Plugin for Stiebel Eltron and Tecalor integrated heatpumps LWZ/THZ 30x/40x.


  • pySerial (sudo apt-get install python-serial)

  • Serial port connected to the LWZ/THZ maintenance port. The wiring description is provided at:

Supported Hardware

Tested with:

  • THZ 404 SOL, software version 5.39, software IDs 5993 & 7278

  • THZ 303i, software version 4.39

According to the FHEM forum (,13132.0.html) the original Perl code also works with other heatpump models (303, 304, 403).



    class_name: THZ
    class_path: plugins.thz
    serial_port: /dev/ttyUSB0
    baudrate: 115200
    poll_period: 30
    min_update_period: 300
    max_update_period: 43200

Description of the attributes:

  • serial_port: serial port connected to the heatpump

  • baudrate: port speed, recent models use 115200 bps, older heatpumps may use 57600 bps or even 9600 bps

  • poll_period: interval in seconds how often the data is read from the heatpump

  • min_update_period: interval in seconds for updating the values changing frequently (e.g. temperature), it should be higher than the poll period

  • max_update_period: interval in seconds for updating the values with infrequent changes (e.g. counters updated once per day)


There are read-only parameters and read-write parameters. Temperature values are in °C. Heat and power values are provided in kWh. For the description of the read-write parameters refer to the heatpump manual. The parameter name includes the parameter number (i.e. the prefix pXX) described in the manual.

.. literalinclude:: thz.yaml :linenos: :language: python :lines: 1, 3-5 :start-after: 3 :end-before: 5

Release history

  • Version overhauled to be a SmartPlugin to 0.2.2

  • Version renamed to 0.2.1

  • beta1, Dec 17, 2016

    • new status parameters iconCooling iconService

    • new read/write parameters: p32hystDHW p34BoosterDHWTempAct p35PasteurisationInterval p35PasteurisationTemp p76RoomThermCorrection p77OutThermFilterTime p89DHWeco p99DHWmaxFlowTemp p99startUnschedVent pClockDay pClockMonth pClockYear pClockHour pClockMinute

    • removed parameters: p99CoolingRtDay (redundant, see p01-p03 summer mode) p99CoolingRtNight (redundant, see p01-p03 summer mode)

  • alpha6, Aug 5, 2016

    • new read/write parameters: p99CoolingRtDay p99CoolingRtNight p99CoolingSwitch

    • new status parameters inputVentSpeed outputVentSpeed inputAirFlow outputAirFlow

  • alpha5, Jan 31, 2015

  • alpha4, Jan 25, 2015

  • alpha3, Jan 5, 2015

  • alpha2, Dec 26, 2014

  • alpha1, Dec 19, 2014