IBC AHU Series, Installation & Operating Manual, Page: 50 / 75

When heating demand is satisfied:
The air handling appliance opens the compressor S1 and /or S2 contacts.
The fan continues to operate for 45 seconds.
3.4.4 Humidification Mode
Upon a call for humidification from the thermostat:
G to W is energized.
The humidifier's contacts (24V output) will close.
3.4.5 De-humidification Mode
Upon a call for de-humidification from the thermostat:
G to W or Y is energized.
The de-humidifier's contacts (24V output) will close.
3.4.6 Freeze Protection Mode
Freeze protection mode monitors the return air temperature into the air handling appliance.
If the internal return air temperature sensor detects a return air temperature below 41°F, the air
handling appliance will energize the fan, the pump contacts, and the TT (boiler) contacts to create a
call for heat. When the return air temperature increases to 46°F or more the air handling appliance
will turn off the fan, TT (boiler) contacts, and pump contacts.
If the internal return air temperature sensor detects a return air temperature below 35°F, the air
handling appliance will turn off the fan, and continue to energize TT (boiler) contacts and pump
contacts.
48
Section: Operation