Any ideas???

[plumb_know]

Hi everyone, just back for some of your wisdom once again,

Have a customer suffering from water hammer/banging pipe noise, I have been on 3 occasions and have only been able to make the noise happen on the 1st visit. This problem only started about 5-6 months ago.

Customer has open vented system with indirect hot water cylinder and open vented heating system also, she had her bathroom replaced about 4 years ago, has a lot to be desired. Customer said the problem only seems to happen when appliances in main bathroom is used and not when kitchen or en-suite taps are used.

All supplies are balanced and fed from CWSC, customer also has shower in the bathroom fed from a pump that is very temperamental but has been since the bathroom was installed. I haven't been able to narrow it down to one appliance and customer has not been able to either and this noise only seems to happen when bathrooms used nothing else.
bathroom is tiled with no access to pipework including under bath as panel tiled.

i have taken the following action so far:

-replaced ball valve in CWSC with part 2 (flushed pipework before fitting)
-replaced diaphragm washer torbeck float valve in toilet
-also replaced kinked flexi tap connector to toilet with solid copper to help make pipework more ridged

can an anyone offer any suggestion as back there Monday??

help appreciated 🙂

 

[Fph]

Have you got room to fit a mini expansion vessel on the the cold main pipework anywhere, the small white ones, it should help absorb any shocks in the pipework causing the banging.

 

[gasmanrob]

What's the pipework like to the cwsc? Clipped all the way?

 

[tamz]

Stick a shock arrestor on somewhere

 

[gasmanrob]

Is there a stopcock on the line and the jumper has slipped?

 

[plumb_know]

Pipework to and from cistern is ok, but I fear pipework under bathroom is not clipped that well but it has been in for 4 years and problem only started 6months ago.

i have thought about arrest or but where to stick it?? As I don't know if it is on gravity hot or cold or on mains somewhere?
anyway I could narrow down the problem?
Dont think it is on mains supply to CWSC as it only seems to happen when main bathroom used according to customer. As I said it is a problem that comes and goes I have tried shutting taps off sharply and things to get it to happen but have only heard the noise once when I have been there.

thanks for all replies

 

[tamz]

Water hammer only ever occurs on high pressure supplies (mains) and you say the bathroom(s) are tank fed. Unless the tank fed stuff is 100ft above the toilet you can discount that lot.
So what does that leave?
A kitchen tap, maybe an outside tap and a ballcock.
What happens when you flush the toilet?
The tank refills!
Thats where to look.
Fit an air cushion at the cws (take the elbow off, put a tee on and a foot of pipe with a cap on)

 

[gasmanrob]

Ok when using a wash hand in a WC you draw of enough water to make the tank trickle on refill. Kitchen sink hot you'd use more but people slap it in a dish washer so you won't really get it often if at all.

however in main bathroom you'd visit the chocolate factory, brush your toothy pegs and jump in the steam box all in 1 sitting so it would be the only time the cwsc got a work out.

Pillar or 1/4 taps in bathroom?

 

[plumb_know]

Yes but surely the water hammer would occur when en-suite shower used if it was high pressure to ballvalve? Also shower in main bathroom rarely used now as they use en-suite most the time if this is of relevance?
I will make an arrestor though just to eliminate this
Also i do not know for if it is water hammer or another reason why there is this rattling/banging noise.
-all taps are 1/4 turn ceramic cartridges.

thanks

 

[plumb_know]

Also I drained CWSC to replace the kinked flexi hose and on refilling the whole CWSC the noise did not occur

 

[tamz]

Electric shower?

Using that won't make the cws fill.

I've explained 2 options what to do but what would this old plumb know :wink:

 

[tamz]

Also I drained CWSC to replace the kinked flexi hose and on refilling the whole CWSC the noise did not occur

What causes water hammer? Think about it.

 

[plumb_know]

What causes water hammer? Think about it.

Tamz bit lost you said in earlier thread that you would look at high pressure causing noise when ballvalve to CWSC refills, sosurely refilling the CWSC from empty would have caused noise?

but I listen and taking on bored your advice and will make an arrestor before CWSC and hopefully that fixes it, also en-suite shower is also mixer.

will let you know results 🙂

appreciate the advice tamz

 

[Best]

But often when you are there the thing that is filling will not make a hammer noise. They can be very intermitant.
Watch out for stopcocks, as has been mentioned. An old hard washer in a stopcock can cause a hammer noise that seems to be at a tap far away. I don't know why this happens, but change any washers if you can't find problem. Also make sure mains stopcocks are full open.
Any other taps, ceramic & ordinary & ballvalves & modern fill valves can cause hammer noises.
I know of a house that the hot water on ceramic disc outlets hammers very badly when taps are closed & that is hot gravity supplies!

 

[plumb_know]

Thanks best, when I go back I will take tamz advice but also change washers in all the stopcocks I can find and the outside tap. I was also considering change ballvalve in header tank incase pressure was causing this one to vibrate, basically clutching at straws lol

will be satisfying when I know the cause 🙂

 

[tamz]

Tamz bit lost you said in earlier thread that you would look at high pressure causing noise when ballvalve to CWSC refills, sosurely refilling the CWSC from empty would have caused noise?

but I listen and taking on bored your advice and will make an arrestor before CWSC and hopefully that fixes it, also en-suite shower is also mixer.

will let you know results 🙂

appreciate the advice tamz

Water hammer at a cws doesn't happen when the tank is empty or running freely it happens as the valve closes. Drawing a small amount of water from a tank fed outlet, pan, basin whatever, will drop the level a few litres and cause the ballcock to open slightly. That is when it happens.
This can also be more prevelant at night when the pressure is slightly higher.
As per good practice, fit an air cushion at the cws or the more modern way stick a shock arrestor on.
Either way you introduce a cushion of air that absorbs the bounce on the pressure and shuts it up.
Basic plumbing principles.

As Best says a loose jumper stopcock can cause water hammer too but the last time i saw one of those i was getting my nat king 3 times a night :wink: but if it is that you can tell straight away.

 

[plumb_know]

Tamz do you always do this when fitting a ball valve as I have never been told it is good practice to do this or come across it to often?
I did try and make the noise by slightly pushing ball valve arm down and up several times when I was there but couldn't get it to make the noise so ruled it out, my mistake will do as you said and see if it cures it.

thanks

 

[Best]

Tamz advice is right. Don't give yourself work. Look at the obvious & easy things first. Start again with the cwt valve.
Don't bother with stopcocks unless they are easy to get at, unless you have ruled out everything else. Do make sure the mains stopcocks are full on, though, because I find the water can cause hammering if they are turned down.
I always replace a stopcock washer, or entire valve, if it is very old & becomes easy to get at when kitchens are being renewed for example.

 

[plumb_know]

Will do best but really don't want to go back again have solved water hammer in past but just struggling with this one, think I ruled out mains to quickly as seemed that only main bathroom was making noise so got occupied thinking it was appliance in there and also tried to make ball valve in CWSC make noise but couldn't.

anyway I will do as mr tamz saids and learn from it 🙂

much appreciated

 

[Thedeester1]

There has to be air in the system. Depending on the severity of the bang there are several causes. Since you say that there is a pumped shower off of the HW then Id check there is a surrey flange fitted to the boiler! The shower could be Draining the cylinder faster than the cold feed can fill it which introduces air into the system. Irregular expansion of the pipes can cause banging!

Second option! Maybe the customer is wrong about when the banging occurs? It happens. Turn on the HW and heating and see if it bangs! Its possible that the banging is coming from the boiler as air reaches the heat exchanger!