jrmurch wrote:fter about eight hours I burned through half a bag (20lbs). Also does the coal have to have a blue flame all the time, or should it just smolder. In order to keep a flame I had keep the ash door open a 1/4 inch, maybe that would explain that fast burn rate.
20 pounds burned in 8 hours is not an excessive burn rate, especially for starting the system up from cold. It's about equivalent to what I put through my hand-fired stove in very-cold weather.
It's not surprising that your fire went out if all you put in the stove was 40 pounds. As PC12 says, coal likes a deep bed, lots of fuel mass. A wood fire, left without new fuel, will often continue burning slowly until practically all the wood is consumed. Coal will not do that. Once you drop below the critical mass, the fire goes out. Just like a nuclear power plant, which would be my preferred heat source if I could fit one in the cellar.
Blue flames: Sometimes you will have them, sometimes not. Judge your fire mostly by its heat output, not its flames. If the whole coal bed is glowing red, you probably will have very few visible flames, and that's OK. The only time I worry about flames is right after I have loaded in a lot of fresh coal. As volatiles are driven off the new coal, gas can build up above the coal bed, and when it reaches the right temperature and air/gas ratio, it can make a (usually small) explosion. The best way to avoid this is by leaving some glowing coal exposed when you load the new coal, so it can help ignite the gas before it builds up. Then you will probably have lots of flames for awhile.