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Would this design work?  RSS feed

 
Posts: 11
Location: UK Expat - Pereslavl-Zalessky Russia
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I am going to build a RMH in my passive solar greenhouse in Northern Russia. Reading about a second bell chamber got me thinking about my design.   I have a single straight 3mm thick steel pipe running 6.5 meters.  I am concerned about losing heat as there is no 180 degree turn in my system. Would a second bell capture the heat before it vents outside?  Or would there be draft problems?  I will be using this in severe cold... -30c is normal for us in winter



I would appreciate comments from anyone on the forum..... I only know what I read in Erica and Ernie's book and seen on YouTube.... So that's me, a total newbie

Cheers Steve

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Posts: 1272
Location: latitude 47 N.W. montana zone 6A
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Hi Steven;  Why can't you have a 180 in your design ? 6.5 meters = 21.3 feet . If your building an 8" system you can push 50' horizontal. You can have a small bell as a 180 turning point and bring your steel pipe back towards the core....   Your current design as it is does look good, including the bell at the end. Although I would make a larger brick transition area with a cleanout door and an ash pit, than you have shown in your drawing.Have you considered a batch box burner over a J tube ?
 
Steven Williams
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thanks for your comments Thomas. 

The pipe was salvaged from a derelict Soviet era factory.... I can not get any more, it's very very heavy (it took 5 men to move it) so to buy more would cost a fortune. Also I do not have a 180 degree section to weld in. I have a smaller length pipe with a 90 degree turn which is destined for the chimney section after the second bell. also space is an issue as I have the plastic pipes for my underfloor climate battery on the edge of the mass. so stuck with  the single long steel pipe. 

As for a Batch Box system v J-tube... I had not given that any thought. May I ask why do you think it could be a better option? I don't really know much about a batch box.
 
Steven Williams
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Location: UK Expat - Pereslavl-Zalessky Russia
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Thomas, I would not need a 180 degree bend as you said I could use the brick bell....   I just don't have enough pipe. 
 
thomas rubino
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Longer burn time on a batch box, and no open flames. It sounds like its very cold there and your going to be feeding your dragon often. My J tube in a greenhouse has to be fed every 40 minutes... if you are working out there  its easy just put another stick in as there is room. After we go inside for the evening we set a timer for every 40 minutes and put on boots and coat to troop out to feed the dragon. On our colder nights we keep the RMH going until 10 or at night it will be 60-70 degrees at that time. In the morning 6-7 it will be 40-45 ...  Fires restart very easy on a warmed up mass so it will light quickly & start raising room temp. I do not have, nor have I built a batch box, but they say it will have apx 1 hour burn time between feedings, the wood lays horizontal rather than stand vertically so less splitting of wood. A closed door so no open flames "could " make an insurance adjuster happy.  The build on a batch box is much more technical than a " J "tube but detailed information is readily available. I'm happy with my J tube... Were you aware that your heat tunnels do NOT have to be tubing ?  They can be built using brick with a thin layer of cob to smooth gas flow.  
 
Steven Williams
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Thanks for the detailed reply.   Yes, I certainly need to do some research on batch box design. It gets pretty cold here... -30/-40 F.     I have a thermal battery system which I hope will help a bit. As for making half the heat exchange 'pipe' , from brick.... Another interesting idea.  I was very happy to get the steel pipe as I thought it would hold heat for longer but I always knew I was limited.  I could use the 4 meter long section I planned for the chimney as additional heat exchange pipe and simply build the chimney from something else.

You have given me some interesting ideas. Thanks Thomas..... I think I will be putting a new design drawing up soon :-)
 
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