Boiler banging when burner reaches max temperature

tombstone

Internal

Thanks for the suggestion but this is definately coming from the interior of the boiler.

Alan (California Radiant) Forbes

Pump

You said you replaced your pump 2 years ago.  Are you able to tell if your pump is working?  Can you hear it? 



When you first turn your boiler on, does the supply pipe coming out of the boiler warm slowly or does it get very hot quickly?

bill_105

It's now been a month

I had a banging C.I. boiler not too long ago. The owners said it was coming from the pipes. It sure did sound like it. I looked at all the stuff you've done. I then found the trouble.

Try this. Remove the gas vent and the motorized vent damper. With a bright light  confirm that the flueways are not clogged with either soot or rust.

Disproportionate temps through the cast iron will cause lots of expansion and contraction.

On the boiler I was on it actually was making CO. And the woman was sick from it.

Take a picture of the flueways.

 Edit - Oh, wait a minute, it's not that easy with that style of draft hood. If all the pipes, pump and other stuff check out okay, well then you need to look elsewhere. Are the buners looking clean? If you were to look at the burners (off) and smack the thing on it's side does anything come out. I know that's highly technical troublshooting:)