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Old 03-23-19, 12:43 PM   #5
Apprentice EcoRenovator
Join Date: Jul 2016
Location: Georgia
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I've had mixed feelings about K&N filters for years. Their off road motorcycle filters improved breathing but were terrible at keeping fine silt out of the engine. Some riders started putting the OEM (oiled) outer foam filter over them to compensate for what was really just a bad filter for the application.

Some reusable filter manufacturers do it better than others but most do it badly. I threw away the last set of washable AC filters because they caused so much pressure drop the evap coil iced over from inadequate air flow.

I installed a substantially oversized filter housing in my parents system to compensate for the pressure drop of a premium Filtrete. It still caused enough pressure drop to collapse the return duct. I gave up using premium filters when the air handler in my house inhaled a clean filter.

The bottom line with filters is this: Improving filtration for a given area results in greater pressure drop. If you want better filtering you really need to increase filter area. My existing 2 ton unit has one 16X20 filter. The new unit will have four 16X20 filters.

K&N filters work great for cars if you keep them clean and oiled. They work great for chainsaws because fine sawdust isn't abrasive and blows through the engine without much affect. K&N might work well as a washable AC filter. Given my experience with them, I share ham789's skepticism if K&N doesn't publish particulate and pressure drop data.

Last edited by CrankyDoug; 03-23-19 at 03:08 PM..
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