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Rocket powered water for heat help plan

 
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Hello, I've been reading for a while and I'd like to build a supplemental heater for my house to offset oil and electric heater costs. I live in western pa so it's typically crazy cold for 4-6 months at a time while my heaters run. I was thinking of building an outdoor rocket stove with vertical feed and either a big water tank (open vented) and either circulate that through water lines to heat exchangers and fans in my house or heat water in a tank (open vented) and draw heat through a copper coil or heat exchanger then plumb that to my house (Geoff Lawton style). I was thinking about 30 gallons of water capacity should give a rather decent mass and be ok for a 1-3 times a day burn. I'm not at the point of wanting to completely drop off oil until it's shown its capable. There is literally tons of wood around my property I can utilize and can get pallets free from some local businesses so the idea of a burn outside with a water pump and 2 fans is much nicer than pumping heat way from 2 1500 watt space heater. Thanks for any input! I am excited to learn
 
Rocket Scientist
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Location: Upstate NY, zone 5
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A Rocket heater outdoors will be both less efficient and more work to maintain than the common RMH inside your house. Unless you have no space at all where you could fit the combustion core inside, that is the only sensible way to build.

Heating water with a rocket stove and pumping that to your house wastes a lot of energy, as all the radiant warmth will be useless, and there are efficiency losses when converting heat from one form to another.

Do you already have a hydronic heating system? If so, it may make sense to add some water heating to your RMH, but it needs to be done in a safe manner or you could end up with steam explosions injuring you or your family.
 
Jon McLain
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Thanks for your input. While I do understand my setup is less than optimal I unfortunately have to work with what I have. I was thinking of building what Lawton did but with hopefully better insulation and setup. My system should put heat into the house as long as the water circulating is warmer than say 110*f. I was thinking the water in the vented tank would provide some time as a heat battery. As much as I'd love this to be my only source of heat it just can't be in my current house. I'm hoping I can offset the oil/electricity costs using the natural power or fire. I could put up some wind shield walls around the unit to help slow down thermal loses from the wind
 
Glenn Herbert
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If you must build outdoors, can you put the unit next to the house and close to a door? If you can somehow create a vestibule with the RMH and the back door, it would become almost practical to tend, and less wasteful of heat. No matter what, you need to keep the unit close to the house and enclosed in a weathertight shell. I would try making a bell-type enclosure, made of interconnected individual barrel tanks if necessary, with lots of insulation outside of the tank cluster. If the whole thing can be lower than first floor level, that would be an added bonus to easy water circulation.

And of course, the only feasible style of combustion unit would be a batch box; a J-tube would take tending too often to be usable.
 
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hey buddy i saw this and thought i might chime in to help. a i use my RMH to heat my water and posted pics of it. and a guy from Alaska chimed in on my post to share his 40 years of experience with the way he heats his water and it may help.
RMH heats water
 
Jon McLain
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Thank you for this replies. I guess I'm ore stumped in deciding if the mass part of a rmh is worth it being this will be fully outside, except for a few water lines. We've been extraordinarily blessed so far for not being cold. Its giving us a nice break in heating costs
 
Glenn Herbert
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Yes, there will be no benefit to having solid mass around an outdoor RMH for indoor heating. Any mass there should be water or fluid that can be piped to the inside, with good insulation around everything.
 
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Location: Southern alps, on the French side of the french /italian border 5000ft elevation
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Jon, do you have an old chimney and fireplace inside? Well, i would say, all that water lines etc adds complication. And may be the barrel and bench isn't for you. But there's several other options. Is your kitchen open plan for example? There's a guy, in belgium iirc, who did his rocket mass as a kitchen island for example. Or you can make it as a range. Use an internal fireplace and chimney as a bell. There is other options than butt uggly barrel in the living room.
 
Jon McLain
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So if the burn chamber, heat riser, and putter shell are all one and very well insulated it should heat water well? The only real heat losses would then be into the water tank or out the exhaust port
 
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GAMCOD 2025: 200 square feet; Zero degrees F or colder; calories cheap and easy
https://permies.com/wiki/270034/GAMCOD-square-feet-degrees-colder
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