Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Boiler ignition/control problems

E.N. Member Posts: 1
I have a Weil-Mclain boiler that over the last several weeks has had issues lighting. Today for example, it was building temperature (about 170 at the time) and the burner shut off but tried to immediately relight (piezo ignition Honeywell S8620C). It never did. The ignition tried to relight the burner several more times but never did. The pump continues to run and water temp falls to nothing. It will not relight unless I shut off the power to reset the system. I have checked for 24V coming in and out of the control to the gas valve. When it doesn't light, there is no voltage sent to the gas valve. With that in mind, I replaced the ignition control. Still no change in symptoms though. Any help is appreciated.


  • A.J.
    A.J. Member Posts: 257
    No ignition

    E.N. your power needs to be shut down to reset the control because the boiler ingition failed to lite the allotted number of times. Check your pilot burner voltage and see if you have 24 volts at the gas valve if you do it's probably the gas valve. If you aren't getting 24 volts it is your interrogated modgal change it out.
    That being said if this is the first time your doing this type of change out you should call in a pro.to be on the safe side.

  • T-O
    T-O Member Posts: 29

    The problem could be in the thermocoupling. Different sensor / controllers are connected in series to each line of the transformer. Use your voltemeter to test the series on one line of the transformer beginning with the first connection (example, thermocoupling), then the second, third, etc, and place and maintain the other probe of your tester on the other line of the transformer. Do the reverse to work on the series of the other side of the transformer.
  • Empire_2
    Empire_2 Member Posts: 2,343

    I cant stress this enough. Service/Maintenance works wonders. Better yet,..call a service contractor.

This discussion has been closed.