Some friends whose woodstove has expired have indicated an interest in a new efficient wood boiler, and tying it into their HW baseboard heat. I have a downdraft boiler myself and am completely happy with it, but for various reasons, I think a Garn in a nearby outbuilding might suit them especially well. I've seen various descriptions of Garn installs with a plate HX between the Garn and the heated spaces, where some of the heat zones are above the Garn. What I am wondering is: just as some do "solar drainback," could one do a system where at least the 2nd floor of the heated space did not rely on the boiler system to stay full of water at all times, and, rather, relied on pumping to get water and heat up there as needed? Seems as if it might simplify things- if it's suitable?