How to Choose and Change Your Air Filter

by Jeremy CookJune 14, 2017

Air filters, like many things in modern life, generally go unseen. However, they can have a large impact on your health as well as the “health” of your heating, ventilation and air conditioning (HVAC) system. These devices are often neglected until obvious problems arise, such as a broken heating unit. It’s a safer bet to change these filters regularly before you experience any issues, helping to keep your system in shape and provide your family with good indoor air quality.

If you’ve been neglecting these devices, though, where do you even start? Here’s a handy step-by-step guide that will take you through all the elements of an air filter change, from picking out the correct filter to performing the change to remembering to do it again in a few months.

Step 1: Find Your Filters

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Don’t forget filters hidden in unused spaces!

If you’ve just moved into a new house, or have simply neglected the filters for a long time, the first step is to locate all of them. Filters will reside under one or more grates in a wall or ceiling. Generally, a quick survey of your house is all that’s needed to find filters, but don’t forget to check closets and other seldom-used spaces where they may be hiding.

Step 2: Open the Grates and Measure the Space

Open the grate with a flathead screwdriver.
Open the grate with a flathead screwdriver.

Once you’ve located all of them, open up the filter grates with a large flathead screwdriver and check inside. You’ll need the dimensions of the space so you can purchase new air filters that fit. You might find dimensions printed on the side of your current filters, or you can measure the space where they fit if you can’t find the right number.

Pro Tip: Common house filters are one inch wide, so this is a good place to start if you don’t know the depth.

Step 3: Decide Between Pleated and Fiberglass

These filters are labeled via the microparticle performance rating or MPR system. Note the dimensions, 12x12x1 and 20x20x1, written on the filters.T
hese filters are labeled via the microparticle performance rating or MPR system. Note the dimensions, 12x12x1 and 20x20x1, written on the filters.

Besides choosing the right size, it’s important to note that standard fiberglass filters, which appear to have a random pattern of strings glued inside of them, filter the air well enough for your HVAC equipment. However, these filters do little to trap smaller particles that can affect a person’s breathing. For this, you’ll want a higher-end pleated filter, which is rated by the American Society of Heating Refrigeration and Air-Conditioning Engineers (ASHRAE) with a minimum efficiency reporting value (MERV). Pleated filters that you will generally see for home use varies between six and 13. See the next step for a more detailed explanation of the rating system.

Pro Tip: Pleated filters are folded in order to increase the surface area for catching debris.

Step 4: Choose Your Rating

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The numbers seen here signify a fairly wide range of what particles they will eliminate from the atmosphere, and making this even more difficult is the fact that there are several competing filter rating methods. If you get used to a certain MERV rating from one manufacturer, you may find that the next filter you come across instead has an MPR (MicroParticle Performance Rating) or FPR (Filter Performance Rating). In order to help you figure out what filter type fits your needs, as well as what the equivalent rating across brands works out to, refer to the chart above.

You may want to start at one of the lower ratings and work your way up. The better these filters are at cleaning the air, the more resistance to air flow they will offer your system.

Step 5: Remove Old Filter

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Once you have your new filters ready to go, open up your vent and pop the old filters out. Have a trash can nearby in which to immediately put the old filters, or be prepared to toss the old filters outside temporarily to keep from contaminating your house.

Step 6: Clean Holder

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Check the area where your filter previously resided, and wipe clean if necessary.

Step 7: Replace with New Filter

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Once you’ve removed the dirty filter, slide a new one into the same space, taking care to place it in the correct air flow orientation marked on the cardboard housing.

Pro Tip: Installing filters in the wrong direction will have a negative impact on your AC unit’s efficiency. Be sure yours are facing the right way based on the manufacturer’s directions.

Step 8: Close the Grate

The writing doesn't have to be perfect, but it helps to write the date down before actually inserting the filter into its housing.
The writing doesn’t have to be perfect, but it helps to write the date down before actually inserting the filter into its housing.

Close the grate up with a screwdriver (and latching tabs, if you need them) and you’re done with the actual filter change. Note the filter’s recommended change interval. You can write the date down on the filter’s housing for future reference, or even sign your initials to make things extra official!

Step 9: Schedule Your Next Change

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In order to keep things functioning correctly, you’ll need to change your filter again in a few months, if not sooner. At that time, you may only have a fuzzy recollection of when you did your last change. Set a reminder in whatever form of calendar you use to tell you to inspect it at the recommended change interval. When the event comes up, you can change and inspect your filter. If it’s extremely dirty, you may need to shorten your change interval, or even adjust it seasonally depending on how much your system runs.

As mentioned in step 8, you can write the date on the filter as you change it. This can be a good visual reminder of when it was changed, allowing you to check the date versus how dirty the filter is if it crosses your mind and you feel like opening up your filter grate. If you need more of a fail proof reminder, there are air filter accessories available, such as Wi-Fi enabled air filter monitors, that will send an alert to your phone when your air filter needs to be changed.

Perhaps being vigilant about changes doesn’t seem necessary, but good air indoor quality can be very beneficial to your overall health, and it’s well worth the few minutes and reasonable monetary expenditure needed to keep things in order!


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About The Author
Jeremy Cook
Jeremy Cook is an engineer and writer living in the Southeastern US. Jeremy holds a BSME from Clemson University and over 10 years of factory automation experience. He’s an avid maker and experimenter who builds anything that comes into his mind and loves testing out different DIYs for the home and writes about it for The Home Depot.

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