Integration of AC Heating heatpump with xCC regulation system

Owned by Miroslav Duschek
15.07 2024
4 min read

Basic


The control system xCC enables remote control by a higher-level control system using the ModbusTCP communication protocol. Using the ModbusTCP protocol, it is possible to configure and read individual parameters of the control system in a similar way to its web interface. Communication takes place through the Ethernet interface on the standard port 502. The address of the xCC system for the ModbusTCP protocol is set to 1 and cannot be changed. The unit allows only one active connection. A basic template is available for the Loxone system, containing basic sensors and actuators for controlling two heating circuits, DHW heating and basic information about the system. If necessary to control other functional xCCs, actuators and sensors can be added manually, according to the attached file with a description of all registers for the ModbusTCP protocol.

General sensors and actuators:

  • Main_switch – The main switch of the entire system, at a value of 0 it turns off all heating / cooling and DHW heating.

  • Err, Err_critical, Err_non_crit – System error signalization. The specific error can be specified via the xCC web interface.

  • Heater_act – External heater activation flag.

  • HP_Power – Current power of the heat pump.

  • LRT – LRT signal – Low rate tarif.

  • Outside_t – Outside temperature measured on the outdoor unit.

  • Sys_act_power – Current system power.

  • T_act – Current temperature of the heating water at the output of the heat pump and backup source.

  • T_req – Current required heating water temperature.

  • T_ret – Current temperature of return heating water.

 

Sensors and actuators for DHW heating:

DHW heating is always controlled using the xCC system for reasons of optimization. From the Loxone system, user heating parameters can be changed:

  • DHW_act – Flag of active DHW heating.

  • DHW_t – Current water temperature in the DHW tank.

  • DHW_min – Setting the minimum required temperature in the DHW tank.

  • DHW_max – Setting the maximum required temperature in the DHW tank.

  • DHW_en – Disabling / Enabling DHW heating.

  • DHW_circ_en – Disabling / Enabling the control of the DHW circulation pump.

  • DHW_circ_manual – Switching on the manual control of the DHW circulation pump.

  • DHW_circ_man_state – If DHW_circ_manual is set to 1, this actuator is used to directly control the circulation pump.

  • DHW_circ_act – Circulation pump active flag.

  • DHW_sanit_en – Enabling automatic sanitation of the DHW tank.

  • DHW_sanit_int – Setting the interval of automatic sanitation of the DHW tank.

  • DHW_sanit_t – Setting the desired sanitation temperature.

  • DHW_last_sanit –Number of hours since the last successful sanitization.

 

Control of heating water temperature and heating circuits

One of 3 scenarios can be used to control the heat pump for heating:

Heat pump only as a source of heating water:

In this mode, the heat pump is in the basic, simplest configuration, and only information about the required heating water temperature and the heating/no-heating signal is transmitted from Loxone.

Actors / sensors used:

  • Heat1_water_const – Requested watter temperature.

  • Heat1_en – Switching off / on the demand for the supply of heating water.

  • Heat1_mode – Circuit mode selection 0=Equithermal / 1=Constant water temperature.

The heating circuit in the heat pump must be set to constant mode:

Heat1_mode = 1

Then it is possible to set the desired water temperature using Heat1_water_const.


The heat pump receives the desired and actual room temperature from the Loxone:

In this mode, the choice of heating water temperature is on the heat pump, its automation adjusts the heating water temperature in such a way as to achieve the greatest possible efficiency of pump operation. The desired and actual temperature in the reference room must be sent from Loxone.

Actors / sensors used:

  • Heat1_en – Switching off / on the demand for the supply of heating water.

  • Heat1_room_Req – Desired temperature in the reference room.

  • Ext_T_1 – The actual temperature in the reference room.

The heating circuit must be configured in sensor mode, an external input must be used as a room sensor. This configuration can only be done by an AC Heating service technician during installation or contact the service line +420 737 039 833.

 

The heat pump receives the actual and desired temperature for each room from Loxone:

In this mode, the choice of heating water temperature is on the heat pump, its automation adjusts the heating water temperature in such a way as to achieve the greatest possible efficiency of pump operation. From Loxone, it is necessary to send the desired and actual temperature for each room separately. The xCC system then regulates the servo drives on the individual heating loops according to these temperatures.

 

ModbusTCP protocol registers used:

  • Holding registers 96 - 111 – Actual temperature for individual rooms.

  • Holding registers 40 - 55 – Desired temperature for individual rooms.

  • Holding registers 72 - 89 – Read only. Desired valve opening value from the xCC system.

  • Coil registers 36 - 51 – Switching on / off the request for heating the given room.

  • Coil registers 52 - 67 – Read only. Signaling of active room heating.

The heat pump must be configured to this mode by an installation technician or a
technician on the AC Heating service line 737 039 833.