Which Air Filter Should I Buy and Does It Matter?

There are many choices when it comes to replacing your heating and cooling system return air filters. With that said; there are many filters that can cause more harm than good! 

Excuse me, what did you just say?

Yes, there are many filters that can cause more harm than good!

If you choose a filter just because the label on the box says it is “High Efficiency or High MERV Value" doesn't mean it is a good choice for YOUR system. (MERV is an efficiency rating for filters. The higher the Merv rating; the more efficient the filter.)

Some filters have a high static resistance and that can harm your heating and cooling system. Static pressure is the pressure exerted against the duct walls in your duct system. The goal is to have a total static air pressure of .5 in your ducts. Without getting technical, ( and most folks could care less); you don’t want to have high static pressure because it harms your system by making your compressor and blower motor work much harder. This will drastically shorten the life and efficiency of your system. It can also cause higher utility bills and noise.

Okay good to know right? How do you know which filter is right for your system? All systems and duct work are different due to design. Some are definitely better designed than others. The simple method to “test” your filter of choice is to follow the steps below:

Step #1

Take out all return air filters (where the air goes in) in your system. They are located in the ceiling, walls, or in the indoor unit.

Step #2

Go to your thermostat and turn the system to off, BUT, turn the fan selector to “ON” from “AUTO” position. This will run only the inside fan.

Step #3

Go to a couple of supply air registers (where the air comes out). Now feel the strength of the air coming out of the vent. Step away approximately 5 or 6 feet from the register. Now feel the strength of the air flow. Remember this feeling.

Step #4

Install (put) in your new filter/s (you may have more than one in some cases for that system)

Step #5

Go back to the same registers as before. Now feel the air flow strength form the same distance as before (5 or 6 feet). If the air flow strength feels about the same; that/those filters will work fine for you. If the air flow feels significantly less; DO NOT use that filter. It creates to much resistance for your duct system and may cause harm.  You may have to purchase a less efficient filter with less resistance.

Step #6

If you are still not sure which filter to use or want to be sure; please contact us to perform a static air test and air flow measurement using our special testing instruments. This will take the guess work out of your choice and we will also inspect your duct work and make recommendations (if needed) that will help you feel more comfortable and help your system last longer while operating more efficiently.

Thanks for reading and we hope this helps you make a smarter choice on which air filter you should buy.