Hi everyone. I'm new here....just signed up. I am a welder and I ran across this site searching for info on building a wood boiler using salvage propane tanks to heat my shop building. I have seen them in the past, and heard of people doing this, but at the time I didn't pay much attention because I didn't think I would be doing it. I have a 250 gallon I was going to use for the fire box, and a 500 gallon to put the 250 gallon tank into to use for the water jacket. I have already cut them open so the threat of explosion is no longer an issue and am ready to get started. I know the specifics of how a wood boiler works and their parts in them because I have been around factory built units, and homeade units that were copies of factory units. I was wondering if there was anybody on here that has built one from propane tanks, and also if there are things I can do to make the boiler more efficient, burn hotter, and use less wood, like many of the factory ones claim due the routing of the exhaust to hold the heat in longer, as opposed to just cutting a hole in the top for a flue pipe? Any opinion from the experienced would be appreciated.