Sam Takoy wrote:

Hi,

I want to put a HEPA filter in my A/C Air Return Grille. I check local
big box stores and didn't find anything. Strike-out at local A/C
suppliers such as Michael.

I did a google search "HEPA Air Return Filters" and got essentially
nothing. Some sponsored links were promising, but I wasn't able find
anything there either.

Is this not a commonly available type of filters? Are they not
recommended for some reason? Can someone recommend an (online) place to
purchase them?

Thanks!

Sam

The 3M Filtrete 1900 MER filters are about the highest filtration you
will find in standard residential HVAC return filter sizes and which
won't produce an excessive airflow restriction and harm the system.

True HEPA filters would be available to fit the ventilation units used
by the asbestos abatement folks, but you would likely need to rework
your return to increase the return filter area in order to be able to
use those filters without excessive airflow restriction which will harm
your system. They are also expensive.

Suggest sticking to the Filtrete filters, they aren't far behind HEPA
and your system probably has too many leaks at duct joints for a true
HEPA filter to matter.