Coalfire wrote:Need to know how many pounds of coal are being burned in a day.
Yes. You mentioned half a hopper burned in 12 hours. That doesn't sound like much coal in cold weather. How many pounds in that half-hopper? And, where on the stove are you measuring 400 to 500 degrees? If you have an infrared heat gun, check it in lots of locations. You can do the same with a magnetic thermometer but it's more tedious moving it around and waiting for it to adjust.
Are you sure you are shaking down the ashes adequately? I have seen cases where I appeared to have a healthy fire when I looked at the top of the coal bed, but not getting much heat, and it turned out the bottom 2/3 of the fire box was ashes so I really had just a small fire. After you shake down, look in through the ash pit door and make sure you are seeing at least a little glow through the grates, not just the darkness of burned ash. If not, shake some more!
You need a bent steel rod to poke up through the grates from the bottom (after shaking), and you should see a few very small burning embers fall through into the ash pan when you poke up through the grate holes and wiggle it around. An old paint roller handle can be made into a nice poking rod by straightening it out then putting a right-angle bend a couple inches long at the end.
P.S. Does your stove have air inlets on the upper door? If so, they should be almost completely CLOSED once your coal fire is established. If you have them open a lot, your chimney draft can suck in a very large amount of air over the top of the coal bed, and all that air and most of your heat just goes up the chimney.