Why Is Your Air Filter So Dirty?
Why is your air filter so dirty? If your HVAC system’s filter fills with debris in record time, clogs, or fails within weeks, take a look at the top culprits behind this easy-to-fix issue.
The Wrong Type of Filter
What type of air filter does your HVAC system use? If you’re not sure, you might have the wrong one.
You don’t just have one type of air filter. From reusable electrostatic filters to replaceable HEPA filters, and everything in between, you have choices — and they won’t all work for your heater/air conditioner or your home. If your air filter is constantly dirty:
- Check the MERV Rating: The Minimum Efficiency Reporting Values (MERV) rating identifies the particle size efficiency of the filter. Higher numbers equal finer filtration — and often dirtier filters.
- Change the Material: Air filters are made from fiberglass, pleated paper, and other materials. A lower-quality paper filter may show signs of wear (and dirt) more quickly.
- Make Sure it’s Reusable: Did you incorrectly assume you could clean and reuse the filter? If the filter isn’t a specialized reusable type, throw it away and buy a new one.
If your air filter is the right choice for your home’s system and you still have dirt or debris problems, read on for more information on what to look for next.
The Indoor Air Contaminants
Your filter might not be the problem. Even though it fills or clogs quickly, the issue may have nothing to do with the wrong type of filter or an HVAC system in need of repair.
An efficient HVAC system with a productive air filter will leave the filter dirty. In this case, the debris and dust you see on the filter is a sign your system works at a high level. Even though the filter and HVAC unit both do their jobs, your home may make the work harder. Indoor air issues that can cause an excessively or prematurely dirty filter include:
- Pets: Your pet’s fur doesn’t just settle on the furniture and flooring. Some, or most, of it will also end up in the air. As your HVAC system circulates the indoor air, this contaminant can clog the filter.
- Dust: Some homes are dustier than others. Excessive dust can quickly clog an air filter — even if you clean your home regularly.
- Construction Debris: Construction can leave behind dust, dirt, and other debris. Your HVAC system can pull this through the return vents and into the filter. While this isn’t a permanent problem, it can cause unwanted filter effects immediately after the contractors leave. While some indoor air contaminants are unavoidable, you can take steps to reduce the damage to your filter. Clean your home regularly. Dust, vacuum, and remove debris that settles on surfaces to decrease the number of particles in the air.
The System's Fan
Is your HVAC system’s fan set to the on position? Even though the heater or air conditioner isn’t running, the fan will continue to circulate air through your home’s system. This can:
- Increase Use: Your HVAC system doesn’t need to push hot or cold air into your home to clog the filter. The fan setting forces the blower to run either constantly or more often than under normal heating/cooling use.
- Pull Additional Contaminants into the System: The more air entering your HVAC system, the more indoor pollutants and contaminants it will pull in. This can result in a prematurely clogged or dirty filter.
- Increase Wear: Without time to rest, a constantly running blower will wear down the system and the filter.
The easiest way to avoid this issue is to turn the fan to the off position or use an auto thermostat setting.