Making Wood Stoves Great Again! (3)
The first tests with the new and improved bed of soapstones have been conducted. With one large wood filling, the 12 kWh JAcobus wood stove burns for two hours. Adding an additional half-filling after that extends the fire to a total of 3 1/2 hours.
In that time, the room temperature became 23 degrees Centigrade. The stones reached 160 to 170 degrees, indicating 120 to 130 kWh of energy storage. Twelve hours after having the fire in the stove go out, the room temperature was still 21 degrees, with the stones sitting at 24,6 C, meaning they still have a few kiloWatts left in 'm.
So, what does this all mean for using the now augmented wood stove? Well, a few things. First, this one wood stove, with added heat battery, is enough to heat the whole house.
Secondly, instead of going for a continuous heating cycle, where the stove is on when we are at home, a new method of heating our home can be envisioned. One where we do one or two burn cycles a day. Fill the stove with wood, and lots of it, and let it burn at high capacity.
A burn cycle like that takes two hours in the JAcobus 12. If - in those two hours - the temperature in the living room reaches 22.5 to 23 degrees, and if the stones are between 140 and 170 degrees Centigrade, well, then you can let the fire die. The stones will now take over and provide heat for another 10 to 12 hours.
Did the stones or your living room not yet reach optimal numbers? Fill the stove with an additional half quantity of wood, to bring the room and stones up to spec, and extend your burn cycle to 3 to 3 1/2 hours.
Thirdly, we can learn from the above, that on a normal working day - say Monday through Friday - one burn cycle is probably enough. You lit your stove as you come home from work. You let it burn for 2 to 3 hours. As you go to bed and sleep through the night, the temperature slowly drops, but it will still be around 21 degrees when you wake up (in a well-insulated house at least).
Weekend days? During the cold season you can run your wood stove twice for two to three hours. The stones will keep the house warm and cosy for the other 18 to 20 hours ...
Based on a cold season of 26 weeks or 6 months, and given that every week sees two days with two burn cycles, and four days with one burn cycle, and one day of you being absent, so no burn cycle at all ... we can now calculate a weekly needed wood consumption of 222 kilo. Based on the fact that every kilogram of wood delivers 3.6 kWh.
A pallet of oven-dried wood weights 1350 kilo. That is enough for 6 weeks of fuel, given the above example. So ... per year, or per cold season, 4,3 pallets are needed. With a price per pallet of EUR 500,-, the yearly costs to heat the house will be around EUR 2.140,-. That's EUR 178,33 per month. And that's not yet taking into account the wood you might cut out of your own garden or fields ...
From 24 to 52 stones ... a doubling in heat retention capacity ... for 10 to 12 hours of additional warmth!
