|reply to misiek |
Re: External air supply for an 80% AFUE furnace?
I am by no means an HVAC expert and in our case we do not even use a furnace, rather a wood stove in the basement.
Our house is very tight so we have a problem with depressurization when exhaust fans are in use. Using the range hood will back-draft the chimney if the stove is not in operation.
I ran a 4" insulated duct out the rear basement wall and put a small fan to bring in air on the wall near the stove. I have no way to measure how effective this is but I have to assume it is better then nothing. I leave it running year round.
The hardest part was finding an inlet. When I first installed it modified a dryer vent. Took out the flapper and glued in some screen. That tended to get plugged up quickly. Recently I found a real inlet that has larger opening screen so it doesn't get plugged up. The louvers are removable for easy cleaning. I added a regular screen on the inside vent to keep out small bugs. That opening is much larger so clogging does not seem to be a problem.