The "HCA_HeaterNordic" macro provides modulating control of the heating coil valve actuator and controls the heating pump. The macro receives its heating control signal from the control strategy. A frost protection thermostat, if connected, will prevent freezing of the air handling unit coils at low outdoor temperatures. Continuous freeze protection can override the strategy signal by the:
The heating coil enables the dampers, only if the coils return water temperature (if configured) is high enough. For energy saving reasons, the heating coil can stop heating at high outdoor temperatures. The macro generates pump-on, fail-to-command and pump-off alarms, if the pump status is connected. Pump and valve exercise prevent the coil's equipment from getting stuck. The calculated heating demand sent to heat generators, depends on the actual heating valve position. Plant- and humidity mode signals can override the normal control signals.
There are several coil variants available: Heating Coil Heater runs as a heater, Heating Coil Preheater runs a pre-heater and Heating Coil Reheater runs as a re-heater.
This coil is defined as heater and is always controlled by temperature.