knocking since replacing steam boiler with Burnham IN9

Ira Reiskin

Replaced very old (former coal coverted to gas) boiler, double pipe system (reverse vacuum?) Jan 2008. Not a big problem with knocking last winter. But we have gone from morning knocking as heat comes on to very frequent knocking. Boiler skimmed twice. National Grid tech. pointed out two traps in basement one of which had insides removed during installation. Why? He showed me a pipe at the other trap which was hot and was cold a foot away. I think the noise is in the basement at the boiler area and maybe at the traps-not at the radiators. Hard to tell, however, since often by the time I get to the basement the knocking has stopped. Despite National Grid's comments he was not definitive re: the problem.

Supply House Rick

boiler hammer

maybe a good test would be for you to go down to the basement early to be there as the heat comes on. wearing some heatproof gloves, maybe you will be able to feel the section of pipe which is producing the noise.

if you had dan's book, "the lost art of steam heating", you would find a list of things, which could contribute to water-hammer.

something must have changed from last winter to the present time to cause this. sometimes a clogged pigtail will raise up the pressure so much, that water stacks up in the returns, and reacts with the steam violently. clogged returns can also cause this. it would be helpful for you to list everything the tech has checked so far.--nbc