Choose the Right AC Filter

When I go to my local “big box” home improvement store, I am strangely drawn to the aisle where they sell air conditioning filters. Sometimes I am educated (or amused) by the vast assortment of AC filters. And, I am often distressed as I see people leave the store with an inexpensive filter that will cost them hundreds of dollars in AC repairs in the future.

Let’s look at a few things that will help you make the right choice from the dozens available:

Begin with a Good Fit

Nearly every AC system is designed with a track for the filter. It may be in the blower unit, the ductwork or a grille. The right size filter fits easily but snugly in the track, without gaps where air can bypass the filter. Never settle for a filter that is ‘almost’ the right size. When in doubt, consult the owner’s manual or ask your service professional.

If your filter is in a grille, it can be frustrating to find that ‘grille filter’ sizes differ from standard sizes. A 20 x 20 filter will not fit a ‘20 x 20’ grille in the ceiling – close, but not quite. If you must force or bend the filter, it is the wrong size. Big-box stores rarely offer filters to not fit properly in your grille. The effort and modest expense to get a filter with a proper fit will pay off in the long run. At Complete Comfort, we will be glad to help you find the right size filter.

The Right Filter Material

One of my first lessons in filter selection came from a man who had sold custom filters for several decades. I asked, “why not use the ‘rug’ filter that you can cut to size?” He picked up an ashtray and a coarse blue filter and invited me to step outside. He dumped the ashes on the filter and gave it one or two shakes – everything went through the filter but the large cigarette butts. “Air conditioning contractors make a lot of money from these filters,” he said. “Not from selling the one-dollar filter, but hundreds of dollars cleaning coils and blowers.” Lesson learned. I don’t carry an ashtray, but I do tell folks, “don’t buy a filter you can read through.”

Check the MERV

The Minimum Efficiency Reporting Value (MERV) is a rating of filter effectiveness. MERV ratings range from 1 to 16. The higher number indicates the filter will remove smaller particles.

Filters with a MERV from 12 to 16 are typically reserved for computer areas and clean rooms. Filters rated 1 to 4 MERV are of little benefit. The most effective for general household use are pleated filters in the 7 to 12 MERV range. You might think the higher MERV would be recommended in every case. But higher MERV can restrict airflow and damage the air conditioner blower fan. Cooling and water drainage problems can also arise.

Consider Deep-Pleated

If your environment, health, and comfort require a highly effective filter, I suggest you consider a deep-pleated filter. In our home, we have a dog and allergies. Surrounded by pine trees, palms, grass, and an unpaved road there are a lot of airborne particulates. Consequently, we use a MERV 16 carbon-pleated filter. But the 5-inch deep pleats provide nearly 60 square feet of filter surface in a 20 x 20 filter. The filter is very ‘dense’ but the air conditioner can breathe easily (and so can I) because of the huge filter area. What is more, I only need to change the filter once a year and the coils are still clean after 4 years.

In the previous blog, I mentioned performance as an optimum balance of cost, comfort, and convenience. These filters are a bit costly, but comfort and convenience are amazing. In my home, the MERV 16 deep-pleated filter is the most effective.  

Whatever your home comfort needs, Complete Comfort is here to help you. Part of our service is helping select the effective filter that will provide you the best balance of cost, comfort, and convenience. Call us today at (561) 529-6262 or visit our website at