downstairs AC filters always dirty, upstairs never


Old 12-05-12, 01:01 PM
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downstairs AC filters always dirty, upstairs never

I have a two story home with two small dogs (that shed a little, but not a lot). The home was built in 2005. The dogs spend most of their time downstairs.
The upstairs has it's own Heat/AC system, and the downstairs has it's own.
I change my filters using Filtrete brand filters about every 2 months.
The downstairs is tile, and the upstairs is carpet. The upstairs is vacant mostly, so during the day I set the thermostat so that it doesn't heat/cool as much as the downstairs (which is occupied during the day).

The 3 filters downstairs are always *very* dirty when I pull them out, and the upstairs filter (only one of them) looks as clean as the day I put it in. I beleive that the system is sucking air through the return vent (upstairs) - when the system is on upstairs, I can feel/here the air being pulled in through the return vent/filter on).

Perhaps it is because of the carpet upstairs that the filter is so clean? Is this normal? If the upstairs filter looks as clean as it does, can I go longer in between changes?
thanks guys!
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Old 12-05-12, 01:26 PM
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Well..if the upstairs unit is mostly off, then of course the filter would be much cleaner. Am I reading something wrong here?

Depending on the type of filter...2 months might be a little long.

In my will get dirtier filters with carpet than you will with hard surfaces...assuming regular floor cleaning.
Old 12-05-12, 01:41 PM
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While it is true that the upstairs is off more than the downstairs (I would say it is on only 50% of the time when compared to the downstairs unit). However, the filter looked so clean, I didn't change it for a year, and it still looked brand new. that is what I am questioning.... could this mean something is wrong?
Old 12-05-12, 05:54 PM
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Ceiling mounted returns will always be less dirty. Also the carpet acts as a sponge if it is good shape. Allso the tile floors will spread the dirty easy
Old 12-05-12, 08:43 PM
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And, a fair amount of the dirt tracked in will stay in the downstairs area.
Old 12-06-12, 07:31 AM
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Additionally, perhaps the upstairs return is not pulling in near as much air through the filter when the blower is operating as the downstairs RA.(?)

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