Hello, I have been contemplating a wood burning pool heater. My initial plan was to turn a 55 gal drum into a wood burning stove and put coiled copper pipe inside. I would have used an electric pump to circulate the water from the pool, through the pipe, and back into the pool to heat the water enough to where I would get 1 more month's use out of it in the late spring and early fall. I came across the rocket stove yesterday while doing research and would love to get some ideas as to how I could convert it to a swimming pool heater.
Does anyone know of a version of the rocket stove that has already been built that would work?
Some concerns are smoke. I know the rocket stove heats up so much that it basically burns off all smoke, but adding copper pipe with a flow of cool water may lower the temp enough to where it would not burn as clean. I also am concerned about safely. I don't think it would happen because I'm not really containing the water, but I wouldn't want to have it blow up or anything because of steam pressure buildup.
Thanks in advance!
posted 8 years ago
One thing with copper tubing over the wood fire is that the copper sweats and the tubing gets covered with creosote. So a very hot fire is needed. I went through this last year with heating my hot tube. The water-jacket surrounding the fire box to me would have to be the best.
When you used the copper piping, did you coil it within the heat riser or around the heat riser within the drum? I was also thinking about just coiling it across every square inch of the inside of the top of the drum where the concentration of heat from the riser goes. I see what you mean about the creosote. I would make it so that I could take apart the drum and clean it out.
I too like the idea of a water jacket surrounding, but I just don't know how to make it or get one.
posted 8 years ago
I used a small propane tank laid on it's side and cut in half similar to a small BBQ. grill. I made a grid out of 1/2'' hard copper and soldered it all together.
Could you just put another small drum on top of the big drum, and pipe water into and from that small drum? If you could run the pipe to the small drum through a length of copper going countercurrent in the exhaust I'll bet you could hit the temps you wanted with fairly little effort and a whole lot less kreosote danger.
well there are a couple ways to do it inside the barrel or in the exhaust piping. inside the barrel is the fast way for making very hot water but it has its attendant problems. it robs lots and lots of heat really early in the burn, it cannot be turned off and on or the pipe will blow you must have water flow no matter what while the stove is burning. the second way is to coil the tubing outside the exhaust duct just past the manifold. build a really insulated box around it so it wont lose heat to the surrounding. the copper tube must be in contact with the exhaust duct. if you are a bit better at coiling than i am you can insert the coil in the duct. with an 8 inch system you should be able to boil water in 1/2 inch tubing its also not going to effect the burn in the stove and wont super heat as fast cutting the risk of a steam explosion. you will have to have flow in the system but you could control the water temp by setting up a pump and a valve to restrict the flow a bit when you want it hotter or open it to full when you want it cooler. dont put any other mass on the system, the water is going to be plenty of mass to heat.
I would do the coil on a 5 foot section in a very heavily insulated box 1/2 inch between each loop of the coil. you will have to tinker till the heat is right and you may find that 3/4 inch is a better coil size.
Need more info?
Ernie and Erica
Wood burning stoves, Rocket Mass Heaters, DIY,
Stove plans, Boat plans, General permiculture information, Arts and crafts, Fire science, Find it at www.ernieanderica.info
Location: Tacoma, WA - Zone 7b
posted 8 years ago
Mother Earth News just had an article in their latest issue about how to build a hot tub. It's not a rocket stove, but it might help you!