Freestanding steam riser makes percolating sounds

nyc10ant

After dealing with this issue for all of last winter, I'm trying to figure out the problem with my noisy steam riser before heat season returns. I'm a tenant on the 3rd floor of a 4-story building in NYC. One-pipe steam system. In the bedroom, there is a radiator and two floor-to-ceiling exposed risers. One riser is connected to the radiator and also supplies the top floor unit's radiator; the other riser is across the room and is free-standing, with no visible valve, and it does not seem to continue into the top floor apartment above me. The free-standing riser is the problem: every morning during heat season for an hour+ straight between 5-6am, it makes a loud crackling, percolating sound much like the second video in this post: https://forum.heatinghelp.com/discussion/161199/noisy-steam-pipes

Outside the bedroom, there are two other semi-exposed floor-to-ceiling pipes without any visible valves (only one of which continues into the apartment above me). At the same time the bedroom riser is making percolating sounds, these two pipes make a very loud sound of water rushing - it sounds like there is an ocean in my apartment.

Also, in case it's relevant, the pipe exteriors show signs of rust (the landlord has painted over that, but the paint is cracking).

Last winter, the landlord sent plumber to bleed out the system, which helped only minimally. Any pointers for me to take back to the landlord would be appreciated!

EBEBRATT-Ed

Someone has to track that pipe from one end to the other. It has water trapped in it for some reason and that reason is causing the noise. Nedd to find out if it is a supply or return and where it goes and whats connected to it.

It could be"

a closed valve
a bad steam trap
bad pitch in the basement
or any one of 100 different things

nyc10ant

Thanks, I realize that having limited access as a tenant could make this a tough one. What is also strange is that my neighbors above and below don't seem to have this problem.