MERV 13 filters are more effective than MERV 8 filters in trapping contaminants, but they come with a few drawbacks. They are more expensive and can restrict airflow to the point of being incompatible with some air conditioning systems. This decreased airflow can cause the cold coil in the air handler to freeze and turn into an ice ball, completely restricting airflow and leading to costly problems. The MERV scale is not linear; the difference between a MERV 6 and a MERV 8 is almost double in terms of the percentage of particles captured.
As the MERV rating increases, the filter becomes more restrictive and more pressure and energy will be needed to get air through. A MERV rating of 13 to 16 is considered to be hospital-grade air quality, so it's unlikely that your home needs more than that rating. The main distinction between a MERV 13 filter and a HEPA filter is that a MERV 13 filter is designed to capture larger particles, while a HEPA filter is designed to capture very small particles. The United States Environmental Protection Agency recommends using filters in the 7-13 range as they will allow the system to operate much more efficiently.
To help protect against the COVID-19 virus, ASHRAE changed its recommendation from MERV 8 filters to MERV 13 and higher, but recent studies have shown that the virus can be transmitted through small particles, so the CDC now recommends using air filters with a MERV rating of 16 or higher. If the boiler's MERV rating is too high, it can force it to work too hard and be exposed to damage. Therefore, it is important to choose an appropriate filter for your home that will provide adequate protection without compromising your air conditioning system. When considering whether or not to use a MERV 13 filter, it is important to weigh both the advantages and disadvantages. On one hand, they are more effective at trapping contaminants than lower rated filters.
On the other hand, they can be more expensive and restrict airflow, leading to potential problems with your air conditioning system. Ultimately, it is up to you to decide which type of filter is best for your home.
