Build a Micro Sized Outdoor Fireplace from Recycled Materials

Everyone loves a nice fire in an outdoor fireplace. . . but not everyone has the room for one. These instructions explain how to build a tiny fireplace that gives off a lot of useful heat for its size. In addition to being a backyard novelty, this is a working model of how a full-size fireplace operates in terms of draft and damper controls.

Steps

  1. Collect your raw materials before you begin construction (see the Things You'll Need list below).
  2. Strip the labels off two steel cans. Remove the top and bottom of each with a can opener, and save the can bottoms for a later step.

Firebox Assembly

  1. Using a permanent marker, make two marks on opposite sides of the bottom rim of one can. Extend these up to about a little more than an inch from the top of the can and across to form a rectangle.
  2. Using your tin cutters (very strong scissors might work here) cut out the rectangular area you marked in the previous step. Use tape to cover the freshly cut edges or smooth them with a metal file to prevent injury. Gently bend the bottom of the cut area out to form a wider opening. Save the cut-out piece for a later step.
  3. Cut around the inner edge of the sardine tin so you have a small metal tray. (See diagram)
  4. Make two cuts on one of the longer sides of the sardine tin from the top to the bottom of the tin, and fold this panel out to form an extension of the bottom of the tin. (See diagram)
  5. Make a mark in the middle of the other side of the tin, between a quarter and a half inch up from the bottom. Using a drill bit just larger than the rivets you plan to use, drill a hole in the tin at this mark. (See diagram)
  6. Place the cut out and widened steel can in the sardine tin with the back of the can up against the side where you drilled the hole. Line up and straighten the can to your liking so that the opening of the can faces the folded-out side of the sardine tin and there is a small gap between the can and sardine tin on either side.
  7. Push the marker through the hole in the sardine tin and mark the can. Remove the can from the sardine tin, clamp it down, and drill a hole of the same diameter as before.
  8. Put the can back in the sardine tin, line up the holes, and push the rivet through. Double check how they line up before riveting the two together.

Damper Assembly

  1. On the second can, make two marks on the opposite sides of the can a little more than one inch from the top. Clamp the can to a table or other solid platform and drill holes slightly larger in diameter than the steel wire you will use where you made your marks.
  2. Insert the steel wire through one hole and thread it out the other. On the free end, bend about one half inch at a 90 degree angle so the wire doesn't pull back out. On the end attached to the spool, cut it about {{safesubst:#invoke:convert|convert}} and bend the same direction at a 90 degree angle as the other side. The bent steel wire ends must be pretty close to parallel with the damper inside to allow better control when operating the fireplace.
  3. Take one of the cut out can bottoms from earlier and cut two slivers off of it, forming a more oblong shape. This will be the damper plate. Drop it in the bottom of the can with the steel wire. Using the rectangular cutout from Firebox Assembly Step 2 as a support, maneuver the damper plate until it is held up against the steel wire from beneath. The long dimension on the damper plate should be parallel to the steel wire (small adjustments can be made in the next step). The bent steel wire ends must be pretty close to parallel with the damper inside to allow better control when operating the fireplace.
  4. Mix up some high-temperature epoxy (about two peas' worth). Using a toothpick as a spreader, generously apply it so that it covers the steel wire and sticks to the can bottom piece. Now is the time to make sure the can bottom piece is aligned parallel to the steel wire. Leave the epoxy to cure overnight or for at least six hours.
  5. Once the epoxy is cured, place the can with the steel wire (the damper segment) on top of the cut-out can with the sardine tin (the firebox segment). Test the damper by moving the longer side of the steel wire with your finger. If it snags, wiggle the it a bit to get it moving. If it swings freely, proceed to the next step. If it catches a lot, check inside to see where it catches; you may need to bend that area to get a smoother fit.
  6. Align the damper segment so that the longer part of the steel wire points the same direction as the firebox opening. Make a small mark at the junction to allow you to easily align it again.
  7. Remove the damper segment and squeeze a very generous ribbon of the high-temp silicone sealant around the top of the firebox segment. Place the damper segment back on the firebox segment and align it using your mark. Use a toothpick to spread the silicone sealant to fill any gaps.
  8. Straighten the damper segment to line up with the firebox segment and allow the sealant to cure as stated on the instructions.

Fire Grate Assembly

  1. While the sealant cures, bend some steel wire into a little frame about 3/4 of an inch high (see picture).
  2. Bend another length of steel wire in a tight back and forth S-shape wide enough to form a grate over the frame. Make sure there is no more than a quarter inch gap between the bars of the grate or burning fuel will fall through prematurely.

Damper Controls Assembly

  1. Bend the long side of the steel wire on the damper segment into a U-turn so that the backwards-facing part is twice as long as the forward facing part (see picture). Place a small nut at the bend, and use a twist-tie to hold it in place. Test the damper; the weight of the nut should make it rotate open. If the damper catches when rotating, you will want to use it on the side with the least snags and resistance when operating the fireplace.
  2. Make a small loop at the end of the damper wire, and tie some thin string to it. Make another length of steel wire into a little pulley loop that is anchored beneath the brick or concrete block base. Create a similar assembly with a bigger, flatter loop to hold a clothespin. (See picture)
  3. Run the thin string down through the loop attached to the brick. Cut the string so that there is about two inches extra beyond the clothespin.
  4. Test your damper; it should rotate from open to closed to open again when you pull the string. Practice opening and closing it, using the clothespin to clamp the string and hold it in position.

Chimney Construction and Final Assembly

  1. Remove labels, tops, and bottoms from three more steel cans.
  2. Stack these cans on top of the damper and firebox to form the remainder of the chimney. (More cans may be used, but too many makes the fireplace top-heavy and unstable.)
  3. Position the fireplace, wire loop pulley, and the clothespin so that the damper string can move freely.
  4. Finally, bend steel wire into two little pokers to adjust the fire with. Do not skip this step!

Preparing the Fuel

  1. Cut open the package of the manufactured fire log. Using a plastic knife, shave off some of the log.
  2. Smush the shavings into marble-sized pellets, then elongate them slightly so they do not roll as easily. Rubber gloves are optional here; the material is non-toxic, but smells gross and sticks to your hands.
  3. Repeat until you have a good supply of pellets. Ten will last a while, and more can be made later when the fire is going.

Operating Your Fireplace

  1. Place one pellet on the grate towards the back of the firebox (but not touching the wall).
  2. Open the damper all of the way. The steel wire ends show the angle the damper is pointing, they should be vertical. If you're not sure, look down the chimney to see what's happening inside.
  3. Light the pellet with a lighter or match. It might take a little while to catch, depending on the type of fire log you bought.
  4. Once the pellet has been fully engulfed for a minute, carefully add a second pellet. This is easiest to place on the edge of the grate and slide it in with the pokers until it touches the first pellet. The second pellet will catch from the first; when you see the first stop flaming and become a little ember, you can push the second pellet further in. The pellets make very little ash, and the glowing remains will slowly burn down and fall through into the bottom of the sardine tin.
  5. Add a third pellet two or three minutes after the second, but sooner if the flames seem to by dying down. This will take practice to determine when is best to add the next pellet.
  6. After the third pellet is burning well, slowly close the damper to about halfway and watch the reaction. If you see the flame and smoke start to come out the front of the firebox, open the damper some until this stops. The most efficient operation is when the smoke all goes up the chimney, but is restricted enough to slow down and heat the cans, causing them to radiate the heat out. Every fireplace will be different, so you will need to experiment with how to best work the damper.
  7. When you choose to stop feeding your fire, the last pellet will burn itself out into a glowing ember. There will be a little smoke when this happens, but not as much as normal wood would produce. Let the fire go out completely and allow the fireplace to cool before moving or disassembling the chimney.



Tips

  • If the bars of the grate are too far apart, the pellets will fall through too soon-- very troublesome!
  • Use the sealant and epoxy recommended. This isn't a place to use Elmer's Glue!
  • Don't forget to make the two little pokers from steel wire. An old pair of tweezers will work for tongs, and an old sugar spoon works as an ash scoop.
  • If you do not have any steel cans or a sardine tin, check neighbors' recycle bins.
  • It's a good idea to have a cup of water nearby for emergencies.
  • It is possible to burn small pieces of normal wood in this fireplace, but due to the wood's very low energy content compared with fire log pellets, a tiny wood fire will be more smoke and trouble than its worth. One smoldering wood chip produces more soot than burning several pellets.
  • Keep the firebox clean and shiny to reflect the light and heat out of the front opening. It is easy to take your fireplace apart and scrub the components with an old toothbrush and some detergent in warm water. This should remove most of the soot and leave you ready for another fire as soon as it is reassembled. For the stubborn baked-on soot on the grate, a scouring pad will work better than a toothbrush.
  • When the sardine tin becomes full of ash, it is easy to pour some water into the firebox. The ash is so light that it will wash away with the water, and the fireplace it good to go again. Rain will do the cleaning for you if you leave it outside.
  • Note: This fireplace may not work well at higher altitudes due to the small size of the fire.
  • Don't do a sloppy job or the final product won't work well at all.
  • Make sure you have everything beforehand, it is very annoying to have to go to the store five different times because you didn't read the materials list.
  • This fireplace may be operated with other fuel sources, such as candles.
  • Learning to operate this fireplace will take practice, because each one is different.
  • Gloves are optional when handling fuel pellets because though they are non-toxic, most fire logs are sticky and have a funny smell to them, in addition to being hard to wash off without dish detergent.
  • Do not get epoxy between the damper plate and the side of the chimney. If this cures, your damper will by stuck very strongly (they don't call it a "cold weld" for nothing.)

Warnings

  • Never leave a fire unattended
  • Cut metal is very sharp. Put a strip of tape over all cut edges until you are finished working to avoid sliced fingers. If you don't mind taking the extra time you can smooth out sharp edges and burs with a metal file (fairly inexpensive ones can be found at "Big Lots" or "Harbor Freight Tools")
  • Be safe and courteous with fire. Don't use your fireplace in a place where the smoke (little at it is) will annoy your neighbors.
  • Beware gusty winds and uneven surfaces, as the fireplace could tip over while in use, sending embers and flaming pellets flying.
  • Do not add more than two new pellets at a time. They have more than twice the energy of wood and can easily overwhelm the epoxy and silicone's temperature limits once they ignite, causing fireplace components (specifically the damper) to fail.
  • The entire fireplace will get very hot during operation. Never move the fireplace until all parts and ashes are cool.
  • Always burn using the base; never directly on a combustible surface. If burning with the base on a combustible surface, extend the base by at least two bricks on all sides.
  • If installing this fireplace in a shack or other makeshift shelter, allow a minimum one-foot clearance between the firebox opening and combustibles, and minimum four inches clearance for the sides and rear of the firebox. Allow a minimum two-inch clearance on all sides of the chimney pipe.
  • Never use this fireplace in a tent or other easily ignited shelter
  • Never use this fireplace inside a house or a closed room, and always vent the chimney properly. While the pellets burn very clean compared with wood, the smoke is still dangerous to breathe.
  • If you need to extinguish your fire for any reason, carefully douse it with a little water. After everything has cooled, remove and discard the half-burned pellets into your compost heap.

Things You'll Need

Materials

  • Five steel food/drink cans (Top and bottom must be removable and the resulting tubes must still be able to stay in a stack--Slim-fast and small soup cans cans work best. Aluminum soda cans will not work)
  • Sardine tin
  • High-temperature epoxy (J-B Weld works well)
  • High-temperature silicone sealant (Permatex Ultra Copper RTV works well)
  • 16-gauge steel wire
  • Thin string
  • A small metal nut
  • Twist ties
  • Manufactured wax-and-sawdust fire log, preferably from natural/renewable resources (e.g. Duraflame Anyfire)
  • A brick or similar fireproof item for the base
  • Rubber gloves for handling fuel pellets (Optional but recommended due to the smell of the fire log)

Tools

  • Tin snips (powerful metal-cutting scissors)
  • Needle-nose pliers
  • Pop rivet gun and rivets
  • Drill with drill bits
  • Permanent marker
  • Tape (masking tape, painter's tape, duct tape, electrical tape all fine)
  • Wire cutters (Optional if needle-nose pliers have a built-in cutter)
  • Metal file (Optional but useful for smoothing sharp edges)

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