I use a wood fired water heater, its a Taylor.
I heat an 4000sq' shop, 4000sq' (1890) 2 story, 2000bf lumber kiln, hot water for dog grooming buis.
nuff of that.
I don't like the "underwater campfire" design for home built.
The mfrs. of metal WFWH's have 1 design consideration that has to be met, portability.
This comes with prices.
Compact.
Lots of welding/metalworking
Anyone build a fixed type like this?
Concrete block walls- about 4' x 8' inside dimensions. Here its 2' to the rock so I would dig to the rock and set the block on the rock, no footers. Walls about 3' high above grade.
back fill with dirt to outside grade.
Fire brick lined walls (no top yet)
Top is water filled exhaust heat exchanger (box of drinking straws design, vertical). 1" steel pipe could be set inside the box for extra heat exchangers (they are pre threaded, just bend to fit inside, make both ends exit the box and plumb/manifold them together with pex)
Burn area is 1 or more full length trough. Made from fire brick. set about 2' off the floor.
Chip feed to the trough (how later)
Auger ash out with full length auger that is about 6"+/- your ash pan above grade.
Bottom line I'm not worried about the btu do-ability of this (thats no prob)
BUT finding a block is the question.
Do you think concrete block would take the heat? Even if it is F/B lined.
Thanks
jim