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

February 26, 2015

Sometimes we’re asked what is the best thing that Longmont area homeowner's can do to maintain their air conditioning and heating system between their scheduled tune-ups? Our advice is simple; remember to change the heating and air conditioning air filter. Replacing furnace and return air filters is crucial to the ideal operation of your HVAC system, as well as your home's air quality. Did you know indoor air pollution is among the top five environmental health risks? You probably don’t consider it as you sit and watch TV, but this is the air you breathe day and night. Changing the air filters is not a tough thing to do for most Longmont homeowners, but there are usually two challenges to actually accomplishing this task:

  1. Understanding just how often to swap out your furnace or air conditioner filter.
  2. Remembering to change air filters when needed.

When To Change Your Air Filters

Most filters have a printed "expiration" date on the box or plastic. It may say "Lasts up to 3 months" or "Change filter every 90 days". Look around at the store and you should see that some are designed to only last one month, while other manufacturers (like Honeywell) have created media air cleaners with filters meant to be swapped once every 6-12 months. The industry standard seems to be once every few months for most higher quality filters, but we have a rule of thumb that we suggest our friends and family to go by. If they're dirty, change them! A dirty air filter can contribute or cause damage to pricey equipment, like your compressor, so it's best to change it out more often than neglect it. If you want to follow the manufacturer's recommended limit, we suggest scribbling the date on the filter when you swap it out, and adding a reminder for yourself in your phone or on a calendar. Keep in mind that your filter manufacturer might have a different recommendation from your HVAC equipment manufacturer.

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

  • Which air filter your system requires
  • The entire air quality of your Longmont area home
  • Pets – Birds, cats, dogs, hamsters (do you have one?), etc.
  • Number of occupants in the house
  • The level of air pollution and construction around the home

For the common 1"-3" air filters, the manufacturer specs basically suggest to change them every 1 or 2 months, which is really a great rule of thumb. However, general guidelines are not applicable to all. If you have to tolerate light to moderate allergies, you may need to upgrade the air filter or change them even more frequently than OEM specifications. On the other hand, if you're in a remote area, own a less occupied home (like a vacation home) or an area with few automobiles and trucks, replacing your air filters each year may be quite sufficient. Why do pets matter so much? They have a tendency to shed, which can clog your air filter in no time, just like a vacuum. 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:

  • Infrequently occupied home or single occupant homes without pets or allergies: Change 6-12 months
  • Common suburban home without pets: Change every 90 days
  • Got a cat or dog: Change every 60 days
  • Several pets or have allergies: Change every 30-45 days

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

Here’s an easy way to stay on top of this; sign up for the Service Experts Email Club. This is a great to receive discounts on service, tips and other helpful information directly to your email. Also, your email subscription preferences let’s you set a reminder to change your Longmont area home's air filter every 30, 60, 90, 120 or 365 days, or any date you find most convenient.

How to replace your return air filter

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

  1. Find your return air vents.
  2. Some covers have screws and some have tabs. Unscrew or pull tabs to remove from the wall.
  3. Check for a filter. If one is in place, pull it out and write down 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 dramatically impact your home's airflow, which is why we recommend asking the manufacturer. A higher quality HEPA filter that is designed to catch tinier debris will restrict airflow more than a cheaper filter. With restricted airflow comes increased pressure on your system, so you need to verify that your HVAC system was built to handle it. Otherwise, you might experience lowered heating and cooling efficiency in your home, and system parts may break down much faster than normal.
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