# 2 filters? 20x25x4 + 20x25x1



## Red Squirrel (Jun 29, 2009)

The very thick ones usually have different stages, so you're probably fine. For the 1 inch you can probably get away with a cheapy one to capture the bigger stuff. Though if you get a slightly more expensive one it should make the 4 inch one last longer provided you place it first. That's what I would do. See what the hvac pros say though...


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## hvactech126 (Nov 11, 2010)

Those are nominal dimensions and there is no REAL difference between a 4" and 5" filter. You should not use 2 filters especially if the 1" is pleated. A fiberglass 1" would be fine though.


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## Yoyizit (Jul 11, 2008)

For that kind of money you should maybe get a plastic manometer and use it to tell when the filter needs replacing rather than following a one-size-fits-all schedule.


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## Marty S. (Oct 31, 2009)

Pull the one inch out and just use the 4". Two filters can really mess with air flow.


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