Just to put in my .02 on something that I know almost nothing about, Have you thought about steam?
I once built a home heating system with sort of a coil in the fire place. It blew up the first time I used it.
Seriously, you can get hurt. My solution was to have the water circulating constantly, and used a 80 gallon storage tank with a relief valve so the water didn't get too hot. Worked perfectly after that mod.
Nice build, good luck.
Judge Jim, Given to me by Terry @ Git R Smoked.
Chef Jim, Gym, Jim, or CJ. I'm not a Chef, but I play one on the internet.
A veteran is Someone who, at one point in his life, wrote a blank check made payable to "The United States of America", for an amount of "up to and including my life." That is honor, and there are far too many people in this country who no longer understand it. Author unknown.