Air Filters

For most homeowners the important information is that Energy Star advises you to check your air filters at least once a month, especially during heavy use seasons. If the filter looks dirty it should be changed. In any case, your air filter should be changed at least once every 3 months. Dirty filters make your system work harder and use more energy to heat or cool your residence and can lead to early system failure.

The United States Department of Energy (DOE) recommends that air handling filters should have a Minimum Efficiency Reporting Value of 13. ASHRAE recommends a MERV of at least 6 to lower the amounts of pollen, mold and dust that can reach the evaporator coils in the air conditioning system where mold can grow. The MERV number should be listed on the filter and also the packaging for the filter.

Many of the filters for home forced air heating and air conditioning systems are made from plain, loosely-spun fiberglass and can be somewhat inefficient when it comes to filtering the air. These filters can be inexpensive and they are disposable, but make sure the MERV value meets your requirements. Other filters made of pleated or denser materials usually have a higher MERV and provide better filtration. As with most things in life, there are compromises to consider when selecting a filter. Generally, the higher the MERV the more often you will have to change the filter since it will get dirty faster and also the air flow through the system will be more restricted. In most cases the less efficient air flow will not be noticeable.