Heat exchanger control

Description
This SCL function block, FB_TempDifferenzPumpensteuerung (Temperature Difference Pump Control), controls a circulation pump and a valve based on the temperature difference between the primary and secondary circuits. Overheating protection functions and a clear HMI status display ensure safe, transparent operation. It can be run directly in the Siemens TIA Portal.

Note: All modules are designed exclusively as a learning and optimization basis and are not approved for live operation. System modules, in particular, must be finally tested and commissioned by qualified personnel before productive use.

How it works

1. Fault detected → Pump & valve off, alarm on, HMI “FAILURE”, RETURN
2. Calculate ΔT = T_Primary – T_Secondary
3. Start enable not active → Pump & valve off, HMI “OFF”
4. ΔT < ΔT_Min → Pump & valve off, HMI “WAIT”
5. ΔT between ΔT_Min and ΔT_Max → Pump & valve on, HMI “OPERATION”
6. ΔT > ΔT_Max → Pump & valve off, alarm on, HMI “OVERHEATING”

Technical details
• Inputs: #Fault, #StartRelease, #T_Primary, #T_Secondary, #DeltaT_Min, #DeltaT_Max
• Outputs: #Pump_ON, #Valve_OPEN, #Alarm, #StatusText_HMI
• RETURN in case of error for immediate termination
• IF/ELSIF logic for five states: FAULT, OFF, WAIT, RUN, OVERHEAT

Possible applications
• Heating and cooling systems in industrial plants
• Heat exchanger and solar circuit management
• Retrofit to increase the efficiency of existing systems
• Training and demonstration projects on temperature difference control

compatibility
Siemens S7-1200 & S7-1500, TIA Portal V13 and higher (V16+ recommended for PLCSIM & HMI)

Scope of delivery
.scl file with input/output declarations, state logic, and comments; download link immediately after purchase

Support
Adjustment of ΔT limits, integration of additional sensors, or HMI functions are available upon request. Contact us via shop message or email.