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Utica Dunkirk 90 hot water boiler for baseboard heat intermittent gas flow trouble

AdamZ Member Posts: 2
This has been happening for years. I found a video on youtube years back with the same issues but can't find it anymore.
The boiler cycles fine, sometimes the gas isn't flowing 100% and I get this intermittent sputtering/thumping exhaust pipes now and then.
Over the years I have replaced the ignitor, the inducer blower(was a recall I found out), brushed out the baffles between the blower inducer and flame compartment, rinsed out the crud and cleaned the water drain hoses often.
When it thumps, I shut off the boiler, it resets and most times works normally.
Any ideas? I'm grateful.



  • Ironman
    Ironman Member Posts: 7,376
    It could be any number of issues.

    Was the boiler setup with a combustion analyzer? If so, what were the numbers?

    Do you know the incoming gas pressure while it’s firing.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • AdamZ
    AdamZ Member Posts: 2
    Thanks Ironman, I have no idea about the analyzer but I'll look. As far as gas pressure, it's not an issue for my house with any other appliances. Never has been.
    If you were to guess best bet, most likely, etc. I'm up for anything. Thanks
  • mattmia2
    mattmia2 Member Posts: 9,660
    Could be the regulator in the gas valve or the regulator for the house. The boiler is probably by far the largest load in the house, the regulator at the service could be fine at low flow rates but fail at higher flow but the first step is to make sure the burner is set up right with combustion analysis instrumentation.