As an HVAC expert, I have seen the benefits and drawbacks of using high MERV filters for air quality. While these filters are highly effective in trapping dust and other contaminants, they can also cause damage to your HVAC system. This is due to the increased resistance and reduced airflow that comes with a higher MERV rating. One of the main consequences of using a high MERV filter is a decrease in comfort. In extreme climates, your system may struggle to provide enough heating or cooling to your home, resulting in uncomfortable temperatures.
This can also be seen in specific rooms that may not receive enough airflow. It is important to note that when using a high MERV filter, it is crucial to remember to change it regularly. These filters are so effective that they can quickly become clogged with pollutants, leading to an increase in pressure drop. This may seem like a minor inconvenience, but leaving a clogged filter unchanged for too long can lead to serious problems with airflow resistance. However, this is an easy issue to prevent by simply remembering to change the filter on a regular basis. The minimum efficiency reporting value (MERV) rating is used to measure the effectiveness of an air filter in preventing dust and other contaminants from passing through and reaching the airflow.
These ratings range from 1 to 16, with higher MERV values indicating better filtration of small particles. To increase the surface area of the filter and potentially reduce pressure drop, it is recommended to choose filters with deeper pleats while maintaining a high MERV rating. It is also important to note that not all filters have a MERV rating, and many are purchased at big box stores without this information. Generally, filters with a MERV rating of 16 or lower are suitable for residential, commercial, and general hospital use. Filters with a MERV rating of 7 to 14 or higher can have pressure drops ranging from 0.05 to 0.3 inches WC, depending on the thickness and airflow velocity of the filter. If your furnace is easily accessible for filter replacement and the location allows for an increase in the width of the return duct, it may be possible to install higher MERV filters.
However, it is important to use a filter specifically designed for this purpose and to maintain it regularly to avoid any negative effects on the system's operation. Increasing the MERV rating of a filter can also lead to an increase in delta P throughout the filter. Using an air filter with a higher MERV rating than recommended by the manufacturer of your oven or air conditioner can affect its performance. For those looking for exceptionally high filtration, some sources suggest using separate air filtration equipment with a HEPA filter that can clean the air without impacting the performance of the oven, although this is only effective for a specific area and not the entire house (EPA 200).For those looking for even higher levels of filtration, HEPA filters with MERV ratings of 17 to 20 are available and can effectively filter particles as small as 0.3 microns, including viruses. Additionally, air filters with high MERV ratings that contain folds create a larger surface area for air to pass through, improving airflow and reducing strain on the system.
However, it is important to keep in mind that as the MERV rating increases, so does the restriction on airflow, requiring more pressure and energy to expel air. Research has shown that while high MERV filters can cause a certain level of pressure drop, it is not significant unless the filter is heavily loaded with dirt. This means that simply using a high-MERV filter medium and inserting it into a pocket of a handmade face mask may not be enough to effectively filter out contaminants.
