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Boiler acting funny when light fireplace

Steltz
Steltz Member Posts: 9
in THE MAIN WALL

Hi all,

This is somewhat random, but looking for thoughts. We don't light our fireplace often (wife doesn't like smell). I am looking to put in a wood insert to seal it up and use it for effiency. I have Viessman combi that is mounted underneath the fireplace hearth (in the basement, fireplace on first floor). In the past when we lit a fire, the boiler started acting a little crazy (weird sounds, and pressure guage would start going all over the place). The boiler vents through PVC out of the side of the house (not flue), and it breaths in the ambient basement air.

I think there are two flues, one for the fireplace and one for the old oil boiler. Is there anything anyone can think of that would cause this odd boiler behavior?

Thank you

Comments

  • ethicalpaul
    ethicalpaul Member Posts: 6,653

    The fireplace is probably creating a vacuum in the entire house, affecting your combustion air supply to the boiler. I would think the solution would be providing combustion air via an outside vent to the boiler, but I'll be curious to see what everyone else says!

    NJ Steam Homeowner.
    Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
    See my sight glass boiler videos: https://bit.ly/3sZW1el

    SuperTechttekushan_3mattmia2
  • Jamie Hall
    Jamie Hall Member Posts: 24,830
    https://forum.heatinghelp.com/discussion/comment/1811933#Comment_1811933

    Agreed. Magnified by the probably unsealed flue in the basement next to the boiler…

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    ttekushan_3
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,378
    edited September 26

    So you boiler is acting funny?

    I'm not sure if this will help, but there is a Fireplace Lounge that has a comedy night in the next town over from the Viessman Factory.

    Screenshot 2024-09-25 at 4.45.40 PM.png

    Perhaps you just happen to have a boiler that was manufactured on a Friday afternoon when everyone at the plant was looking forward to quittin' time!

    Edward Young Retired

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

  • mattmia2
    mattmia2 Member Posts: 10,917

    I can't explain the pressure gauge with the combustion air.

    ethicalpaul

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