jeff
New Member
Posts: 12
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Post by jeff on Dec 29, 2009 13:40:14 GMT -8
I've noticed in a lot of the mockups and such, people will use a double wall insulated pipe. However, there is often mention that the pipe is only for demonstration purposes. Any particular reason why this kind of pipe may not be used/recommended as the riser?
Thanks,
Jeff
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Post by Donkey on Dec 29, 2009 13:51:03 GMT -8
They have a short lifespan. It gets hot enough inside to melt 'em.
Also, the galvanized ones off-gas noxious poisons.
Welcome to the board.
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jeff
New Member
Posts: 12
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Post by jeff on Dec 29, 2009 15:28:20 GMT -8
Ah, makes sense. So it is safe to assume that any of the metallic liners with in the burn chambers turn to dust and act initially as forms for the insulation mixtures? And thanks for the welcome.  I am starting the process of designing and collecting materials for a green house project. I'll open a new thread once I get going to share my situation and the assumptions (design) I've created. I still need to do some more research and play with more bricks. Kindly, Jeff |
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Post by Donkey on Dec 29, 2009 16:58:37 GMT -8
Thin metallic liners, yes.. Stove pipe and such will melt relatively quickly. Pearlite/clay mixtures do well poured between thin metal sleeves. The inner sleeve will melt and you will need a good way to get it back out later, leaving the pearlite/clay. If you opt for a barrel, which is standard, Just don't put too much cob over it so it comes out easily later.
I've thought that cardboard and/or sonotube (for pouring concrete footers) would make a good form which would just burn out later.
1/4 inch steel piping can be expected to last a little while. While it's (most likely) hot enough to burn through it over time, the environment is too oxygen deprived for the metal to burn up quickly.
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jeff
New Member
Posts: 12
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Post by jeff on Dec 29, 2009 23:33:48 GMT -8
Good idea with the cardboard as a form. Just need an inner tube ID of 8" and an outer tube ID of 12"? What about just using fire brick and forgo the cardboard and clay/perlite insulation?
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Post by Donkey on Dec 30, 2009 10:14:42 GMT -8
You still need to insulate around the brick, but it works fine.
I've found that since brick is heavy, it will take time to get up to a good working temp.
Lighter weight, well insulated heat risers take off fast and burn like the dickens. I prefer them.
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