Welcome, Guest. Please Login or Register
Welcome To Ask The Trades!
Mar 28th, 2024, 2:07pm
Quote: If you want the rainbow, you got to put up with the rain.


Pages: 1 2 3 4
Send Topic Print
A strange situation ... (Read 33164 times)
rgirling
Junior Member
**
Offline


Posts: 137


Total Thanks: 2
For This Post: 0


Crowborough, East Sussex, United Kingdom
Crowborough, East Sussex
United Kingdom

Gender: male



A strange situation ...
Nov 4th, 2015, 9:39am
 
I have a conventional household water system, in that it consists of a storage tank in the loft, an indirect cylinder one floor below and hot and cold taps on the first and ground floors. The central heating is pressurised and separate, but I'm sure that's not relevant.

A while back a noise started, something like water hammer, but different as it would occur every 40 seconds or so and only last for between 2 and 10 seconds. It sounds like a brief but soft engine-revved noise, as opposed to the normal "done-donk-donk" noise of hammer I've heard in the past.

Feeling the pipes running through the airing cupboard, the vibration comes from the pipe that supplies cold water to the storage tank. The rising main stopcock is on the ground floor and there is another mains-pressure supply reaching the kitchen sink. I suppose that tees off the other riser. All other supplies are fed from the storage tank, as far as I can tell.

Now for the strange part: the noise can be stopped immediately by opening (even very slightly) any of the tank-fed cold water taps - NOT the hot taps, just the cold ones. The only way I've found to eliminate the noise is to crack open one of the tank-fed cold taps, but I cannot understand why this is, as there is little pressure in the gravity-fed supply, compared to the mains-fed tap.

I've tried replacing the storage tank ball-valve (three different types), making sure that the connection to the ballcock is as rigid as possible, putting in an air trap at the top of the tank cold supply (teeing a closed-end pipe above the bend to the ball valve) and I thought about replacing the main stop cock, until - when fully shut off, the noise continued! How is that possible?

I don't have that much hair left to pull out, but this is getting ridiculous. Where should I look next, please?

Ray
Back to top
 

At the younger end of the "old fart" scale.
Thank User For This Post WWW argee45 View members image gallery  
IP Logged
 
thescruff
Global Moderator
Trade Member
Author
*****
Offline

Who said plumbing was
easy.
Posts: 6037


Total Thanks: 147
For This Post: 0


Gender: male

Trade: Plumber



Re: A strange situation ...
Reply #1 - Nov 4th, 2015, 10:27am
 
Can you make the noise happen. ?.

The air pipe is about the worse thing you could do as it will cause the water to bounce, get a proper shock arrester if anything
Back to top
 
Thank User For This Post View members image gallery  
IP Logged
 
Headrush
Trade Member
*****
Offline

Ask The Trades
Posts: 147


Total Thanks: 10
For This Post: 0


Nottingham, United Kingdom
Nottingham
United Kingdom

Gender: male

Trade: Plumber

Re: A strange situation ...
Reply #2 - Nov 4th, 2015, 11:00am
 
Only thing I can think of would be the WC inlet valve, it fits with the profile of your description. Quick and cheap to replace and will eliminate another suspect..
Back to top
 
Thank User For This Post  
IP Logged
 
thescruff
Global Moderator
Trade Member
Author
*****
Offline

Who said plumbing was
easy.
Posts: 6037


Total Thanks: 147
For This Post: 0


Gender: male

Trade: Plumber



Re: A strange situation ...
Reply #3 - Nov 4th, 2015, 9:50pm
 
Headrush wrote on Nov 4th, 2015, 11:00am:
Only thing I can think of would be the WC inlet valve, it fits with the profile of your description. Quick and cheap to replace and will eliminate another suspect..


One type of ball valve is common to make groaning loud noises when the diaphragm is worn
Back to top
 
Thank User For This Post View members image gallery  
IP Logged
 
rgirling
Junior Member
**
Offline


Posts: 137


Total Thanks: 2
For This Post: 0


Crowborough, East Sussex, United Kingdom
Crowborough, East Sussex
United Kingdom

Gender: male



Re: A strange situation ...
Reply #4 - Nov 6th, 2015, 10:52am
 
The noise happens if none of the CW tank-fed taps are open. Simply cracking open any of the CW tank-fed taps stops the noise at once. I'll replace the pipe with an arrestor ASAP. Thanks to all who responded, much appreciated!

Ray
Back to top
 

At the younger end of the "old fart" scale.
Thank User For This Post WWW argee45 View members image gallery  
IP Logged
 
thescruff
Global Moderator
Trade Member
Author
*****
Offline

Who said plumbing was
easy.
Posts: 6037


Total Thanks: 147
For This Post: 1


Gender: male

Trade: Plumber



Re: A strange situation ...
Reply #5 - Nov 6th, 2015, 10:35pm
 
I would sooner you changed the ballvalve to a brass equilibrium valve first.

You should also check the WC ballvalves
Back to top
 
Thank User For This Post View members image gallery  
IP Logged
 
rgirling
Junior Member
**
Offline


Posts: 137


Total Thanks: 2
For This Post: 0


Crowborough, East Sussex, United Kingdom
Crowborough, East Sussex
United Kingdom

Gender: male



Re: A strange situation ...
Reply #6 - Nov 12th, 2015, 3:25pm
 
OK, done that. Do I need to pressurise the arrestor (bicycle valve), or will it sort itself out? It's fitted in place of the previous air pipe on a short 15mm stub.

Ray
Back to top
 

At the younger end of the "old fart" scale.
Thank User For This Post WWW argee45 View members image gallery  
IP Logged
 
thescruff
Global Moderator
Trade Member
Author
*****
Offline

Who said plumbing was
easy.
Posts: 6037


Total Thanks: 147
For This Post: 0


Gender: male

Trade: Plumber



Re: A strange situation ...
Reply #7 - Nov 13th, 2015, 12:19am
 
The pre-charge pressure is marked on the vessel and usually pre-set
Back to top
 
Thank User For This Post View members image gallery  
IP Logged
 
rgirling
Junior Member
**
Offline


Posts: 137


Total Thanks: 2
For This Post: 0


Crowborough, East Sussex, United Kingdom
Crowborough, East Sussex
United Kingdom

Gender: male



Re: A strange situation ...
Reply #8 - Nov 14th, 2015, 11:37pm
 
I guess what I'm asking is how does it work and/or how do I know it's working? I suppose it contains a diaphragm which gives some leeway to sudden increases in water pressure, but do I need to check the pressure at the Schrader valve or not? If so, when (water running, still, etc.), and is an accurate tyre pressure gauge good enough?

Sorry, that's more than one question!

Ray
Back to top
 

At the younger end of the "old fart" scale.
Thank User For This Post WWW argee45 View members image gallery  
IP Logged
 
thescruff
Global Moderator
Trade Member
Author
*****
Offline

Who said plumbing was
easy.
Posts: 6037


Total Thanks: 147
For This Post: 1


Gender: male

Trade: Plumber



Re: A strange situation ...
Reply #9 - Nov 15th, 2015, 8:22pm
 
I wouldn't touch it unless there's a problem a few years down the road.
Back to top
 
Thank User For This Post View members image gallery  
IP Logged
 
rgirling
Junior Member
**
Offline


Posts: 137


Total Thanks: 2
For This Post: 0


Crowborough, East Sussex, United Kingdom
Crowborough, East Sussex
United Kingdom

Gender: male



Re: A strange situation ...
Reply #10 - Dec 4th, 2015, 12:31pm
 
Well, I've felt a few in my time, but I feel like a very big one at the moment! I now discover that - far from being the cold supply pipe to the tank that is vibrating, it's the cold water supply pipe FROM the tank that is at the root of the problem. It seems that the pipe is "thrumming" when the storage tank is full. Any release of cold water, however small, at any tank-supplied cold tap, halts it at once, but it re-appears when the tank is full again.

I thought that it might be the level of water in the tank was too high, creating too much pressure in the supply, so I reduced the level by adjusting the float downwards, but no luck. I feel that it may be caused by vibration where the pipes pass through joists below the floors. I can get to most of these but - before I do - may I seek your indulgence with another question, please?

If you think there is no other cure, would it be OK to use expanding foam to insulate the pipework from the joist timbers, or is there a better way?

So sorry to be such a pain. If only I'd have counted the emerging pipes correctly in the first place, I wouldn't feel such a t***!  Roll Eyes

Ray
Back to top
 

At the younger end of the "old fart" scale.
Thank User For This Post WWW argee45 View members image gallery  
IP Logged
 
thescruff
Global Moderator
Trade Member
Author
*****
Offline

Who said plumbing was
easy.
Posts: 6037


Total Thanks: 147
For This Post: 0


Gender: male

Trade: Plumber



Re: A strange situation ...
Reply #11 - Dec 4th, 2015, 9:15pm
 
Ray can you post a pic shower where the ballvalve connects to the storage tank inside and out please, include the ballvalve as well
Back to top
 
Thank User For This Post View members image gallery  
IP Logged
 
rgirling
Junior Member
**
Offline


Posts: 137


Total Thanks: 2
For This Post: 0


Crowborough, East Sussex, United Kingdom
Crowborough, East Sussex
United Kingdom

Gender: male



Re: A strange situation ...
Reply #12 - Dec 5th, 2015, 9:49am
 
I could, but I'm back on my FluidMaster valve, as the equilibrium brass one was too noisy and made no difference anyway.

It's not the CW supply pipe to the tank that's thrumming, it's the cold supply from the tank. The noise can be halted immediately by opening any non-mains-fed cold tap, returning immediately when closed. Leaving such a cold tap cracked open by the slightest amount is a cure, but not an environmentally-friendly one!

When the pressure is released by opening a tap, the vibration can be felt in the tap itself and I've made sure that the vibration is only coming from the "down" pipe from the tank, not the supply, nor is it transmitted by contact with the rising main to the tank. Thanks, BTW, for all the help.

Ray
Back to top
 

At the younger end of the "old fart" scale.
Thank User For This Post WWW argee45 View members image gallery  
IP Logged
 
thescruff
Global Moderator
Trade Member
Author
*****
Offline

Who said plumbing was
easy.
Posts: 6037


Total Thanks: 147
For This Post: 0


Gender: male

Trade: Plumber



Re: A strange situation ...
Reply #13 - Dec 5th, 2015, 10:11am
 
Ok perhaps a little plumber lesson.  Grin

As the storage tank fills the ballvalve slowly closes, and its the last half a pint shall we say that causes the noise, therefor when you run any cold tap the ball drops slightly and the noise stops.

Low pressure tank fed supplies do not make vibrations, unless there's a pump or anything mechanical that can cause it.

The above is why I want the pics to see whether anything is noticeably wrong.

It may be a loose washer/jumper in the stopcock or several other problems like unfixed pipes but at the moment it points to the storage tank.

You can easily proof my point by pressing the ball down next time it makes a noise.

There's is also a chance it may be your neighbour, so we should explore that posiblity as well, if it's a shared main, so some back ground info please.

Have you checked all the outlets especially the wc valves.

Is the cylinder fed from the tank or mains.

Is there an expansion vessel anywhere near the pipes.
Back to top
« Last Edit: Dec 5th, 2015, 10:20am by thescruff »  
Thank User For This Post View members image gallery  
IP Logged
 
rgirling
Junior Member
**
Offline


Posts: 137


Total Thanks: 2
For This Post: 0


Crowborough, East Sussex, United Kingdom
Crowborough, East Sussex
United Kingdom

Gender: male



Re: A strange situation ...
Reply #14 - Dec 6th, 2015, 12:21pm
 
Thanks for the comprehensive reply - I do appreciate the help. I'll answer in the order asked:

The main is not shared.
All valves have been renewed, including the three toilet valves.
The cylinder is tank fed.
There is an expansion vessel for the pumped CH system, but nowhere near the pipes in question.

The noise does not occur as the tank is completing being filled. The tank valve, when closed, does not allow any by-pass, as it's new. Three different types of tank valve have been tried, resulting in no difference whatsoever.

I accept that - when cold water is used from a tank-fed tap - this will eventually cause the tank level to drop, opening the valve and replenishing the tank. This, of course, also applies to the tank-fed hot taps, but opening those has no effect on the noise whatsoever.

I have felt the vibration in the cold feed coming from the tank. There is no vibration from the mains feed to the tank at any stage. The vibration can be also felt in the tank-fed cold taps as they are released by the slightest fraction and before this stops the vibration. The vibration re-occurs as the tap is closed. Running the tap sometimes cures the vibration for different lengths of time.

I cannot imagine that letting a couple of drops of water per second will cause an instant drop in the level of the storage tank, as it takes quite a while for the tank valve to react to a drop in level (the release of the tank valve can be heard as the valve opens (after washing or a toilet flush, for example) and no such noise occurs when cracking open the cold tank-fed taps by such a tiny amount.

Photographs will follow, once the noise re-occurs and I've had a chance to depress the tank valve as you suggest. The noise is not constant, occurs randomly - mostly after a long period of tank inactivity - but is unbelievably annoying, as you can imagine!

Ray
Back to top
 

At the younger end of the "old fart" scale.
Thank User For This Post WWW argee45 View members image gallery  
IP Logged
 
rgirling
Junior Member
**
Offline


Posts: 137


Total Thanks: 2
For This Post: 0


Crowborough, East Sussex, United Kingdom
Crowborough, East Sussex
United Kingdom

Gender: male



Re: A strange situation ... UPDATE
Reply #15 - Dec 8th, 2015, 10:30am
 
Update

When the vibration occurred again, I went to the loft and depressed the float. Although water came in, the vibration was unaffected. I have confirmed that it is coming from the cold supply that emerges from the base of the tank and I have taken pictures as requested. To save forum space, I've written a page to host the pictures at http://www.raygirling.co.uk/loftpics.htm

I hope the pictures are good enough, if not I'll take others with a SLR instead of a mobile.

Ray
Back to top
 

At the younger end of the "old fart" scale.
Thank User For This Post WWW argee45 View members image gallery  
IP Logged
 
thescruff
Global Moderator
Trade Member
Author
*****
Offline

Who said plumbing was
easy.
Posts: 6037


Total Thanks: 147
For This Post: 0


Gender: male

Trade: Plumber



Re: A strange situation ...
Reply #16 - Dec 8th, 2015, 6:01pm
 
Ok quicly because I have to go referee.

Where does that pipe go and is it connected to another pipe ?.

Looking at the pics my original suggestions haven't changed.

The mains feed is swinging about in the breeze, and still the most likely problem.

I'm sure if we stick with it we'll track it down eventually
Back to top
« Last Edit: Dec 8th, 2015, 6:08pm by thescruff »  
Thank User For This Post View members image gallery  
IP Logged
 
Pages: 1 2 3 4
Send Topic Print