John Lambert

Daniel,

Thanks again. I just relaized I forgot to say I'm im Northern Ohio and the barn proper is 26x48 with an additional semi-seperated 10x28 bay that shares a full wall with my garage.

I also have 4 south facing 3x11ft tall clear windows (plexiglass wall panels that I'm hillbilly double paning with other plexi and caulk inside. They help raise the interior barn temp pretty significantly on a sunny day on their own. Although, this is the first time I've had any floor besides dirt in there. I've got 2/3 of my limestone/portland floor installed right now.

I see what you're saying about the mass below sucking up a bunch of heat... Wouldnt the same thing happen to an RMH with bench or bell sitting on a concrete or stone slab, though? It wouldn't be spread out as much, but I would think the same physics would come into play...

Thanks for the replies. I should add that I do have 1.5" foam all around the base of my barn to help isolate the soil in the barn from the surrounding soil. I also have a vapor barrier around the outside perimeter to help create an insulation blanket.

From the video in first linked thread, the description of what theu did seemed pretty close to what I was thinking. I do agree to not put any iso around the pipe, but from that other thread, it sounds and looks like they just cobbed around the pipe on the dirt and then built a wood floor over it, so their mass is in contact with the lower soil.
I will have a vapor barrier between my mass and the lower soil as well...

One of the reasons I want to have in floor ad opposed to a bell or bench is to pipe some of the heat over to the bathroom to make sure my toilet and pipes don't freeze. While it may not be a perfect solution,

I am, at least temporarily changing from total concrete to 411 limestone with a thin cement top coat for the floor. Much cheaper for now. Maybe in the future I'll get concrete. But I still think having the pipe in contact with at least some of that. I will have ti get better pipe tho, as what I was gonna use would smash when i compact the stone...

Edit to add: Am I just off my rocker on this? Anybody else want to chime in? Or have I added more clarity?

Hello. I've been browsing these forums a bit, off and on, for the past couple years. I built a barn/shop and I'm looking at eating it with a rocket mass heater. I have toyed with a couple ideas, and I'm getting closer to needing to make a decision. What I'm thinking would be my best bet overall is, because I haven't poured my concrete yet, to run my flue pipe in the dirt, with a little bit of mass directly on it, and some insulation boards to the side and bottom to help the heat go up, and then have my slab go over top of that. In my thinking, this would essentially turn my concrete slab into the thermal battery mass. I recall reading that regular concrete does not do well as the main mass directly on the flu, which was why I was thinking to have some Cobb in between, as well as allowing for some clean outs.

I had tried searching and didn't see anything. Has anyone currently on here try this or know someone who has tried something similar, and what were the results?