Air Handler

What's inside an air handler and how it differs from a furnace

An air handler looks like a furnace cabinet but contains no burner. Its core components are a blower (increasingly a variable-speed motor), a coil where air is cooled or heated, a filter rack, and the control board that coordinates with the outdoor unit and thermostat. In an all-electric home, the air handler pairs with a heat pump: the coil carries refrigerant that cools in summer and heats in winter. Electric resistance heat strips can be installed inside the cabinet as supplemental or emergency heat for the coldest nights. In a home with a furnace, the furnace itself plays the air handler's role, with the AC coil mounted on top.

Air handlers are installed in basements, attics, utility closets, and crawlspaces. Wherever they sit, they are the lungs of the duct system — every cubic foot of conditioned air in the house passes through this one cabinet.

Air handler decisions for area homeowners

Matching matters: an air handler and outdoor unit are engineered as a pair, and mismatched replacements sacrifice efficiency and capacity, so the indoor and outdoor units are usually replaced together. A failing blower motor, rusted coil cabinet, or repeated control-board issues in an older air handler are common tipping points. For homes converting away from oil or adding cooling to a heat-pump setup, the air handler choice — including variable-speed blowers and heat strip sizing — shapes comfort and electric bills for the next 15 years. PJ MAC HVAC installs and services heat pump and air handler systems across the Greater Philadelphia area and provides free installation estimates.