I€„¢ve got a problem with water hammer on the kitchen cold tap. The
noise is horrendous. Can anyone point me in the direction of a good cure.
On the advice of a friend I drained the system with the stop cock closed and
reopened the bottom tap with the stop cock still closed to drain off any air.
Then re-opened the system and this worked for about 20 minutes when the noise
returned.

Any advise much appreciated.
pfj

Do you have a way to turn the actual flow rate down before the part where
the hammering happens? I I remember when we had an increase in pressure here
on top of a hill it would hammer if certain taps were used. A mere tweak on
the stopcock where it comes in from outside seemed to fix it.
Brian

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"pete" wrote in message
vidual.NET...

I?Tve got a problem with water hammer on the kitchen cold tap. The
noise is horrendous. Can anyone point me in the direction of a good cure.
On the advice of a friend I drained the system with the stop cock closed
and
reopened the bottom tap with the stop cock still closed to drain off any
air.
Then re-opened the system and this worked for about 20 minutes when the
noise
returned.

Any advise much appreciated.
pfj

pete wrote:

I€„¢ve got a problem with water hammer on the kitchen cold tap.
I fitted one of these damped pistons right after the internal stopcock

https://toolstation.com/p85345

It stopped all hammer from e.g washing machines and taps within my
house, though occasionally a single thud from somewhere in the street
will enter and make itself heard from my pipes.

They sell a 3/4" inch rather than 1/2" version which presumably has more
capacity to absorb the hammer ...

https://toolstation.com/p64117

Andy Burns wrote:

They sell a 3/4" inch rather than 1/2" version which presumably has more
capacity to absorb the hammer ...

Actually looking closer, the difference seems to be that it's easier to
fit inline with a 3/4" washing-machine hose, and is probably only the
same size piston/cylinder.

On Sun, 30 Dec 2018 09:07:12 +0000, pete wrote:

I've got a problem with water hammer on the kitchen cold tap. The
noise is horrendous. Can anyone point me in the direction of a good
cure.

Learn not to turn that tap off so quickly.

If there is an isolator valve in the feed to that tap, try closing it
a little to reduce the flow rate. Thus the velocity of the water in
the pipe that is being brought to a sudden stop by the tap being
closed too quickly.

You could fit one of those hammer arrestor devices but that really
only treats the symptom, by providing a cushion of trapped air to
absorb the momentum of the moving water, rather than being a cure.

I suspect that your mains water pressure is quite high. Can you open
a mains fed cold tap quickly to fairly fully open without the water
bouncing staight out of the basin/sink all over you? A PRV (Pressure
Reducing Valve) in the rising main will stop the hammer and remove
the caution required when opening a mains fed tap.

We had hammer here and rather "vicious" flow rates with incoming
mains pressure around 4 to 5 Bar. Fitted a PRV, set that to 2.5 Bar,
no hammer and "safe" taps. B-) If you do fit one and if you have
any loft tanks make sure you don't reduce the pressure below that
required for the water to reach the tanks.

--
Cheers
Dave.

Could it be the washing machine hose being too flexible? I get hammer if I
leave my hose pipe turned on at the tap but off at the far end - sames sort
of thing I guess.Sets up a rhythm

pete explained :
I€„¢ve got a problem with water hammer on the kitchen cold tap. The
noise is horrendous. Can anyone point me in the direction of a good cure.
On the advice of a friend I drained the system with the stop cock closed and
reopened the bottom tap with the stop cock still closed to drain off any air.
Then re-opened the system and this worked for about 20 minutes when the noise
returned.

A cheap fix couple of feet of vertical pipe with the top end capped,
connected to the problem pipe via a T, will help reduce hammer. The
pipe will be full of air, which will act as a cushion, giving the
rapidly flowing water some space to slow down into, helping avoiding
the sudden rapid stop as a tap is turned off.

DerbyBorn submitted this idea :
Could it be the washing machine hose being too flexible? I get hammer if I
leave my hose pipe turned on at the tap but off at the far end - sames sort
of thing I guess.Sets up a rhythm

I would not have thought - the hose pipe will expand to allow the water
to slow down more gently. Its the sudden hard off, which causes hammer.
Water rushing through rigid pipe, you suddenly shut off the outlet and
the inertia of the rushing water has no where to go.

The other problem is vibration when water does flow, which is usually
the tap washer at fault, setting up a vibration like the reed in a wind
instrument.

On Sunday, 30 December 2018 09:07:16 UTC, pete wrote:

I€„¢ve got a problem with water hammer on the kitchen cold tap. The
noise is horrendous. Can anyone point me in the direction of a good cure.
On the advice of a friend I drained the system with the stop cock closed and
reopened the bottom tap with the stop cock still closed to drain off any air.
Then re-opened the system and this worked for about 20 minutes when the noise
returned.

Any advise much appreciated.
pfj

fixes:
replace the rubber washer in the offending tap/cistern
turn a valve down, reducing flow rate.
Fix the pipe to the wall better or add damping material - mildly effective
Add a tee & an upright bit of capped off pipe.


NT

On 30/12/2018 09:21, Brian Gaff wrote:
Do you have a way to turn the actual flow rate down before the part where
the hammering happens? I I remember when we had an increase in pressure here
on top of a hill it would hammer if certain taps were used. A mere tweak on
the stopcock where it comes in from outside seemed to fix it.
Brian

+1