Introduction: Outside Wood Stove Shop Heater
In this instructable i will show you how i made a wood stove heater for my shed. I didnt want to sacrifice the space in the shed for a small wood stove or need to run propane or a flue pipe through the wall or roof. This stove uses a 55 gallon metal drum and steel pipe as a heat exchanger to keep the fire and smoke outside my shop.
Step 1: DISCLAIMER
Making a stove or anything using fire or metal can expose you to hazardous items and chemicals. this is for instructional purposes only. if you choose to make some variation of this heater be sure to understand all elements and hazards involved with such projects. I am not responsible for the actions of others.
Step 2: Materials and Tools
Gather all necessary tools and items you will need to make the heater.
1 55 Gallon drum stove kit - 50$
1 55 Gallon drum - free
misc steel pieces (searched the scrap bin at a local store)
3" schedule 40 steel pipe - sourced from junk yard
3" pipe 90s - 20$ each at local plumbing supply
1 3" pipe nipple 6" long - 5$
1 4" duct fan - amazon 17$
2 8' pieces of rigid dryer vent/ducting - 15$ each
3/8 rod with nuts and washers
4 large hose clamps (for 4-5 inch pipe) - 1$ each
high temp paint (auto parts store) - 6$
Drill and bits
screw drivers/ sockets
plasma cutter (optional)
Personal Protective Equipment (PPE)
Safety glasses / Shield
Leather/cut resistant gloves
Welding mask/shirt (optional)
Step 3: Prep the Drum
** REMEMBER - If your drum is painted or not washed out there could be harmful or flammable vapors inside, or while cutting the patterns out. WEAR YOUR PPE AND RINSE YOUR DRUM!
I recieved mine from a local guy i know who refurbishes drums and i know it was washed out, but it was still painted.
This part is essentially written in the instructions in the barrel kit so I won't be spending much time on it. Take the door piece out of your kit and place it on one end of the drum. then trace the inside edge and mark all drill holes. Cut the door and vent out and drill the holes. Attach with supplied hardware. Do the Same thing for the flue/chimney piece and legs.
Step 4: Prepare the "Heat Exchanger"
In a standard furnace a heat exchanger is essentially a set of tubes where air is moved thru to be warmed up by a source of heat. The idea is to keep the source of heat and exhaust gases seperate from the air that is to be heated.
Here i welded up some pipe i got at a scrap yard together to make a "U" shape. You can use any size pipe you like and get it threaded so no welding is needed as long as the connections are tight. DO NOT USE GALVANIZED PIPE!! Galvenized steel has a coating on it that releases TOXIC fumes when heated/cut/welded.
for this i bought a short pipe nipple, cut it in half and welded it to the end of the scrap pipe from the scrap yard. Alternitively you could buy a 10ft piece and cut it in half and already have the threads on it or use 2 3' pieces and cut off one end for the duct connections.
Step 5: Attach Heat Exchanger to the Drum Stove
After trying to weld the pipe to the sheet metal barrel and failed by burning a hole in it, I decided to to use a piece of 3/8 threaded rod from the hardware store and some washers and nuts to attach the heat exchanger to the drum. My drum had a removable top so at this point cut or drill holes in the top so that the pipes stick out the back. if you used 3 foot pipe sections it doesn't matter how far inside the drum the pipe sits as long as there is about 3-5 inches of pipe sticking out the back to attach the duct to.
Step 6: Burn It Off!! and Paint
At this step before we attach the heat exchanger to something you should be ready to burn off your barrel and heat exchanger pipe. Simply grab some wood and get a roaring fire in the barrel hot enough to melt all paint and mill scale from the barrel and pipe. On my pipe section there was smoke for a short time which I suspect to be mill scale and oils from the steel foundry, this smoke only lasted about 25 minutes. Once it looks like it is clean burn it for another half hour to one hour to make sure. Once this process is done you can use some high heat paint from an auto part store (exhaust manifold) to paint the drum to prevent exterior rust (non contact pyrometer had my barrell temps around 650 at the highest so far). After this, all should be ready to attach to your heat setup.
Step 7: Heater Fan Setup
This is fairly simple, cut a piece of scrap plywood that will fit your opening, in my case it was for the window of my shed that doubles as a shop in the winter. cut 2 4" holes in it for the duct work and fan. install flanges and a fan on one side that blows out toward the heater. I used a jigsaw for this but anything will work. make sure the fan air flow direction is facing out toward the heater. in this picture i just stuck the flex duct in the window and took some readings with a no contact pyrometer and was pleased with the results.
Step 8: Done!
You are now ready to heat! Here is some pyrometer readings from inside the shop and as you can see, the air is plenty warm. I still plan on keeping a carbon monoxide/smoke detector combo in the shop at all times just to make sure i will be safe as well as a fire extinguisher...I do weld and cut in here as well.