For this winter I calculated that we would need around 700 kg of wood. It turned out to be 736 kg. We light a fire in the morning, 1.8 kg of wood to warm the stove up, and then another 1.8 kg on the embers with reduced air supply. The process lasts between 3 and 5 hours. When it's still not warm enough after that, we add another 1.8 kg. At 6 o'clock, depending on the temperature, we may do another round of 1.8 kg to warm up and then another portion of 1.8 kg to keep the room temperature around 20 °C until we go to bed.
Neven's stove is really nice. The small fireplace is a good thing. I have to load mine (8kW) it with about 2,5 kg of wood each time, it makes a big difference in kWh, an my parents have an even bigger one (they use 0.5 m logs), I guess this is the reason for the overheating.
When I'm home, I usually turn off the heating oil heater. When it is very cold, I load the stove about every two hours, a little bit more in the evening or when the kids do homework, but the days were I'm home alone, I usually just do fire in the morning when everybody stands up, and start the fire again before the kids come back from school for lunch, then back again when they comes back in the afternoon. My wife wants more heat so when she's home, we use more heat (let's be honest, also sometimes from heating oil, anyway, some areas are too far away from the stove when it's cold outside). When temperature goes under 5°C, the heating oil heater doesn't agree to be turned off, so I have to turn of the radiators.
Temperature goes up and down very fast and at a much higher level than Neven describes (up to 22°C when it's very cold, up to 23°C or 24°C right now). This is because we leave all the doors open in order to heat the kitchen as well as upstairs the bathroom and the sleeping rooms because we want to limit the heating oil consumption. Furthermore everybody enjoys the infra-red radiation which means that the stove is sometimes loaded faster than really needed, but it's only hot air and temperature goes down quite fast when the wood is burned. We don't make fire long enough to really heat the walls at a high temperature.
A smaller fireplace would make it possible to enjoy as much the infra red radiation without heating so much the room, but than I would have to turn on the radiators in the sleeping rooms and in the bathroom.
I still didn't found the best way to improve energy efficiency. Some more thinking is needed.
I also tried briquettes (
http://www.equiwood.be/) and found that heat was produced more regularely and with a lower intensity than with wood, but the municipality provides local wood at a very good price that is prepared in a back to work project for long time unemployed people, these were too many good arguments to stay with wood. Cost per kWh would have been similar (these briquettes are made of wood sawdust mixed with horse excrements).
Thank you for all the shared experiences.
Etienne