Quote Originally Posted by Kasey Maxwell View Post
its only a 3/4hp fan, i can use it up to 8 hours a day here and there, the heat bill is the same because I don't heat this room, it stays cool and I close the door when I'm using the fan. If im going to be working in there I open the heat vent and let it warm up then close it before I start, with the door closed I don't get much if any heat loss from the house, just the room.
So, either that room doesn't get down to -20, which means you're pulling heat from the rest of the building (likely), or you're running your laser in -20 degree weather (unlikely). If it's neither of those, you have near zero airflow in your exhaust.