[HcrPltMod22] Plant operating mode determination for heating circuit, for precontrol

Determines the plant operating mode by considering various possible sources (e.g., scheduler, manual operation, room unit).

The operating mode is shown on BACnet with a multistate calculated value "Present operating mode" with the states "Off" and "On".

A parameter in the program is preset to prevent the plant from running. This is useful for testing data points. It must be switched off to start the plant.

"Startup function and alarm handling" controls the startup behavior of the plant after power-on. There is a delay after startup, "DlySttUp", of about 50 seconds. Do not change this delay. Change the delay, "DlyOn", so that it is different for each plant. This ensures that plants start one after another and do not overload the electrical system. There is also a collection and aggregation of all faults and alarms from the plant. If a local alarm lamp and/or reset button is required, an alternative can be selected.

Outside air temperature

The outside temperature [TOa] is used unfiltered and filtered. Two different attenuated signals result from the filtering.

Signal name	Description	Filter constant	Use
TOa	Outside temperature	Unfiltered	Pump run when the outside air temperature is low Heating curve OSSC
TOaEff	Effective outside air temperature	1h	Heating curve Heating limit
TOaBldg	Outside temperature, strongly filtered	50h (Building constant)	Heating limit

This program block has the following optional functions:

Option: External off

Interface that can be connected to a program logic for shutting down the plant.

Option: Heating limit

The heating limit is defined by an analog configuration value.

The plant is enabled for automatic operation, e.g., by the scheduler, when both filtered outside temperatures are below the heating limit value. The plant is not enabled for automatic operation if one of the two values exceeds the heating limit value.

Option: Operating mode switch (1xMI=2xBI)

Reads the state of an operating mode switch, normally at the front of the electrical panel, and has the states "Auto", "Off", and "On".

Option: Operation indication (1xBO)

Commands a lamp (usually green) that turns on if the plant is running or that blinks if a switching operation is in progress.

Option: Scheduler

Scheduler of type MSCHED with the states "Protection", "Economy", "Pre-Comfort", and "Comfort" that switches the plant off and on.

Option: Setpoint reduction

The setpoint reduction is defined by an analog configuration value and affects the flow temperature setpoint of the optional heat curve.

See also

• Predefined I/Os
• Trend types
• Module families

See also

• Predefined I/Os
• Trend types
• Module families