When it comes to air quality, the highest MERV ratings are the most effective. But, they can also cause damage to your air conditioning system. A higher MERV rating means greater resistance, which in turn reduces airflow. When researching HVAC systems, it's important to consider the airflow that will be generated.
The higher the filter rating, the smaller the particles it will capture and the higher the percentage of particles that will be filtered out. Low-efficiency filters are usually within MERV 1-4 and high-efficiency filters are MERV 13 and above. 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. It's also important to remember that as the MERV rating increases, the filter becomes more restrictive and more pressure and energy will be needed to expel air. Using an air filter with a MERV rating that is too high can be just 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. In particular, using an air filter with a MERV rating that is too high can damage the compressor, heat exchanger and air conditioner coil. Higher MERV ratings are more effective at improving air quality, but they also come with a higher price tag. Plus, higher doesn't always mean better for homeowners. MERV ratings greater than 16 are generally used in specialized commercial environments where air filtration is critical, such as hospitals.
Generally speaking, a filter with a higher MERV rating will reduce airflow. However, there are many other factors at play, such as the size of the filter and the type of fan motor in your air conditioning system. When selecting the right filter for your application, higher isn't always better. Using an air filter with a MERV rating higher than recommended by the boiler or air conditioner manufacturer may affect its performance. It's important to consider all factors when selecting an air filter for your home.