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Viessmann trimatik MC B control cutting out on heat up

Hi all , any help on this would be appreciate, my friend has a viessmann vitola biterral oil boiler fitted with aTrimatik MC B control panel

All worked fine for some years now, but recently problem on the central heating it will start to heat up then after a short time 20 mins approx, it will actuate the mixing valve and begin to close this until eventually it goes into blue zone and cuts off the boiler

the only way I have been able to make the boiler function is to disconnect the heating flow sensor situated on the flow pipe about 1meter away from the boiler.

I have checked all fuses wiring etc

the sensor appears to give the correct values but I am not convinced

the diagnostics on the Trimatik do not indicate any fault with sensors

any thoughts or comments ?

many thanks


  • CMadatMe
    CMadatMe Member Posts: 3,086

    That is an old control you have. I don't have the manual and can't even find it in the historic documentation on Viessmann's web site. I do know that the only parts available for this control is just the timer clock. They do make a retrofit kit to up grade to the Vitotronic 200 Control for Vitola. Suggest you call Viessmannn Tech at 888-484-8643.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
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