LOUD heating pipes

[Pat Ackroyd]

I live in an older [c. 1910], 6-storey apt. bldg. in NYC. I have 2 steam radiators, and a heating pipe runs through each room [floor to ceiling]. Here’s the problem–the pipes do nothing but clank, and I mean LOUD, whenever the heat is on. Super. has bled the radiators and changed their valves, but it’s not just the radiators–it’s also the heating pipes themselves that make a godawful noise. Does anyone know why they do this, and is there ANY way to get rid of the noise, or at least reduce it? Please help put an end to my sleepless nights!

[HaroldParticipant]

Clanking steam pipes are a symptom of water being slammed against elbows and fittings by the high speed of the steam picking up water and slamming it against the pipe. Also, when hot steam passes over the condensed steam that is still close to the boiling point some of the steam ‘explodes” into vapro again making sizzling and clanking noises.

Over many years, buildings settle, so pipe runs that used to slope toward the boiler move downward to trap water and steam in pockets, making them available for steam to pick it up and splash it at high speed. Water moves around obstacles gently at low speed, but at high speed it is like steel shot and can actually break fittings off the ends of pipe when stopped at high speed.

To make the problem worse, steam moves faster the higher the pressure behind it, so making the pressure in the boiler higher than necessary makes the problem worse. A problem is that people know less about steam as the generations die off. Superintendents sometimes think that if the steam pressure is one pound, the heat is better at 5 pounds. However 1 pound of steam pressure in hot pipes will rise to the top of the World Trade Center, so 5 pounds will heat the superintendent’s astronaut relative in space. After all, clouds are cool steam in the sky.

So see if the pipes can be levelled and the pressure reduced to where it is supposed to be and the world will seem a quieter place in spite of New York sirens and traffic.

[RickParticipant]

The noise is because live steam is hitting condensate (water). This indicates one or more bad steam traps. You probably have steam traps on each register. They are intended to open when condensate hits them (to allow the condensate to return to the boiler), and close when the condensate has emptied, and steam is present.

You may be able to tell the most likely steam traps to replace by either the register with the most noise, or feeling the condensate return piping on the register side of the trap. If the piping is not really hot, it means condensate is sitting in the pipe, and the trap is not opening.

The two most common types of steam trap are the inverted bucket trap

and the thermal disc trap

Either of these work pretty good.

If you try to replace the bad traps yourself, make sure you shut off the heating system and allow it to cool – steam and hot water both cause serious burns. It might be best left to a professional.

Good Luck,

Rick

[Edited by Rick on 26 January 2001]

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