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Oil Boiler short cycling

Just_Jack
Just_Jack Member Posts: 5
in Oil Heating
I have a new-to-me home and a Weil-McLain Oil fueled boiler (heat only) which was installed in 2018. It runs all the time, even when the thermostat is not calling for heat nor is the circulator on. I realize the boiler is designed to keep water hot and "at the ready" for when the thermostat calls for it, but it seems to not hold heat for longer than 15 minutes. For example, I have timed it to cycle on for about 2 minutes to get up to temperature. Then it holds the high temp for about 4 minutes before dropping a degree every 30 seconds after that until it reaches low temp and fires back up. I have had the service repair company look at this 3 separate times, and they keep telling me it's operating as it should. It is burning oil like crazy, I can't imagine this is energy efficient.
Any help is appreciated :)

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,157
    edited November 2023
    What you have described is a WTGO boiler operation. that is used for domestic hot water. You mentioned that you have a heat only boiler. That should be the WGO boiler, that does not maintain temperature as you describe. Which boiler do you have and are you sure you are not using it for Hot Water.

    Picture of boiler and piping around it
    Picture of the label with the model number

    This is what I'm talking about. WGO v. WTGO


    Looking for your reply.

    Edward Young Retired

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

  • Just_Jack
    Just_Jack Member Posts: 5
    Yes, it is heat only. The model is Weil-McLain WGO Gold Series 3. I have hydronic baseboard radiators, and an electric hot water heater.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,157
    edited November 2023
    Someone has an extra wire connected somehow that is turning the burner on when it does not need to be. Then the heat is thermosyphoning through the home to drop the boiler temperature. If it was originally installed to maintain temperature, the installer would have installed a check valve to keep the heat in the boiler. I will bet that there is no such check valve and there is a wiring or control problem that is keeping the burner operating on the short cycle.


    Can you post the pictures I requested?

    Edward Young Retired

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

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,283
    @Just_Jack

    You boiler should not be running when the thermostat is not calling. Sound like you have an issue.

    How is the heat in the house? Does it stay steady or is it over heating.
  • Just_Jack
    Just_Jack Member Posts: 5
    @EdTheHeaterMan

    Thank you, that is quite helpful. Here is a photo of the setup as you requested. It was taken when the boiler was off.


  • Just_Jack
    Just_Jack Member Posts: 5
    @EdTheHeaterMan


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    I’d first make sure your aquastat is properly programmed. Sounds like it’s set up to maintain temperature and it should be set up as cold start with circulator hold off.

    There was an error rendering this rich post.

    MikeAmannSuperTechEdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,157
    It is clear that the installer has some things to learn. This leads me to believe that he has made some mistakes that are not obvious from this picture. Look inside the control to see if the wires are set up like this


    No wires are connected to ZC or ZR

    The dial for the low limit should be set to OFF



    Edward Young Retired

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

    dko
  • Just_Jack
    Just_Jack Member Posts: 5
    Here is a photo of the control panel. I have since switched the dial to 'off', and I believe this solved my issue! Thank you so much for pointing me in the right direction, much appreciated. :)
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,157
    You should save $$$ on fuel now.

    I only take 5% fee for this advise. Or you can do it the old fashion way and send be a crate of chickens

    Edward Young Retired

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

    dko
  • dko
    dko Member Posts: 668
    Time for a new service company?
    SuperTech

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