[HCcrPltMod21] Plant operating mode determination for heating/cooling circuit
Program block, name / node subtype: [HCcrPltMod21] Plant operating mode determination for heating/cooling circuit
Library hierarchy: Universal equipment
Family: HCcrPltMod
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*SttUpAlmHdl21a in controllers with system version < 1.5 |
Configurator
Program blocks are stored in the library without I/Os. Use the auto-create and auto-connect functions to create I/Os and/or to connect them to the interface blocks, e.g., R_A, CMD_B. Alternatively, take the I/Os from the folder containing the predefined I/Os in the library and/or from the plant and connect them to the interface blocks.
Determines the plant operating mode by considering various possible sources (e.g., scheduler, manual operation, room unit).
Possible operating modes
Operating mode | Description |
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Off | The hydraulic circuit is off (the pump is off and the valve is closed). The optional flow and return shutoff valves are in their off position (depends on the hydraulics and how they are installed but in the program it is set to "heating"). |
On | The hydraulic circuit is on (the pump is on and the valve is following the output of the temperature controller). The optional flow and return shutoff valves are in their heating or cooling position (depending on the heating cooling state). |
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.
A logic determines a heating or cooling state based on different conditions and sources (HCChovr21).
A logic for setpoint determination coordinates the setpoints for flow temperature for heating and for cooling from different sources (from external sources or from optional setpoints) and displays it as a present flow temperature setpoint (analog calculated value). For cooling, the present flow temperature setpoint can be shifted by the optional dew point temperature calculation.
This program block has the following optional functions:
Option: Condensation monitor (1xBI)
Reads the signal from a condensation monitor and stops the plant.
Option: Dew point temperature calculation (2xAI)
Creates analog inputs for room air temperature and room air humidity and reads their signals. Based on this information, it calculates the dew point temperature and adds an offset, e.g., 1 K. The resulting dew point temperature is displayed as an analog calculated value.
Option: External off
Interface that can be connected to a program logic for shutting down the plant.
Option: Flow temperature setpoint for cooling
Analog configuration value for flow temperature setpoint for cooling. This is required when only a binary cooling request is collected via a coordination function or for applications without coordination.
Option: Flow temperature setpoint for heating
Analog configuration value for flow temperature setpoint for heating. This is required when only a binary heating request is collected via a coordination function or for applications without coordination.
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: Outside air temperature (1xAI)
Creates an analog input for outside air temperature and reads its signal.
Option: Scheduler
Scheduler of type MSCHED with the states "Off" and "On" that switches the plant off and on.
Even with two states only, this is a multistate scheduler (not binary) that can be extended more easily if the project requires it.
Name | Description | Type | Alarm / Notification class | Trend / Type | |
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OpModMan | Manual operating mode selection | MCnfVal: Multistate configuration value | N/A | Yes, 4 | |
PrOpMod | Present operating mode | MCalcVal: Multistate calculated value | No | Yes, 4 | |
RsnPrOpMod | Reason for present operating mode | MCalcVal: Multistate calculated value | No | Yes, 4 | |
SttUpAlmHdl | Startup function and alarm handling | [SttUpAlmHdl22a] Startup & alarm handling, acknowledge & reset, 3 priorities | N/A | N/A | |
PrSpTFl | Present flow temperature setpoint | ACalcVal: Analog calculated value | No | No | |
HCChovr | Heating/cooling changeover | N/A | N/A | ||
Name | Description | Type | Alarm / Notification class | Trend / Type |
|---|---|---|---|---|
OpModSwi | Operating mode switch | MI: Multistate input | No | Yes, 4 |
Sched | Scheduler | MSchedule: Multistate scheduler | N/A | N/A |
OpInd | Operation indication | BO: Binary output | No | Yes, 3 |
SpTFlH | Flow temperature setpoint for heating | ACnfVal: Analog configuration value | N/A | Yes, 4 |
SpTFlC | Flow temperature setpoint for cooling | ACnfVal: Analog configuration value | N/A | Yes, 4 |
TOa | Outside air temperature | AI: Analog input | No | Yes, 3 |
Dew point temperature calculation | ||||
TR | Room temperature | AI: Analog input | No | Yes, 3 |
HuR | Room air humidity | AI: Analog input | No | Yes, 3 |
CdnMon | Condensation monitor | BI: Binary input | Yes, 5 | No |
Description |
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External off |