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Lochinvar WHB 155 vibration / noise at startup when there is a DHW call

JRaposo Member Posts: 2
edited July 2021 in THE MAIN WALL
Hi Everyone
I have a Lochinvar Knight wall mount boiler that is producing a low rumble/vibration sound specifically when firing up, usually only experience this when the boiler receives a DHW call. It will ignite but will rumble when the flame rate hits 10-14% then as the firing rate increases the rumble stops. Funny thing is it only does this after a very heavy rain storm pass through. Is it possible that it's being caused by water entering the boiler via the flues? I have had the installer in to look at this numerous times, they have done a combustion analysis, gas pressure check etc but it will still does this on occasion but only after a heavy rain storm.

Would appreciate any help you can provide.


  • Zman
    Zman Member Posts: 7,543
    What were the combustion readings at high and low fire?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Boon
    Boon Member Posts: 260
    edited July 2021
    This topic is near and dear to my heart pain receptors. I had similar one-off days throughout the year when combustion at low fire would rumble on start-up. Eventually got mine adjusted & it has been running trouble free for years; you'll get there.

    Post those readings when you can. If you don't recall the installer giving you a print out with the numbers, check for hand-written notes in the boiler manual.
    DIY'er ... ripped out a perfectly good forced-air furnace and replaced it with hot water & radiators.
  • JRaposo
    JRaposo Member Posts: 2
    Thanks for the replies everyone. I think I have the initial reading done at time of install but the reps have been in on a number of occasions and adjusted the gas valve so I assume they are no longer the current readings. I have a Tech coming in next week so I should have them by them.

    I did speak to the Canadian Lochinvar Support guy and he thinks that there maybe water entering into the combustion area because of the way the intake pipe has been installed so I'm having the venting changed.

    I have a horizontal run on the air intake pipe that slopes down towards the boiler so if water gets into the intake vent it is likely running into the combustions area but I'm not sure if that is the cause of the rumbling. I would have thought that the air intake pipe should not slope towards the boiler to prevent any water getting into the combustion area.