Bolier go's on & Off ? ? ?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by JoeD, Jan 8, 2006.

  1. JoeD

    JoeD New Member

    Messages:
    9
    Just put a new honeywell L8124C Aquastat Relay on my Weil-McLain
    hot water boiler. I replaced the Relay because my burner clicks on Ignites for 30-90Sec and then pops off. This does not happen EVERY time. Otherwise runs well. The house is warm and I have 3 zones. After replacing the Aquastat I STILL have this problem.
    (ie Burner Turns Off after short run time) HELP!!!

    Two plumbers told me the problem is with the Thermostat not the boiler!

    Thanks
    Joe
  2. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    Watch and Wait

    When you have an intermittent problem in a system, such as your heating system or your car or your body, you have three choices:

    1. Invest time and money for a diagnostic system to catch the event when it occurs and record the status of the system; like a flight recorder for your boiler system.

    2. Keep trying to fix it by replacing things that may not be broken.

    3. Accept the idea that it may be benign and watch and wait for more evidence that it may be a symptom of a serious problem.

    Since we aren't talking about a risk of inoperable cancer or a massive heart attack, I suggest the third option. That is what I am doing with exactly the same symptoms that you report.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,183
    Location:
    New England
    If you don't have the documentation for the boiler, check out the website. It typically has a troubleshooting section in it.

    Short-cycling of the boiler can occur for numerous reasons, the more sophisticated the system, the more reasons. For example, if the boiler is a condensing closed combustion system, there will be vacuum and pressure sensors in the intake/exhaust. You could have an obstruction in the piping (ice buildup on the exhaust) or a crack in one of the pipes that is being detected as an imbalance between intake and outlet. It could be the flame sensor is defective, and it is not detecting the flame, is going through a post-process purge cycle, a delay, then trying again. This has happened to me, and will keep the system running, is hell on the life - things work better if they don't cycle as often. You could be marginal on the system pressure - it could be too high. As things expand when it is heating, it exceeds the max pressure. The pump may not be working properly, and the overtemp sensor is shutting things down (easily can happen if the pump is not working properly). So, many things. A real problem or a sensor not working properly...either can shut the boiler down.

    My unprofessional experiences.
  4. Tekmar1

    Tekmar1 New Member

    Messages:
    10
    Location:
    Grand Prairie, Alberta
    One other option maybe.Your boiler is oversized.
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