How Often Should You Change Your Furnace Filter?

The filter is the cheapest part of your HVAC system and the one most likely to cause problems when it is ignored. A dirty filter restricts airflow, which makes the blower work harder, reduces comfort, and can lead to overheating or frozen coils.

As a general schedule, thin one-inch fiberglass filters should be changed about every 30 days during heavy heating or cooling months. Pleated one-inch filters typically last 60 to 90 days. Thicker media filters, four to five inches deep, often run six to twelve months depending on the manufacturer.

Shorten that interval if you have pets, allergies, a wood stove, ongoing remodeling, or a home near unpaved roads. Central Oregon's dust and wildfire smoke seasons can load a filter far faster than the label suggests.

The simplest habit is to hold the filter up to a light once a month. If light no longer passes through the media, it is time to change it, regardless of the date on the frame.

Also match the filter rating to your system. Very high MERV filters can restrict airflow on equipment that was not designed for them. If you want better filtration, ask about a whole-home filtration cabinet sized for your blower rather than forcing a dense filter into a standard slot.