Hi Eric and welcome to the forum. Well, I'm one of the Clayton 1600 guys here to help you. Here is a few threads that should get you started on the right track. Slow Blue Dancing with Red Dressed Ladies in a Clayton CLAYTON FURNACE FIRED ON WOOD
Here is a teaser for you if you ever want to convert it to a stoker. CLAYTON FURNACE WITH DUAL READING STOKERS
Your Clayton should fire very well on anthracite, but you are going to be in for learning a totally different method of firing than wood or bituminous coal. When burning wood or bituminous coal it is fine to use the thermostatically controlled combustion blower, it will burn extremely well doing so, and a very fast hot fire can be obtained. But when burning anthracite, I've found that it will only give you short, hot, clincker results. I've also found that the anthracite burned in the Clayton will be very lazy to start, but will gradually build up heat over a much slower pace than burning wood or bituminous coal. This is where you have to learn patience.
The different size anthracite will also have different heat and firing results. The stove sized anthracite will be harder to get going and if the ash is shaken too much or too often, the fire will cool enough to go out. So I don't use it.
The nut anthracite does much better, catches faster, packs tighter, and should give a fairly good steady fire.
I've found that buckwheat or a mixture of buckwheat and nut anthracite gave me the best results and the longest burn times. The ash was finer and didn't clog up the grates.
But if you want a really hot fire fast, I've found that the Clayton burns best on Wood or Lump Bituminous Coal. The design of the firebox makes the Clayton an awesome performer with these fuels, but maybe as short as four hours and as long as ten hour firings of quality heat before it needs recharged. I've found that the Anthracite Coal does not burn as hot as the Wood or Bituminous without clinkering, but it will supply a very long moderate fire of 12 to 16 plus hours easily.
The key to getting these long results is the draft control. You are going to need at least .05 inches of daft to fire well with this stove, otherwise you will be constantly fighting to keep her going. That's a chimney issue and another topic.
So, I hope this will help with your coal burning experience. I'll be happy to answer anymore questions. DOUG