Vibration in pipework - NOT water hammer!!

[bonzo1974]

Hi there, have just been to a customer's house and whenever she flushes the WC on the first floor and once it's stopped re-filling there's a loud vibration - almost like a macerator pump starting and stopping. It's not in the cistern itself, and I can't trace it without raising floorboards etc. Seems weird that it happens only when there's extremely low flowrate, and the valve stop in the WC is very gradual, not a hint of waterhammer there.

Has anyone heard this sort of sound before and what was it? I can't make sense of it enough to suggest where to start other than getting under the floorboards.

I'm stumped! Please help me!!!!

Thanks,

Giles
Drip Doctor

 

[H20:)]

Sounds like it is the washer in the ballcock the diaphragm type will make noise that reverberates round the house sometimes..

 

[zillaplumb]

I agree with H20 check the diaphragm washer for tearing or holes and replace as necessary as it may be causing the sounds your hearing good luck!

 

[Bernie2]

Hmm!

Could be washer, ballvalve plunger needs greasing, float to small, length of ball valve arm to small, plates required on float, ballvalve orifice to big. Its usually when the ball valve is nearly closed, that you get the noise when any of these problems are about. But could also be elsewhere on the system.

 

[bonzo1974]

Many thanks for all your help, will try what you've said, otherwise I'll be under the floorboards to upgrade their bathroom in the next couple of months and will hopefully find it then! If I find something unusual (like the teaspoon in the washing machine waste pipe I found at the same address!!) then I'll post it here.

Thanks again,

Giles

 

[stevetheplumber]

I agree with H20 check the diaphragm washer for tearing or holes and replace as necessary as it may be causing the sounds your hearing good luck!

in practice you would just replace, why inspect a 50p item

 

[zillaplumb]

yes it may be an inexpensive item and would probably be replaced regardless but what this particular engineer is looking for is a CAUSE of the noise, it takes 10 seconds to inspect the washer its no extra effort to check, finding a small hole or tear would explain the nature of the noise, why replace a diaphragm when it doesn't need to be, regardless of the price or effort involved its extra work that need not be done, if the diaphragm has not perished. 50p or not its still money and materials!

 

[Plumbstar Tom]

why do you think it is not water hammer?

It has all the signs of it

 

[fagsanbooz]

Guys, you are all right, i've done this so many times before and yes it is a form of water hammer. The washer trying to force against the flow causes the vibrations or in some cases a banging noise, within reason there both the same thing!

 

[bonzo1974]

why do you think it is not water hammer?

It has all the signs of it

I am very much obliged to all of you for your advice and help, trust me I am open to suggestions, but the vibration isn't coming from the bottom entry valve, it's from further down the pipework, as I've had my hand on the valve when it's happenned and the noise and vibration is not felt there, it's under the floor at least a few feet away.

I'm not averse to exchanging the diaphragm or even the entire valve but I dn't think it'll solve the problem. As I'm stumped though I'd better try it anyway!!

I'd understand it if it were as the valve was closing, I've also seen damaged diaphragms causing noises from the valve, but this is a noise related to the pressure/flowrate in the pipework once the valve is already closed.

I'm now closer to winning the contract to fit her bathroom so will investigate further once i can get under the floor - perhaps it just needs some holy water and three hail mary's!!! This is really bugging me now!!!!

 

[turnpin]

check the ballvalve in the cwsc in the loft and change the one in the w.c for a fluidmasterregards turnpin

 

[BLOD]

As turnpin said, change ballvalve in cwsc
Last one I had like this sounded like concorde trying to take off - was frightening the life out of the customer!

 

[raymondo68]

Is the wc mains fed or tank fed? If tank fed then the ball valve on the cold water storage could be causing the problem. If mains fed you could look at the main stopcock in the house, these will sometimes jump. Where the noise is actually coming from is not always a good indication of where the fauly lies.

Good luck with the bathroom re-furb.

Regards