Best AC Air Filters and How To Improve Your Indoor Air Quality

All You Need To Know About AC Air Filters and Improving Your Indoor Air Quality

There are three types of filters in our home, listed below in descending order of priority…

1. The air filter we should all be changing every month.
2. The AC coils which catch the particulates that the air filter does not (not a good thing).
3. Our lungs, which catch everything else (worst filter of all).

Knowing that we don’t want to breathe in all the harmful particulates, chemicals and dust it is important to know which home air filters are the best and how we keep our indoor air quality clean. 
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We have all heard that the EPA estimates that our inside air is 10 times more pollutant than the air we breathe outside, but where does that come from in Arizona homes?

What is the source of indoor air quality pollutants in Phoenix?

Air leakage in the wall behind the TV allows dirty attic air to come into the house through electrical penetrations

The main source of dust and poor air quality can be attributed to what is behind the ceiling and in your attic.  Have you been in your attic lately?  It’s a nasty place filled with itchy, dusty and chemical filled insulation that is supposed to be separated from the inside of the house… right???  Not exactly.  Builders certainly intended the attic to be separated from the inside of the house but it’s what you don’t see that can harm you.  Behind the drywall are lots of connections from the attic into the house that you can’t see?  Don’t believe me?  Take a look at this thermal image of an interior wall and the heat gain coming in behind the mounted TV.  That heat gain is coming down the wall via air leakage from a simple electrical wire hole that was never sealed.  Ever see little crickets or ants in your home?  They know where those air leakage pathways are and they are experts at exploiting them, in just the same way the Laws of Thermodynamics bring in contaminated attic air through air and duct leaks.
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Duct leakage is present in every home, even new ones, and duct leakage, especially on the return side can be the reason why you have to dust your furniture off every week.  When your air conditioner turns on, the return sucks air from inside the house and blows air out of the supply registers.  Well, lots of times, the return duct is not sealed well and every time the return kicks on it sucks not only the inside air but also a good amount of attic air as well.  How much?  Try 10-20% on average.  By sealing the return duct all the air that goes into the system now is coming from the house, not the attic.

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What’s the best filter for indoor air quality?

Let’s start with assuming that your ductwork is sealed with mastic so we aren’t breathing and bringing in any more attic air inside.  Now that we have a sealed ductwork system, next let’s start with what filters you don’t want. 

You want to stay away from:

1. 1” pleated filters
2. Washable filters

Why, it seems like every store is promoting these filters as good filters?  Wrong.  These filters make the AC system work harder because they are restrictive.  They don’t have enough surface area for the unit to breathe in, so it has to work harder and starts to over-amp the components.  Have you had to replace your capacitor again and again?  Look to restrictions in your ductwork and filter for the answer.  Stay away from these filters at all costs, there are better options.

Filters that we recommend to all homeowners are:

1. 4” HEPA filters
2. 6” HEPA filters

These filters work very well as a filter and they don’t make the AC system work any harder.  The 4” deep pleat give the unit plenty of surface area to breathe in without restrictions.  They are more expensive but they last 6 months and a small investment beats having to replace your HVAC system or chronic health problems down the road.

Filters that are good, but not great are:

1. The cheap 30 day throw away filters

​These filters are inexpensive and they allow the AC unit to breath without restrictions.  They are readily available however they do not filter as well as our 4” HEPA filter.

How often should you change your air filter?

​ The common 1” pleated air filters are good for 90 days because that’s what it says on the packaging… right? If you read it carefully, it actually says they are good up to 90 days.  Unfortunately, for Phoenix homeowners the packaging should read for 30 days.  Yes, we recommend replacing your 1” pleated filter every 30 days.  How important is it?  Very, unless you want to pay hundreds every year or two to replace AC parts in the middle of the summer than feel free replace it every 90 days.  

Are washable/reusable air filters good?

Some AC companies offer washable air filters to their customers but the only person you would be hurting is your AC technician’s commission by passing on them.  Fact: washable air filters are an unneeded add on.  You may hear, “it’s the last filter you’ll ever need,” and that may be true but it’s also going to increase your energy bills and put more stress on your system which causes the AC parts to fail faster.  Washable AC filters are similar to the hazardous 1” pleated air filters because they are both restrictive to your AC system.  Image breathing through a shirt compared to a slotted mesh, which would be easier? 

On top of the restrictions washable filters take a long time to dry, leaving an open invitation for bacteria, mold and fungi to thrive.  The MERV rating is also one of the lowest on the filtration scale, meaning that your home isn’t even getting a good filter from it.  We encourage homeowners to get rid of their washable filter and go back to the 30 day filters.