If you have a dirty air filter, it can cause low air flow and make your HVAC system work harder. Yes, pleated air filters do restrict airflow to your HVAC system, but all air filters will restrict air flow to some extent. The key is to find the right filter for your unit and overall system to reduce pollutants in the air. Usually, a filter with a higher MERV rating will reduce airflow, but other factors like size and fan motor type also play a role.
High MERV pleated filters capture a lot of contaminants, but they also restrict air movement into the blower or oven. This can make the fan work harder and reduce efficiency. It can also cause liquid to flood back into the compressor, leading to premature equipment failure. Therefore, HEPA filtration is not suitable for all residential systems.
An HVAC contractor can measure airflow and tell you if your system can support HEPA filtration in the duct. Alternatively, residential HEPA filtration options include whole-house air filters that connect to the ductwork via a bypass circuit. These units extract air from the duct, transport it through the HEPA filter array, and then draw it back into the duct without restricting airflow. Keep in mind that as the MERV rating increases, the filter becomes more restrictive and more pressure and energy will be needed to exhaust air.
Air filters that are MERV 13 and above are recommended for those who prioritize air quality and may have to handle asthma, severe allergies and other similar circumstances.