I'm a little late to the thread but to answer the original question, the last burn at our homestead was May 11... we were blessed with 18" of wet heavy snow here. For those who live off-grid and depend on battery storage for power when power is not being generated you may find our thermal battery storage system interesting.
It's based on a rocket stove combustion core embedded in a thermal mass. I built this over the winter to do a better job at maintaining heat overnight in my shop and at the same time significantly reducing the amount of wood I burn and time I spent tending to fires. The long name for this design is a batch rocket masonry mass heater. It takes relatively small loads of wood in the firebox which is lit from the top and burns down. The combustion gases travel horizontally through a venturi port which speeds up the flow and make a 90 deg turn up a riser that is about 3' tall. The entire combustion core is made of high temperature refractory brick and the gases exit the riser into a double skin brick enclosure that is almost 6' tall. I embedded several thermocouples in strategic locations to monitor the temperatures. The gases in the riser reach almost 1,600 deg F where they exit the top into the brick enclosure with is a huge mass of roughly 7,000 lbs. The heat is absorbed into the mass and cools the gases until they drop to the exhaust port at floor level and then exit up the chimney. The mass does a fantastic job at capturing the heat that the chimney exit temperatures as it leaves the mass is only 175 deg F. There is zero smoke due to the high combustion temperatures ever last bit of combustible fuel is consumed. Consequently, there is also zero soot or creosote in the system, almost 100% clean burn. With the rocket mass heaters you also don't have to be so choosy with what you burn. A bundle of sticks off of your land will work just as well as carefully seasoned hardwood. It takes a few days to get the mass up to temperature, roughly 140 - 150 deg, but once it is it only requires a couple quick burns a day to maintain it. We used to burn about 7 cords a year and I'm guessing from our brief experience that this will at least cut in half (I only finished building the heater in March).
Here's a picture showing the combustion core and a picture of the finished heater which sits behind the bar in the shop.
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