Firstly my smoke house is made of 1/16" steel rolled round to five foot diameter standing six foot high , blanketed by 4" fiberglass insulation and then covered in stucco wire and mortared up field stones set up on a concrete pad with a 12" square hole in the middle which is in turn covered by a steel smoke diffuser. My smoke and heat source is an old airtight coal stove which sits downhill from the smoke house at about 8'. This stove is connected to the smokehouse by a length of 8" insulated stainless steel chimney. This setup works just great for hot smoking, for cold smoking "not so much".
Talking to the little woman about this problem last fall, (yes I do talk to her sometimes and it's not just when I want something special

Sooo what I did was install a heater core plus the squirrel cage fan that I got from the auto wrecker for six bucks. The 110 volt motor came from the same old air conditioner that I used for the house. I installed this core at the bottom of the smokehouse with a duct connected to the smoke pipe. It is connected to the house water by a garden hose and it works great and it's completely controllable dependent on the flow of cold water I can make the temp inside of the smokehouse drop like a rock or hardly at all.
Sorry no pics, firstly because I haven't figured out how to post pics on this forum and secondly because it's -34f with blowing snow outside and I ain't going out to take any pics of a snow covered smoke house.
Now I realize that this method would not work for everyone but out here in the wilds of Manitoba it is a good ,easy and CHEAP way of doing things.
So what method do you fellas use?
Swallow