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Discuss Water Hammer+Bouncing Watertank Ballcock in the DIY Plumbing Forum area at PlumbersForums.net

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Hello everyone. Minor issue I'd like to try and adjust before I call a plumber back out. I have mains water to the kitchen and to the water tank in the loft.

3 weeks following having a kitchen tap fitted by a plumber I was running a bath suddenly there was this loud pipe/plumbing noise and the water turned brown. I called out the same plumber again and he said it was the ballcock in the water tank bouncing causing the valve to stop/start. There was also some sediment hence the brown water. This he said was due to an increase of pressure from the way he left the mains kitchen valve open. Previously he'd found it locked tight and had to use a tool to loosen it so left it with a tiny amount of slack(had also tried street isolation valve, but that was filled with debris). To resolve the water tank issue he adjusted the mains isolation valve in the loft and that stopped it.

Now 2 months later I'm getting the same thing, but not as bad, but its still noticeable and concering. So having seen the problem in action last time I was thinking of looking to to adjust the mains valve in the loft myself and seeing if anything on the ball cock can be adjusted.

Firstly though should I have any concerns? The whole thing was working fine until the tap was replaced and its concerning that a tiny change in the position of one valve can cause this. I mean is there an issue with the tanks ballcock or something else? Also If I'm looking to adjust the mains valve in the loft should I be opening or closing it more to decrease the pressure?
 
First thing you cannot adjust pressure by partly closing a valve all your doing is reducing volume not pressure.
If your water pressure is genuinely too high you need a pressure reducing valve.
Certainly in the areas I work in the water supplier with clear the outside stop tap box for free.
 
First thing you cannot adjust pressure by partly closing a valve all your doing is reducing volume not pressure.
If your water pressure is genuinely too high you need a pressure reducing valve.
Certainly in the areas I work in the water supplier with clear the outside stop tap box for free.
I've reported to the water supplier to clear the outside stop valve box. It's their responsibility.

Could the ballcock have developed a fault or sediment in the tank help cause the waves?
 
The problem you have is most likely related to flow and delivery position as well as pressure. It sounds as though you have an oscillating ball valve. The flow of water into the tank can cause ripples/waves to form on the water surface, this in turn causes the ball/float to move up and down with the water as the waves return from the side walls and therefore the valve will open and close. The opening and closing will allow water to splash into the tank intermittently and increase the waves which in turn increases the bouncing effect so the hammering gets worse. (apologies for waffle).

It should be a part 2 ball tap in the tank and if it is it will have a white plastic delivery pipe off the top. Try turning that into a different position first of all. From my experience it tends to happen more in smaller tanks and quite often you would see it in fortic cylinders because of their shape (circular).
 
Just one thing to add to @Last Plumber's explanation. It's possible that the tank has a 'low pressure' valve fitted and needs a 'high pressure' version. These typically have a restriction to reduce the flow of water into the tank. It seems that, before your plumber arrived on the scene, the stopcock had been left partially closed. This was having the same effect, i.e. restricting the flow into the tank.
 
This may be the answer.
FluidMaster Pro 75 B. with brass shank with side entry.

 
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I'm not going to be fitting any valves myself just not confident, just seeing if a turn of a valve does anything.That's the thing outside of the pressure changing from the supplier all that's changed is a tiny turn in one kitchen valve adjusting the flow as I'm told here. Any idea why this slight change could cause the issue after never having this issue before? I mean I'm assuming he never turned the street valve due to the debris.

Regarding the pressure valve at the tank I'd need to see if that can be identified from photos, but before the kitchen tap was replaced I tested its pressure and it was low pressure however that increased with the new tap.
 
Water hammer is probably a very complex issue but sometimes simple solutions like the suggestion above may cure it, it won't take your plumber very long to install it and will not cost a fortune.
 
Any idea why this slight change could cause the issue after never having this issue before?
If the stop tap was only cracked open previously, it would reduce the flow through it and it sounds as though your flow rate is the issue.

If you are not confident in Plumbing, fair do's but it isn't a major task to sort this one.

The most positive answer if you are paying for it is to replace the valve. Most Plumbers will recognize the symptoms (I hope) and have a replacement with them (I would expect).

It is better to have the stop tap fully open - minus a quarter turn to prevent it seizing - in my opinion.
 
Always used in ship's enginerooms as well, a crack open here and a crack open there on different valves, overall, the crack was mighty on these ships.
 
Ok thanks. The mains kitchen valve was fully open and locked tight when the plumber found and I guess left it a quarter turn away from that. No idea of the position of the mains loft valve position before and after though. I tried fully locking the mains kitchen and there was a whistling sound as such when water ran so put it back the way it was.
 
Street chamber has been cleared and tested working(fast response from supplier). Turned the Loft Valve a quarter turn closed and ran the taps. No noise or boucing ball. Will see if that lasts.

Thought I'd share some photos. I clearly need to clean the tank.
 

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That's a part 1 or Portsmouth pattern valve I would personally change it for a fluidmaster both quicker filling and quieter.
Tank could usefully do with a clean out and lagging set . Has it got a lid?
 
That's a part 1 or Portsmouth pattern valve I would personally change it for a fluidmaster both quicker filling and quieter.
Tank could usefully do with a clean out and lagging set . Has it got a lid?
It's got a lid and everything is lagged(Brown cloth looking stuff). The tank is then completly covered then more stuff piled against it. You

I know the original metal tank was replaced maybe in the last 10-15 years. Guess that could be the original valve though. As long as it's behaving as it always has I'm in no rush as I've got a list of things I want done before winter.

Out of interest when buying a new valve should I be checking diameter or any other measurements?
 
The valve John G listed on #6 is the one you want,.
As you have reduced flow to ball valve make sure you don't empty tank running a deep bath or having long shower!
 
Hmmm tested it today and it's happened again. Don't think I've reduced the flow that much as when I push the ballcock down a torrent comes out. I've try closing the valve more, but I think time for a plumber to do as suggested by yourselves.
 
Regarding the water hammer and the ball valve "bouncing", you use to be able to get equilibrium ballvalves, which stopped this, as the valve had a hole through its body which "equilised" the pressure on both sides, so stopped the bouncing. So that might be an option? Also the side walls on plastic tanks can flex, which can also cause water hammer / bouncing, so an old trick was to place a thin sheet of metal plate behind the valve assembly, with a suitable hole so the valve thread would go through it, (on the outside of the tank) which would reinforce the plastic tank wall, thus reducing any flex, etc.
Hope you get it sorted, cheers...
 
No, if you bend it downwards you will have a few litres less in the storage tank, if you bend it upwards water might start overflowing.
 
Fun and games. While waiting for the plumber due soon it's stopped oscillating even when I run the taps for ages. Valve is open half way and only change I can think of is a temperature change with the winter coming in and heating being used. So annoying.
 
Plumber came out and not so happy with the work. I didn't get the valve as suggested here and let them supply one. They turned up they had was the wrong size valve and went to get another one. Basically they've replaced the valve with one that looks identical which after posting on here is a surprise. Noticed the water level was lower now, but no boucing ballcock so good there. However now when the bath runs you hear a strained noise coming from the valve which has an affect to act like water hammer. It also dribbles for ages when it's filling back up. Groan.
 

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