My dad heats his couple greenhouses with wood, used to heat them with propane but it was running $60k plus a year to do so. He switched to wood and now goes through 20-30 cords. His heating now is accomplished by double barrel 55 gallon drum stoves in the smaller greenhouses and a large forced air wood furnace for the larger one. He then has kerosene torpedo heaters to act as backup. Problem is he is getting old and to keep the greenhouses warm through the winter he has to feed the fires ever 2 hours and by feeding the fires I mean 1 wheelbarrow full of wood per stove and two for the furnace. I am looking to see if this can be accomplished by a wood boiler and very large storage system so that he can load up a hell of a lot of wood during the day and let it burn and the heat is used during the night. Also a boiler that could take 4' long pieces and be loaded by a tractor to reduce the amount of cutting and lifting. Going off of the propane heater size before the switch to wood, there are 2 smaller greenhouses and their heaters were 350k BTU each and one larger one that had 900k BTU worth of heaters. Due to the extreme amount of work it is to keep them heated with wood he shortened some of the greenhouses so there is roughly 1 MBTU heat load total now in-between all of them. What I was thinking: 1. Several large popane takes to act as storage. Insulated, 2. Fan coils in each greenhouse running off the propane tanks. The greenhouses are generally held at 40-45* so there should be a large delta for good efficiency using the fan coils and 180* tank temp. 3. Very large central wood boiler. Not a gassifier as he burns fresh cut and somewhat green wood and I do not think that will ever change (getting 2-3 years ahead at 30 cords per year is quite a task!). If a secondary burn stove could handle it then great, otherwise an old smoke dragon style. 4. Would prefer if somehow the boiler could be loaded by a set of forks on the back of a tractor 5. Boiler would have a huge firebox size to try and minimize the reloading The heat loss is almost always during the night unless it is cloudy during the day. Even at single digit temps if it is sunny the greenhouses generally stay warm enough.