Bought my Surdiac Gotha 511 used along with 3 ton of coal to supliment my oil burner. It's rated 30,000 to 44,000 Btu/hr so I didn't figure it could handle heating the house by itself. The house is about 2,200 sq ft built in 1941 without much insulation. It has turned out that we have used very little oil since starting the stove the end of Nov. Even during this cold snap the oil burner hardly came on. Of course letting the temp drop to 58 F helped a bit too
My stove looks just like the one at this linkhttp://www.hearth.com/econtent/index.ph ... r_fed_coal
The grate is only about 18" wide by 6" across and the hopper is about 4" above it, so it really doesn't have much of a fire box. It looks bigger than it is because of the duct work around it. It has been a challenge to keep it going overnight at times. When I go down in the morning all the coal in the box will have burnt and the fire will be working its way up into the hopper. It can only go a couple of inches up in before it runs out of air.
The first night after starting it it will burn for 9 hours no problem, but after that it's more like 7 hours. Where it is being pushed hard it forms clinkers that get in the way of fresh coal coming down. It doesn't help that the coal that came with it is junk. It has a high mineral content or something so the ash doesn't break up easy, and it doesn't have as much heat per pound as it could. After a couple weeks of fighting with it I went to Agway and bought a 50# bag of Kimmels low ash pea coal. As it burnt the ashes crumbled and made room for coal to come down from the hopper. Also got a longer burn with more heat. But it cost 9.25 for a 50# bag ($370 per ton) so I figured I'd try to make the junk I had work.
So long as I dig out any big clinkers and shake it down well before going to bed it makes it through the night ok. I shake it down and load the hopper before going to work. My wife gives it a quick shake a couple of times during the ten hours I'm away.