• Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education skip experiences global resources cider press projects digital market permies.com pie forums private forums all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Nancy Reading
  • Carla Burke
  • r ranson
  • John F Dean
  • paul wheaton
  • Pearl Sutton
stewards:
  • Jay Angler
  • Liv Smith
  • Leigh Tate
master gardeners:
  • Christopher Weeks
  • Timothy Norton
gardeners:
  • thomas rubino
  • Jeremy VanGelder
  • Maieshe Ljin

dual-fired RMH

 
Posts: 6
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
New to RMH but having big plans ..... and questions. Is anyone aware of the existence of a "dual-fired" (for lack of a better term) RMH, i.e. with firing and combustion set up at each end but sharing the tubing inside the cob/mass heat storage/ structure ("bench, bed, etc.) and exhaust? I haven't thought this completely through and have not the technical oversight of such an arrangement, so wondering on consensus in the community???
Thanks.
 
Rocket Scientist
Posts: 4527
Location: Upstate NY, zone 5
575
5
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
You can't make two combustion cores share the same mass ducting from opposite ends. They would each have to have their own ducting. If you had a huge heating load that needed two full-size RMHs, setting them up in a counterflow arrangement to keep the overall mass temp uniform is workable.

Building codes forbid two heating appliances from sharing a chimney, and even if you ignored code, it would probably cause some sort of draft issues depending on the exact layout and weather conditions.
 
Vega Nunez
Posts: 6
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Thanks for your reply. I was thinking about the dually to increase length potential without reducing heat effect due to the cooling air in the ducts. But from the diagrams and photos you suggested seems like that may not be necessary.
 
Glenn Herbert
Rocket Scientist
Posts: 4527
Location: Upstate NY, zone 5
575
5
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
How large is the space you want to heat, how is it built & insulated, and what is your climate? What configuration are you thinking of for mass, including approximate dimensions?

For ordinary houses in cold climates, one 8" system is usually sufficient. This can support up to 50' of duct in the bench, minus 5' for every 90 degree elbow. If the bench is wide enough, you can double back and have the duct return to near the barrel so the bench is heated uniformly on average. 20' of bench is a pretty long stretch for most house layouts.
 
A tiny monkey bit me and I got tiny ads:
Heat your home with the twigs that naturally fall of the trees in your yard
http://woodheat.net
reply
    Bookmark Topic Watch Topic
  • New Topic