I have a 95% furnace with a two 3" pvc pipes (exhaust and combustion supply) and my water heater is the same (two pvc pipes (exhaust and combustion). Fireplace is a direct vent as well (not power venting). So in terms of combustion make up air, I'm ok.

The delema is what to do with the 6" fresh air intake on the cold air return of my furnace. I want to try and minimize the cold air that leaks into the basement when the furnace is not running. Right now there is manual damper at the furnace connection that is about half way open. I also run my thermostat on "CIRC" mode which kicks the fan on for 10 minutes if there has not been a A/C or heat call.

I'm very interested in hearing thoughts on the pros/cons of a motorized damper vs barometric damper vs the old fashion P trap.

My current thought is to use the "Aldes 6" Backdraft Damper - BDD6" - has anyone had any success with these?

The motorized damper didn't really make sense cost wise when I'd be opening the damper on each "FAN" call.