How a Dehumidifier Circulating Fan Works

A dehumidifier circulating fan is responsible for drawing in humid air, passing it over the evaporating and condensing coils, and then releasing it back into the environment. When a dehumidifier is activated by the appliance’s humidistat, the fan and compressor will switch on simultaneously, setting in motion the dehumidification. The fan is an essential component in this process, as it moves the air through the condensing and reheating processes.

Dehumidification Process

In order to understand how a dehumidifier circulating fan works, it is necessary to have a sense of the first steps of the dehumidification process as a whole. First, when triggered by the humidistat reading, the circulating fan turns on and draws in humid air. This air then passes over cooling (or evaporating) coils where the water molecules in the air appear as condensation. This condensation is then released into the dehumidifier’s reservoir and disposed of manually or through a drain hose. Then, the air is warmed by the condenser and released back into the room.

Airflow Across Cooling Coils

Most dehumidifiers are run via a refrigeration unit, and make use of a refrigerant for the warming and cooling process. This refrigerant goes through alternate warming and cooling cycles manipulated by the evaporator and condenser, but the success of these processes themselves rely on the ability of the dehumidifier circulating fan to pass the air over the evaporating coils first. The fan puts the air in contact with these coils, which is cooled by the depressurized refrigerant, allowing for the water molecules in the air to adhere to the coils via condensation.

Airflow Across Heating Coils

Up to this point in the dehumidification process, the extra humidity in the air has been removed and deposited in the reservoir bucket. After the refrigerant moves through the dehumidifier condenser it is reheated, warming the evaporator coils. At this point, the dehumidifier circulating fan moves the air over the condenser coils to rewarm the air. In the final step, the fan circulates the air back into the room, drier and a bit warmer than it was when the dehumidification cycle began.

Icing Prevention

The circulating fan also helps to prevent the icing over of the evaporating coils, which can occur when the dehumidifier becomes too cold. When the automatic defrost function is triggered, the circulating fan will actually reverse the flow of air that has already been warmed by the condenser, sending it back over the evaporator. This has the effect of speeding up the reheating process of the evaporator coil, shortening the period of time in which they remain cool and thus decreasing the opportunity for icing.

A dehumidifier circulating fan performs some of the most essential functions over the course of dehumidification, as it is responsible for executing both the first and last steps in the process. Because this component plays such a central role, it is important to ensure that it is properly cared for. The circulating fan should be cleaned regularly, by wiping the blades with a damp cloth. If repairs are necessary, it can be unscrewed and lifted out of the appliance.