Dehumidification control can be supported two ways:

1. Utilizing a central dehumidifier that can be used independently from the cooling operation. The IDT must have an ACC relay configured for “Dehumidification” and “Dehumidify with AC-Fan” as an option. The central dehumidifier should be a powered device (24V) and will use the Equipment Interface, ACC relay to open/close the circuit. When the IDT calls for dehumidification it will close the ACC relay activating the dehumidifier and the blower (if enabled) on the furnace/air handler. The IDT will display the dehumidify and fan icon. Dehumidifier operation will be maintained until the “Dehumidify Level” set-point is reached. If there is call for Cooling at the same time, the dehumidifier will run concurrently with the AC operation. During this period the IDT will display the snowflake, dehumidify and the fan icon. If the cooling set-point is reached before the “Dehumidify Level” set-point the AC will shut-down and the dehumidifier will continue to operate and vice-versa. This method will provide the most effective dehumidification control.
2. The 2nd form of dehumidification support will work in conjunction with an Air Handler/Furnace that provides a Dehumidification mode. The IDT must have an ACC relay configured for “Dehumidification”. A jumper will be required from RH/RC to one side of the ACC relay. When the IDT calls for dehumidification it will close the ACC relay sending a 24V signal to the dehumidifier terminal on the furnace/air handler control board. The IDT will display the dehumidify icon. This alone will not provide any dehumidification and must work in conjunction with the AC operation. When the IDT signals for cooling operation it will turn on the AC condenser and the blower control board will slow down the variable speed motor based on the manufacturers recommendation to provide more effective “Latent” cooling across the evaporator coil. The IDT will display the snowflake, dehumidify and fan icon. If the air temperature set-point is reached before the “Dehumidify Level” set-point the IDT will shutdown the condenser and blower fan but the IDT will continue to display the dehumidify icon until set-point has been reached on a future cooling cycle.