rocket stove water heater
 

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This is the rocket, I built to use as a backup hot water heater. I been using it to make hot water for my BBQ kitchen. It works but it needs to be better.

A bi-metal switch kicks on a 12v DC pump at 150F. It has a 20 degree differential. Circulates water from the 500 gallon storage tank.

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What I'm planning to do is, instead of the rocket venting up the chimney. I'm going to vent it into another barrel containing the hot water tank in the picture. Then up the chimney. Have it on a separate bi-metal switch and pump. Try to capture as much heat as possible.


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Here is the part where plan to make the rocket better. Instead of the furnace pipe I'm going with masonry and stainless steal. I built this as a cooker for now to work the bugs out. When I go to rebuild the rocket water heater. copper tubing well be wrapped around the top of the half barrel and a barrel well be placed over the riser.

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You can almost see the flame burning sideways in this picture.

Looks cool, can you give a source & spec for your pump control thermostat?

I'm still getting things squared away. Here is where I got the snap switches.
Fan and Limit Controls
Snap Disc Fan Controls , Fan Controls , White Rodgers Fan Controls - PexSupply.com

Since I'm using Firestone 45 mil EPDM Pond Liner, I need to keep the temp limited to 140F to get long life from the liner.

Need to base the temp control on what your water storage container can tolerate.

I plan to use a bi-metal snap switch to set off an alarm (a 12v light) if the temp gets to high.

Hope to go this rout, later on with a differential thermostat controller
12 Volt Differential Thermostat Controller

Thanks for the info KB, I had no idea that you could buy bi-metal thermostats. Can you tell me the current rating for these? I need one for a solar hw heater & another for my redneck (stock tank) hot tub.
Thank you again

I am guessing that this isn't like the "rocket stoves" I have seen in the past, burning wood. If it is, you will have to ask yourself, what is the water being used for? If it's potable, I would not recommend venting the exhaust THROUGH the water, for contamination issues. If it's being recirculated, I would guess you will eventually have buildup of junk in your pipes and pump causing issues.

Cool setup. I'm anxious to see the water heater stove. :)

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So far I've tried different lay outs for a rocket water heater. I tried heating a old hot water tank but even with a pressure relief valve I didn't feel it safe. Wood is not easy to keep at a set temp burn. So I'm using copper tubing to catch the heat.

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I wanted to do a little cooking when fired the rocket. I'm cobbing, mudding, insulating the barrels in. All very wet and not done. I hope to have it, so the short barrel gets hot enough to make flat breads (pancakes). I have my doubts that will happen.

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A note to thank you for telling about snap switches, I installed one today on my hillbilly hot tub, it works like a charm. The hot water heater now controls the circulating pump, way more efficient than trying to remember to cycle the pump.
Thank you!!

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Me and my Dad built this about 25 years ago. The framing material, recycled from a tornado. 448sqf garage and 784sqf living space. Right now it's just a garage and storage. Was never finished out to live in. It has a 20 amp 110 v circuit running to it and no plumbing. Plan to use radiant water heat.


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About the fifth built. Still have copper coiled around the riser. Added a drum on top filled with about 35 gallon of water. Kind of a batch heater.

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pump hot water to these old tanks. using them as radiators. My cat likes the heated shed.

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cobbed my smoker for mass and insulation. Much improvement. Takes less charcoal. More maintains more even higher temps.

this heater is looking really good.

Rocketstoves in all their forms are very interesting.

I built a RocketStove Grill this summer. Fun to cook on.

A local energy group is currently building a "gasirockifier" - it is a combination of rocketstove and gasifier to be used as a boiler. The fire to water heat exchange area is double-walled, welded steel tubes, one inside the other. Essentially, it's a big water jacket.

I would think a drum-within-a-drum would be a simple way to create a rocketstove with water-heating capabilities.

Isn't a natural gas water heater just a big drum with a tube up the middle? I wonder if an old gas water heat COULD be easily modified into a rocket boiler?

I did a websearch for "gasirockifier" and couldn't find it.

Is this project on the web anywhere? What's the current status? I'm interested in a rocket stove boiler, for heating water for use in my in-floor heat tubing.

No, the "gasirockifier" isn't on the web anywhere that I know of. It's more a group of hard-core, hands-on kind of guys, but other than taking some digital still photos, none of them are great with blogging about the projects.

Next time I am over there, I will have to take some photos and maybe do some video interviews.

I did recently post my Rocket Grill over on Instructables if anyone is interested.

Thanks, that would be much appreciated.

I've already printed off a copy, and put it on my todo list.

Are round burn tubes a lot better than square or rectangular burn tubes? The cuts would be a lot simpler for the feed-tube-burn-tube connection with rectangular or square tubing.

I hadn't even thought about using square tube. I guess it's just that I have access to a fair amount of round tube, old water heaters and that sort of thing.

Some square tube would be special order and cost money.

I would imagine that round would be SLIGHTLY better than square in terms of airlflow going through with less turbulence.

The other thing is that if you want to wrap soft copper pipe around the outside of a tube, square wouldn't work so well.

I got the idea when I saw the Heavy Duty Grover Stove on the Internet:

Heavy Duty Grover Rocket Stove

With a square tube the pipe could be placed in the tube filling the corners making it more of a round shape but a small heat shield might need to be placed just below the bottom corners of the pipe so the elbows or bent pipe is not getting over heated.

This is cool - a mini rocket stove made from soup cans, concrete, and perlite. He designed it to be portable and use in his fireplace. It is still in progress, but it looks like it will be a pretty sweet little setup. With such a small burn chamber he could easily connect it to a 3" flue. With the firebox heating water, it may be a viable water heater.