As I wrote a few days ago I'm installing the 45,000 BTU model. Since I have worked hard to seal the cracks and insulate my shop, I'm concerned about possible negative pressure and starving the heater for air, possibly creating a CO problem.
I hate to just cut a 7-8" opening in the wall that would allow cold air in all the time. (And we do have cold air here in the winter!) The instructions call for a 1" square opening for every 1,000 BTU's.
So I wonder if this would work: Cut a 4" hole in the wall under the heater and install 4" metal ducting entering the shop for 1-2 feet. Then a 90 degree elbow and continue 4" duct up close to the heater. (A "L" shape) The heater is close to the wall. In the long vertical section I would install a 4" duct booster fan. I would get a switch, that I can't remember what it is called. I have one from Sears that I can plug tools and my Fein vacuum into so the Fein comes on when the tool is started and they both go off together.
I would wire the heater with a plug and plug it into the switch and then the fan so the fan only works when the heater is running, demanding air.
I would also put a flapper in top of the 4" duct, kind of like the flapper on top of the vertical mufflers on old farm tractors. This would prevent air from entering all the time, but would move up when the duct fan pushes air out. I would insulate the ducting.
The switch is about $25, the duct booster is $22 at HD and some ducting. Probably a total cost of $60 or $70.
I'm planning on maintaining the shop at 40 degrees during the winter, then when I'm working I'll fire up my wood stove to bring the temp up to 60-65 degrees. So I'm figuring the Hot Dawg won't be running a lot.
What do you think? Or am I being paranoid??
Thanks, Rick