When it comes to air quality, the highest MERV ratings are the most effective. However, they can also damage your air conditioning system. A higher MERV rating means greater resistance, which in turn reduces airflow. If you want to remove more contaminants from the air, you can use a filter with a different material.
The pores of these filters are much smaller, allowing them to capture more particles from the air stream, but also adding more resistance. Good airflow is essential when researching HVAC systems. Higher MERV filters have higher resistance, so it's important to ensure that the rest of the system is configured to handle the increased restriction created by these filters. Using an air filter with a MERV rating that is too high can be as bad as using one that is too low.
Air filters with higher MERV values may filter more, but the thickness of the filter material may restrict air flow. This can decrease comfort, increase energy use, and accelerate wear and tear on HVAC components, particularly damaging the compressor, heat exchanger, and air conditioner coil. ASHRAE is now encouraging the change to MERV-13 (ASHRAE's position paper on infectious aerosols) as a measure to provide cleaner air in non-sanitary facilities. Low-efficiency filters are usually inside the MERV 1-4 range and high-efficiency filters are MERV 13 and above. Generally speaking, anything under a MERV 13 air filter should provide very efficient air purification in a home without affecting air flow. If someone has an allergy or a breathing problem, choose a MERV 11 air filter or even a MERV 13 air filter.
Fortunately, there is a comparison chart that helps highlight the differences between MERV 8 and MERV 11 filters to make it easier to decide which one will work best. Raising just three MERV rating levels can be a smart decision that makes the air cleaner, or a harmful option for your entire HVAC system when you consider the air flow capabilities of the MERV 8 versus the MERV 11. Since the MERV classification system is standard, it makes it easier to compare filters with different MERV ratings. It's important to remember that higher MERV filters should be changed more frequently (at least every three months) to avoid airflow restriction that can cause the system to operate inefficiently or even damage it. In conclusion, while higher MERV filters are effective at removing more contaminants from the air stream, they should be used with caution. Make sure your home's air conditioning system is able to handle the increased resistance created by these filters before making any decisions.