Conceala cistern problems with inlet valve

[sasquartch]

I have an issue with my concealed Ideal Standard Conceala cistern

Just don't seem to be able to fix this - the problem is intermittently that the inlet valve will dribble, making a hissing noise.

It's been doing this for a while and assumed it was because the syphon seal was leaking very slightly and the very slow drop in level caused the torbeck style valve to not seal.

However, after replacing the syphon assembly (the whole thing including the fitting that the syphon sits on) as well as the inlet valve and flex hose I'm still getting this issue. Genuine Ideal Standard parts were used.

The cistern will flush as normal, fill as normal and the valve will shut off. However several hours later the inlet valve will start leaking slightly.

I've checked there is no water leaking into the pan (as you'd expect after replacing it), the float moves freely and doesn't foul on anything, the level is correct (at about the 6 litre mark on the cistern which it's always been at).

Any ideas ? I'm tearing what little hair I have left trying to fix this, as effectively everything has been replaced what can it be. The Conceala cistern seems a pretty common unit so maybe someone has seen this before

Unfortunately it seems you can't put a generic flowmaster valve in as the inlet valve slides into a slot into the cistern, at least without changing the pipework around

All suggestions welcome !

 

[Ben-gee]

There must be loss from the cistern.

With cistern full dry the back of the pan scrupulously, you’ll probably see a fine trickle running down.

Add food colouring to a full cistern and you’ll see where it’s going a lot quicker. Either down back of pan or onto floor.

 

[sasquartch]

There must be loss from the cistern.

With cistern full dry the back of the pan scrupulously, you’ll probably see a fine trickle running down.

Add food colouring to a full cistern and you’ll see where it’s going a lot quicker. Either down back of pan or onto floor.

Yes, after closer inspection you are right, there's a slight trickle into the pan
I've removed the (brand new) syphon, nothing found, no scale etc
If you listen very carefully you can even hear it dripping
Is there a trick to getting these to seal ? As said previously the syphon is brand new, I even changed the coupling that the syphon twists into so cant see what else to do ?
It's a genuine part from my local plumbers merchant, not something dodgy off ebay
ANy ideas ?

 

[Ben-gee]

Assuming that you’ve fitted it correctly so that there is not a leak from between the rubber on the basket cage and the cistern.

The only time I’ve had a new one fail is when the bellows for the pneumatic flush were not seated correctly in their housing - once reseated all worked properly.

 

[sasquartch]

Assuming that you’ve fitted it correctly so that there is not a leak from between the rubber on the basket cage and the cistern.

The only time I’ve had a new one fail is when the bellows for the pneumatic flush were not seated correctly in their housing - once reseated all worked properly.

Update :

Despite there being no visible defect with the rubber seal the plumbers merchant replaced it with another new one and the problem is solved

A frustrating job but learnt a bit along the way, hadn't realised that torbeck valves could dribble as a result of a very slow leak down.

Thanks to @Ben-gee for your advice, you were right all along, I had naively assumed that because the flush assembly was all new it couldn't be faulty. Fortunately my plumbers merchant resolved everything without quibble, just makes me glad I hadn't tried to save a couple of quid by buying the bits online.

 

[Ben-gee]

Well done resolving it, glad to be of help.
Now you’ve had a taste of the frustrations us plumbers face daily!