clang clang clang goes the pipe

steam_in_my_house

Have a single pipe steam system. Always has worked well (thanks to many tips from this board). Gorton #2 mains and gortons on the rads.

Over the summer we had our sunporch converted into a bedroom. Being this used to be a porch, the piping for this room runs through the crawl space as opposed to the basement (like the rest of the house)

Room has the correct size radiator in it and it heats just fine. Problem is during when the steam hits the pipe in the crawlspace, it goes "clang clang clang" for about 4 minutes. This happens every at the beginning of every heating cycle.

So I crawled into the crawl space and discovered a couple things..The pipe IS pitched correctly BUT 1) the contractor used copper pipe instead of cast iron. 2)the pipe runs through the bat insulation underneath the floor BUT it is not insulated itself like the rest of my system (1" fiberglass split tubes)

Is it clanging because it is copper and is expanding and contracting too much? Of is it clanging because it is in a crawl space in much colder ambient temperature than the pipes that run in the basement?

ideas?

Charlie Taylor_2

I think you are right on. Being colder, the temperature rise is far greater when the steam hits. The copper is expanding rapidly, which will cause you problems in the future. The cold pipe is causing the steam to condense to water and block the steam coming in, causing the noise. As the pipe heats up, there is less condensate, permitting the steam to flow better. This is why steam pipes are bigger than water pipes.

Insulate the pipes and see the difference. But keep an eye out for future leaks.