I have installed 2 of the USStove add on furnaces one is a clayton 1557m currently burning wood and soon to make the change to coal. The second is a the clayton 1600 in my own house burning coal. This site is what brought me to burning caol from two wood stoves and ok heat with cold rooms in areas of the house. I started mine 3 weeks ago and am still learning.
I now have it down pretty good and I hope this helps, I am set up with a baro and a manual damper and having been a wood burner for quite some time I started as if coal was wood. My first mistake! I got a wood fire going and added coal as I had read on this site adding some and getting it going and so on till a real nice bed of coals,great heat and this is going to be great. Now as a wood burner what did I do? You guessed it I close down the manual damper as all wood people do. Wrong! I could go on with the story that you all can just chuckle over.
Open the manaual damper your draft is weak due to short chimney. A draft guage will verify that. Keep it in place should you burn wood you will need it.Get it going and don't rush it. I found before I got the inducer I had to keep the air intake open considerably.This link to usstove is their draft inducer for your unit,I needed one I have similar draft issues and it has made a world of change. http://www.usstove.com/proddetail.php?prod=11DIKL
This link is broken, either the page no longer exists or there is some other issue like a typo.
Don't shake it for 6 hours or so and add coal in small doses when needed you'll learn it. I got a metal grain scoop from Tractor Supply for adding coal and all I can say for that is SWEET!
I hope this helps and if you need more support I'll be back later.