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Boiler short cycling?

Dianapagu
Dianapagu Member Posts: 11
edited October 31 in THE MAIN WALL

Hi All,

Im the past ive found the experts on this forum very helpful. Hoping again for that knowledge. As the weather starts to get colder its that time for the boiler to turn back on. In the past we've had our issues like not turning on completely leading to a replacement of the ignition box and pilot. This was 2 years ago. This time around we think its short cycling since it does turn on for a 1-2 min run and then it beeps calling for heat , turns on for a under a 1min then off/on all until the thermostat reaches its temperature.

This is a Williamson boiler to a one pipe system , steam gas boiler. We had someone come by to take a look but they didnt feel confident. Still suggest the ignition box ,pilot and gas valve be replaced

So im wondering does this somewhat sound correct. Trying to research short cycling on steam boiler and get lots other trouble shooting suggesting before having to do a complete replacement. I tired uploading the video but its too big. But any other advice would be much appreciated.

Comments

  • neilc
    neilc Member Posts: 3,062

    post a general picture, floor to ceiling, showing the controls side,

    post a closeup on the controls and site glass, and gage while it's firing,

    low water cutoff, pressuretrol, may need service,

    known to beat dead horses
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 11,280

    Does the flame light? YES = the ignition box, pilot and gas valve is working.

    When it goes off you need to determine what is causing it. There are several things that can cause the flame to go out so quickly after it starts up. Most of them are electrical. Are you handy with an electrical meter? I can talk you thru the diagnosis process.

    Edward Young Retired

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

  • Jamie Hall
    Jamie Hall Member Posts: 26,525

    Before you even start thinking about the gas valve and ignition… there are a number of other things that could be the problem. Poor main venting (or non-existent)? (suggested by the initial short run 1 to 2 minutes is way too short for a starting run!). Low water level and surging causing the LWCO to trigger. Poor of otherwise inadequate radiator venting. Even poor near boiler piping… and that's for starters.

    You need to begin by figuring out what is shutting it off.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 18,856

    Short cycling can have many causes. If it is ignition /flame proving issue some boilers will try to star 4-5 time before they lockout, so the flame can light…go out…light …go out.etc.

    Other than that short cycling can be caused by the low water cutoff not enough water in the boiler or a surging water level.

    Also could be the pressure control, it could be adjusted wrong or you could have a plugged pigtail.

    There are other causes but those are the most common.

    Dianapagu
  • 109A_5
    109A_5 Member Posts: 3,071

    If you post your video on a web site that hosts videos and then post the link to it here.

    Is the short cycling issue new to the system, that is it never did that before ?

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Dianapagu
    Dianapagu Member Posts: 11
    edited 1:31AM

    All things I have also thought of. I did notice the radiators closest to the boiler were not heating while the others furthest did. I dont think i have an electrical meter around but can definitely get one. The ignition box / pilot was replaced only 2 years ago unless thats how long they only last? Low water meter light isnt lite , smallest dim but i heard that was a "normalish" feature on Williamson. But the boiler is definitely full. Has it done this before? Not like this i want to say , only one winter we didn't get heat at all which is why I had an emergency service call done bc it was middle December and a weekend unfortunately but pilot wouldn't go off completely and company that serviced changed the ignition box n pilot for that reason.

    Short video link here to view. https://youtu.be/uGI-CWdgn0M?si=xghWxldILpHoIh_1

  • 109A_5
    109A_5 Member Posts: 3,071

    What looks like the main burner drops out and intermittently the pilot stays lit and/or goes out then it restarts again. I'd verify that the 24 VAC to the Spark Ignition Control module is consistent and stable when the burner drops out. If the 24 VAC is good the Spark Ignition Control module is probably bad again. However before changing the module I would verify the flame sense rod is clean and there is 24 VAC from MV/PV to PV only when the pilot is lit.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • neilc
    neilc Member Posts: 3,062

    loose wire, bad ground, somewhere there,

    all spades snug? all screw type wire terminals tight?

    somebody's loose,

    known to beat dead horses

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