[HCcl22] Heat pump, temperature-controlled

Delay of time for the operating state in case of cooling:
There is a delay off time, e.g., 5 minutes, for the signal for the operating state that keeps its value to "True" after the cooling coil becomes inactive. Both operating states of the valve and the optional pump are "False". The operating state of the cooling coil is read by CMDSEQ_B if used in an air handling unit plant (which is most likely the case). If the plant is about to be switched off and the cooling coil was active, the plant runs for some time with a cooling coil switched off to dry the coil. During the switching-off, CMDSEQ_B receives the operating state "True" for the duration of this delay and waits there before continuing with the switch-off. This helps to dry the coil.

Delay of time for the operating state in case of heating:
A delay-off time for the signal for the operating state keeps its value to "True" after the heating coil becomes inactive. Both operating states of the valve and the optional pump are "False". Keep the delay-off time low, e.g., 5 seconds, unlike the electrical heating coil or the cooling coil, to not delay the switching-off sequence of CMDSEQ_B if used in an air handling unit plant (which is most likely the case).

This program block has the following optional functions:

Option: Defrost state (1xBI)

Reads a signal from the control unit and indicates that the heat pump coil is defrosting and does not deliver power in case of heating. If active, the temperature controller for heating is disabled to pass the token to the next controller in the temperature control sequence.

Option: Disable cooling at low outside temperature

Cooling and dehumidification are disabled below a certain outside air temperature, e.g., below 12 °C.

Option: Disable heating at high outside temperature

Heating is disabled above a specific outside air temperature, e.g., above 18 °C.

Delete this option if this coil is used as a reheater.

Option: Disable temperature control in case of dehumidification

Provides an interface (most likely to the cooling coil) and logic to disable the temperature control in case of dehumidification to not preheat the air when the cooling coil performs dehumidification.

Delete this option if this coil is used as a reheater.

Option: Do not generate disturbance signal switching off the plant at high outside temperature

To increase the availability of the air handling unit at high outside temperature, the generation of a disturbance signal that switches off the plant is disabled, and the plant continues running in the event of an alarm from the heating/cooling coil.

Option: Fault (1xBI)

Reads a fault contact and generates an alarm.

Option: Feedback (1xBI)

Reads the feedback signal and generates an alarm if feedback is missing when the coil must run.

Option: Flow detector (1xBI)

Reads the signal from a flow detector and releases the output interface and the control.

Option: Maintenance switch (1xBI)

Reads the signal from the maintenance switch and generates an alarm. If active, the outputs are stopped with very high priority (priority 2).

See also

• Predefined I/Os
• Trend types
• Module families

The extension for alarming for the predefined I/O for the optional element "Feedback" must be deactivated.

See also

• Predefined I/Os
• Trend types
• Module families