Water hammer causing humming in main cold feed pipe....Please help

[racdan]

I have recently had a new Oso mains pressure tank installed.Since the installation i am getting a dreadful humming in the cold feed pipe when opening or closing taps or using toilets.It can be intermittent but normally happens a few times after using a tap.The Plumber who installed the new tank has asured me it can not be anything to do with the tank as he has closed the stop tap on the cold feed as it enters the tank and the humming still continues which is true.He says it must be main stop tap,ballvalve on toilets or washers on taps.We have already tried washing mashine and dishwasher and ruled these out.He is coming tomorrow to replace main stop tap which he thinks could be the problem.Any advice would be greateful as it is driving me to distraction!!

 

[PlumbBobBob]

probably loose washers get your plumber to check before changing the stoptap

 

[racdan]

Most of the taps are 3/4 turn ceramics.Could it be ball valves in toilets or washers in taps that arn't ceramic? Would a faulty stop tap make an awful high pitched humming noise through the cold main?

 

[kay-jay]

is it a loud (ish) vibrating hum? if so it is usually associated with float operated valves toilets being the main culprit. it will usually be louder near the offending valve but can be heard all around the system

 

[racdan]

It is a very loud hum,which gets worse the more you open and shut a tap.At times it only happens for a second as you close the tap,at other times it goes mad and goes on for a couple of mins.I have isolated the new oso cylinder by closing the stop tap on the cold feed as it enters the tank and the dreadful noise still happens so i am assuming the problem is somewhere on the cold feed below the tank i.e taps,ball valves on toilets or main stop tap under kitchen sink.It happens on all taps throughout the house but can be intermittent!!!

 

[Best]

Less likely to be stopcock, very likely to be a ball valve somewhere, which would be easy to test first & change washers in them, or renew whole valve if thought better. After that I would check taps & mains stopcock last. Washer on stopcock can cause noise, but humming doubtful.

 

[< 0.004 = :-)]

diaphram washer (s) in the ballcocks

 

[racdan]

Plumber said he checked ball valves by looking for ripples in water whilst using taps.Is this the correct way to check a ball valve in a toilet.Would a faulty ball valve omit a dreadful high pitched noise through the cold feed and be intermittent.Sometimes it can be worse first thing in the morning and last at night.I thought it might be a faulty pressure valve on my new Oso but as stated it still happens when the stop tap on the cold feed entering the tank is turned off.I assume this rules out any problems with tank but noise has only started since tank installed

 

[Best]

Even the old standard brass ball valves ( piston type) without diaphragm washers can make a humming noise or worse. Diaphragm washers tend to stretch towards the seating that they close against, so slow the flow & can cause noise. Worth thinking of renewing any ball valves with more suitable valves that are ideal for high pressure & less noise. Fluidmaster Pro valves with a brass tail or similar, are worth a look.

 

[Resolute]

Plumber said he checked ball valves by looking for ripples in water whilst using taps.Is this the correct way to check a ball valve in a toilet.Would a faulty ball valve omit a dreadful high pitched noise through the cold feed and be intermittent.Sometimes it can be worse first thing in the morning and last at night.I thought it might be a faulty pressure valve on my new Oso but as stated it still happens when the stop tap on the cold feed entering the tank is turned off.I assume this rules out any problems with tank but noise has only started since tank installed

Sounds like a ball valve to me and would be worse early in the morn or last thing at night cos pressure tends to be higher then as less people calling for water.

 

[racdan]

Would turning a tap on and off affect a faulty ball valve.Is the only way of checking the ball valve by isolating it or can you look for ripples in the water in the the cistern as you use taps in house

 

[Resolute]

I'd try isolating it fully to check.

 

[< 0.004 = :-)]

isolate the wcs, should be service valves fitted on cold supplies into cistern. if your still getting the resonance its a worn ceramic disc valve or washer/jumper in the taps, more likely a cdv that can really scream rather than washers that tend to hammer.
has there been a change in the cold supply pressure to taps and wcs ,from gravity to mains, or now through a prv for balanced hot and cold ?

 

[racdan]

It has always been mains.Sorry i don't quite understand the prv for balanced hot or cold.I have ceramic discs on all upstairs taps.If one of the discs was faulty would you get the noise whilst using any taps in the house?

 

[< 0.004 = :-)]

had electric showers ,taps, wms and dws that hammered when used , nothing to do with them , 20p ballcock diaphram washer to fix. great when you ve been given a shift to sort out bad water hammer , all pipes to be properly checked and properly clipped .............., back in the house for 9 , before the days off the dreaded tracker rackers

 

[Best]

It has always been mains.Sorry i don't quite understand the prv for balanced hot or cold.I have ceramic discs on all upstairs taps.If one of the discs was faulty would you get the noise whilst using any taps in the house?

PRV - pressure reducing valve is to keep the pressure correct for the unvented cylinder but it often has also a connection ( if used) which goes to cold supplies to keep them same pressure, hence balanced with hot. As has been said, it's normally just a few pence washer on a ball valve.

 

[< 0.004 = :-)]

the main cold supply to taps and wcs might now be reduced to the the working pressure of the unvented to give balanced supplies to taps and showers. the reduction in water pressure/flow through the ballcocks stretched diaphrams cause the resonance.

or any taps dripping , obviously worn , cdv taps with hardly any resistance when open/shut.
i doubt its the main stopcock , 1 st i d check the wcs , then the taps, should nt take a half decent plumber long to suss it out.
let us no what was the problem

 

[jeff parker]

fit shock resister from toolstation or screwfix and it will be cured.had same problem for four years,tried everything. now cured for less than 20 quid!!!

 

[kay-jay]

It has always been mains.Sorry i don't quite understand the prv for balanced hot or cold.I have ceramic discs on all upstairs taps.If one of the discs was faulty would you get the noise whilst using any taps in the house?

yes! if it is a washer problem (highly likely) using any draw off point on cold supply will make minute changes to pressure at the faulty valve and can set it off. i changed a inlet valve on saturday morning and that started humming when the neighbours used their draw offs!!

 

[jeff parker]

toolstation catalogue page 294.mini-rester,13m/m(1/2") Mini-Rester.To prevent water hammer.it worked for me on cold mains in,fitted just before pressure reducing valve.humming resonated right through house up to me fitting this.just t into pipe,cured in less than ten minutes!!!!

 

[PJS]

Try a PRV if the pressures high, and are the pipes clipped properly? Had one recently and eventually found it was the seating on the hot tap on the basin after changing washers clipping and packing pipes. changed the tap wholesale and no noise.

 

[sollyhouse]

My Son's is the same, I changed the ball cock in the main tank a few weeks ago and it was fine for a while, but now I guess that it's got limescale built up inside and soon as you open and switch off a cold tap or flush the Loo then the whole house starts humming (you can hear it as soon as you walk in the front door)

Whilt it was humming I went into the loft and where you have the Brass leaver on the Ball Cock, I just touched it and you could feel the vibration, as soon as I touched it the humming stopped and started again about 2 seconds after taking my finger off.

The ball cock is nearly new so I was going to order the Mini - Rester and see if that helps?

 

[2 cautious]

Jeff Parker
Thanks for advice , have just bought one , but notice it has a "1/2 inch tapered thread" can I fit this say with a "tee" onto "mains in" with a "tap connector" -- with plenty of tape and ensuring it "bottoms" onto the tap washer?-- Ere! if not, how do you recommend that it is fitted.

Fairly handy , but prof. advice would be much appreciated.

Thanks

2