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Viega Hydronic Mixing block kicks off heat mode after just a few minutes.

Having trouble with my Viega Hydronic mixing block's controller. It turns red for heat for only a few minutes then kicks off. Replaced the TPC sensor, no change. Disconnected thermostat, no change. Help!


    EBEBRATT-Ed Member Posts: 15,344
    edited December 2021
    The manual is attached.

    Looks like you can bypass the thermostat by jumping terminals 1 & 2 on the mixing block in most cases. Read the manual before trying this.

    Make sure it is plugged into a working 120 volt outlet

    Check the wiring connections for the thermostat and the two sensors.

    You could have a bad sensor. You have a boiler temp sensor on the boiler and an outdoor temp sensor.

    To check the sensors disconnect them from the mixing block and ohm them out with an ohm meter. Take the outdoor air temp and the boiler temp with a thermometer and compare the ohm readings you get with the chart Page 19 I think.

    If the ohm readings don't agree you may have a bad sensor

    Also read the programming instructions and see if the sensor temps are reading on the screen
  • johntlukens
    johntlukens Member Posts: 2
    Thank you! I have tried all of your suggestions with no luck. A new question: If I choose "constant" in the menu of choices, will the mixer just run?
    EBEBRATT-Ed Member Posts: 15,344
    It looks like in constant it will run all the time if the outdoor sensor is telling it to. You would need to go through the manual