On 04/02/2018 13:58, Roger Hayter wrote:
Grumps wrote:

On 28/01/2018 09:43, Grumps wrote:
Hi all.
This sounds a weird one to me. In the bathroom of my daughter's flat
there is a toilet, sink, and bath. The bath has mixer taps and a
flexible hose to a shower head. Cold water is mains fed. Hot water is
from a water tank at mains pressure.
Everything works, but...
When you turn the shower head on, after several seconds water starts
dripping/running into the toilet bowl. I've only tested this briefly
using the cold water to the shower head. Running the sink or bath taps
does not cause this to happen.
What's the cause?

The toilet cistern is ceramic with a dual push button thing on the top.
If I try to lift the cistern lid, I am stopped by the mechanism attached
to these buttons. How do I remove the lid?

Ta.

So, I've managed to get the lid off the cistern just by lifting the two
plungers and unscrewing the large plastic screw that is revealed.
When the shower is in operation, it is obvious that the toilet fill
valve (like this:
http://www.flushking.co.uk/adjustabl...ve-brass-shank) admits
water until it reaches the internal overflow.
The fill valve operates normally when the toilet is flushed.
I'm still at a loss to explain fully what is happening, but does this
type of fill valve rely on incoming water pressure to hold it closed?
That, as I think others have mentioned, might explain it.
Solution: replace fill valve?

It shouldn't leak at any pressure. But as someone said a very small
leak is less likely to be a problem if you adjust the float so the water
level is at least a cm (or 1/2" in old money) below the overflow when
the valve closes. If it does leak at any pressure at all then it might
be worth replacing. It may be possible to replace the washer/diaphragm
but it the valve is such a mass of fiddly little plastic bits that it is
probably better to replace the whole lot.

If its like the one in the link, then its probably worth popping the top
off and cleaning any crud out from around the diaphragm.

With many like that, if you turn off the water to the valve. Fully lift
the fill arm, then push down on the cap and give it a firm 1/8th turn
anti-clockwise, it will unclip from its bayonet like fitting. You can
then take the pin and rubber bit out, and flush some water through the
valve stem to clear anything trapped under it.

--
Cheers,

John.

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