[HcrPltMod21] Plant operating mode determination for heating circuit, for room heating

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

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: Heating curve

Calculates the setpoint for the flow temperature based on a heating curve (Hcrv21). It uses the function block HCRV.

Different room setpoints (depending on the operating mode) are fed to the heating curve and influence (increase or decrease) the calculated flow temperature setpoint.

A setpoint correction for the flow temperature is connected to the optional room influence.

Option: External off

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

Option: Frost protection

Performs room frost protection.

It switches on the plant (it goes into "Comfort") if the room temperature drops below the setpoint for Protection. It switches off the plant (it goes into "Protection") again with a hysteresis of, e.g., 2 K.

This option can only be applied successfully together with the optional room temperature

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: Heating limit for economy

The heating limit for Economy is defined by an analog configuration value.

The plant is enabled for operation in Economy mode if the economy mode is requested, e.g., by the scheduler, and both filtered outside temperatures are below the heating limit value for economy. The plant is not enabled for operation in Economy mode 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", "Protection", and "Comfort".

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: Optimum start stop control

Performs optimum start stop control (using the function block OSSC) when the plant is in automatic mode (no manual intervention or external on or off) and released by the optional heating limit functionality.

This option can only be applied successfully together with the optional room temperature

Option: Request from room operator unit

A binary simple process value that can be read/written from the device chart of a room unit. It can switch on the plant.

Option: Room influence factor

The heating limit for Economy is defined by an analog configuration value.

The difference between the room setpoint and the room temperature is multiplied by the room influence factor. The resulting value is connected to the optional heat curve and influences the flow temperature setpoint.

This option can only be applied successfully together with the optional room temperature

Option: Room temperature (1xAI)

Creates an analog input for the room temperature and reads its signal.

Option: Scheduler

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

Option: Switch-off in Economy mode when room temperature higher than setpoint

If the current operating mode is Economy and the room temperature exceeds the Economy setpoint, the hydraulic circuit is switched off with a hysteresis of, e.g., 2 K.

This option can only be applied successfully together with the optional room temperature

Option: Timer button (1xBI)

Reads the state of a timer button and switches the plant on for a specified time (adjustable in the program).

See also

• Predefined I/Os
• Trend types
• Module families

See also

• Predefined I/Os
• Trend types
• Module families