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

AdamZ

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.

https://youtu.be/k4F_8O2dgjg
https://youtu.be/ebDlq8BY3cY
https://youtu.be/pHXGExS4WSo

Ironman

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.

AdamZ

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
AZ

mattmia2

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.

AdamZ

Follow up two years later…

It was the exhaust pipe, when I disconnect the exhaust pipe from the boiler the flame burns perfectly. I cleaned out the exhaust pipe and it's been great. Maybe spiderwebs?

Anyhow that's all set. Now for the circulator pump… new thread

• AZ