Ducted heat pump systems rely on proper air filtration to do their jobs properly and provide years of worry-free use. Occupants of homes with ducted HVAC systems also depend on air filtration to protect their health. The air filter you choose as an installer is the first point of defense against airborne particulates that, if allowed to pass through the filter medium, can shorten heat pump lifespan, as well as put occupants’ health at risk, so choosing the right filter is crucial.
Air filters are installed on the return side of the ducted system and housed in a slot so that the air passing through the filter is scrubbed of the particulate before entering through the evaporator coil to be conditioned and transported through the ducts to the supply registers. Particulates that bypass the filter medium become lodged in the evaporator coil fins, decreasing airflow and causing the unit to work harder to draw air through the clogged evaporator coil. This results in reduced performance, higher energy bills, poor air quality and ultimately, shorter system lifespan.
There are also potential health effects from poor air filtration. Unfiltered air passing through the supply vents includes irritants like dander, dust, pollen and wildfire smoke particulates. The cumulative effect of poorly filtered air at the return can lead to avoidable HVAC repairs and, for some occupants, expensive medical bills.
Return air filter ratings are rated in tiers based on the size of the captured particulates. Minimum Efficiency Reporting Value (MERV) ratings are measured on a scale from 1 – 16, with 1 being the lowest filtration level and 16 being the highest. It is recommended that the installer outfit a new ducted heat pump with a filter meeting MERV 8 or higher for normal daily use. For customers with allergies to pet dander and pollen, a MERV 11 is recommended. A MERV 13 filter is recommended for temporary use during periods when wildfire smoke is present. (Note that a MERV 13 rated air filter should be used only as a temporary measure to filter dangerous particulates from wildfire smoke because the dense filter medium causes additional strain on the HVAC system.) These three air filter tiers are widely available at local building supply retailers and online.
Some air handlers come equipped with a MERV 1 nested fiberglass filter, which is considered insufficient for adequate protection of the evaporator coil and the occupant’s health. These filters should be removed and replaced with a pleated, electrostatically charged synthetic fiber MERV 8 filter—the minimum recommended MERV rating for proper air filtration.
The evaporator coil should be periodically cleaned by an HVAC technician to ensure maximum efficiency and lifespan of the system. HVAC professionals should recommend this service to their customers as preventative maintenance, along with regularly scheduled checkups to ensure maximum efficiency and happy, healthy customers.
Indoor air quality and HVAC equipment longevity are of primary importance when installing a new ducted heat pump, so installing proper air filtration is a vital step. Taking the time to educate customers about reliable air filter options can save repair costs and result in healthier air quality, leading to many years of worry-free use of their new energy-efficient heat pump.