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Brick core, cast riser, Hawthorn Bond 40 for mortar? Second guessing myself.  RSS feed

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First of all, thank you Permies users!  What a fantastic place I have been seriously educated. 

I am building my first RMH, I live in Eastern Ohio, about 45 minutes from Pittsburgh...

Just wanted to be sure this is ok, I am getting a little nervous, the more I read the more difficulty I have deciding what to do since there are so many ways to build a RMH.

I want to build the core, which I take to mean the J-box burn chamber, out of firebrick (found it for $1.00 each) and use the Hawthorn Bond 40 as the mortar.  Is that acceptable?

I want to cast the heat riser using the perlite, Hawthorn Bond 40 as the material and will use metal as the form knowing it will burn away in time.  Is that acceptable?


Posts: 2596
Location: Upstate NY, zone 5
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Both your core and riser construction methods sound fine. For the riser, be sure to use only enough fireclay to hold the grains of perlite together - the more clay, the less the riser will be insulated.

You will also want lots of perlite or perlite-clay around the core to insulate it and let it get hot. The less mass in the core, the better it will perform.
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