I don't disagree, Boiled Over, and I haven't soured! Someday I'll return to wood heating. I do miss it. Someday..... I just think going through this work for an unoccupied building is a lot. I recall fondly how piss poor my system would run when the temps dropped below 140. I also spend a lot of time in my garage. I am merely projecting (perhaps wrongly) how frustrated I'd personally be if I went out to the workshop to enjoy a day of working and I had to spend a considerable amount of time getting the system up to speed again. If the OP goes all-out on insulation maybe this frustration can be avoided? I'm just picturing the UP of Michigan...a metal building...and marginal insulation. With this setup could the system shed 10,000 btu per hour when not in use? Maybe, Maybe not? But if it does...he's dropping 20 +/- degrees a day on those tanks. Two consecutive days of not using the workshop in the dead of winter and he's drifting into "I wish I could just start a fire and start working on cool stuff" territory.