Boiler rumbling like a hwt

Bob_98

I have a small hot water Dunkirk boiler natural draft 105000 btu's with 2 zones installed in 1999. It rumbles and perculates like a dying water heater.The noise starts almost immediately and is very loud,all the noise is in the boiler itself none in the piping. There in no infloor or underground piping. Heating in fine around the house. Customer swears hasn't even had a clean and check since it was installed and no radiators or baseboards have been moved or repiped or chemicals added. Upon arrival boiler was running at 28psi I dropped to 15. Gas pressure was at 4.25 I dropped to 3.3. Curious as why this occured what to do to correct and what to do to prevent reocurrence.

lee_7

The popcorn noise is from sediment on bottom of boiler, that when heated, the air in the sediment pops and cracks. Also the sediment pops off bottom. Boiler needs a flushing and possible chemical cleaning.

Bob_98

Yes I agree it is probably sediment and rumbling just like a water heater. My questions are more what caused this so soon, How do I prevent it from reoccuring, and as far as "chemicals" which ones would you recommend. Typically as a company rule we try to avoid chemicals as all cost. Every other time I have run accross this it has been on older boilers with a cracked infloor returns that we have ran new returns with a new boiler. P. S. Some other info that may or may not help is limit was and still is at 170 the pump was replaced 3 days ago "Red Fox"[not by us]. There is a combination of copper and blk. pipe thru-out the house and near piping.