Merv Filters can impact HVAC pressure

Yes, changing to a different MERV (Minimum Efficiency Reporting Value) rated air filter can indeed affect the pressure in an HVAC system. Higher MERV filters generally introduce more resistance to airflow, which can increase static pressure in the system25.

Impact of MERV Ratings on Pressure

• Higher MERV filters typically create more resistance, potentially increasing static pressure2.
• Low-MERV filters (<4) have an average pressure drop of 0.10 inches water column (i.w.c.)2.
• Mid-MERV filters (8) can increase pressure drop to 0.19 i.w.c.2.
• High-MERV filters (11) may further increase pressure drop to 0.32 i.w.c.2.

Considerations When Adjusting Filters

1. Filter Size: Larger filters generally allow more airflow, reducing pressure drop8.
2. Filter Thickness: Deeper pleats or increased pleat numbers can lower pressure drop without changing MERV rating5.
3. System Compatibility: Ensure your HVAC system can handle the pressure drop of higher MERV filters5.
4. Airflow Velocity: Pressure drop varies with air velocity; lower velocity typically means lower pressure drop5.

Alternatives to Manage Pressure

• Modify return ductwork to increase filter surface area5.
• Consider separate air filtration equipment for high filtration needs without impacting HVAC performance5.
• Implement a static pressure reset schedule in newer DDC systems to optimize airflow and energy efficiency9.

When adjusting HVAC pressure using filters, it’s crucial to balance filtration efficiency with system performance to avoid straining the HVAC equipment10.