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gas valve

Gas fired weil mclain boiler 9 series com 25 a model. The burner keeps cyclying on and off. It has a standing pilot. burner will fire up and then shut off after about 2-3 seconds. Approx. 10 seconds later it does it again. The customer said that it started doing this after a service company cleaned the burner. I am an installer and proficient with piping and accessories but very limited with gas burner trouble shooting.


  • Tim McElwain
    Tim McElwain Member Posts: 4,588
    Attach a multimeter

    to the gas valve and see if it keeps doing the same thing with 24 volts applied. If so the valve is bad.

    Make sure it is not a powerpile self generating system. If it is do you know how to take Millivolt readings?
  • Marty Henry
    Marty Henry Member Posts: 3
    cycling gas valve

    Thanks Tim. When I got finally get to the job the next morning, I discovered it was powervented. The proving switch was extremely dirty. After a thorough cleaning it worked fine.
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