We are having a problem with some sort of airlock - a buzzing noise. I
live in a block of flats. I believe the problem lies with the rising
main, though neighbours disagree.

The rising main terminates at a storage tank in the loft. I believe
think various neighbours have taken feeds from it over the years. At
the entry to the storage tank there is an vertical extension to the
pipe, about 12 inches long. I *think* that was put there as a
silencer previously. Should this extension contain water or air? Is
there any action to take, such as bleeding it, if we are now getting
water hammer?

I have tried pushing down the ball cock in the hope of releasing air.
This seems to have helped but not fully resolved the issue. Any
advice welcome.

On 09/04/2021 15:38, Scott wrote:
We are having a problem with some sort of airlock - a buzzing noise. I
live in a block of flats. I believe the problem lies with the rising
main, though neighbours disagree.

The rising main terminates at a storage tank in the loft. I believe
think various neighbours have taken feeds from it over the years. At
the entry to the storage tank there is an vertical extension to the
pipe, about 12 inches long. I *think* that was put there as a
silencer previously. Should this extension contain water or air? Is
there any action to take, such as bleeding it, if we are now getting
water hammer?

I have tried pushing down the ball cock in the hope of releasing air.
This seems to have helped but not fully resolved the issue. Any
advice welcome.

The idea of the air column is to provide an air cushion to stop the
water hammer. It should be filled with air, and you also hope that
trapped air in the cold water supply will keep the air pocket topped up.

Changing the valve to another type can also change the precise
characteristics and stop the resonance. It's all very hit and miss.

Even moving the float can change the resonance of the float arm and make
a difference.

On 09/04/2021 15:38, Scott wrote:
We are having a problem with some sort of airlock - a buzzing noise. I
live in a block of flats. I believe the problem lies with the rising
main, though neighbours disagree.

The rising main terminates at a storage tank in the loft. I believe
think various neighbours have taken feeds from it over the years. At
the entry to the storage tank there is an vertical extension to the
pipe, about 12 inches long. I *think* that was put there as a
silencer previously. Should this extension contain water or air? Is
there any action to take, such as bleeding it, if we are now getting
water hammer?

I have tried pushing down the ball cock in the hope of releasing air.
This seems to have helped but not fully resolved the issue. Any
advice welcome.



Its a worn out ball cock valve.

The valve is not shutting off cleanly when the tank reaches its final
water level.

the buzzing sounds is caused by the ball bobbing up and down in the
water which is causing a pressure ripple through the rising main and
hence the sound you hear.

although you could replace the washer, its better to replace the whole
thing.

In article ,
Fredxx wrote:
On 09/04/2021 15:38, Scott wrote:
We are having a problem with some sort of airlock - a buzzing noise. I
live in a block of flats. I believe the problem lies with the rising
main, though neighbours disagree.

The rising main terminates at a storage tank in the loft. I believe
think various neighbours have taken feeds from it over the years. At
the entry to the storage tank there is an vertical extension to the
pipe, about 12 inches long. I *think* that was put there as a
silencer previously. Should this extension contain water or air? Is
there any action to take, such as bleeding it, if we are now getting
water hammer?

I have tried pushing down the ball cock in the hope of releasing air.
This seems to have helped but not fully resolved the issue. Any
advice welcome.

The idea of the air column is to provide an air cushion to stop the
water hammer. It should be filled with air, and you also hope that
trapped air in the cold water supply will keep the air pocket topped up.

Changing the valve to another type can also change the precise
characteristics and stop the resonance. It's all very hit and miss.

Even moving the float can change the resonance of the float arm and make
a difference.


with our last tank, I fitted a "damper plate" to stop the valve shutting
off too quickly. Worked perfectly.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On Fri, 9 Apr 2021 15:52:07 +0100, SH wrote:

On 09/04/2021 15:38, Scott wrote:
We are having a problem with some sort of airlock - a buzzing noise. I
live in a block of flats. I believe the problem lies with the rising
main, though neighbours disagree.

The rising main terminates at a storage tank in the loft. I believe
think various neighbours have taken feeds from it over the years. At
the entry to the storage tank there is an vertical extension to the
pipe, about 12 inches long. I *think* that was put there as a
silencer previously. Should this extension contain water or air? Is
there any action to take, such as bleeding it, if we are now getting
water hammer?

I have tried pushing down the ball cock in the hope of releasing air.
This seems to have helped but not fully resolved the issue. Any
advice welcome.

Its a worn out ball cock valve.

The valve is not shutting off cleanly when the tank reaches its final
water level.

the buzzing sounds is caused by the ball bobbing up and down in the
water which is causing a pressure ripple through the rising main and
hence the sound you hear.

although you could replace the washer, its better to replace the whole
thing.

This is interesting. The 'argument' I alluded to is that two of my
neighbours think the problem is with the toilet in the first floor
flat. I think the noise is permeating the whole pipe and thought we
should start at the top (where I assumed the air would be). Of course
both these installations include a ballcock valve. Is there any way
of knowing which of the two valves needs to be replaced.

From my point of view, if it's in the downstairs flat, it's an
enforcement problem and if it's in the loft it's a funding problem
(though I would be inclined to go ahead with repairs in the loft if I
could confirm the fault).

On 09/04/2021 16:17, Scott wrote:
On Fri, 9 Apr 2021 15:52:07 +0100, SH wrote:

On 09/04/2021 15:38, Scott wrote:
We are having a problem with some sort of airlock - a buzzing noise. I
live in a block of flats. I believe the problem lies with the rising
main, though neighbours disagree.

The rising main terminates at a storage tank in the loft. I believe
think various neighbours have taken feeds from it over the years. At
the entry to the storage tank there is an vertical extension to the
pipe, about 12 inches long. I *think* that was put there as a
silencer previously. Should this extension contain water or air? Is
there any action to take, such as bleeding it, if we are now getting
water hammer?

I have tried pushing down the ball cock in the hope of releasing air.
This seems to have helped but not fully resolved the issue. Any
advice welcome.

Its a worn out ball cock valve.

The valve is not shutting off cleanly when the tank reaches its final
water level.

the buzzing sounds is caused by the ball bobbing up and down in the
water which is causing a pressure ripple through the rising main and
hence the sound you hear.

although you could replace the washer, its better to replace the whole
thing.

This is interesting. The 'argument' I alluded to is that two of my
neighbours think the problem is with the toilet in the first floor
flat. I think the noise is permeating the whole pipe and thought we
should start at the top (where I assumed the air would be). Of course
both these installations include a ballcock valve. Is there any way
of knowing which of the two valves needs to be replaced.

From my point of view, if it's in the downstairs flat, it's an
enforcement problem and if it's in the loft it's a funding problem
(though I would be inclined to go ahead with repairs in the loft if I
could confirm the fault).



Tie up the ball cock in the loft tank with some string.

Then flush all the toilets one by one in the building and use your ears
or even a stethosope on teh pipework to see which one then buzzes as the
toilet cistern approaches its final cistern water level.

Once you've identified the problematic toilets, you can then release the
ball valve in the loft tank. Listen to this to see if it buzzes as it
reaches final tank level.

(the loft tank will be several hundred litres of capacity and the
typical toilet cistern is around 3 to 6 litres.)

Then order and replace the toilet and/or ball cock valves as required.

On Fri, 9 Apr 2021 16:34:53 +0100, SH wrote:

On 09/04/2021 16:17, Scott wrote:
On Fri, 9 Apr 2021 15:52:07 +0100, SH wrote:

On 09/04/2021 15:38, Scott wrote:
We are having a problem with some sort of airlock - a buzzing noise. I
live in a block of flats. I believe the problem lies with the rising
main, though neighbours disagree.

The rising main terminates at a storage tank in the loft. I believe
think various neighbours have taken feeds from it over the years. At
the entry to the storage tank there is an vertical extension to the
pipe, about 12 inches long. I *think* that was put there as a
silencer previously. Should this extension contain water or air? Is
there any action to take, such as bleeding it, if we are now getting
water hammer?

I have tried pushing down the ball cock in the hope of releasing air.
This seems to have helped but not fully resolved the issue. Any
advice welcome.

Its a worn out ball cock valve.

The valve is not shutting off cleanly when the tank reaches its final
water level.

the buzzing sounds is caused by the ball bobbing up and down in the
water which is causing a pressure ripple through the rising main and
hence the sound you hear.

although you could replace the washer, its better to replace the whole
thing.

This is interesting. The 'argument' I alluded to is that two of my
neighbours think the problem is with the toilet in the first floor
flat. I think the noise is permeating the whole pipe and thought we
should start at the top (where I assumed the air would be). Of course
both these installations include a ballcock valve. Is there any way
of knowing which of the two valves needs to be replaced.

From my point of view, if it's in the downstairs flat, it's an
enforcement problem and if it's in the loft it's a funding problem
(though I would be inclined to go ahead with repairs in the loft if I
could confirm the fault).

Tie up the ball cock in the loft tank with some string.

Then flush all the toilets one by one in the building and use your ears
or even a stethosope on teh pipework to see which one then buzzes as the
toilet cistern approaches its final cistern water level.

Once you've identified the problematic toilets, you can then release the
ball valve in the loft tank. Listen to this to see if it buzzes as it
reaches final tank level.

(the loft tank will be several hundred litres of capacity and the
typical toilet cistern is around 3 to 6 litres.)

Then order and replace the toilet and/or ball cock valves as required.

Thanks, but the problem is that I am not getting much in the way of
co-operation from my neighbours. No-one really wants workmen in the
flat during the Covid. The first floor flat is tenanted with an
absentee landlord. I think he would want evidence of liability before
carrying out any repairs. I don't even know if the toilet in question
is fed by the loft tank or the rising main.

Some places where the new plastic pipes in the ground have replaced the old
metal ones this sort of issue has got worse.Water is funny stuff. I
distinctly remember duct taping a plastic bottle to the ballcock in our loft
before the tank and valve were replaced for a least ditch fix for strange
phutting noises from the mains water plumbing.
It way in fact coming from a bit of vertical main in lead that tended to
flap about when the sound happened.
New tank and valve fixed it till now, some 30 years later, even though the
same old bit of lead piping remains. I don' even pretend to understand the
reason, but it obviously had something to do with resonance.
Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Fredxx" wrote in message
...
On 09/04/2021 15:38, Scott wrote:
We are having a problem with some sort of airlock - a buzzing noise. I
live in a block of flats. I believe the problem lies with the rising
main, though neighbours disagree.

The rising main terminates at a storage tank in the loft. I believe
think various neighbours have taken feeds from it over the years. At
the entry to the storage tank there is an vertical extension to the
pipe, about 12 inches long. I *think* that was put there as a
silencer previously. Should this extension contain water or air? Is
there any action to take, such as bleeding it, if we are now getting
water hammer?

I have tried pushing down the ball cock in the hope of releasing air.
This seems to have helped but not fully resolved the issue. Any
advice welcome.

The idea of the air column is to provide an air cushion to stop the water
hammer. It should be filled with air, and you also hope that trapped air
in the cold water supply will keep the air pocket topped up.

Changing the valve to another type can also change the precise
characteristics and stop the resonance. It's all very hit and miss.

Even moving the float can change the resonance of the float arm and make a
difference.

On Fri, 09 Apr 2021 15:38:09 +0100, Scott
wrote:

We are having a problem with some sort of airlock - a buzzing noise. I
live in a block of flats. I believe the problem lies with the rising
main, though neighbours disagree.

The rising main terminates at a storage tank in the loft. I believe
think various neighbours have taken feeds from it over the years. At
the entry to the storage tank there is an vertical extension to the
pipe, about 12 inches long. I *think* that was put there as a
silencer previously. Should this extension contain water or air? Is
there any action to take, such as bleeding it, if we are now getting
water hammer?

I have tried pushing down the ball cock in the hope of releasing air.
This seems to have helped but not fully resolved the issue. Any
advice welcome.

Neighbours were correct. I was wrong. Problem was the toilet in one
of the flats. The tenants reported it and now it is repaired.