Filtered Combustion Air?

[Matt Fellman]

This is a new for me.... I'm thinking maybe I should start filtering the air I put in my tires just to be safe :)

It's on a 90% Bryant forced air gas furnace. It was in an attic where I suppose there could be more dust.

Has anyone else seen this?

[James Duffin]

It looks like the house is so tight they are required to bring in fresh air from outside to meet the ventilation requirements. This filter is to keep the bugs out of the furnace. A guess with not much info to go on!

[Jim Luttrall]

According to their labeling, it is a "fresh air" intake, not combustion air.
Quite common here on larger homes. This likely ties into the interior return air to keep stuff out of the conditioned air stream, NOT the combustion air. Of course you were there. Filters that could be clogged should not be present on combustion air intakes.

[Rod Butler]

This is actually a pretty tight looking installation with a couple of exceptions:

1. I hate filters in the attic, they are a pain to service.
2. That's a pretty radical bend on the flex duct on the leaving side.
3. The uninsualted duct has a chance to heat the air before it enters the cooling coil.

Either way you put it, I'd call it acceptable and unremarkable.

:cool: