Originally Posted by Sam Kade
I buy coal and logs from Dairygold as I have a boiler stove as the only heat source. To keep the stove going for 12 hours a day costs roughly €8.5 and the house is still comfortably warm in the morning until the stove is lit at 1pm. The last fill is 9pm and it lasts until 1am. If I were to get the same heat from oil even with an efficient modern burner I would use 3L/hour @ 58c/L that would cost €20.88/day. So how do you come to the conclusion that oil is cheaper?
Its nowhere near double the cost for the same heat, thats not to say you wouldn't burn twice as much fuel, people with oil/gas boilers tend to put significantly more heat into their home, partly dues to the convenience, running heating for longer periods,being too lazy to turnoff radiators program zones and in general heating the entire house - you wouldn't find many people with boiler stoves heating the utility room or empty guest bedrooms.
At current prices the coal probably just about pips the kerosene. Its not so long ago the kerosene was 90+c a liter though at which time coal was saving several hundred euro a year versus oil for the average house.
Kerosene = 9.8kwh per liter 58c / 9.8 = 5.9c/ kwh
Assuming 85% efficiency for a real world condensing boiler with appropriately sized radiators, flow rate etc.
5.9c/kwh / 0.85 = 6.94c/kwh
Hiqh quality Bituminous coal = 8.5kwh /kg = 4.7c/kwh (assuming €16 per bag bought in bulk from coop - in Dublin probably more like €20 per bag)
Quoted solid fuel stove efficiencies are derived from an unrealistic test, real world efficiency of a modern boiler stove burning coal is probably 75% at best with dry fueld, appropriate loading, riddling, water circulation, draught adjustment, etc.
4.7c/kwh / 0.75 = 6.27c/kwh @75% efficiency