Purchasing a furnace air filter can be confusing with so many options available. So, which one should you use? Size, thickness, MERV rating, pleated or non-pleated, which one is your best choice. Let’s look at the differences. Replacing your furnace filter will improve your indoor air quality.


MERV (Minimum Efficiency Reporting Value) rating indicates the filter’s ability to filter or trap small particles within the air stream. The higher the MERV rating the more pet dander, pollen, and bacteria, the air filter can trap. Typical MERV ratings you will see are 6, 8, 11, and 16.

Furnace Air Filter Thickness

The majority of air filters installed are 1 inch thick, but some systems can accommodate filters up to 5 inches thick. The thicker the filter the more surface area of the filter material. So, thicker filters allow for more airflow through them and may not require replacement as often.

Pleated Or Non-Pleated Furnace Air Filter

Pleated filters offer a higher level of filtration than non-pleated filters. Non-pleated filters don’t do a good job of trapping small particles in the air stream.


At Twin Peaks Plumbing, Heating & Gas we recommend using a pleated filter, but you have to be careful to ensure your heating system has adequate airflow. We use a MERV 6 pleated filter on systems with a 1-inch thick filter. On systems with thicker filters (4 or 5 inches), we recommend higher MERV 11 filters. This method provides a good balance between efficient filtration without affecting system performance by restricting airflow. If your system currently has a 1-inch filter, a filter cabinet to accommodate a thicker filter could be installed to allow for a higher MERV filter.

If you have questions or would like assistance, give our professionals at Twin Peaks Plumbing, Heating & Gas a call today.

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