Why Filters Matter

Person sliding a filter into an HVAC unit past ductwork

Your air conditioner keeps you comfortable, and you can keep your air conditioner comfortable by making sure it has a clean filter.
Why is having a clean filter important?  A clean filter has two purposes: 

  • to remove allergens, dust, and other contaminants from the air you breathe, and
  • to keep your system clean and running efficiently. 

Air Quality

As air circulates through your home, the air filter removes harmful contaminants, dust particles, pet dander, and more from the air. ​In the past 20 years, an expanding body of evidence shows that indoor air quality has a significant impact on human health and indoor comfort. Here are a few of the effects of poor indoor air quality:

  • asthma, irritation, rhinitis, sinusitis, and allergic respiratory disease
  • excessive dust, dirt, and smoke
  • increased utility bills due to decreased air flow
  • unpleasant fumes and odor

Air filters are rated on their ability to remove these contaminants, called the MERV rating (Minimum Efficiency Reporting Value). The higher the value, the better the filter is at removing dust particles and contaminants from the air. 

System Performance

A dirty filter chokes the A/C, increasing the risk of the A/C overheating and failing sooner. According to Home Comfort Experts, 80% of all furnace service calls are related to dirt. [Source] 


As the filter accumulates dirt, less and less air can pass through. The dirtier the filter gets, the harder the motor has to work to pull air through it. Thus the more electricity it uses, causing your utility bill to go up.


The increased pressure can also damage the filter, letting dirt enter your A/C system. There, it can accumulate on the coils and internal parts. The dirtier the system, the harder it has to work because it needs more energy to cool the same amount of air. Without sufficient airflow, ice can build up on the evaporator coils. This will lower the performance and may damage the coils. 


Clogged air filters can also cause problems with the compressor, which is very expensive to repair.

Replacement

We recommend you inspect your home's air filter every month. If the filter is dirty, then it should be discarded and replaced immediately. In a typical home, the filter will need to be changed every three months. If you are making improvements, or your home is dusty, or you have pets, you may need to replace the filters more frequently.