Weird plumbing

[The Medway Handyman]

Changed a ball valve in an upstairs WC today, old one was dripping a bit & causing an overflow.

Adjusted to fill line, job done. Not a drip in sight.

No header tank in the loft, everything connected direct to mains, downstairs WC & basin, kitchen cold tap, dishwasher, washing machine, upstairs WC, bath & basin cold taps.

Really odd thing, turning any of these taps on, then off, caused a large drip to come out of the new ball valve. Never seen that before.

I'm guessing this unusual feature + the old dripping ball valve was causing the overflow.

I'm baffled - any idea why its happening?

I'm thinking maybe a non return valve might be an idea.

[Jim K]

faulty/cheap/"not spec'ed for mains pressure" ball valve?

Cowboy plumber I hired had to swap ball valves on a new comparatively low pressure holding tank, the first leaked, the second was for

*mains* pressure and wouldn't open "enough" apparently, 3rd time lucky it seems...

Not sure whether I believe him still, but if he did spake the truth then that may explain what you;re seeing??

Cheers Jim K

[John Rumm]

Sounds like a bit of water hammer...

You turn a tap on, and the static pressure in the pipework falls a bit. When you turn it off it rises sharply (and may peak above the normal static pressure due to arresting the flow of water). Meanwhile the ball valve was sat at an equilibrium point where the force closing the valve was just adequate to close it against the nominal static pressure - but not enough to hold back the water hammer peak.

Chances are once the tank fills a bit more, the equilibrium point will again be reached where there is enough force to counter the raised peak during the water hammer.

Can't see that would do much in this case. A shock arrester may help:

[cynic]

A surge caused by closing the tap downstairs. As long as it doesn't result in elevated water level after repeated surges forget it. As a simplified explanation all that happens is the water is flowing from the underground feed to the open tap. When the tap closes there is a natural tendency for the water to try to keep flowing for a moment. as it has nowhere to go the pressure rises and drops back to mains pressure when the moving column of water stops moving..

[A.Lee]

I'm guessing, but when the other taps are turned on/off, there is a 'pressure boom' down the pipe. which makes the new seal in the ball valve lift off its bed slightly, causing a quick drip. Alan.

[Dave Liquorice]

That is what I thought as well.

And may cause damage depending on where it is fitted. It would let the pressure spike through but not back...

Aye.

[Unbeliever]

The above may be the answer to your question.

Presuming it is the 'bog' standard ball valve, you may have fitted a low pressure one to the high pressure mains - yes, there are two types of these little valves.

Dismantle the valve and look at the hole in the valve seat - big one = Low pressure, small one =.....yep you guessed it.

To resolve the problem without changing the valve -- just change the seat, easy eh?

If it's not the standard valve, then please feel free to pass on the necessary information.....

It must be presumed that you have checked to see that there is no grit floating about and that the ball valve arm is free to move, or not catching on the syphon body due to poor positioning/bending of the arm - or if you have actually adjusted it properly?

[D.M.Chapman]

Yep, exactly the same problem we had

Yep (well, it did in our case). Bloody annoying though when you are trying to get to sleep and someone downstairs turns a tap on and the toilet cistern makes a stupid noise :-)

ours is in the loft on the main near the boiler. Certainly cured the problem (and made the plumbing in the house a lot quieter in general)

Darren

[John Rumm]

Wow!

I clicked on this response expecting the usual pouring fourth of invective, and was greeted by a sensible and mostly polite post. May I be the first to thank unbeliver for making a useful contribution at last.

Most of the fluidmaster/torbek/siamp valves cover both high and low pressure with a single unit, however they supply a restriction spiral to be fitted to the inlet when used on mains fed systems.

[Unbeliever]

Oh yea of little faith John! ROTFL

I must be in a good mood tonight - I had thought of a bit of "invective", but for once, a sensible question that has foxed a few in my time which deserved sensible answer.

My answer may not be the right one in this case, but it is a possiblity - especially as those 'not in the know' don't realise that there are two 'separate' bog standard brass valves for high pressure (mains) and low pressure (header tank) supplies - and that the only difference between the two, is the size of the hole in the ball valve seating.

Ah well.

[The Medway Handyman]

Oh hello. Shit for brains has woken up. How did I know that would happen?

Actually, there aren't idiot. There is one type supplied with a high and a low pressure nozzle. Do try & keep up. It's 2010, not 1958.

Errm. I fitted the high pressure nozzle automatically - on account of the pressure being high.

You can't bend the arm pillock. They are made of plastic these days, not brass.

Still being a f****it I see. Hope the caravan is OK.

[Unbeliever]

I forgot to add John, that as there was no information forthcoming on the type of valve installed, I simply took the easiest route and presumed that the valve in question was brass and not the more modern type - it's too much of a headache to try and 'second guess' [or even get the crystal ball out for] this sort of question when even the most basic info is not given to be able to base an answer on.

[The Medway Handyman]

Bought from my regular 'real' plumbers merchant, never had trouble before. They come with high & low pressure nozzles, fitted the high pressure one.

[The Medway Handyman]

Thanks John & Darren, that may be the solution - the plumbing is extreemly noisy. According to the client, the pressure varies between 'normal' and really high. It was really high when I did the job.

[The Medway Handyman]

The sarcasm is a little more sophisticated this time. He probably hasn't had a drink yet.

He wouldn't know that, being stuck in a 1950's time warp.

[The Medway Handyman]

If only you were capable of a sensible answer.

Those 'in the know' realise that (a) nobody has used brass valves in cisterns since God was a boy and (b) that modern ball valves come with 2 nozzles, one high pressure & one low pressure.

Do you think that 'Heartbeat' and 'The Royal' are current TV shows?

[Unbeliever]

I don't drink Meddler - unlike you.

Perhaps that's why your brain is so addled that its impossible for you to to do a simple job without resorting to the drama queen act.

Nope Meddler, I just know what I'm doing, but it would appear that you lack the knowledge to actually explain the details of a problem - and I think you'll find that even today, they still install brass ball valves with copper or plastic balls in modern houses/factories/offices/shops/pubs/public buildings, but your experience is too limited to understand that.

But there were are then, you are someone who gives the impression that he knows every thing, yet knows absolutely f*ck-all really.

[The Medway Handyman]

That Alzheimer's must be a right bugger. It's 2010 FFS. Keep up.

And do stop trying to suck up to John, its nauseous.

[Unbeliever]

With an answer like that, you know I'm right Meddler, but a few buildings were constructed before 2010, but your experience is so limited you don't realise that.

At least he is an equal of mine - rather different to you. Your such a small fry in a big world, the only way to can be heard is by shouting absolute bollocks all the time.

[Unbeliever]

If only *YOU* were *CAPABLE* of a *SENSIBLE* question!

So your experience is so limited you have only worked on 'plastic' houses? I can't be responsible for that.

Well it beats watching Childrens Hour - as you do.