What Does an Air Handler do?

What is an Air Handler

An air handler regulates the circulation of the heated or cooled indoor air to help reach the temperature that you have set on your thermostat or control system. Depending on the design of your home, an air handler may be a principal indoor component of your split heat pump system.

When properly matched with your heat pump, the indoor air handler is designed to circulate conditioned air through your home’s ductwork efficiently.  Most often, air handlers are located in the attic, basement or a dedicated closet, and may closely resemble the shape of a gas furnace.


Parts of an Air Handler


Your air handler consists of an evaporator coil, blower motor, air filter and the electrical and electronic components required to deliver enhanced levels of indoor comfort.

Coil:  The evaporator coil (indoor coil) is a crucial component of the refrigeration cycle. 

  • When you want cool air inside your home, the evaporator coil becomes cold through the refrigeration process and removes humidity as the indoor air passes over it. This makes the conditioned air feel cooler throughout your home.
  • When you want warm air inside your home, the evaporator coil becomes warm by the reversed refrigeration process and transfers heat to the air that passes over it. This makes the conditioned air feel warmer throughout your home.

Blower Motor: The blower moves the cooled or heated air to the connected ductwork to circulate it into your indoor spaces. The blower motor may be a single speed, multi-speed or variable speed model.

  • Single-speed: Operates at one, fixed speed. These motors are cycled on and off, as required by a thermostat or control system.1
  • Multi-speed:  Designed to operate at multiple speeds, depending on the demand. The multi-speed blower motor may run at 100% to meet a high-demand thermostat or control system setting. A low-stage demand will reduce the speed of the blower motor. This low speed may maintain reduced humidity levels, provide sustained comfort and be more energy-efficient than when used in a single-stage system.
  • Variable-speed: Varies the fan speeds to precisely control the flow of heated or cooled air throughout your home based on your indoor comfort requirements.  A variable speed motor can help control indoor humidity levels and achieve a consistent temperature in your home. According to the Office of Energy Efficiency & Renewable Energy, “variable-speed motor running continuously at a half speed uses up to 25% of the power to move the same amount of air.”2 

Plenum Connections: Ductwork is connected to your air handler by a plenum to:

  1. “supply” or deliver the conditioned heated or cooled air to your interior spaces 
  2. “return” the air to the air handler that needs to be heated or cooled

Filter: Before air enters your ductwork, it passes through an air filter. The filter is intended to minimize the number of particulates circulated throughout your home, accumulate in the duct work, and land on the indoor components of your heat pump system.

Optional Electric Heat Strips: Provides an auxiliary, electric heating option when conditions arise that require activation.


The Cycle of Handling Air

In coordination with your HVAC system’s ductwork, the air handler simultaneously creates a recurring cycle, delivering air out to your indoor spaces through supply vents and drawing air in through the return vents.  Even if your air handler is properly sized with your outdoor heat pump, a licensed professional HVAC dealer should ensure that the air supply and movement through the air handler are balanced. 

According to the Air Conditioning, Heating and Refrigeration Institute (AHRI), a mismatched heat pump and air handler may be at least 30% less energy-efficient than matched systems.3 Homeowners should keep this efficiency loss in mind when they are considering replacing only the outdoor unit portion of their split system.

An inadequate amount of air flow in the supply vents, return vents or ductwork may reduce the HVAC system’s balance which can potentially cheat you out of your equipment’s efficiency and sacrifice your indoor comfort. This is one of the many reasons why proper installation by a licensed professional HVAC dealer matters to your HVAC equipment’s longevity, energy costs, and indoor comfort.

Amana brand heating and cooling

1, 2 Office of Energy Efficiency & Renewable Energy. Variable-speed, low-cost motor for residential HVAC systems. 1 May 2017.
3 AHRI. HVACR Replacement Guidance. 15 January 2013, 12 April 2017.