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Opinions, advice and comments on alternative configuration for larger scale RMH  RSS feed

 
Posts: 19
Location: Emerald, Australia
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Hi guys, I'm very new to this RMH stuff, but have been doing a lot of research over the last couple of weeks. I've come up with a concept that I think could work quite well in our new home. See what you think.
Our house is a steep gable with a loft main bedroom covering half the ground floor level, so we have high cathedral ceilings in one end of the house. I was thinking of having a large scale RMH in this end of the house, but instead of incorporating a cob bench or bed, I thought it would be good to utilize the vertical space. for the heat battery. Instead of using a 55 gallon drum as the barrel, I thought of using 600mm to 700mm diameter thick wall pipe. Maybe with a wall thickness of 12 - 15mm. I could have this go vertical for say 3 metres and capped on top with say a disk 25mm thick.. I could also weld a series of radiating fins around the circumference. Then I could have a water storage on top of that for another 2 metres, so the total height of the heat battery would be around 5 metres. The heat riser could be around 2.8 metres high and made of cast refractory, in lock together segments of course. I would like to exit the exhaust under the floor and out the back wall. Any thoughts on this style? Thanks for your time.
Eric
 
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Posts: 2712
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
93
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What do you need, quick heat or heat storage?

If quick heat, a tower of barrels has been done before. If storage, i'm not too keen on the water tank on top idea.

Check my post there

http://www.permies.com/t/38135/rocket-stoves/Advise-request
 
Eric Kendall
Posts: 19
Location: Emerald, Australia
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Hello Satamax, Thanks for the reply. I'd be looking for heat storage, hence the water battery and the thick wall piping.
Is there a reason that you don't like the water tank idea? Do you think this will cool the heat riser too early? Any feedback much appreciated.
Eric
 
Satamax Antone
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Posts: 2712
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
93
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Well, my opinion is, having the weight up high isn't too good. As well that this mass will only heat the top part of the house. Plus, you'd have to leave an opening in the tank, so you would get steam in the house. And you would have to have a refill pipe, with a mechanism like the one of toilets. Another problem is that the water only stores heat to 100C° (even less depending on altitude!) And you always have the risk of legionella!

Far too much risks and problems imho.

While a barrel or metal radiator around the heat riser, would heat up the top of the house via convection rather nicely; you could always add a bit of mass to the surounding walls etc up there to keep the heat. And with a nice mass or bell, you'd keep some slow release heat for the bottom of the house. And thoses don't have temperature limitations or spilage problems
 
Eric Kendall
Posts: 19
Location: Emerald, Australia
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Hello Satamax, Thanks for the feedback. You do raise some interesting points. I'm not that concerned about the weight being elevated. I would intend to mount the structure on independent footings, so the whole unit including the water reservoir would be bolted together.
I understand the need for the venting, etc., but wouldn't have thought that temperatures of nearing 100 degrees would be reached. Is there any way to calculate the BTU output of the fire and relate it to the energy requirements to bring say half a cubic metre of water to the boil? Can you tell me what would be the maximum temperature that a cob bench may reach? Could this temperature be related back to the water storage temperature?
I think the risk of legionella would be very slim due to the fact that it would be a closed system.
Yes I think it would be a good idea as you say to add mass at the base also. I'm wondering if the mass could be made up of heavy radiating fins welded to the barrel.
Thanks again for the feedback. I'll get something drawn up.
 
Satamax Antone
gardener
Posts: 2712
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
93
 
Eric Kendall
Posts: 19
Location: Emerald, Australia
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Thanks Satamax, that's a good resource and could come in handy.
 
We noticed he had no friends. So we gave him this tiny ad:
Would you replace your oven with a rocket oven?
https://permies.com/t/90099/replace-oven-rocket-oven
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