boiler knock

fritzer435

I own a gas 140,000 btu Crown boiler for 18 years in my residential home. The boiler this year developed a knock but only when the burners are on. I don't think there  is air entrapmentr but i manually released the air valve in case it was. Can you offer a cause and how to remedy? thanks

KCA_2

Hi Fritzer

Well...  The knock can be a few things....  The first thing that comes to mind is that the water is boiling inside the heat exchanger.. so....



1.  Not enough flow through the exchanger = Bad circulator or clogged exchanger



   a.  Make sure that you have flow through the boiler...  Do you have power to the

        boilers circulator? Is the circulator working?



   b.  If all of A is OK..  and even if it isn't....  hook a hose to the boiler drain down valve

        and blow out the boiler exchanger...  You might have sediment lying on the

        bottom of the heat exchanger..



  Look at those items and I bet that your problem will disappear..



  I hope I helped



  :-)  KCA

furnacefigher15

The boiler

may need a chemical cleaning.



It is likely that there is a sediment build up in the boiler. The sediment has probably hardened.



Try the steps outlined by KCA. If still having issues, call a pro to have the boiler chemically cleaned / and or inspected for other causes.



With out repair, this may lead to the premature failure of the boiler.

Steve Whitbeck

Knocking

What you are hearing is more than likely due to sediment in the boiler heat exchanger.

Turn the water off to the boiler on a warm day - after you turn the boiler off and see if the boiler pressure stays about the same. You may have a leak in the system that is causing the boiler to take on fresh water constantly - this brings in sediment and that will distroy the boiler.