HEPA filters for central air?

I have two air handlers with slide-in filters (12×24 and 16×25). I am wondering if it is possible to use some sort of HEPA filter? I have read that the MERV rating is what is important and for a filter to be as effective as a typical HEPA filter, it must be at least a MERV of 17. But I only see filters with considerably lower MERV rating (a max of 11). Plus, I wonder if an an older system will be able to handle the higher resistance trying to pull air thorough a higher MERV filter? Installing auxiliary air filtration probably isn’t possible given the space limitations. Any ideas?

housepoor

in General Discussion 4 years and 10 months ago

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housepoor | 4 years and 10 months ago

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Thanks for everyone’s response. The HEPA filter question is obviously new post-COVID. But the brokers are being asked and they have no expertise in A/C systems.

nyc_sport | 4 years and 10 months ago

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The slide likely only accommodates a 1 inch filter, which will not get above MERV 14. A typical furnace/AC setup could not handle a HEPA filter, both because of the resistance and because it likely would be several inches thick. It would be fairly unusual to have a HEPA system on residential ductwork. An AprilAire type filter might get you to MERV 16. But I suspect your AC person would tell you to put one of those blue fiberglass MERV 4 filters in for best AC performance and dehumidification.

Guest User | 4 years and 10 months ago

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Wow, were sellers getting these types of questions before COVID? If you have an agent hopefully they’re talking to the other agent to explain to their client that this isn’t a worthwhile question because the answer will be regularly no?

housepoor | 4 years and 10 months ago

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Thanks. OP here. The house is for sale and people are asking if the A/C has HEPA filters.

Guest User | 4 years and 10 months ago

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Not all systems will be able to operate correctly with the additional resistance of the higher MERV filters. You risk burning out motors and/or freezing coils. If you do go this route you will need to replace the filters more often and potentially get the units serviced more often as well. I would recommend contacting the manufacturer of the unit to see if they can offer any advice as to what level filtration is appropriate to your units.
if you are doing this for Covid reasons you may want to consider UV installation within the unit to disinfect the air – this doesn’t filter, but will reduce bacterial/viral load.