extra water running into toilet cistern?

[wrathkeg]

From time to time our toilet makes a sound as if there is water going into the cistern, but only very briefly: it only lasts only a second or so, if that. There seems to be no obvious reason for it happening (it doesn’t seem to happen when we run taps, or when we have just flushed it etc). I’d say we hear it maybe every couple of days but of course it might happen more often than that and we just don’t notice. It doesn’t sound like water going into the pan though I haven’t seen into the pan when it happens. It's probably been happening for a couple of weeks.

So, thinking it might be the fill valve I did a like for like replacement but heard the short ‘extra’ sound again last night. Does anyone have any suggestions as to what it might be and/or how to fix it (e.g. replacing the flush valve?) There’s no sign of a leak into the pan.

I’ve put a picture of the set-up below. The fill valve is new, the flush valve probably 5 or so years old. Except for the sound of ‘extra’ water, the whole thing works fine.

Thanks,

wrathkeg

 

[footprints]

Might just be fluctuations in the water pressure overcoming the inlet valve till the level rises slightly to exert more pressure on the float. I have a similar effect if the toilet is flushed just before showering, it fills and stops whilst you are in the shower but briefly trickles as soon as the shower is turned off.

 

[terryplumb]

there is a seal on the flush valve , not the one that seals it to the cistern ,its on the end of the drop valve. if the condition is poor ,it allows a tiny amount of water to pass and you can hardly notice it running into the pan. eventually the water level drops in the cistern and the float valve opens ,only momentarily ,tops up the level and closes . this cycle repeats non stop ,but it can be hours in between. if you grab hold of your flush valve at the top ,and turn it about half a turn ,it will separate from its base and you can withdraw it from the cistern .the seal is at the bottom of the section you have withdrawn . turn off the water supply before you do this and flush WC before you start as well.

 

[wrathkeg]

Thanks. That would certainly explain the randomness of it happening. It doesn't seem to be cause by any other changes in the pipework (starting shower, turning taps etc.) I'll try to have a look tonight and see if I can identify the seal you describe.

 

[just pumps]

Looking like this one
https://www.mytoiletspares.co.uk/fl...4fluidmaster-mechanical-dual-flush-valve.html

So guess the seal is this one but worth checking first.
https://www.mytoiletspares.co.uk/seals-washers/fluidmaster-550-toilet-flush-seal.html

 

[wrathkeg]

So I got the top of the flush valve off and had a look at the seal. (Thanks for the tip: had no idea they did that.) All looks to be absolutely fine (not perished, gunged etc.) but presumably for such an intermittent fault there might be nothing to see? The valve isn't a Fluidmaster, but made by Watermark.

I wonder if I would be as well to look to replace the whole valve rather than just the seal. If so, are dual flush valves pretty much interchangeable? I was thinking of something like this. And presumably the cistern needs to come off to fit the new one?

Thanks for the help,

wrathkeg

 

[just pumps]

Some are interchangeable, however if you can source another one the same then no need to remove the cistern which might involve replacing the seal between cistern and pan
Keep things simple

 

[terryplumb]

can you post some pics of the seal ? also check the basepart of the valve ,the bit that is left in place in the cistern. see if it is seated tight against its seal against the cistern ,by trying to rotate it slightly.if that seal is letting water pass you get the same effect.

 

[wrathkeg]

Aha.

The basepart won't budge, so I'm confident it's not that. But when I removed the seal to take photos look what I saw...

The underneath (the bit that makes contact with the basepart) looks fine.



but the other side (the side that's concealed when the seal is fitted) has a series of bubbles in it.



Maybe that could account for the problem? In any case, it doesn't look good.

 

[just pumps]

Try bursting the bubbles as a short term fix but yep there's your problem

 

[terryplumb]

as just pumps says thats exactly your problem ,the little bubbles stop it from sealing fully. just change the seal.

 

[wrathkeg]

Thanks, folks. Off to find a seal. Wouldn't have got this far without your help.

 

[wrathkeg]

For anyone with the same set-up as me with the same flush valve (might be a few as it's the valve that came with a Wickes toilet): seals by that manufacturer don't seem to be available, but a Geberit seal with 63mm outside diameter, 32mm inside diameter and thickness of 2.8mm seems to work. They are readily available online.

 

[John D v2.0]

I know you solved it but for others, another fix that worked for us (rented house, it was leaking around the valve base seal onto the floor in a rotting boxed in bit) was to loosen it and whack on a bit of bathroom sealant then tighten. Cheaper if you already have a tube, and universal fit.