Can my HVAC system handle a MERV 13 filter?
EPA recommends MERV 13 for home heating and cooling systems. What it catches, when a system can take it, and how to fit and change it.
Published 2 min read
In short
Usually yes. EPA says most furnaces and HVAC systems can accommodate a MERV 13 filter without creating equipment problems, provided the filter is replaced frequently.
Check your system's manual or ask an HVAC technician before changing filters, make sure the filter fits snugly with no gaps, and change it on the manufacturer's schedule, typically every 60 to 90 days.
A filter in a forced-air heating or cooling system does two jobs. It protects the equipment from dust, and it cleans the air that passes through it. EPA’s recommendation for the second job is a filter rated at least MERV 13, or as high as your system will accommodate.
What does a MERV 13 filter catch?
MERV reports how well a filter captures particles between 0.3 and 10 microns, under an ASHRAE test method. EPA’s figures for MERV 13:
| Particle size | Captured by MERV 13 |
|---|---|
| 0.3 to 1.0 µm | at least 50% |
| 1.0 to 3.0 µm | at least 85% |
| 3.0 to 10.0 µm | at least 90% |
EPA notes that filters rated MERV 13 or higher can trap smaller particles, including viruses. HVAC filters are usually designed for particles; they are not a way to remove gases.
Will a MERV 13 filter harm my system?
EPA’s guidance is that “most furnaces and HVAC systems can accommodate a MERV 13 filter without creating equipment problems, provided that the filter is replaced frequently.” The condition matters: the recommendation assumes the filter is changed on time.
Because systems differ, EPA advises consulting the HVAC manual or an HVAC professional before changing the filter. A technician can tell you the highest-efficiency filter your system handles and, EPA notes, can also modify the system to use a higher-efficiency filter.
How do I fit it?
- Snug, with no gaps. EPA: make sure the filter fits snugly so air does not leak around it, and you do not have to bend or crush it to fit. Air that goes around a filter is not filtered at all.
- Correctly in place. EPA’s reminder: be sure the filter is correctly in place.
How often should I change it?
Follow the filter manufacturer’s recommendation. EPA notes that many factors affect how quickly filters get dirty, and that manufacturers typically recommend replacement every 60 to 90 days. Check the filter rather than relying on the calendar alone, especially after a period of heavy use.
Does the fan setting matter?
Yes. HVAC systems filter the air only when the fan is running. EPA suggests running the system fan for longer or continuously when you want more filtration, and during wildfire smoke specifically recommends switching the fan from “Auto” to “On”. Running the fan more also uses more electricity.
For a single room, EPA’s guidance on portable air cleaners sizes them by clean air delivery rate.