OAT-based Anti-Freeze Protection - Application Guide - POL224.00 - POL224.05

OAT-based anti-freeze protection is enabled when OAT temperature falls below the OAT lockout setpoint (3OAT LOCK).

If unit type is conventional unit and cooling/heating conventional operation mode is enabled:

• The compressor is closed.
• The damper either fully closes or opens to the minimum position depending on occupancy status:
• If the space is unoccupied, the damper fully closes.
• If the space is occupied, the damper opens to the minimum position.
• If the space is detected as occupied, the actual opened position of the damper depends on CO₂ sensor configuration:
• On the call of cooling when no CO₂ sensor is configured, the actual minimum position is obtained from 2FAN L ACT. If a CO₂ sensor is configured and the measured CO₂ concentration value is below the DCV setpoint (2DCV), it is from 2VENTMIN L. If the measured CO₂ concentration value is above the DCV setpoint, it is from 2VENTMAX L.
• On the call of heating when no CO₂ sensor is configured, the actual minimum position is obtained from 2FAN H ACT. If a CO₂ sensor is configured and the measured CO₂ concentration value is below the DCV setpoint, it is from 2VENTMIN H. If the measured CO₂ concentration value is above the DCV setpoint, it is from 2VENTMAX H.

If unit type is heat pump and heat pump operation mode is enabled:

• The compressor is closed when there is cooling demand. On the call of heating, the controller opens the compressor.
• The damper behaves the same as the conventional operation mode. See the above for details.

NOTICE

DCV PID function works during OAT-based anti-freeze protection.