The sky is clear, and the outside temperature is 3*- 4*. The house has dropped off from 70* to 68* or so. The hotwater baseboards are only luke warm. But I'm a long way above the 58-60* that I kept the house at when I burned only propane. I burned only $5 of coal last night, if that, which is much better than the $30-$40 of propane to keep the house 10* cooler.
However, I am a bit disapointed, I had a large load of coal in my boiler last night, in anticipation of the temperatures dropping below 10*.
The house stayed warm but the heat load from the house really pulled a lot of heat from the boiler. This meant that the combustion blower ran most of the night and the coal was being burnt at a high rate. The pile of coal after 9 hours had burnt down to mostly glowing embers with a little blue flame dancing above. The 8"-10" deep pile of coal was only 2"-3" deep and not putting out much heat.
The water temp was down to 120* which is barely enough to keep the temperature sustained in the house.
I 'gambled' with an experiment last night, I used only coal, [I can find only Bituminous here] and didn't toss in the usual three big oak logs into the back of the firebox behind the coal. I needed those logs last night, but thought that with the larger than normal load of coal I would get through the night and maintain 140*+ water temp.
The ash pan was very full this morning, and a lot of the ash was thumb-sized 'clinker' and burnt-out coal. My coal is apparently poorer quality than I had thought.
So tonight, I'll go back to my normal routine and add a few logs to the firebox for extra heat. I need to find another source for coal in Michigan, hopefully anthracite is available somewhere.
Greg L LsFarm