Instructables

Convert a Hot Water Heater Into a Wood Stove

Picture of Convert a Hot Water Heater Into a Wood Stove
Photo A.jpg
About 6 years ago, with the cost of heating my house rising, I began looking at designs for wood stoves. In The Mother Earth News (Issue # 49- January/February 1978) I found a promising article about using discarded hot water heaters. Using that article as a guide, I constructed a wood stove that I have been using for about 6 years.

The stove is used in the first floor of a 20 foot by 36 foot uninsulated brick house. When the temperature is 20 degrees outside, the basement is 80 degrees and the floor above is 55 degrees. The temperature difference would be reduced by connecting the floors with ducting.

Here in the city, it takes about 16 square blocks of scavenging territory to scrounge up enough discarded wood to supply one house with one years worth of fuel. It helps to have a car or truck to transport the wood that people throw in the alleys. Discarded furniture made from particle board is great because it is easy to break into small pieces. Keep an eye out for folks with dead trees that you can offer to remove.

The Mother Earth plan calls for electric water heaters. My variation uses a gas heater, which is much more common in cities. For this instructable, I made a second stove and documented what I did. Since there are so many metal scavengers in my area, it is very difficult to find a heater in the alley, so I traded an old car battery for a water heater from a nearby scavenger.

Note, before starting this project, check with your homeowners insurance to make sure there won’t be a problem.

Photo A shows the heater with the covering and insulation removed.

 
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dbcooper6569 months ago
Great stuff! Just a very important comment about your fuel. Wood fuel 'is not created equal'. Although fiberboard and presswood are easy to break up, NEVER USE IT, the adhesives used in its manufacture (adhesives that are banned in Europe and by most industrialized nations) are highly toxic and create poisonous fumes and ash. The worst product of all is any type of 'pressure treated' wood which are full of arsenic and copper compounds that are lethal to inhale. Google 'pressure treated wood fire death' if you want to read about entire families that have perished from burning the stuff in their fireplaces. Burning it creates an even more toxic mix and your neighbors will all be suffering the same fate. Discarded oak pallets are the best firewood, great long-burning, high energy density, low smoke. And pallets are plentiful and not pressure treated, at least I've never come across a pressure treated pallet.
hey greetings from POLAND with us too so do podbne kociołłki but Niewiedział from among you they use so many chemicals in the production of discs derwnianych and others that I'm glad that there are some detrimental things banned in Europe but I wish you good luck and cutting costs because of tv planeteplus learned in August which was the crisis and what the government was doing about the towns that Americans have lost their jobs and are living in tents in the woods in August of Americans bear with us crisis it too reaches only one I have a better system of health fund which cared for the unemployed and gives you the silent salute as the unemployed Robert
ShutterBugger (author)  dbcooper6569 months ago
About a third of the wood I burn is particle board, with small amounts of pressure treated wood. There have been no problems or complaints yet. I put the ashes on the lawn every year and the grass loves it. I find very few pallets because there are companies that buy used ones, making them valuable.
blakep823 years ago
grinders are easier to control if you cut with the sparks coming towards you (just be careful you don't set light to your trousers...) reason is the grinder is always trying to pull away from you, and if you lose grip, it flies away from you.. the way shown above, the grinder is always trying to pull towards you, and when it cuts through, it tries to jump back out. if you lose grip now, its going to fly towards you, which is the last thing you want!
The disc pictured also appears to be very dangerously worn or damaged. Using a disc in such condition is shower of shrapnel waiting to happen.
ShutterBugger (author)  balisticsquirel2 years ago
Yes indeed, it was in bad condition. I had goggles and used a light touch. Almost all my tools are from the alleys.... discarded stuff that I repair and make use of.
~Bob~
This is called kick back, And it is VERY Dangerous. You see it more with chainsaws and the large cut off saws. Good points people. Keep up the good work.
ShutterBugger (author)  blakep823 years ago
Good point.
~Bob~
Vyger3 years ago
I have been heating with a wood stove for about 30 years now and I still think its the way to go in spite of the amount of work it takes. Turning up a thermostat is a lot easier but getting out and moving wood and ashes and all the associated work is probably a lot healthier for you. In Montana it gets really cold so I sometimes go through a lot of wood. its a challenge.
Anyway, 2 things I noticed that could be a problem. The first is the stand. Yours appears to be mounted firmly but anyone else doing something like this needs to have good strong mountings (legs or whatever.) What I see is that it is round and if it rolled with the fire going inside it could be a disaster. I sometimes put pretty heavy logs in my stove, it even moves it around on the floor, so whatever is used for mounting has to be stout enough to handle a lot of weight, just in case.
The second area is the stove pipe or flue.
The flue on a wood stove can get a lot hotter than a normal furnace so you might want to make certain yours can handle it. As you brought out stuff builds up in them and it can burn at very high temps if it lights. Again something that doesn't happen with gas.
When I installed my stove I used what is called triple wall pipe. It is what was required for the installation and I did not have an existing chimney. Its expensive but the idea is that the inside pipe (made of stainless steal) does not touch the middle pipe and that is separated from the outside pipe. So the outside one cannot get hot enough to ignite anything, like wood rafters even if the inside one gets very hot. Bottom line for my concern here is that anyone putting in something like this be very careful about what flue pipe you use.

Something you might find interesting, and I have been thinking of doing an instructable on it. I have found a way to burn used oil in a stove SAFELY)

Use plastic drink bottles, like those from vitamin water. Poor about 1/3 to 1/2 full of used oil, then get shredded paper, crosscut is the best, and pack it into the bottle with the oil. Keep packing the paper in until the bottle is filled and hard packed, then cap the bottle. The oil will soak into all the paper in a day or so. You can store these safely and with the caps on tight they won't leak. To use them just throw one on top of the wood in the stove. The plastic bottle shrinks at first and then as the plastic melts the paper/oil lights. It produces a lot of heat for a short time and since most of the oil is contained by the paper until its burned, it burns completely and slowly enough to stay under control.
ShutterBugger (author)  Vyger3 years ago
I like the oil burning idea.

My stove pipe is just the ordinary single wall type. It is far from anything flammable, so it just adds heat to the room when the soot ignites.

My stand is made from a discarded gas grill. I have never had any stability problems with it. It wasn’t included in the instructions because they are hard to find in the alley.

I have been reading “The Book of Masonry Stoves” by David Lyle. It is full of ideas and stove designs. Great book.


I have also been researching Sterling engines, with the idea of running one from the heat of the stove and powering a generator that keeps storage batteries charged. One could perhaps modify discarded fire extinguishers as the gas cylinders.
~Bob~
gmoon3 years ago
Excellent job, really great project. The photos are very illustrative.

One request: I'd really like to see a photo of the stove with the door open, and fuel being loaded...
ShutterBugger (author)  gmoon3 years ago
Hi gmoon
The picture you wanted has been included.
~Bob~
Cool. Thanks!