HVAC technology has advanced significantly in recent years, and most modern units should be able to accommodate a MERV 8 filter. However, older units may not have enough air pressure to push air through a higher-efficiency filter, which could lead to serious problems and the need for repairs. Generally, our recommended MERV rating for furnace filters is between 6 and 8, as this provides the perfect balance between maximum efficiency and home comfort. The Minimum Efficiency Value (MERV) rating of an air filter measures how well it prevents dust and other contaminants from passing through the filter and into the air stream.
MERV indices range from
1 to 16, with higher MERV indices trapping small particles more effectively than lower MERV indices.Studies have found that filtering recirculated air can improve microvascular function in healthy older people, improve other types of vascular function in healthy adults, and improve lung function in indigenous communities, among other benefits. When used in a multi-filter system, prefilters trap dirt and large particles before the air reaches the final filters downstream, which then remove the smallest particles. If you're concerned about outdoor air pollution, have family members with respiratory problems, or have pets at home, then opting for a higher MERV rating might be a good idea. If the MERV rating is too high for the furnace motor or air controller fan to handle, it will result in low airflow. Using an air filter with a MERV rating that is too high is just as bad as using one that is too low. There are several types of filters to choose from and it can be difficult to select the one that best suits your needs. Meanwhile, air filters with a MERV 14 rating or higher are designed for commercial air conditioning systems that can withstand the coarser filter material.
The fan draws air through the air filter and takes it to the furnace or air controller, where it heats up or cools before passing it through ducts to the rooms of the house. In particular, using an air filter with a MERV rating that is too high can damage the compressor, heat exchanger, and air conditioner coil. Read the EPA's “Guide to Home Air Filters” for information on how to place and operate a portable air filter. Some large retailers use the filter performance rating (FPR), which ranges from 1 to 10 and measures a filter's ability to capture large and small particles. Air filters with higher MERV ratings may filter more but the thickness of the filter material may restrict airflow.
The classification of a filter is determined by the minimum particle size it is capable of trapping (measured in microns). If your system can't support the MERV ratings you need, there are always other options available to improve indoor air quality. You can use the following table to better understand how filters classified with FPR and MPR compare to those of the more standard MERV classification system. MERV 8 air filters are very common because they offer a fairly complete option at an excellent price but still provide good performance.
