When it comes to air filters, the higher the MERV rating, the better the filtration. But is a Merv 12 filter too high for HVAC systems? The short answer is that it can be, 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 your filters regularly, you're unlikely to experience filter-related issues with your HVAC system. When installing an air filter with a high MERV rating, two things happen. First, the air becomes cleaner, which can help improve the longevity of your HVAC system. The more particles are trapped, the less they stick to the inside of the vent and the better the air flow.
In general, filters with higher Merv ratings are more effective and improve air quality, but they are also more expensive. MERV ratings above 16 are commonly used in specialized commercial environments where air filtration is critical, such as hospitals. 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 of the HVAC system.
When buying oven air filters, don't confuse MERV with other sorting systems that may appear on packaging (especially from large home improvement stores). Filters with higher MERV ratings should be changed more frequently (at least every three months) to avoid restricted airflow that can cause your system to operate inefficiently or even damage it. A higher MERV rating often means lower airflow, which can cause the system to work harder and use more energy to do its job. If you want you to at least clean your air and handle dust, mold, pollen and bacteria, then a MERV 8 will do the job.
If you want to use pleated filters and superior MERV filters, the only sure way to do that is to have a 5- to 6-inch media filter installed by a professional. 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. Fortunately I have a 3D printer and have printed a mask with a MERV 13 filter.According to the US Environmental Protection Agency, filters in the 7-13 range often have little difference from higher MERV ratings, but will allow your system to operate much more efficiently. I have three MERV-13 filters in my house and the pressure drop in all of them is less than 0.06 i.It seems that it would be enough to use the high merv filter media, blasting it with compressed air, and then insert the filter into a pocket of the DIY mask, between the two layers of fabric. In conclusion, while Merv 12 filters can be used in HVAC systems without any major issues, it's important to remember that they should be changed regularly in order to avoid any potential problems caused by restricted airflow.
