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Weil Mclain 97+ 155: Manual states Internal primary/secondary valve to be OPEN, mine is closed

skiereric Member Posts: 66
edited December 2023 in Radiant Heating
For context, the boiler is providing DHW as zone one (with a dedicated circulator) and heating via radiators as zone two (with a dedicated circulator).

Unsure if the tech who recently cleaned the heat exchanger closed it and never opened it, or if it has been that way the entire time. Any risk in opening it?

www.weil-mclain.com/sites/default/files/field-file/wm97-ct-manual_1.pdf Page 41 " The internal primary/secondary valve MUST be OPEN for all applications except for installations with multiple WM97+ boilers, piped as shown in this manual. "

From the photo, I have attached, the Internal primary/secondary valve is closed.

The question is, should I open it?


  • skiereric
    skiereric Member Posts: 66
    edited December 2023

  • skiereric
    skiereric Member Posts: 66
    Update: I opened the valve. During the pre-ignition phase, with the heating circulator + boiler circulator running, the boiler out temperature sensor remained constant, however, the supply leading to the manifold started to get colder.

    Since the boiler out temperature was above the target temperature, ignition never occurred.

    It seems that now, during a heating call, water is not circulating through the heat exchanger.

    Unsure why this might be.
  • skiereric
    skiereric Member Posts: 66
    Looks like I am missing a Flow/check valve on the DHW loop. This is probably the culprit