If you're burning the Kimmel anthracite from Tractor Supply don't worry too much about the coal coking. In my experience it doesn't. Then again you might come across a bag of coking anthracite from them. I found the Kimmel to be of erratic quality. Some bags would burn very cleanly while others would quickly load up the firepot with clinker.
Also, the bigger and straighter you can make the chimney for your hood the better. Two pieces of six inch chimney can be zipped together to give a good diameter when nothing else can be found. I'm told that a 55 gallon drum will **** the fleas off a dog if it gets too close. Best of luck and happy hammering.
Thanks for the info.
I went with a powered vent hood, I decided that I did not want it permanently attached, during the warmer months I may move the forge outside. I also wanted to be able to move it out of the way in the winter and use the hood for my foundry furnace. It seems to be working well, with little smoke in the shop even at start up.