I am heating a 2500sf block building with only insulation in the ceiling and no windows (normally an icebox in the winter). So far this furnace is holding its own. It had some help from the pellet stove the last week or so with the single digit temps we had, but the cold was short lived.
I have been inspired by forum member Lightning to modify my furnace to be better suited to burn anthracite. In addition to secondary combustion air, I have added a window to the load door, and retrofitted a real set of shaker grates. The "shaker grate" from DAKA left a lot to be desired. I have since fitted a set of shaker grates from a woodchuck 2900 furnace and couldn't be happier. Tending is now a few throws of the handle instead of 20 minutes of poking, raking,and bouncing grates.
