Overflowing cistern - where?

[VisionSet]

I have a fluidmaster valved cistern with internal overflow. I thought and posted previously about the damaged fluidmaster intermittently filling, I think this was a cause that I have cured with a new one. However I still have the symptom and it seems that the cistern is overflowing by virtue of a constant dripping sound, but I don't see how. This overflowing is now *I think* the cause of the intermittent filling. I thought the overflow was the uppermost lip of the red plastic in the picture. But the level is always below that. The critical level of the fluidmaster is set above the 25mm req'd from the overflow. What's causeing the overflowing and WHERE is it overflowing?

[Roger]

The message from "VisionSet" contains these words:

flush and I was under the impression that with those the internal overflow was down the syphon by the same route as when the cistern is flushed. The cistern itself (or perhaps the syphon housing) should have a maximum level marked on it so that it doesn't constantly trickle feed. If the flush is by valve rather than syphon then it would make sense for the lip of the red plastic thingy (TM) to be the overflow level.

Either way the overflow should end up in the toilet bowl and you should be able to see it in operation even if the discharge is very small. To me a dripping sound is indicative of a leak.

[VisionSet]

That'll be it then. I was convinced the overflow was via the lip, so that'll be my float setting then. I'll listen tonight...

Thanks Roger

[VisionSet]

No it still flows! So it must be constantly syphoning, so I guess the syphon assembly must be buggered? What else can it be? Anyone have any knowledge of this model:

?

[Roger]

The message from "VisionSet" contains these words:

Are you sure the escaping water is ending up in the pan? That you can hear a dripping sound bothers me.

As I said before I am not familiar with that particular make but a normal syphon is an upstanding tube with some mechanism around it to initially swamp the top of the tube to establish a water flow that continues until air enters the syphon when the cistern has largely emptied. That being the case the overflow should only run when the water level in the cistern is higher than the upstanding tube. Any leaks are much more likely to between the cistern water and the outside via either the water supply or syphon entry holes or the bottom fixing holes rather than between the cistern water and the inside of the upstanding tube.

The Fluidmaster valve is American so what is the source of the flushing mechanism? If it is American then perhaps it is not a syphon. (I am not sure the Yanks bother with syphons). Does the red thingy just lift out so you can see what is underneath?