Water Supply to Toilet Cistern

[dennohue]

I want to fit a new valve and float to the toilet cistern in the bathroom and cannot isolate the water supply.

The cistern is fed via a gate valve from the storage tank in the loft. With the valve fully closed and all sink and bath taps open there is little reduction in the flow of water. It IS the correct valve, and all other cold feeds are dead ends i.e. showers, central heating and hot water cylinder. And, no, it is a modern house and is certainly not directly fed!

I know I can do the job by draining the storage tank or using Arctic Spray, but it bugs me! Why will the flow of water not stop? Any ideas out there?

 

[kevplumb]

err gate valve is "kerry packered"

 

[dennohue]

err gate valve is "kerry packered"

Nope!

I'm a Chartered Engineer, and all gate valves in the house are moved regularly to avoid scaling up. If a gate valve is fitted in a verical run the design is so simple the only thing that can go wrong is scaling, if it has not been moved for many years.

Appreciate the comment.

 

[kevplumb]

you are assuming it worked when fitted

 

[doitall]

A Chartered Engineer for what

Only the very best, gate valves (Hattersley-Crane) will hold off water 100%, the cheap rubbish you find in domestic homes seldom work reliably.

Perhaps you get getting a backflow from an illegally installed mixer or shower valve.

The washing machine is another good place to look.

 

[kevplumb]

A Chartered Engineer for what

Only the very best, gate valves (Hattersley-Crane) will hold off water 100%, the cheap rubbish you find in domestic homes seldom work reliably.

Perhaps you get getting a backflow from an illegally installed mixer or shower valve.

The washing machine is another good place to look.

are you suggesting they don't use top quality fittings

 

[dennohue]

Nothing illegally installed, therefore no backflow.

In a lifetime career using gate valves in industry I have never known a gate valve to fail, when used in a vertical run, other than scaling up if not moved regularly.

If you have experienced this I would be interested to know.

 

[doitall]

All I can say to that is, I don't know what industry you have spent a lifetime in, because it ain't plumbing and heating.

Most gate valves will hold off enough to work on the service, Most will let by some water after a few years.

I assume you've never come across a sheared gate either, very common in the domestic industry.

 

[Rico99]

Yep I concur with Scruff on this one.

Had a couple of these and it is a right P.I.T.A,on was on cold feed to hot cylinder and another was on central heating feed.

Still not sure which is best wahy for it to go, ie shear off shut or open.

Rico

 

[JayJay1978]

Scruff AKA doitall ?

As a DIY'er I can confirm that gate valves are unreliable to say the least, when they're new they're great but after a few years they will scale up inside and the metal to metal contact becomes scale to scale contact and as a result they let water past when closed.

Gate valves on c/h pumps are the same, after a decade or so they just become part of the pipework and cease to function as a valve.

 

[dextrous]

I want to fit a new valve and float to the toilet cistern in the bathroom and cannot isolate the water supply.

The cistern is fed via a gate valve from the storage tank in the loft. With the valve fully closed and all sink and bath taps open there is little reduction in the flow of water. It IS the correct valve, and all other cold feeds are dead ends i.e. showers, central heating and hot water cylinder. And, no, it is a modern house and is certainly not directly fed!

I know I can do the job by draining the storage tank or using Arctic Spray, but it bugs me! Why will the flow of water not stop? Any ideas out there?

Well, either there is backflow from a mains supplied device (which I query as this would cause the CWS to continuously overflow IMO), or OP, regardless of your experience within industry, you may have to accept that the gate valve has developed a malfunction.

As you are no doubt well aware given your experience and training, another way of isolating the supply to the cistern quite apart from draining the CWS (wasteful) or freezing the pipework (overkill and unneccessarily expensive) would be to stick a bung or even a carrot in the outlet at the base of the tank

Recommend you replace the gate valve with a full bore isolator and while you're at it, insert an isolating valve - again full bore - near the WC cistern (as required within the water regs).

 

[bathstyle]

Bung the tank connector inside your cold storage cisern and then crack the nut on your Gate valve and all will be revealed.

 

[kirkgas]

if a gatevalve turns and closes it MUST reduce the flow, (as some have said not 100% closed in some cases but the OP says the flow hardly reduces) so it cannot be closing, it may be turning and jamming therefore not shutting, i have seen plenty of snapped valves again some jam but obviously dont slow flow as the shaft is snapped.
plug the tank outlet and change the valve, 10 mins
who else actually goes round shutting valves on a cyclic maintenance programme in their house? too much time on their hands, leave the valve alone for donkeys years if not required then change it if it snaps when you shut it

 

[dextrous]

if a gatevalve turns and closes it MUST reduce the flow, (as some have said not 100% closed in some cases but the OP says the flow hardly reduces) so it cannot be closing, it may be turning and jamming therefore not shutting, i have seen plenty of snapped valves again some jam but obviously dont slow flow as the shaft is snapped.
plug the tank outlet and change the valve, 10 mins
who else actually goes round shutting valves on a cyclic maintenance programme in their house? too much time on their hands, leave the valve alone for donkeys years if not required then change it if it snaps when you shut it

Speak for yourself - I do it on an hourly basis, 24/7

 

[doitall]

I actually tried to turn mine off the other week, because I need to service the shower valve, in others it's leaking

1st time in 10 years, no problem, it wouldn't move, so gave up after 5mins and went out.