rmh with a bottom manifold

hey folks,


need of some of your pyrothology advice.

i am in the design process of a rmh with the thermal mass beeing underfloor.

du to some special condition i wont be able to sink the combustion unit all the way underfloor level see detail at: https://permies.com/t/238089/culvert-hobbit-home-rmh

my question is what would be the best aproach to transition from the combustion unit to underfloor piping.

my idea so far, manifold install on the side as usual but at an angle, and cobing everything around , having a small ''leg'' sticking out.

what would be your design for such a problem? any issue i should foresee with underfloor thermal mass.


thanks for the incoming brainstorm

With the combustion core centered in the culvert, you could easily sink it to the level of the ducting. Obviously this is not practical, but if you have it offset a bit but not against the side of the culvert, you could sink it a few inches. Every bit helps. Aligning the burn tunnel with the culvert axis would allow the most sinking and the least center floor obstruction. Placing the core near the bed area say 2/3 of the way back would give some separation of functional spaces, instead of being an obstruction in the middle of a space.

As for the transition to the underfloor duct, that is a very site-specific detail. All I can really say without being there at the layout is to make it as smooth as you can with the fewest bends possible. If the edge of the finished core surround is near the culvert centerline, leaving a couple feet of flat floor plus wall curve to walk around it, you will have little problem getting from manifold to duct.