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Which Return Air Filter Should I Buy?

We frequently get asked, “Which Return Air Filter Should I Buy?” from our heating and air conditioning customers. They want to know which filters are the best at stopping dust, smells, allergens, etc.

It is a very confusing subject for many customers because of the many, many choices available and the hyped-up advertising associated with the filters.

MERV ratings are used to rate the ability of removing dust from the air as it passes through the filter.  MERV is a standard used to measure the overall efficiency of a filter.  The higher the MERV rating means the fewer dust particles and other airborne contaminants that are able to pass through the filter.  MERV ratings range from 1-16.

Please Google the filter or brand of filter you are thinking about purchasing to get the MERV rating information. There are too many different filters and options to mention here.

The important thing to remember is to buy a filter that will give you the most filtration for your money and that will not harm your system. If you buy a filter that has too much air resistance; it will cause your system to work much harder than it was designed for.

This can cause premature blower motor, heat exchanger, and or compressor failure. Your utility bills will also rise and the comfort level of your house will decrease because of this situation caused by the “wrong” filter for your system. This is a bit scary.

All duct work is unfortunately not designed well and by installing an incorrect filter for “your” system can cause serious issues mentioned above.

The simplest way to choose a filter that will not cause harm to your heating and air conditioning system is to pick the filter/s you want to install and:

1)     Turn on your heating and air condition system’s indoor fan motor (Fan “ON” position from auto)

2)     Remove all return air filters and refasten the grille doors. (Air goes in)

3)     Go to two or three different supply air registers (Air comes out) and feel the amount/force of air that is coming out of these registers. (You can also measure with a tape measure and a tissue the distance the air travels between the register and the tissue as you go away from the register until the tissue doesn’t move.)

4)     Now install the new return filter/s and repeat the #3 process.

*** With the air filter of your choice in place and with the indoor fan on; if the air flow feels about the same – you are probably “good –to-go” with that choice of filter.

**** With your choice of filter/s in place; you noticeably feel LESS air; this filter/s will not be a wise choice for your system and may cause harm to your system as discussed above.

Bottom Line: Purchase the best filter you can afford that will pass the above simple test and you should be fine.

Note: You may find that only the very inexpensive blue filters that you can buy anywhere is all your system can tolerate due to your duct work design. If this is the case; you can purchase a can of Endust and spray it on the air entering side of the filter only and improve the efficiency of that filter by up to 10 times. There are no chemical smells to be concerned with. The spray improves the “static cling” only.

We hope this helps answer which return air filter should you purchase.  If you have any questions or concerns please contact us at allseasonshvac@cox.net or (757) 421-9790.  We are here to serve you with quality and integrity.