observations of a first time coal burner Suggestions welcome

Did my first coal fire last night... I picked up 300 lbs of Bituminous coal to give it a try. First thing I noticed is that it clumps together when it starts burning, I broke these up to keep air flowing and built a nice coal fire (about 6-8 inches deep) what surprised me was the heat (or lack there of) that came off of it. I had read stories, and heard relatives talk about the massive amount of heat that coal produces... This was not the case with my fire, I get WAY more heat/minute out of a good hard wood than I did with coal. It did however burn all night long, but I was not able to get my garage over 68 degrees with it, and it was down to 55 in the morning, I typically get it to about 75 at night with a wood fire and it is about 40-45 in the morning (outside temp of about 15-20)

Is this typical of a coal fire or do you have suggestions for me?

This question woiuld be easier to answer with more information. US stoves has different models.
You might also find out your coals BTU per pound rating, I need to burn twenty pounds of coal to eaqual one gallon of diesel.
Recently I learned there are different types of Bituminous coal, sub-bituminous C, sub-bituminous A, and probably many more, in this case the A and C indicate how much volatile gass can be expected as the fuel gets up to temperature.
The coal I burn is 25% water and will sweat if the stove has too little heat when I add coal, I wieghed a piece of coal, left it inside my house, in my low humidity climate and it lost 20% of it's weight, water I assume.
The web site from the local coal mine was very helpfull.
The more fires you have, the more you will learn if you keep an open mind.

Anyway,
The type and model of stove, will invite others with the same to coment.
How much grate area is inside your stove?
Can your grates be shaken, this is a requirment for bituminous coals, as far as I know.
As much information as you can get about the fuel is good also.

The model is a 1537 hot blast, and the BTU rating of the stove is 135,000. As for information on the coal, I am very limited, as It is very hard to find in Minnesota... I found a guy that had about a ton, and bought 300 lbs from him, He has had it for a couple of years, and it had been stored indoors, So I assume that it is fairly dry,

The stove has a shaker grate that is about 6" wide by about 24-28 inches long. This stove also has a thermostat that kicks to blower motors on when it hits a set temp (I have it set at 130 degrees on and 100 degrees off) While burning my first round of coal, I was having a hard time keeping the temp high enough to keep the blower fans running.

When you say that the coal needs to be shaken... how often, is this only on start-up, or does it need to be done even after the coal is burning nicely? With the fire I had going last night, there was still blue flames, and it had burnt down to about 1/2 of the size it was(after sleeping for about 7 hours)

use a deeper bed and/or different bituminous coal. you have coal with a high swelling index, it produces less heat per hour because it swells together and chokes itself off. where are you located?

A typical wood fire burns hot and fast,, unless you starve it for combustion air, then it smolters and smokes, and makes creosote.
Your first burn with your Bit coal sounds like it did OK.. you recognized the coal bridging and you broke it up,, so air could get through the coalbed and burn.
The next step will be to slow the heat down as it leaves the fire and travels up the chimney.
Do you have a thermometer on or stuck into the flue pipe?? Any MPD [manual fluePipe Dampers] ??
I think your US stove furnace has a sliding 'bypass' in the top of the combustion chamber, it should be positioned to route the hot exhaust around and keep it in the steel box as long as possible..
The US stove products make a much better wood burner than a coal burner.. with coal, you need to extract as much heat as you can from the exhaust gasses then let it up the flue.. with wood, you need access to clean out the creosote, which means a very simple box for the combustion/heat exchanger..

I'd try it again, Break up the coal into small as possible chunks after it has stuck together, Make the fire as deep as possible,, mound it up in the center, with the sides at the top of the firebrick..
ONly use under fire air from the ashpan air inlet.. shut off the over fire air through the loading door after about 20-30 minutes, or once the initial yellow /smokey flames have turned blue.
close the MPD if you have one, this will help slow the exhaust leaving the steel box
Slow the fire down, and run the circulation fan all the way down the 85* or so.. get the heat off the steel box, and into the room.

You can put a wood split or 4" round down the middle of the coal, then load up coal on each side, this will leave an open path that burns away, leaving a combustion air pathway through the coal..

hope this helps..
Greg L.

Thanks for the advice Greg, I actually did the log down the center before I read your post, and it is the hottest fire I have ever had burning..... It is -2 outside and 82 inside right now... I am impressed, I will try closing the damper and see how it does tonight

Your firebed needs to be deeper.
I think the hotblast's firebox tapers down at the bottom. You need full air through the bottom. i.e. the ashpan should be as big as the firebox. If not you can't get enough air, and you probably can't efficiently handle the good amount of ash bit produces.