• Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies living kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education experiences global resources the cider press projects digital market permies.com all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Nicole Alderman
  • raven ranson
  • paul wheaton
  • Jocelyn Campbell
  • Julia Winter
stewards:
  • Burra Maluca
  • Devaka Cooray
  • Bill Erickson
garden masters:
  • Joylynn Hardesty
  • Bryant RedHawk
  • Mike Jay
gardeners:
  • Joseph Lofthouse
  • Dan Boone
  • Daron Williams

Cob manifold, thermal or structural?  RSS feed

 
Posts: 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi everybody,
I'm just getting started on my first rocket mass heater.
I'm planning on making the manifold with bricks and cob. Should I add straw to the cob?

Also, the core of the heater will be thermal cob (no straw). How thick should the final layer of structural cob be?
Thanks
 
gardener
Posts: 2581
Location: Upstate NY, zone 5
92
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I would use straw in the manifold cob, largely for wet strength so it holds its shape well until it stiffens. If the cob gets hot enough near the inner faces (as it surely will) to char the straw there you will get little airspaces which will have a touch of insulating effect (a good thing there).

I think a couple of inches of straw cob around the outside of the mass would be sufficient. The bigger, thicker, or more complex the mass shape, the more straw I would use.
 
I knew I would regret that burrito. But this tiny ad has never caused regrets:
Do you prefer white or black rocket ovens?
https://permies.com/t/90003/prefer-white-black-rocket-ovens
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!