smallish RMH with heated back

[carolothdac]

Hi everyone. greetings and salutations. Could use some validation and/or constructive critique on a build..Its for a 200sq ft shed/studio. The old man who is requesting needs a nice warm back integrated...I've come up with this basic idea and sketched it but have some questions.

The basic idea is to build a back on a single spaced bench seat that gets the heat prior to the seat so that the back is at least or greater in warmth than the seat. To that end I thought of trying to visualize the back as sort of a small bell or stratification chamber. The back itself will be a piece of steel and standard issue red bricks adhered to it creating an effective space/bell of say 4-5 inches of inner air space and that will be spread over the size of the back, say approx 2 ft x 2ft.

Any thoughts on the idea, drafting, where to put cleanout(s), possible small 2nd draft location etc

 thanks much

the burn chamber and the back will be using the common white ceramic fire bricks. After that will be red brick, as the temps should be OK by the time the heat gets to the seat. Was thinking of putting this right on the concrete slab, without any insulation there or around the inside of the burn chamber . But am open to changing one of those decisions...thanks

[masonryrocketstove]

I think if you build the bench and seatback as one open bell, without partitioning between the two, (and with the gas inlet below the seatback, the gas outlet at the bottom side of the seat) ..then the seatback should remain the hottest portion simply because of the gas stratification effect within a bell. If you add partitioning walls between the back and the seat, you might end up with a backrest that’s significantly hotter than the seat itself. Like, it might get uncomfortably hot to lean against if the backrest is the first section piped with the flue run, immediately downstream of the firebox?

(Edit) Oh, and adhering bricks to a steel inner core is gonna cause cracking in the brick facing adhered to it. Steel expands and flexes a lot more with heat than bricks do, and that’ll cause the adhered brick to separate and crack at the joints between them.

[carolothdac]

thanks, yes to keeping the back and seat as one uninterrupted unit. and I can turn it 90 degrees so that the first entry is at the back. As to using metal with brick. I see what you mean.. Was trying to keep the back as slim as possible but will have to use all bricks ..thanks

update:so did some dry stack test burns and didnt have great success and am reluctant to pursue the chair idea as it may be hard to get to draw, or get temps correct at various critical bench areas, or is over complicated. So the other idea is to have a flat horizontal surface to lie on - Do not really want typical bench heated by lingering smoke as that may not be hot enough. We want quite hot surface almost like a dry sauna. More than a 'warm place to sit/lie'. To that end, the only other idea is to make the typical Jtube or batch box design but instead of having the flame tower vertical, it would need to lie on its side. I assume this is not possible as its never been done as far as I can tell, but wanted to exhaust that as an option before giving up on the desire to have a hottish/very warm place for a human back. If this option isnt feasable, then a warm bench is the best we can hope for.

IF the above will not work, this is the compromise of original idea. Instead of a 'seat', the covered side of the burn tower would serve as the back rest and the horizontal bench would incoroporate a little S tunnel and then exit out the end and provide the seating portion

[carolothdac]

ALTERED IDEA- INSTEAD OF A 4 SIDED BELL - THERE IS JUST ONE 'SIDE'/SPACE FOR HEAT. ANYONE THINK THIS WOULD WORK?

ALSO, ANYONE SEE A REASON WHY THE END OF THE BURN CHAMBER WOULDN'T BENEFIT FROM CREATING A VENTURI CONSTRICTION LIKE IS DONE IN BATCH BOXES?