Frost protection strategies

Units with preheating register

The electric heat register keeps the unit free of frost and protects the heat exchanger from icing over. The ventilation unit controls the temperature at the unit inlet to the minimum air inlet temperature (factory setting -1°).
Comments: The minimum air inlet temperature is set on units with an enthalpy heat exchanger and preheating register.
If the outgoing air temperature falls below the Outgoing air min. value set in the factory (with a defective electric heat register), the ventilation unit switches off. A frost protection fault appears on the control unit.
If the heater power rating is not sufficient for extreme conditions (high volumetric flow and very low outside temperature), the ventilation unit switches back one ventilation level.

Units without preheating register

If the outgoing air temperature falls to the set value T outgoing air min. (fixed factory setting), the supply air fan switches off (regardless of heat exchanger type).
If further exhaust air causes the outgoing air temperature to increase again (set increase in temperature in outgoing air, fixed factory setting), the supply air fan switches on again.
If using another upstream, controlled form of pre-heating (electric pre-heating), the pre-heating is used to keep the unit free of frost. Should the outgoing air temperature fall below the set “Outgoing air min.” despite this, the ventilation unit switches to fault after a short delay time.