How Often Should You Change Your HVAC Air Filters? | APHW Skip to main content

How Often Should You Change Your HVAC Air Filters?

America's Preferred Home Warranty, HVAC Filters

One of the biggest joys – and challenges – of being a homeowner is doing home maintenance tasks. Thankfully, most basic home maintenance tasks are easy to do, like changing your HVAC filters. In this article, America’s Preferred Home Warranty (APHW) provides helpful guidance on:

  • How often you should change your HVAC air filters
  • Where HVAC filters are commonly located
  • What size of HVAC filters you should use
  • What MERV rating or filtration level your HVAC filters should have
  • How to change your HVAC filters

Ready to discover more about maintaining your HVAC filters? Let’s get started!

How Often to Change HVAC Air Filters

The International Association of Certified Home Inspectors (InterNACHI), which is the world’s largest residential and commercial property inspection trade organization, recommends changing your HVAC filters at least every 90 days. However, there are some good reasons to replace your HVAC filters more often. These include:

  • Making your unit more efficient to last longer, so energy, maintenance, and repair costs are lower
  • Improving your home’s air quality, which is essential for people with allergies or breathing problems
  • Helping your entire HVAC system – and your home – stay cleaner and smell fresher

Where is Your HVAC Air Filter Located?

Depending on the size of your home and its number of air conditioning units, your HVAC system could pull air from one or more locations around your home. You will need to inspect each of these locations to determine how many air filters you need to replace every 30 to 90 days.

The most common locations for HVAC air filters are:

  • Horizontal HVAC units typically have air filters located in a slot at the side of the unit.
  • Vertical HVAC units typically have air filters located in a slot above or below the unit.
  • Other HVAC systems use air filters located in your home’s walls, ceiling, or utility closets. You can usually find them behind a removable grill or grate.

If your HVAC system has a return in each room, you may need to replace multiple filters as part of your regular HVAC maintenance.

What Type of Air Filter is Best for Your HVAC?

First and foremost, the size of your HVAC filter is important to consider. Once you remove your old air filter, inspect the filter’s frame, or edge, for its dimensions. There should be three sizes listed. If your HVAC filter only has two sizes listed, or no size listed at all, your next step is measuring the filter.

To determine your HVAC filter’s size manually, simply use a measuring tape to get the filter’s length, width, and depth (L x W x D). If your air filters are square, the length and width (L x W) should be the same. If they’re rectangular, however, the length of your air filter is always the smallest number (e.g. 14 x 20 x 1).

If you measure your filter by hand, be sure to round up if your measurements include fractions of an inch. For example, if your HVAC filter measures 13.75 x 19.5 x 1, a 14 x 20 x 1 air filter should work just fine. This rounded-up measurement is the nominal size, which allows you to use standard-sized air filters instead of custom-made filters or ones you can only purchase from the manufacturer.

Your HVAC unit may use more than one size of filter throughout your home, so it’s important to check beforehand to ensure you have the right number of filters, and they all fit as expected.

Filtration Levels or MERV Ratings

HVAC filters use the Minimum Efficiency Reporting Value (MERV) system to determine their efficiency. This helps homeowners know how effective an air filter is at capturing particles that can range in size from pollen and dust mites to mold, bacteria, and smoke. The higher the MERV rating, the better filtration an HVAC filter delivers.

Most households use HVAC filters with MERV ratings in the 5 to 8 range. However, if you have allergies, pets, or a large household, you may want stronger filtration, such as a filter with a 10 MERV rating or higher.

An important note about MERV ratings and older HVAC systems: Older HVAC systems may struggle with pulling air at higher filtration levels, causing resistance that could reduce airflow, make your HVAC less efficient, and potentially damage the unit. If you have an old HVAC system, you may need to use filters with a 1 to 5 MERV rating.

How to Change HVAC Air Filters

Changing your home’s HVAC filters is a pretty straightforward process and only takes a few minutes. Whether you’re replacing HVAC filters located next to your unit or somewhere else inside your home, follow these steps to make the process easier.

Replacing HVAC Filters on Vertical & Horizontal Units

  1. Turn off power to the unit
  2. Open the filter compartment and slide out/remove the old filter
  3. Inspect the filter – if light passes through easily, it may not need replacement yet
  4. Vacuum and/or wipe around the area with a dry cloth
  5. Install the new filter and close the filter compartment
  6. Turn power to the unit back on

Replacing HVAC Filters in Return Air Ducts

  1. Open the grill or grate (you may need to unlatch it) and remove the filter
  2. Inspect the filter – if light passes through easily, it may not need replacement yet
  3. Clean the grill or grate with a vacuum and/or a dry cloth
  4. Install the new filter
  5. Close and secure the grill or grate
  6. Replace any other filters in your home using the same process

Having issues with your HVAC system? If you’re an APHW customer, simply start a claim now online. With an APHW home warranty, you can contact your preferred licensed plumber to get your HVAC system working again. Learn more about APHW home warranties to see what else we cover!

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