Do heat pumps provide air filtration?
Yes, both mini-split and central air source heat pumps are able to provide air filtration.
The air filtration system of the heat pump filters indoor air rather than fresh air coming in to the home and has the ability to capture airborne contaminants including dust, dirt, allergens, smoke, fibers, bacteria, viruses, fungi, and mold spores. Because the heat pump filters indoor air, it is important to minimize air leakage into the house by draftproofing the building envelope. Heat pumps can help people manage allergies by reducing airborne irritants like dust and wildfire smoke, and improve the overall air quality in the home.
Air Filtration for Central Heat Pumps
The air filtration systems for central heat pumps works the same way as it does for conventional furnaces. The air filtration component consists of an air purifier which is placed after the return vent, leading into the indoor unit (the fan evaporator coil/air handler). The three main choices for the purifiers are:
- media air purifiers,
- media air purifiers with photocatalytic oxidation (PCO)
- Electronic Air Cleaners (EACs)
Air Filtration for Mini-split Heat Pumps
Mini-split heat pumps have air filters built into them. They are usually located at the top of the indoor head, covering the heat exchanger, and are easily accessible to allow for cleaning. A typical air filter will be able to filter particulates but are not able to filter volatile organic compounds such as formaldehyde from particleboard and benzene from paint.
Selecting Filters for Your Heat Pump
When selecting filters check for the Minimum Efficiency Reporting Value (MERV) or the Microparticle Performance Rating (MPR).
- MERV rates the overall effectiveness of the air filter. A high MERV rating means a finer filter, which removes more airborne contaminants.
- MPR is a system that ranges from MPR 300 – 1900. It rates the ability of the filter to capture airborne particles smaller than 1 micron.
- Another common filter type is High Efficiency Particulate Air (HEPA) filter. In order to be HEPA rated, the filters must trap 99.97% of particulates 0.3 microns or larger. Some HEPA filters can trap particulates smaller than 0.3 microns. The chart below lists common particulate size.
| Common Items and their respective particle sizes (in microns): | |
| Mold Spores | 10 to 30 |
| Pollens | 10 to 1000 |
| Hair | 5 to 300 |
| Pet Dander | 0.5 to 100 |
| Typical Atmospheric Dust | 0.1 to 100 |
| Bacteria | 0.3 to 60 |
| Cooking Oil Smoke | 0.03 to 1 |
| Tobacco Smoke | 0.01 to 4 |
| Viruses | 0.005 to 0.3 |
Maintaining Your Heat Pump’s Filter
Regular cleaning of the filters in mini-splits and replacing filters in the media air purifiers are recommended. Refer to the system’s user manual for further guidance on how and when to complete maintenance.
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