Bard WG242DA, Installation Instructions Manual, Page: 47 / 81

Manual 2100-376L
Page 47 of 81
33. WG DEHUMIDIFICATION UNIT RELAY LOGIC
The WG Wall Mount Gas Fired Units equipped with the Dehumidification Circuit employ several components to
control the Heating, Cooling and Dehumidification process (excluding blower control). These components include
the following:
CR1 Control Relay #1 Part # 8201-071
CR2 Control Relay #2 Part # 8201-062
CR3 Control Relay #3 Part # 8201-062
TDR1 Time Delay Relay #1 Part # 8201-089
TDR2 Time Delay Relay #2 Part # 8201-045
RAT Return Air Thermostat Part # 8408-037
CR1
This relay completes the “Y” or compressor signal to the CCM (Compressor Control Module) during either a call for
Cooling or a call for Dehumidification.
CR2
Part of the Bard Manufacturing Company, Inc. control strategy on Dehumidification units is that Cooling always
takes precedence over Dehumidification. This relay opens the circuit to the Dehumidification Solenoid Valve on a
call for Cooling, effectively overriding the Dehumidification function in favor of the Cooling call.
CR3
This relay terminates the signal to the Dehumidification Solenoid and also the “Y” signal to the CCM during a call
for Heat.
TDR1
This time delay relay is a 10 second Delay On Break device. On shift between Cooling and Dehumidification, this
relay assures the Compressor signal does not drop to the CCM. This will keep the CCM from going into time delay
as the unit shifts from Dehumidification mode to Cooling mode and back.
TDR2
This time delay relay is a Delay On Break device. After a call for heating is terminated, this relay assures sufficient
time for the evaporator coil and heat exchanger to cool off before allowing the compressor circuit to be completed.
This protects the system in the event of a rapid mode change from Heating to Cooling.
RAT
The Return Air Thermostat is a safety device that guards against a Low Ambient condition during Dehumidification
mode that may result in coil freeze-up or damage to the system. In the event the Return Air temperature drops below
the RAT setting, the RAT will terminate the Dehumidification call. The RAT will re-establish the call for
Dehumidification when the Return Air temperature rises sufficiently for the RAT to reset.