How Do I Change My Air Filter?


You are a busy homeowner and you want to regularly maintain your mechanicals in the home.  One way of extending the life of your heating and cooling systems is to regularly change your air filters.  Not only will it help the units be efficient, but it will maintain good air quality in your home.  That should also translate to consuming less energy and lowering your utility bills.  

Some suggest that you need to change your filter every 30 to 90 days.  it can depend on the type and efficiency of your filter.  Try to change them during the peak summer and winter months when your system is at its highest use.

Should you have cats and dog in the home, you may want to change more regularly to catch dander.  Having little ones in the home with allergies or health issues might also be another reason to purchase a case so that you have all the clean filters easily within reach.

To change your filter, follow these easy steps:


• Step 1: Buy a New Air Filter – Before buying a replacement filter, check your owner’s manual to identify the right number or size of your filter – it could also be printed on the side of your existing air filter.(see How do I Measure My Air Filter)

• Step 2: Turn Off Your HVAC Unit – For safety, turn off your HVAC unit before attempting to change the filter. If you can’t figure out how to turn off the unit, turn off the breaker.

• Step 3: Remove the Dirty Filter – Most air filters are located to the right or bottom of the unit and should easily pull out of the slot. Although not common, some filters are found in air vents instead. If that is the case, you might need to contact a HVAC professional for assistance.

• Step 4: Insert Your New Filter – There are arrows on the new filter to indicate which side should be facing the outside air. The filter should slide into place easily.  (I might suggest that you take a Sharpie Marker and put an arrow on the outside of your unit to remind you which way the air flows! ) 

How Do I Measure My Air Filter?


When needing to replace your filter, these simple steps will help you measure!

        To measure your filter, follow these easy steps:

      • Step 1: Measuring Length and Width (L x W). (If your filter is not a square, the smallest measurement goes first).

     • Step 2: Measure Depth (D) – Measure the thickness of your filter.

     • Step 3: Put Your Measurements Together (L x W x D).

     • It’s as simple as that! You are now ready to buy the right filter for your AC or Furnace

How often you need to change your furnace or air conditioner filter?

This will depend on the type of material and efficiency of the filter you select.

Fiberglass Filters – Fiberglass filters are a low cost, disposable solution but need to be changed every 30 days or less.

Pleated Filters – Pleated air filters are also disposable but typically have better efficiency than fiberglass and can last longer – up to 90 days depending on the season.

• Important Factors – If you live in warm climates and your unit is always running you will want to change more frequently.   If you live in a colder climate, you may not use your AC as much.  There are no wrong answers.  Just be sure that you are changing your filters !!!

Actual vs. Nominal Size      (The Size Of Your Air Filter)

Not to confuse you but filters have a “True size” and a “store size”.   But they are called “Nominal size” and “Actual size”.  

Actual Size consisting of the true dimensions of your filter when measuring length, width and thickness, and typically includes a fraction of an inch. For example: 19 1/2 x 19 1/2 x 3/4

What you might not realize is that filters are not sold by their actual dimensions!   Instead manufacturers use a “rounded up number” on their packages.  This measurement is referred to as the “Nominal Size”.

          So a filter with:

          • Actual Dimension of 19 1/2 x 19 1/2 x 3/4

         • Will have a Nominal Size of 20 x 20 x 1

         • Nominal Size is the measurement to look for when buying your replacement filters


              Nominal Size

            Actual Dimensions

                        Example A

                                  20 x 20 x 1

                                 19 1/2 x 19 1/2 x 3/4

                        Example B

                                 16 x 25 x 1

                                 15 1/2 x 24 1/2 x 3/4

Please keep this in mind and you will be rolling when ordering !! You now know the difference between “Actual Size and Nominal Size”.



Why 3 different rating systems?

Someone somewhere decided to make things confusing.  The three rating systems were created by different organizations. MERV is the domestic and international Industry Standard rating system established by the American Society of Heating, Refrigerating, and Air Conditioning Engineers. The other two rating systems were created by “3M” and “The Home Depot” —- imagine! but at the end of the day they are rating the SAME filter!

           So, what is a MERV Rating? 

MERV Rating (Minimum Efficiency Reporting Value): The MERV Rating is the primary rating system used in the industry, both domestically and internationally. Established by the American Society of Heating, Refrigerating, and Air Conditioning Engineers, MERV rates a filter’s ability to capture and hold particles and pollutants.

MPR (Micro-Particle Performance Rating): MPR Rating is a rating system developed by 3M. It rates the manufacturer’s filters and their ability to capture airborne particles smaller than 1 micron.

FPR (Filter Performance Rating): FPR Rating is a rating system developed by The Home Depot for brands sold through their stores, including Honeywell. It utilizes a color code and number scale (4 to 10) that closely resembles the MERV rating.

Please call us if you have any additional questions.  We can ship you an affordable filter that will fit your unit at a good price and ship it right away.