My furnace/hot water heater room has louvered doors that open into the rest of the basement. When the furnace kicks on it's pretty noisy for TV viewing, and wakes up guests sleeping in the room next to the furnace. I'd like to close off the furnace room with a solid door, which presents a combustion air problem. I had an HVAC guy take a look and he said it'd be easy to add two flexduct pipes (one near floor level, one near the ceiling) into this room connected to the fresh outside air, which would then allow me to close up the room. That sounds great, but two questions:
- Will these pipes to the outside make the furnace more or less efficient? My understanding was that they might actually improve efficiency, since the only fresh air being drawn in is the air being combusted, which today with the louvered door solution is being pulled in from the rest of the basement/house, which itself gets sucked in from the outside through cracks/leaks. Giving a direct line to the furnace room means I'm not combusting conditioned air, which theoretically would improve efficiency. But the HVAC guy said no, it'll probably make things slightly less efficient?
- Are the 2 required ducts basically passive inlet/outlet? i.e. when the furnace runs it pulls combustable air in through one, and exhausts the combusted air out the other?