made a proper adapter that fitted tightly inside the collar, preventing dripping, and that simultaneously reduced the pipe from 7 to 6 inches (Figure 21.6). This type of adapter is easy to make with only a few simple tools:

1. Obtain a piece of heavy-gauge commercial stovepipe, preferably galvanized, in a diameter 1 inch larger than the larger of the two elements to be connected.

2. Cut off the self-locking seam. The easiest way to do this without distorting the metal is to use a Bernz-cutter, available at most hardware stores (Figure 21.7). (Note: The little turned flap on the other edge of the pipe need not be removed, since it will be on the inside of the adapter.)

Figure 21.7 - Removing the seam of a stovepipe with a Bernz-cutter. This tool does not distort the metal, as conventional tin snips do.

3. Form the uncrimped end of the adapter pipe around the crimped end of the next pipe up, squeeze it down tightly, and mark at the overlapping edge with a felt-tipped pen. Remove the adapter from the form, match up the mark, and clamp securely.

4. Form the crimped end into a circle and stick it into its receiver (either the stovepipe collar or the uncrimped end of the next pipe down, as the case may be). You will find it awkward to expand the pipe all the way so that the fit is snug, since it is hard to get a grip; but do the best you can and then mark the position (Figure 21.8). Remove the pipe, match up the mark again, and then allow the pipe to expand just enough to guarantee a snug fit. Clamp securely and drill a hole just above the crimping for the first rivet (or sheet-metal screw). Drive the rivet and unclamp the crimped end of the pipe.

5. Test the fit If your estimate was correct, the fit will be just right, and you can go on to the next step. But don't feel bad if you have to remove the fastener, re-estimate, clamp, drill, fasten and check again; usually it comes out right the second time. (The original hole will be blocked off, since the two sides of the seam will have shifted.)

6. Mark for the other rivets. Make the last mark 2 inches from the uncrimped end, to give clearance for the crimping on the adjoining pipe. The fasteners need not be spaced any closer than 3 inches.

7. Install a rivet next to the first one. Avoid the temptation to place the second rivet at the uncrimped end of the pipe to replace the clamp, because the finished adapter will not be lined up the same way it is at this stage. Remove the clamp at the uncrimped end of the pipe, realign the mark, and reclamp.

8. Install the third rivet next to the second one. Now you can do without the clamp at the far end of the pipe. Continue riveting in the same direction until all the rivets are in place. You'll notice that one edge of the seam protrudes farther at the end of the stovepipe than the other one does. This is because the adapter has a slightly conical shape. If you had started out by riveting both ends, the extra metal would now be distributed along the length of the pipe, and the seam would be puckered.

9. Finally, dress off the protruding edge at the uncrimped end of the adapter. Again, the Bernz-cutter is the handiest tool to use. Touch up the last rough edges with a file, and your dripless adapter is ready to install.

It is worth noting that makeshift adapters can also be fashioned from tin cans. A No. 10 can, for example, fits 6-inch stovepipe perfectly, and a hole can be cut in the closed end to receive 5- or 4-inch pipe. A 4-pound lard can makes a nice adapter for joining 6-and 5-inch pipes (Figure 21.9). And when I made the Three-Way Stove, I fashioned an elbow from an old spice can (Figure 13.17); the lid opening was just about right for 5-inch pipe, and I cut a hole in one side to admit the stovepipe collar. None of these adapters is really leak proof; but then, neither are most of the ones that are found on the shelves in the hardware store.

Figure 21.9 - A lard-can adapter made by the author. Six-inch pipe fits into the open end of the can, and 5-inch pipe fits into the hole cut in the other end.

Chapter 22

Hot-Water Systems

A typical gas or electric hot-water heater ranks among the major energy users in the American household. If a wood stove supplies all or even part of the family's hot-water needs, the savings of energy can be significant.

The simplest hot-water system consists of a 5-gallon can and a kettle that sit on top of the stove. The can is for volume, the kettle for quick hot water. We find that this quantity of hot water - about 6 gallons - is enough to meet all of our household needs, except on laundry day. Then we substitute a second 5-gallon can for the kettle and add a 16-gallon galvanized container as well.

Figure 22.1 - How to make a handle and a wooden lid for a five-gallon stove-top hot-water can.

Since a spill would be dangerous, I always attach sturdy handles to the 5-gallon cans. And since water in an open can steams up the room and doesn't get as hot as water in a closed container, I also use a simple wooden lid (Figure 22.1). To encourage heat absorption, I blacken the bottom of the can, and also the side that faces the stovepipe, with stove enamel (Figure 8.1).

How to Mend a Leaky Hot-Water Can

Rust eventually eats holes in the bottom of a hot-water can, especially if it is allowed to sit around empty, but wet. Most of the holes are very small, and are easily sealed with Weld wood Metal Mender, as follows:

1. Scour the rust off the inner and outer surfaces of the bottom of the can with steel wool. This will generally expose other pinholes that were still sealed with rust and hadn't leaked yet.

2. Locate the holes by looking against the light, and circle each one with a felt-tipped pen, both inside and outside the can.

3. Put a dab of Metal Mender on each hole from the inside of the can. The circles marking the holes enable you to work without having to hold the can up to the light.

4. Turn the can over and put another dab on each hole from the outside. The circles are very necessary on this side to locate the holes, which are now plugged from the inside and won't pass light.

5. Set the can in a warm place and allow the Metal Mender to dry overnight. (I always place mine on the stove top, upside down.)

These patches will withstand hot water indefinitely, and succeeding generations of holes can be treated in the same way. The can won't have to be discarded until a long hole opens up along the bottom seam. After losing a few cans this way, I learned to seal that seam with Metal Mender before putting a can into service.

Some commercial wood ranges feature built-in hot-water reservoirs, complete with faucets, and the same feature could certainly be built into a homemade stove. The tank should be of stainless steel or some other rust-resistant material, and provision should be made for cleaning the inevitable soot from any surface of the tank touched by the smoke.

More complex hot-water systems employ copper heating coils. In the system shown in Figure 22.2, cold water enters the firebox coil from the lower part of the tank, picks up heat, rises, and re-enters the tank near the top. As the process continues, the interface between the hot and cold water slowly moves down the tank.

Figure 22.2 - Firebox-coil hot-water system. The interface between hot and cold water gradually moves downward as water heats, and upward as hot water is drawn off and replaced by cold.

If the stove operates at a high setting for a long time and no hot water is drawn off, the interface eventually reaches the bottom of the tank, and hot water begins to enter the coil. Heat build-up is then rapid, and the water may actually boil. This sounds dangerous, but actually the pressure can't ever be greater than that of the incoming water main.

I had this sort of system in my bachelor days, when I lived in an old house in Anchorage. When the water in the tank got especially hot, I'd take the opportunity to throw a load of laundry into the washing machine. Talk about frugal! I'd even reclaim the heat by running the outlet from the washer into the bathtub and holding the wash water there until it went stone cold.

Since homes heated by wood stoves may have cold, damp walls at floor level where circulation is poor, it is appealing to think about a system whereby hot water from a coil in the firebox could be circulated through a baseboard heater of some sort. A small electric pump would make the project perfectly feasible, of course. But if there were no electricity, could the hot water be made to circulate by itself?

Since the inlet and outlet of such a system would both be at the same level, the hot water wouldn't be able to rise out of the coil, and so there wouldn't seem to be much chance of inducing self-circulation. But I know a man who claims to have gotten such a system to work by installing check valves in the line (Figure 22.3).

Figure 22.3 (above) - Self-circulating firebox-coil baseboard heater system. Modified from design by John Topkok.

Figure 22.4-Stovepipe hot-water unit sold in kit form by Blazing Showers Company. The unit is substituted for the first section of stovepipe.

When the water in the coil reaches the boiling point, it tends to boil in surges. Each "bump" sends some hot water through the outlet check valve. During the brief interval of reduced pressure following each surge, water that has cooled after circulating around the system enters through the inlet check valve.

Figure 22.5 - Greenbriar Hydionic system. Ready-made coils fit inside Greenbriar fireplaces, and the company also makes fittings for integrating the resulting hot-water output into various types of heating systems.

Hot-water coils are usually placed in the firebox, but suitable results can also be obtained from coils placed in or around the stovepipe, or in the chimney. A company called Blazing Showers offers ready-made stovepipe coils that can be attached to a wood stove and connected to a hot-water tank (Figure 22.4). Greenbriar Products sells ready-made coils that fit inside their fireplaces, along with fittings for integrating the resulting hot-water output into various types of heating systems (Figure 22.5).

Figure 22.6 - Chip-heater hot-water system.

In Australia we ran into yet another type of copper-coil hot-water system - the chip heater. Most homes in Australia's rural areas have at least one wood-stave water tank tucked under the eaves. A chip heater fits in very nicely with this ecologically sound water supply, since it operates only when hot water is actually needed and fires up quite nicely on chips of wood, pieces of bark and other scraps, including trash.

Figure 22.7

The body of a chip heater (Figure 22.6) is similar to a standard airtight heater, from which one could easily be made. Water is piped through the firebox coil to the point of use, where the faucet is located. The temperature of the emerging water is determined both by the intensity of the fire and by the rate at which water is allowed to flow out of (not into) the coil - the smaller the trickle, the hotter the water. Our particular chip heater was out in the washing shed, next to the bathtub, so the fire also took the chill off the room. It was even possible to add more fuel to the heater without getting out of the soak.

Figure 22.7 shows one more possibility for heating water in quantity. This unit happens to be a dog-food cooker, but the same sort of system can be used for heating water. The tank is made from the lower third of a barrel, and the firebox is just a section of the middle of the same drum, with a stokehole and a smoke outlet cut into it. The remaining third of the barrel would provide plenty of metal for fashioning a proper door, draft system, and stovepipe collar, if desired.

Chapter 23

Epilogue

Ken Kern, in his article "Heating and Cooking with Wood," offered the opinion that "in recent years, more wood heaters have been put together in small blacksmith and backyard welding shops than in all stove foundries combined." It would be hard to gather statistics on something like this, but two things are certain: (1) a lot of people are making a lot of interesting stoves; and (2) for the most part, they are working independently, largely unaware of the work of others and unable to profit from it.

Alternative-energy enthusiasts who are working with wind power or solar heating have their own journals, and are exchanging stimulating accounts of individual work and experimentation in their rapidly evolving fields. But as far as I know, there has never been any significant nationwide exchange of information among and between stove builders. Wood-stove information is scattered in bits and pieces among a variety of publications that somehow touch upon the simple life.

This is bound to change. When the Whole Earth Catalog burst upon the scene some years ago, it tapped a previously undiscovered lode of interest that surprised even the editors. I have a hunch that the interest in homemade wood stoves also runs deeper than anybody has previously suspected, and that stove builders will eventually have their own organization and periodical. There already exists a more general periodical on wood stoves and alternative sources of energy (see Bibliography).

In the meantime, this seems to be the only book ever published on designing and making wood stoves. If you are aware of an idea or a design that doesn't appear in these pages, I'd be grateful if you'd send it along, so that it can be added to the growing body of information to be shared with all those who seek to extend their proficiency in the art.

Appendix:

Bibliography

Buyer's Guide to Woodstoves. Bennington, VT: Vermont Woo Stove Co., 1975. Coleman, Peter.

Wood Stove Know-how. Charlotte, VT: Garden Way, 1974. Gay, Larry.

The Complete Book of Heating with Wood Charlotte, VT: Garden Way, 1974. Kern, Ken.

"Heating and Cooking with Wood." In Producing Your Own Power, edited by C. H. Stoner. Emmaus, PA: Rodale, 1974. Ledger, Ted.

"Build Your Own Wood Stove." Alternative Sources of Energy, no. 14 (May 1974), pp. 35-36. Rombauer, IrmaS., and Becker, Marion R.

Joy of Cooking. Indianapolis: Bobbs-Merrill, 1964. Ross, Bob, and Ross, C.

Modern and Classic Woodburning Stoves and the Grass Roots Energy Revival. Woodstock, NY: The Overlook Press, 1977. Shelton, Jay. Woodburner's Encyclopedia. Williamstown, MA: Jay Shelton. Sundance and Louie.

Blazing Showers: Stovepipe Water Heater Manual. Point Arena, CA: Blazing Showers, 1975. Vivian, John. Wood Heat. Emmaus, PA: Rodale, 1976. Wik, Ole.

How to Build an Oil Barrel Stove. Anchorage: Alaska Northwest, 1976.

Periodical

Woodburning Quarterly and Home Energy Digest, 8009 34th Street South, Minneapolis, MN 55420.

CREDITS

WOOD STOVES

How to Make and Use Them

Ole Wik

Photographs by Manya Wik

Anchorage, Alaska

Copyright - 1977 by Ole Wik.

AH rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission of Alaska Northwest Publishing Company.

Third printing 1979

Library of Congress cataloging in publication data: Wik, Ole, 1939-

Wood stoves.

ISBN 0-88240-083-5

Grateful acknowledgment is given to the following companies for permission to reproduce photographs and drawings: Ashley-Spark Distributors, Inc. Atlanta Stove Works, Inc. Autocra* Corporation. Blazing Showers. Colorado Tent & Awning Co. Emr ire-Detroit Steel Division, Detroit Steel Corporation. Fatsco Stoves. Fire-View - Distributors. L.W. Gay Stove Works, Inc. Greenbriar Products Inc. J0tul. Inc. Kickapoo Stove Works, Ltd. King Products Division, Martin Industries. Kristia Associates. Locke Stove Co. Louisville Tin & Stove Co. Malleable Iron Range Co. Markade-Winnwood. Merry Music Box. Patented Manufacturing Co. Portland Stove Foundry, Inc. Riteway Manufacturing Co. Shipmate Stove Division, Richmond Ring Co. Southport Stoves. Torrid Manufacturing Co., Inc. Union Stove Works, Inc. United States Stove Co. Vermont Woodstove Co. Washington Stove Works.

Design and illustrations by Jon. Hersh

Alaska Northwest Publishing Company

Box4-LLE, Anchorage, Alaska 99509

Printed in U.S.A.

For Alexander John Klistoff Sr., Master Welder