So, I wanted to build a wood-fired water heater outside the house on the west patio where I could plumb it into the house system. I started out cobbing together some chunky old urbanite to make a base, and threw a bunch of trash in the center just to get rid of it:
The base got flattened off and then sat there for quite a while. I wanted to get the 'firebox' up to about mid thigh, for easy loading.
After FINALLY getting an old non-leaking water heater, I was able to get it up onto the base without too much trouble. This photo is from my beginning plumbing work. (I'd already filled up the tank to check for leaks)
Here's a shot of the tank sitting on the base with the trench for the pipe going to the house. You can also see the ropes going to the trees to hold it up, as it was just balanced on 3 urbanite chunks that I had cobbed into place. Seemed quite stable, actually. I was a bit worried the wind would move the trees and be a bigger problem.
And then I cobbed up a firebox, using the old 'sand mound as the void' technique, like one normally does with cob ovens. I have since pulled out the sand and had a fire in it and did heat the house. Oh, and yes, there are 2 temp/pressure release valves, so I won't be blowing anything up with steam power here.
The only trouble is the circulator pumps on the radiant floor system use more electricity than I anticipated, about 2.4amps each, and there's 3 of them (one is really the most useful, but still). Not sure what the next step might be.