DIY water heater 2 boiler experiment

[lectraplayer]

I've seen many such projects online and doing one seems like it might have potential. I'm wanting to take a 33K-BTU propane hot water heater and turn it into a wood-fired hot water heater/boiler for domestic hot water and/or hydronic floor heat. It will go in my wellhouse (though I have utility water), not in my house, and I will use the same safety valve that comes with it. I also am not replacing my electric hot water heater until I see what this project will do. It has what looks to be a 4 inch chimney pipe with a vent collar.

A) How much chimney pipe do I need to get a proper draft? Should I forego the vent collar and run my chimney directly into my tank flue? Also, the vent collar has a small "blockage" (circular disk suspended on "crosshairs") designed into it. What is this for?

B) The tank has a twisted metal "divider" in the flue (through the center of the tank). What is this divider for? Will it help me or harm me on my draft?

C) I am thinking about using cinder blocks with portland cement & rebar built on the concrete floor of my wellhouse as the firebox. What (if anything) do I need to line it with and what would be the optimal size space for the firebox? What size intake air holes do I need? Would a 16x8 inch (one block out) opening on bottom course suffice?

 

[Boil&Toil]

Not a good idea as proposed. If you forge ahead anyway, be sure to put a pipe on the T/P valve so it will spray into the firebox in the event of an overfire, that might save your bacon a little.

The twisty thing is a turbulator - it helps get more heat from the hot gas into the water. While it won't help the draft, it's kind of the whole point of a water heater...the disk may server a similar function, or be for draft control.

Before introducing the exhaust from a wood fire into a water heater, the wood fire products should have fully combusted at high temperatures. Think 2-3 feet of very well insulated refractory tunnel between firebox and the W/H.

You'll probably kill the W/H if you forge blindly ahead.

 

[lectraplayer]

That's part of what I was thinking. This is as the projects I'm seeing online are, but I'm thinking a rocket stove based design may be better.