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.