Changing and Maintaining Your Home HVAC Filter

by | Energy Conservation, Energy Resources, Sustainable Energy

Why Should I Change My AC Filter?

Air filters may just seem like little boxes of cardboard with coffee filter-like material inside them, but they actually play a large role in the indoor air quality of your home. Without them, airborne debris can roam free and leave you exposed to harmful particles and allergens that can lead to illness in the long term. Making sure your home is well-ventilated and rid of pollutants can improve the air quality of your home and prevent conditions that may show up later, such as respiratory diseases like asthma.[1,3] Today we take a look at the importance of HVAC Filters

The Function of HVAC Filters In Your Home

An air filter functions just like any air filter does: air enters the HVAC equipment and is conditioned to be distributed back into your home. When the air is forced through the filter, the pleated material removes particulates and other contaminants that may be flowing through the air. Usually, when we think of “pollution,” we think of the outdoors. But the air in your home can also be polluted. Major sources of indoor air pollution include:

  • Mold and pollen
  • Smoke
  • Household products and pesticides
  • Gases
  • Asbestos, formaldehyde, and lead

Typically, long-term exposure to these pollutants will only lead to discomfort and you can feel better after removing yourself from the indoor environment. However, in more serious cases, long-term exposure to indoor pollutants can lead to Legionnaire’s disease (a severe form of pneumonia: lung inflammation usually caused by infection.)

What Are Air Filters Made of?

For something that serves a big role in the indoor air quality of your home, there isn’t much to an air filter. They are typically made of spun fiberglass material, pleated paper, or cloth in a cardboard frame.

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How Do I Know When It’s Time to Change My Air Filter?

How often you need to change your air filter can depend on a number of factors. Manufacturers usually recommend you change them every 30 to 60 days, but most HVAC professionals suggest that you change them quarterly (every three months). You should also consider changing your air filter based on other factors such as:

  • The type of air filter you are using
  • How many pets are in your home
  • The number of people in your home
  • The level of air pollution and construction around your home

If you have pets in your home, you may need to change your filter sooner—around every 60 days. If you have someone in your home that has allergies, you might need to change it every 45 days. If you own a vacation home or you live alone with no pets, you may not need to change your air filter but every six to twelve months!

What Happens If I Don’t Change The Filter in My HVAC?

If the possibility of allergies and becoming ill isn’t enough to convince you to change your AC filters, just think about the cost of not changing them. Sure, remembering to change them out and having to go buy more filters regularly can be an inconvenience, but it’s actually saving you a good chunk of change. It is estimated that HVAC systems with clean filters can be 5-15% more efficient than systems with dirty filters. Replacing your air filter can save you about $9 to $22 a month. [8]

A dirty air filter can lead to reduced airflow, resulting in no air infiltration at all. This causes your air conditioner to work harder to keep your house cool (or warm), which results in a higher electricity bill. Furthermore, it can lead to premature equipment failure and force you to repair or replace your HVAC unit.[1]

An AC filter exposed to any sort of condensation is also prone to mold growth, which can spread throughout your home through your HVAC system and lead to health problems. Depending on the severity of the moisture, you may also need to have your unit serviced or replaced. [1] Therefore, it’s just better to prevent all of these problems by replacing your air filter regularly.

How Do I Know Which Air Filter to Buy for My HVAC?

It’s important to know what filter your HVAC unit needs to ensure it gets the job done right. You should use a filter that fits properly. To check the size of your air filter, just take a look at the current filter in your HVAC unit and the size will be printed on the sides of the frame. If you don’t currently have a filter, you can measure the length and width of each return vent. You should also keep in mind the MERV Rating of your filter.

What Is a MERV Rating?

MERV stands for Minimum Efficiency Reporting Value. It was developed by the American Society of Heating, Refrigeration, and Air Conditioner Engineers (ASHRAE). The rating values value from 1 to 16 and the higher the MERV rating, the more efficient the filter will be. ASHRAE recommends a filter that has a MERV rating of 6 or higher.

Though there are filters with MERV ratings higher than 16, it is recommended that you be sure your heating and cooling equipment can handle the higher-MERV filters before buying or installing one. They are very thick and can interfere with airflow inside your HVAC system, making your unit work harder and costing you more in the long term.

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Different MERV Ratings

  • MERV 1-4: Common standard filters that provide a basic level of filtration for a low cost.
  • MERV 6-8: Provide good filtration and are the most common filters used in homes. They are usually made of pleated cloth or paper to provide more surface to capture particles.
  • MERV 9-12: Mid-range filters that are of above average quality and can capture smaller particles of 1 micron or larger.
  • MERV 13-16: High-efficiency filters that are the best standard filters available. They can remove particulates as small as 0.3 microns. [9]

Can I Order My AC Filters Online?

You can order anything online today. AC Filters are just another one of those things that have become very convenient to have delivered. In 2016, Just Energy announced its partnership with FilterEasy, a subscription-based service that delivers air filters directly to your home or business so you can avoid searching for the right sizes in stores.

You are able to select the filter of your choice, the size you need, and how often you want it changed. The filters are delivered to your doorstep as a reminder to change your filter. This completely eliminates the hassle of keeping track of your next scheduled switch. You’ll receive an email in advance to let you know your filters are on their way.

How Do I Change My HVAC Filter?

Changing an HVAC air filter is quick and easy for most homes. All you have to do is slide out the old filter and slide the new one in. If you’re using an electrostatic filter, take it out and wash it, then slide it back in facing in the same direction. The most challenging part of changing your filter is setting up the ladder if your intake vents are in the ceiling. [1]

Change your filter when the AC is on and running. If you’re teetering on a ladder, keeping your unit on will suction and hold the filter into place so you can safely close the intake vent cover and secure it.

Only use undamaged filters and watch for gaps around the frame. Gaps around the frame indicate that you bought the wrong size. Clean any residual dust on the vent with a rag. Create a calendar alert for the next time you need to change your filter. We recommend that you inspect your filter about once a month.

How Do I Maintain My HVAC’s Air Filter?

As mentioned, you shouldn’t have to change your air filter more often than three months, but if you do your monthly inspection and see that your filter is dirty or clogged, it may be time to replace it. Dirty air filters can reduce the airflow of your HVAC system and cause the fans to work harder and wear out sooner. They can also cause contaminants to accumulate in your HVAC system’s ductwork and allow materials that should be filtered out of your air back into your home. If you ever have any doubts, hold your filter up to a light. If you can’t see any light coming through the filter, it is time to change it. [1]

What If My Filter Still Looks Clean When It’s Time to Replace It?

If your filter has been in place for its recommended amount of time and still looks clean, there are a few things you should check:

  • Is the filter fitting properly? If it is too big or too small for the space, air might be flowing around it instead of through it.
  • Is it upside down? There is a correct airflow direction for most filters. Look for the arrows on the frame and install it so that the arrows point towards the fan.
  • Is the filter you’re using right for what you want it to do? Remember, if you’re using a filter with a MERV rating of 1-5, it won’t catch much dust and other particulates. [10]

General Tips for Good Indoor Air Quality

Other than keeping your air filters maintained, there are many ways you can maintain the indoor air quality of your home.

  • Make your home a smoke-free zone.
  • Test your home for radon.
  • Keep humidity levels under control by using a dehumidifier.
  • Fix all leaks and drips.
  • Put away food and use baits to control pests instead of pesticides.
  • Avoid burning wood indoors.
  • Don’t use scented candles to hide odors. Instead, find out what is causing the odor and get rid of it.
  • Use less toxic cleaning products and don’t store hazardous chemicals in your home.
  • Put indoor air cleaning plants in your home.

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  2. Gromicko, Nick, and Kate Tarasenko. “Homeowner Maintenance: Changing the HVAC Filter.” InterNACHI, International Association of Certified Home Inspectors, Inc., Retrieved from
  3. Spencer, E. (n.d.). Fight Fall Allergies and Save Energy by Checking Your HVAC System. Retrieved from
  4. Indoor Air Pollution. (2018, April 17). Retrieved from
  5. How do I know what size filter I need? (n.d.). Retrieved from
  6. Will regularly changing my home’s air filters really help lower my energy bill? (n.d.). Retrieved from
  7. Residential Air Cleaners (Second Edition): A Summary of Available Information. (2018, February 16). Retrieved from
  8. Will regularly changing my home’s air filters really help lower my energy bill? (n.d.). Retrieved from
  9. The Air Filter in Your HVAC System: An Easy Guide to MERV Ratings. (2013, June 11). Retrieved from
  10. Kolich, H. (2009, May 18). If my home’s air filters are clean when I change them, are they really working? Retrieved from