I'm prompted to ask this today after one of our kids had a friend for a
sleepover last night... none of ours ever need to use the bathroom
during the night but this kid evidently has a smaller bladder than ours
and we were woken at 5 am by the almighty crashing sound of the plumbing
after he'd flushed the toilet. Bless.

Bit odd this. The noise developed a few months ago for no apparent
reason. What happens now is that whenever a tap is turned *off*, or the
valve on a toilet cistern *closes* after it's refilled, there's a
massive *thunk* which makes the whole house reverberate.

There's no 'oscillation' noises while the water's running, and if you're
careful and turn the tap off slowly, you can avoid the thunk
(10-year-old guests, take note).

My thought is that it must be being caused by a length of unsupported
pipework somewhere in a stud wall or under a floor (maybe popped out of
a clip?) If so, unfortunately all my efforts to find it have failed;
I've checked everywhere accessible but just can't localise the noise at
all; I've tried lightly touching the pipework everywhere I can to see
where the vibration is at maximum, and even injected expanding foam into
a boxed-in area I suspected, all to no avail.

Any ideas? Could it be caused by anything else than unsupported pipework?

Thanks
David

"Lobster" wrote in message
...
I'm prompted to ask this today after one of our kids had a friend for a
sleepover last night... none of ours ever need to use the bathroom
during the night but this kid evidently has a smaller bladder than ours
and we were woken at 5 am by the almighty crashing sound of the plumbing
after he'd flushed the toilet. Bless.

Bit odd this. The noise developed a few months ago for no apparent
reason. What happens now is that whenever a tap is turned *off*, or the
valve on a toilet cistern *closes* after it's refilled, there's a
massive *thunk* which makes the whole house reverberate.

There's no 'oscillation' noises while the water's running, and if you're
careful and turn the tap off slowly, you can avoid the thunk
(10-year-old guests, take note).

My thought is that it must be being caused by a length of unsupported
pipework somewhere in a stud wall or under a floor (maybe popped out of
a clip?) If so, unfortunately all my efforts to find it have failed;
I've checked everywhere accessible but just can't localise the noise at
all; I've tried lightly touching the pipework everywhere I can to see
where the vibration is at maximum, and even injected expanding foam into
a boxed-in area I suspected, all to no avail.

Any ideas? Could it be caused by anything else than unsupported pipework?

I had something similar. I found by closing or opening the mains tap by a
quarter of a turn, it solved the problem.

"Lobster" wrote in message
...
I'm prompted to ask this today after one of our kids had a friend for a
sleepover last night... none of ours ever need to use the bathroom
during the night but this kid evidently has a smaller bladder than ours
and we were woken at 5 am by the almighty crashing sound of the plumbing
after he'd flushed the toilet. Bless.

Bit odd this. The noise developed a few months ago for no apparent
reason. What happens now is that whenever a tap is turned *off*, or the
valve on a toilet cistern *closes* after it's refilled, there's a
massive *thunk* which makes the whole house reverberate.

There's no 'oscillation' noises while the water's running, and if you're
careful and turn the tap off slowly, you can avoid the thunk
(10-year-old guests, take note).

My thought is that it must be being caused by a length of unsupported
pipework somewhere in a stud wall or under a floor (maybe popped out of
a clip?) If so, unfortunately all my efforts to find it have failed;
I've checked everywhere accessible but just can't localise the noise at
all; I've tried lightly touching the pipework everywhere I can to see
where the vibration is at maximum, and even injected expanding foam into
a boxed-in area I suspected, all to no avail.

Any ideas? Could it be caused by anything else than unsupported pipework?

Thanks
David


The system sounds like it is mains supply all round, is this correct? The
mains supply where it enters the house could be your culprit. Check it for
sturdiness around the main stopcock. If it moves even the tinniest bit, it
might be causing the hammering you hear.

Also, if you have any check valves on the system. These too can cause
hammering as they loosen off after being under tension of flowing water.
You may be able to adjust the valve using the little screw head thing on the
side of it, and it prevents the valve from closing to quickly and causing
the hammer across the pipes.

Bit odd this. The noise developed a few months ago for no apparent
reason. What happens now is that whenever a tap is turned *off*, or the
valve on a toilet cistern *closes* after it's refilled, there's a
massive *thunk* which makes the whole house reverberate.

Not sure whether they're common, but I recently spotted an expansion
vessel for pipework that is supposed to stop water hammer.

(they might also be known as "shock arresters", a quick google brings
up prices from £16 for a box of 25, right up to £25 each)

"Colin Wilson" o.uk wrote
in message g...
Bit odd this. The noise developed a few months ago for no apparent
reason. What happens now is that whenever a tap is turned *off*, or the
valve on a toilet cistern *closes* after it's refilled, there's a
massive *thunk* which makes the whole house reverberate.

Not sure whether they're common, but I recently spotted an expansion
vessel for pipework that is supposed to stop water hammer.

(they might also be known as "shock arresters", a quick google brings
up prices from £16 for a box of 25, right up to £25 each)

The use of a vertical blind stub in the pipework where the pipe transitions
from a vertical to a horizontal run will probably do the trick.
(i.e. incoming pipe comes up to a T piece, which has a short length of
capped pipe
continuing upwards, the pipe continues via the "arm" of the T piece.)

The airing cupboard of my flat is festooned with these stubs.

Another, even cheaper option where the hammer is occurring at a ballcock
valve, is
to tie a piece of string from the ballcock into the water and tie an old CD
on the end.
This acts as a damper on the ballcock valve, and stops it bouncing up and
down
on the surface ripples in the tank.

/john