Inside Air Handling Unit Blower CompartmentThis photo shows the air handler blower compartment. This is how the air handler is opened when the blower needs service or repair. The evaporator coil is on top of the blower which makes this an upflow air handling unit. The supply air ductwork will be above the AHU. Since this air handler is installed in a closet then the ductwork is installed in the ceiling and makes this an ideal installation for AC since cool air falls.

Inside Air Handling Unit Blower Compartment

When the air handling unit is serviced the blower door panel is removed the HVAC technician has access to the blower compartment and all the controls that make the unit work such as a control circuit board or a smaller compartment with relays that are electromechanical in nature and are controlled by the thermostat and cause different functions to occur such as defrost mode for a heat pump or blower fan control. The panel above is where the evaporator coil is housed. Under the evaporator coil is a condensation pan.

The PVC pipe is attached to the condensation pan to allow the condensation to drain after the evaporator has absorbed the moisture from the air. The evaporator coil condenses moisture from the air because the evaporator coil operates below the dew point. Sometimes the condensation drain gets plugged up by debris and other things. If the air handler is a condensing gas furnace you will also have a drain pipe for the secondary heat exchanger inside the furnace.

Condensing furnaces produce a lot of moisture that needs to be drained. It is possible for this to be a shared drain with the evaporator coil so if it gets blocked or plugged in some way you could also experience a leak in the wintertime. Condensing furnaces can and will leak water in the wintertime to the surprise of many people.

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Inside Air Handling Unit Blower Compartment