How to Stop Your HVAC Filter From Getting So Dirty So Fast

When you change the air filter in your furnace, you expect the old one to be dirty. But let’s say that when you go to make your regularly scheduled switch, you find that your old filter isn’t just a little grimy—it’s completely filthy. And it’s not as though you left more time between filter changes, so it somehow ended up getting this dirty in a relatively short period of time.

Here are a few of the reasons why your HVAC filter got so dirty so fast, and what you can do to prevent it from happening again.

Your home is extra dusty

Whether you’ve deep-cleaned a room or have been in the process of a renovation project, doing anything to disturb (or create new) dust can send more of it into the air, and then, into your furnace air filter.

Solution: Try vacuuming more often. The dust and dirt that the vacuum sucks up means less will make it to the filer.

Your HVAC system is on the wrong setting

Most thermostats have two fan settings: “On” and “auto.” When it’s on “auto,” the fan only blows when your HVAC system is actively heating or cooling your home. But if you switch to the “on” setting, it’s constantly running, meaning that air is continuously passing through the filter, giving it more of a chance of getting dirty.

Solution: Switching your thermostat to the “auto” setting will extend its life of the filter.

The filter has a high MERV rating

Some high-performing furnace filters have the ability to trap substantially more indoor air contaminants than your run-of-the-mill filter. Some may even offer the protection of a HEPA filter. But because it traps so much of what’s in the air (which is what you want it to do), these filters get dirty very quickly.

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Solution: Pay attention to the MERV rating when buying a new filter, and be aware that the more protection one offers, the faster it’ll be coated in grime.