An air handling unit is an essential component of many heating, ventilation and cooling (HVAC) systems. Also known as an air handler, it circulates air through the equipment and into the ductwork. If you have a heat pump-based HVAC system, it probably has an air handling unit. The air handling unit is a large box-shaped unit that’s installed indoors. It typically contains the following parts.
Blower
The blower is a motorized fan that’s responsible for circulating air into the ductwork. As the fan spins, it will move air into the ductwork so that it can be distributed throughout your home. The fan will turn on automatically when your HVAC system is heating or cooling your home. You can also turn on the fan manually at the thermostat.
Coil
Your air handling unit probably has a coil. Coils are used in both conventional air conditioning systems as well as heat pumps. They both feature an indoor coil and an outdoor coil. Conventional air conditioning systems and heat pumps use these two coils to transfer heat.
Assuming you have a heat pump, you can expect to find the indoor coil in the air handling unit. When cooling your home, the heat pump will transfer heat from the indoor coil to the outdoor coil. When heating your home, the heat pump will transfer heat from the outdoor coil to the indoor coil.
Air Filter
Nearly all air handling units contain an air filter. The air filter is typically found directly below the blower. Upon turning on, the blower will pull air from the surrounding space through the air filter. The air filter will then clean the air by removing dust and other forms of particulate matter.
There should be a panel on the front of your air handling unit that you can remove or open to access the air filter. Once every few months, you’ll need to change the air filter to ensure your HVAC system works efficiently.
Dampers
If your HVAC system is zoned, the air handling unit may contain dampers. Dampers are valve-like devices that control the flow of air. They are positioned to redirect air to specific air ducts.
A two-story home, for instance, may have a separate zone for the upstairs and a separate zone for the downstairs. The dampers in the air handling unit will determine which zone or zones receive the conditioned air. Along with the blower, a coil and air filter, dampers are commonly found in air handling units.