Your heat pump’s motor has to work twice as hard to pump air through clogged and dirty filters, which dramatically shortens its lifespan.
The best practice is to replace your heat pump’s filters when they’re dirty. Sorry — we’re not trying to be smart-asses! Here’s what we mean:
Replacing your filters twice a year (fall and spring) is a good rule of thumb. But if the outside air is very dirty (like when wildfire smoke blows through), then replacing it more often is a good investment in your health and your heat pump’s lifespan.
But most homeowners forget this important chore entirely. Any replacement schedule is better than none!
To replace your filters properly, you need to know:
The filter’s size
The filter’s MERV rating
Most filters are 16” wide and 25” tall, but the thickness varies. Take a look at your current filter—it should have 16X25Xsomething printed on it. This “something” is your filter’s thickness (usually between 1 and 4 inches).
Now onto MERV ratings. Filters have a MERV rating (which stands for Minimum Efficiency Reporting Value). That’s just a measure of how large the filters’ holes are. A MERV 1 has large holes that let most dust through. The filters catch more dirt as the MERV number goes up.
Your heat pump’s “just right” MERV rating depends on your ducts and your heat pump’s motor — in other words, your installer should have a recommendation for you. But we’ll note that anything below MERV 11 will not catch viruses or PM2.5 (like wildfire ash).