I just bought a house in the Tampa area. It has a 5 yearl old Trane system. Supposedly, a pretty nice system (according to the AC guy that i trust). Variable speed, new media filter on the air handler etc...
Anyhow, I moved in in May and the system ran alot through the summer. It's hot in Tampa, in case you were wondering.
But now that it has cooled down a little, the system isn't running nearly as much (hooray!) But when the system is off, i notice a musty smell coming from the lone return grate in the house. It is in a hallway and when the system isn't running, there is a distinct musty smell that is coming from the return.
My question is this... Can I put a filter at the return even though there is a large media filter in the handler (located in the garage) or will this restrict air-flow.
Also, what can I do to clean the return duct... It appears to have quite a bit of dust in it. Which makes sense as it has been unfiltered for 5 years...
I also have a biocide chamber (UV Light) installed in my air handler just below the coils, so I am not too worried about the air coming through the supply vents. But I am concerned about the air that is coming back through the return vent when the system is off.