When Should I Change My Air Conditioner's Air Filter at Home?

February 26, 2015

Every once in a while we’re asked what is the most important thing that Houston area homeowner's can do to maintain their air conditioning and heating system between their scheduled tune-ups? The answer is simple this; remember to change the heating and air conditioning air filter. Replacing furnace and return air filters is extremely important to the proper performance of your HVAC system, not to mention your home's air quality. Did you know indoor air pollution is among the top five environmental health risks? We know it's the last thing on your mind, but this is really important stuff. Changing the air filters is not a tough thing to do for most Houston homeowners, but there are often two challenges to actually accomplishing this task:

  1. Understanding just how often to swap out your furnace or air conditioner filter.
  2. Replacing them at the proper time.

When To Change Your Air Filters

Most filters have a printed "expiration" date on the wrapping. It may say "Lasts up to 3 months" or "Change filter every 90 days". Pay attention at the store and you'll see that some are designed to only last one month, while other manufacturers (like Honeywell) have produced media air cleaners with filters meant to be changed once every 6-12 months. The standard seems to be once every three months for most higher quality filters, but we have a rule of thumb that we recommend our readers to go by. If the filter is dirty, change it! A dirty air filter can exacerbate or cause damage to pricey components, like your compressor, so it's best to change it out more often than neglect it. If you want to listen to the manufacturer's recommended limit, we suggest marking the date on the filter when you swap it out, and adding a reminder for yourself in your phone or on a calendar. Also note that your filter manufacturer sometimes has a different recommendation from your HVAC equipment manufacturer.

Figuring out how often to change your air filters hinges on several factors:

  • Type of filter your A/C system requires
  • The overall air quality of your Houston area home
  • Pets – Cats, dogs, birds, etc.
  • Occupancy of the home
  • The level of air pollution and construction around the home

For your typical 1"-3" air filters, the manufacturers basically tell you to change them bi-monthly, which is in fact a great rule of thumb. But general rules aren't always for everybody. If you have to endure light to moderate allergies, you may need to upgrade the air filter or change them even more regularly than OEM specifications. On the other hand, if you're in a remote area, own a seldom occupied home (like a vacation home) or an area with few automobiles and trucks, changing your air filter every 12-months may be quite sufficient. Why do pets matter so much? They have a tendency to shed, which can clog your air filter fast. Clearly, the air filter is just doing its job by trapping pet hair and dander, but exceptionally dirty filters can cause weak HVAC performance.

In summary:

  • Seldom used home or single occupant homes without pets or allergies: Change 6-12 months
  • Common suburban home without pets: Change every 90 days
  • House with a pet: Change every 60 days
  • Multiple pets or have allergies: Change every 30-45 days

How To Remember To Change Your Air Conditioner's Air Filters

Church Services offers a simple solution; sign up for the Service Experts Email Club. When you do, you can elect to receive (or not) great email coupons and newsletters with a lot of tips and discounts on AC repairs and tune-ups. But wait… there’s more, your email subscription preferences let’s you set a reminder to change your Houston area home's air filter every 30, 60, 90, 120 or 365 days, or a specific date of your choice.

How to replace your return air filter

Most of you know how to replace the air filter in their unit, but some homes have an extra filter in the return ducts. Whether you have one or not is dependent on which HVAC system you have. Your system is engineered to handle a set amount of pressure in your home, and the more filters you have the more the blower motor works, which can shorten the life of your system if it isn't designed for it. Discovering whether you have a return filter and replacing it is easy:

  1. Locate your return air vents.
  2. Some covers have screws and some have tabs. Unscrew or pull tabs to take off the wall.
  3. Check for a filter. If one is there, pull it out and note the size.
  4. Verify the filter type is the one recommended by the manufacturer.
  5. If filter is dirty, replace with the manufacturer's recommended filter of the same size and type.
Amazing as it may seem, filters can really affect your home's airflow, which is why we recommend referring to the manufacturer. A higher quality HEPA filter that is designed to catch tinier particles will reduce airflow more than a cheaper filter. With restricted airflow comes greater pressure on your system, so you should verify that your HVAC system was built to handle it. Otherwise, you might experience reduced heating and cooling efficiency in your home, and unit parts may die off much faster than the standard.
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