Does a Merv 11 Air Filter Restrict Airflow?

Learn about how Merv 11 air filters affect airflow from an expert's perspective! Find out what factors play into restricted airflow & how you can prevent it.

Does a Merv 11 Air Filter Restrict Airflow?

Keep in mind that some retailers also use their own rating system instead of MERV. 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 too high a MERV rating can damage the compressor, heat exchanger and air conditioner coil.The short answer is that a Merv 11 air filter can restrict airflow, 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. Researchers found that airflow in high-MERV filters dropped by 7% and 11% in two HVAC systems compared to low-MERV filters. Similarly, the medium MERV filters also showed decreased airflow relative to the low MERV filters, this time 3% and 8% lower in both systems. If your furnace's MERV rating is too high, it can force it to work too hard and leave it vulnerable to damage.

In addition, you may not get the air velocity needed to reach all parts of your house, leaving inconsistencies in temperature.Using an oven filter with a higher MERV rating than your use case requires may have adverse effects. The thickness of the filter material in a Merv 11 filter, for example, is greater than that of a MERV 8 filter. Therefore, in order for enough air to pass through the filter, a greater amount of energy is consumed. More use can lead to increased wear and tear, so be sure to maintain your oven regularly.

However, MERV 11 filters are not considered too high for residential use. Anything higher than a MERV 11 is designed for commercial households or households with family members suffering from respiratory problems.MERV stands for Minimum Value of Efficiency Reporting. A MERV rating indicates a score of 1 to 16 for residential air filters sold in the United States and 17 to 20 for commercial air filters. The scale evaluates how well a filter removes fine particles from the incoming air.

The higher the MERV rating, the more particulates the filter will remove. On average, it is recommended that most homes and retail spaces in general have a filter with a MERV rating of at least 5 to 12 in the high-end. However, for a person with respiratory problems, a specialist may recommend a different filter. Hospitals use air filters with a MERV rating of 13 to 16.Second, ASHRAE is now encouraging the switch to MERV-13 (ASHRAE Position Paper on Infectious Aerosols) as a measure to provide cleaner air in non-sanitary facilities.

With the lowest MERV rating (1-), the filter will continue to capture pollen, dust mites, cockroach debris, sanding dust, spray paint dust, textile fibers and carpet fibers. When you have a filter of merv 13 and above, it is more similar to the material you would find in an n95 dust mask. According to Avery, in a new construction it is easy to accommodate a high MERV filter without static pressure penalty (see my previous comment).As the MERV rating increases, fewer and fewer contaminants and dust pass through the filter, improving the quality of the incoming airflow. In addition, high-performance air filters that contain pleats create much more surface area for air to blow, which can improve airflow and reduce strain on the system.

As for the need for high-MERV filtering, it's easy to pass up until you meet someone with allergies or asthma. For residential use, the standard recommendation is to choose a furnace filter with a MERV rating between 7 and 13.If you're concerned about the effects of breathing fine air particles, that's another reason to choose a Merv 11 air filter instead of a MERV 8 air filter. In fact, researchers have found that while high-MERV filters can create a pressure drop, the impact is not significant unless the filter is laden with dirt. A MERV 11 filter only needs to stop 20% of particles 0.3 to 1.0 microns (three to ten times larger than a COVID-19 particle), a MERV 12 only needs to stop 35% of particles smaller than 0.3 microns, and a MERV 13 only needs to stop half.

Finally, I say that there is no price for peace of mind and that if they feel that a high merv filter would provide that they should do so with the warning that they should replace dirty filters often enough &; it may be a week or two depending on the MERV rating, effective filter area and amount of particles entering your home.It may seem that they are almost the same but Merv 8 air filters and Merv 11 air filters have some distinct differences. In this case you want to have clean air without restricting airflow to your HVAC unit and wasting energy. Increasing from one filter to another can increase delta P throughout the filter.