Steam heat gurgling noise

rih

Actually, I'm not sure how to describe the noise. It comes from the pipes and sounds like gurgling. Maybe it's what's known as "chattering." There is also some fairly loud tapping when boiler first fires up--gurgling follows. Very disturbing because people on this floor get up at 5 AM, pipes pass right by our bedroom.

This is new this year. There was hammering a while ago, but I think the people had someone in to fix that.

Essentials. Gas boiler, just cleaned the boiler. Odd, though, that the water drained was green, rather than rust colored. Not sure what that means. Also after plumber refilled boiler, I had to drain 2 gallons because system was overfilled and hammering.

Boiler is in basement, radiator is two floors up from basement. Single pipe to and from radiator involved--seems to be only one that is causing problem. Radiator heats. Radiator may need pitch adjustment--it seems flat to the floor. There is no valve to turn that I can see, just something jury rigged there. Not sure what it is, but can check later. Plumber who adjusted the pipes thought the system was working and no new air vent was needed--but did ask me to check back with report. Waiting to hear back, but holidays have slowed things down.

Since then I put insulation around the part of the pipe making noise that I could get to, but the noisest parts are in the walls where I can't reach.

Adjusting the pitch of some pipes helped, but noise remains.

Any thoughts, ideas, comments appreciated.