Skip to Content

How Often Should You Replace Your HVAC System’s Air Filter? It Depends

dusty hvac air filter

As Milford’s HVAC maintenance, repair, and installation experts, one of the questions customers ask us the most is, “How often should I be changing my heating and cooling system’s air filter?” While there isn’t really a strict number of days, there are some general guidelines to go by.


As long as you keep the following tips in mind, you shouldn’t run into any problems with your HVAC system’s air filter.

1. Most people should be changing their air filter BEFORE 90 days are up.

If you look at your air filter’s packaging, typically the manufacturer states that the air filter will last for up to 90 days. Keep in mind that this refers to times of the year when you aren’t relying heavily on your HVAC system.

If you’re running your AC or heater daily, your air filter is going to get dirty before 90 days are up. During summer and winter, you may need to change your air filter every 30 to 45 days to keep your system in tip-top shape. Make sure to check on it frequently and keep a couple of replacements on hand.

2. If you own pets that shed, your air filter will get dirty faster.

As pet parents ourselves, we know that pet hair on clothes, furniture, and carpeting is simply a fact of life—and well worth it for the companionship of a canine or feline friend. However, people often don’t realize that their pet’s fur also ends up in their air filter. If you own a cat or dog that sheds, you may need to change your air filter every 45 to 60 days to prevent it from getting clogged with dust and fur.

3. Check your air filter after activities that kick up a lot of dust.

At times, your indoor air can be much dustier than others. For example:

  • During a remodeling or renovation project
  • While you’re moving or rearranging furniture
  • During spring cleaning
  • While you’re moving seasonal decorations in and out of your closet, attic, or basement

These activities can stir up dust into the air, and that dust can end up in your air filter, making it dirtier much faster than you might expect.

Remember: a clogged air filter can lead to lots of problems with your system, including decreased efficiency and increased breakdowns. Stick to the guidelines above and set reminders on your phone or calendar if you need to so that you never leave an air filter in too long!

At Tri-City Heating and Cooling, we’re proud to offer top-quality HVAC services throughout Milford with our team of licensed and fully trained HVAC technicians. For trustworthy service, give us a call at (203) 303-5700 or contact us online today!