Banging Radiator Pipes

[NickHil]

Well, it's that time of year for banging pipes...

I live in a 6-story building, in a top-floor apartment. The pipes leading up to the radiator bang like crazy when the boiler starts up. It's a two-pipe, steam system. The pipes come up through the far wall, then travel horizontally under the floor to the radiator (and under the wall to the neighbor's unit).

The banging is much louder than what I'd consider "standard" in New York City (I certainly expect some...). It happens regardless of whether the radiator valve is open or closed. However, I've noticed that if I open the valve as soon as the banging starts, the noise goes away much more quickly than if I left it alone... also, if the valve is open and the banging starts, closing it will help the problem as well.

I've been speaking with my landlord, but they are very slow to do anything about it. They came in once and replaced the steam trap, tilted the radiator, etc... but they've since told me "we're not going to fix it -- it'll be too expensive". But I can't give up on it, and I figured any direction I could provide them might help get the process moving...

My initial thought was that the pitch of the pipes under the floor was off -- maybe a sag somewhere that allowed the condensate to pool. But since I figured out that changing the state of the valve (open to closed or vice versa) seems to solve the problem, I've started to wonder if it's a pressure issue -- maybe a bad trap or valve somewhere else in the system?

Any help would be much appreciated!

 

[world_of_woodchip]

I'm not sure I can provide specific advice, but in general, here goes.

Pipes can start banging for a number of reasons for example the pump kicks in and you get a pressure wave running along a pipe run until it hits an obstruction such as a valve, that can set up an echoing pressure wave running back the other way. if these pressure waves meet on a long unsupported run, the pipe can start 'flapping' and if that's close enough to a solid object, bang bang bang.

You say the banging stops quicker if you open your valve, after it starts, this is allowing that pressure wave to dissipate into the volume of your bit of the system.

There can be a whole bunch of other reasons such as worn out steam valves, condensate - as you suggest thrashing around.

What I would suggest to start with for free is to try and get any condensate drained from radiators and pipe runs, try and jack up any sagging pipes to drain them, if that's not possible, maybe get a drain valve installed anywhere at the bottom of sags. - you may need a spirit level to find these. Also an easy one - and great to get all your neighbours involved in, is to look for pipe brackets or supports that may have come off or are broken. You could also play detective and position various people around the system when it comes on to see if you can isolate where the noise is originating. Where is it may not be where you hear it as the noise will transmit along any solid object - like metal pipes.


If none of the free stuff works, then you may need to fit a pressure expansion tank www.amtrol.com seem to have quite a good range. These allow the pressure wave to be absorbed so that the vibration doesn't start. Only a professional could advise the best place (or places) in the system for this. If your system has one, maybe it needs servicing or replacing.

I hope any of this helps, if not at least you may get to meet people! Let us know how you get on.

All the best

Andrew

 

[NickHil]

Thanks - I'm pretty sure I found the spot that vibrates the most -- but it's under the hardwood floors. I was hoping it might be a valve issue, but I'll resort to pulling up the floors if I need to (don't tell my landlord!) and wedging something under a saggy spot...