Air Handler

An air handling unit, AHU, conditions and circulates air through ducts to ensure a residential or commercial building is heated or cooled. It contributes to an HVAC system and works with outdoor units, either a condenser or heat pump, to do its intended job of heating, ventilating and air conditioning.

It is all electric and does not utilize a burner to heat air, like a gas furnace does. Depending on the system, it runs with an air conditioner and uses the indoor coil to heat or cool a building. An air conditioning system with an air handler can also use outdoor heat pumps or a different electric heat system to heat air.

Most of the time, an AHU sits in a central location in a building. It presents as a large, metal box and incorporates a blower, sound attenuators, air filter, and heating and/or cooling coils.

Evaporator Coil

This part absorbs the heat from the air and assists with the refrigeration process. If you need cooled air, the coil removes humidity and provides conditioned air. If you need warm air, the heat coil transfers heat to the passing air.

Sound Attenuators

These reduce the noise generated by the AHU. The two shapes of attenuators include rectangular and round. They are designed to limit noise channeled through the ductwork.

Air Filter

Before going through your ducts, the air conditioned or heated air passes through the air filter. It minimizes the particles throughout your home, in the duct work, and parts of other HVAC systems.

Blower Motor

This component moves air through the connected ductwork to supply air to inside spaces. Typically they utilize an axial or centrifugal fan to move the air. The speed model varies in different air handlers.

An AHU contains a blower motor.

A single speed blower motor uses a single setting. It turns on when your thermostat signals for more heating or cooling. Once it fulfills the correct temperature, the motor turns off.

A variable speed blower motor runs at different speeds to precisely control airflow. It uses less energy than a single speed motor because it can run at lower speeds to maintain air circulation.

Single speed raises efficiency concerns because it always runs at full capacity. Variable speed monitors the airflow and adjusts accordingly, which saves you money over time and improves air quality.

Yes. A proper load calculation ensures a comfortable and energy efficient system. If your HVAC system is too small, it will not heat or cool rooms properly. If it is too big, issues with energy efficiency and the system itself arise.

Some factors to consider when calculating the load are:

• Square footage and ceiling height of building or home
• Number of people
• Number and sizes of windows and doors
• Local climate

Air handlers work in various climates but are commonly found in warmer climates. AHUs work in cooler climates as well, because they can heat and cool air inside your home or building.

Certain sources provide estimates of how to calculate load size. If unsure how to calculate it yourself, contact an HVAC technician for professional assistance.