Does Higher MERV Rating Reduce Air Flow?

A higher MERV rating means greater resistance, which can lead to less airflow. This is because it is very important to the performance and longevity of your oven or air handler. Airflow is also the key to a comfortable home. The short answer is that it can, but it's not really a problem except in extreme circumstances.

Most modern HVAC systems have no problem working with higher MERV filters, so millions of homeowners rely on them. The main risk of high-efficiency air filters comes from the fact that they are not modified for long periods of time. If you're aware of changing filters, you're unlikely to experience filter-related issues with your HVAC system. Typically, 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 HVAC system. Research shows that overall, HVAC systems with high MERV* filters have a higher pressure drop across the filter. This part is common to the three previous studies. In general, filters with higher MERV ratings capture higher percentages of particulate matter as well as smaller particles.

And MERV-13* is practically where you want to be. Using an air filter with a MERV rating that is too high is as bad as using one that is too low. Air filters with higher MERV ratings may filter more, but the thickness of the filter material may restrict airflow. Restricted airflow can decrease comfort, increase energy use, and accelerate wear of HVAC components.

In particular, using an air filter with a too high MERV rating can damage the compressor, heat exchanger, and air conditioner coil. A MERV rating is a good indicator of the effectiveness of an air filter in your central HVAC split system. The higher the rating, the better the filter. As the MERV rating increases, fewer and fewer contaminants and dust pass through the filter, improving the quality of the incoming airflow.

Those suffering from idiopathic pulmonary fibrosis can reasonably expect that a higher quality air filtration will help prolong their life, already shortened by the disease. Home Energy published an article by Dave Springer of Davis Energy Group at the time, on the pressure drop and energy use of various MERV filters. Based on these characteristics, a MERV 8 is considered superior filtration compared to air filters with a lower MERV rating. The higher the MERV rating, the less airflow there will be.

There will be many references to airflow while analyzing HVAC systems because it is critical to the efficiency and lifespan of your oven and air handler. Of course, it is also a function of the tightness of a house, but for 99% of existing homes, the phrase “hermetic” should not be used in any description of them. The higher the MERV rating, the more work your oven will have to do and the more sensitive it will be to damage. This is because air molecules make them bounce quickly compared to flow velocity and they collide with fibers of mask and stick together.

However, high MERV filters offer superior filtration, trapping everything from construction dust and tobacco smoke to bacteria. My impression is that ductless heads do not have ability to mount much pressure head and therefore I would look elsewhere for high-efficiency filtration such as plug-in HEPA cleaners or dedicated ducted fan designed for use with HEPA or MERV-13 filter. If you want to use pleated filters and superior MERV filters, only sure way to do this is to have professionally installed 5- to 6-inch media filter. They are similar to fiberglass filters but have higher resistance to air flow and better ability to stop dust.

In fact even filters with high MERV ratings can be used in some systems with minimal pressure drop while maximizing airflow and room air changes using MERV 13 filter or higher is direction that would protect most people. Low-efficiency filters are typically found within MERV 1-4 and high-efficiency filters are MERV 13 and later. Build return so that it can house 2 Merv 18×18 high filters side by side giving you 648 SI of surface area for filtration. A MERV rating is to ensure that incoming vented air meets area-specific air quality standards.

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