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Weil-McLain boiler going on but not heating

madler718 Member Posts: 2
edited February 26 in Gas Heating
Hi all, I have a Weil-McLain CGa-25 SPDN boiler in my basement heating up baseboards. All of a sudden the boiler is turning on and sending water through the coils in response to the thermostat, but it's not heating up at all. Basically sending room temperature water into the baseboards. Any potential causes/easy fixes? Or do I need to call my installation company. Boiler is about 12 yrs old. Thanks.


  • Ironman
    Ironman Member Posts: 7,376
    Do you mean the circulator is running but the burner isn’t coming on? Your description is a little confusing.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • madler718
    madler718 Member Posts: 2
    The boiler is clicking on as normal, and water is flowing through the coils, but the water is not being heated and the gauge where the white needle goes to the red needle is not moving
  • Jamie Hall
    Jamie Hall Member Posts: 23,324
    Sounds like the boiler is not, in fact, turning on. Do you have a regular service person? There are a number of things which could keep the boiler from firing... is this operating on natural gas or on LP?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,852
    edited February 25
    There are 2 different items that "TURN ON" when your thermostat calls for heat.
    1. The circulator pump
    2. The gas burner
    To tell if the burner is on or off can you tell us if there is a blue glow of a gas flame at the bottom of the heater?

    That would indicate that when the heater turns ON but there is no flame, that there is a problem with ignition. You need 3 things for ignition to happen, Fuel, Oxygen, and Heat. That is known as the fire triangle. If any one of those three things are missing, you will not get a fire.

    Since there is oxygen in the air around the heater, I'm going to guess that the oxygen is not the problem
    So that leaves the fuel and the heat.
    The heat to start the flame comes from an igniter of some type. It could be a spark or a hot surface ignitor. The CGa boilers have been equipped with both over the years of production. A professional would be able to tell if that is the problem. A good professional may even have that part on the service truck to make the repair in just one trip.

    The Fuel could be missing because of a bad part or it could be missing because of the many safety limits that are on the CGa heater. If the vent is clogged there is a spill switch, If the boiler heat exchanger is clogged, there is a roll out switch, if the automatic vent damper is not opening, there is a safety end switch, and if your heater has a Low Water Cut Off added (as it should) the water in your boiler being too low would keep the fuel from getting to the burners.

    Now if you are familiar with all these different safety features, you may be able to figure out which one is causing you to have no heat. If you are not able to safely understand how the functions of the many safety features built into the Weil-McLain CGa boilers keep you from burning your house down, then I would suggest you hire a professional that understands how this stuff works.

    You certainly don't want to become a story on the 6 o'clock news tomorrow evening.

    If you are getting that flame under the front door to work, then you may have air in the radiators. That I can help you with.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?