Banging and surging

tom_131

I live in a 4-story brownstone row house attached to neighbors on both sides. I have a one-pipe steam heating system. The system is only vented by the air vents at the radiators. There are no vents on the horizontal mains or risers.

My big problem is banging and surging on the ground floor southwest radiator (the tenants radiator). I discovered that the radiator was reversed pitched and I corrected this problem. The banging was reduced, but not eliminated.

The horizontal main leading to the south side travels about 25’ pitched toward the south return where the main branches off to the east. About 4’ later, continuing south, the supply pipe for the ground floor radiator branches and is properly pitched. The next 2’, the main is reversed pitched before branching to the SW riser, then the return.

This reverse pitch could cause the banging, but I can’t imagine it causing the surging as it is so gradual and it is after the supply pipe to the problem radiator.

During the last two evenings, my tenant noticed more water surging out of this radiator air vent.

This morning, the banging from the SW corner started at system start-up, about 5:45 AM, and continued on every cycle for about 1 hour when the heat just started to reach my SW radiator (3rd out of 4 floors) and up the riser about 4 feet. The SE radiator was heated all the way through by this time.

After the hour, about 6:45 AM, the banging reduced to distant clinking on the SW riser side, but there was no noise on the SE side.

By 8 AM, finally, all of the radiators were hot.

So...why the nightly surging in the ground floor radiator? Since it is now pitched properly and the supply pipe is pitched properly, shouldn't the condensate flow back to the return? Is their clogging or sclerosis in the return line? Is there a way to investigate the return without taking it apart? Is there a way to flush the line?

I stay awake thinking about these things?

Steamhead

Fix the pitch problem

and the surging will go away.



What's happening is the steam hits the water and some of it condenses. Then more steam comes in and makes the whole mess expand. This causes the surging and also can cause banging.



There should be no water at all standing in those pipes. None.