9.9 External temperature request settings

The heat pump can be controlled by a higher-level automation system, either via an analogue input (AI) or a Modbus interface. The control can be based on either the temperature setpoint (°C) or heat request (%).

External temperature request is activated when setting the hardware configuration. After a restart, the settings can be found in the service menu, under Device settings ► External temperature request.

Setpoint settings

When the request is based on the setpoint from the higher-level automation system, the minimum and maximum heat pump setpoints – ExtSpMin (factory setting = 20 °C) and ExtSpMax (factory setting = 100 °C) – are specified in the settings. This function is controlled by the supply temperature sensor, which depends on the heating system:

  • single heat pump: internal supply temperature sensor (B21)
  • cascade system: cascade supply temperature sensor (B10)
  • heat pump controls additional heat sources: common flow sensor (B11).

When controlled via an analogue input (AI), the heat request is given at a 2–10 V control voltage. The controller generates the request linearly based on the minimum and maximum setpoints, after which the controller calculates the capacity need and controls the compressor. The operation at different control voltage values is as follows:

  • 0 V: the device is in STOP mode
  • 0.5 V: charge pump (Q9) shuts down
  • 1.5 V: charge pump starts
  • 2 V: minimum setpoint
  • 10 V: maximum setpoint.

When controlled via the Modbus interface, the device is switched to start mode from the registry 102 (activation of the charge circuit) to start the charge pump. The controller then receives the setpoint in the registry 104 (the heat pump’s setpoint °C).

Heat request settings

When the request is based on the heat request, the minimum and maximum heat request values – ExtDmdMin (factory setting = 0 %) and ExtDmdMax (factory setting = 100 %) – are specified in the settings.

The higher-level automation system monitors the temperatures of secondary circuits and controls the heat pump as needed. The heat pump takes care of the internal functions of the device and controls the circulator pumps according to the values set.

With the Taurus Inverter Pro heat pump, the device starts when the minimum speed of the compressor is exceeded, and shuts down when the request is removed (0 %). The device rotates at a minimum speed when the request is 1 % – Compressor’s min speed.

The Taurus EVI heat pump operates at different control voltage values as follows:

  • 0 V: the device is in STOP mode
  • 0.5 V: charge pump (Q9) shuts down
  • 1.5 V: charge pump starts
  • 2 V: heat request 0 %
  • 6 V: heat request 50 %, the first compressor starts
  • 10 V: heat request 100 %, the second compressor starts

The second compressor shuts down when the capacity drops to 50 %, and the first compressor shuts down when the capacity drops to 0 %.

Parent topic: Heat pump settings