I'm trying to replace the water input valve
on the side of my ceramic WC cistern.
The problem is that I cannot undo the join
(outside the cistern) where the short plastic pipe
from the input valve screws or is glued into a copper/brass fitting
on the copper pipe bringing in the water supply:
(Not sure if I have this right - it is my first dip into photobucket.
Any advice on this most welcome.)
Is the plastic pipe likely to be glued into the copper pipe?
If so, do I need to cut through it?
Whoa with the cutting! Undo the nut on the copper pipe and pull the pipe ou
t of the fitting. That will then allow you to undo the brass fitting off th
e plastic pipe with a pair of pliers, wrench or mole wrench which ever you
have that will fit. You will then be able to unscrew the white plastic nuts
to remove the float valve. When reassembling the valve and reconnecting th
e pipe discard that brass fitting and replace it with a 15mm compression to
3/4" BSP bend so if you ever have to replace the float valve again it will
be a single nut to unscrew rather than having to undo the whole fitting. I
f you do not have an isolating valve in the pipe run up to the cistern cons
ider putting one in that way you do not have to turn all the water off to c
arry out any maintenance on the cistern.
The fitting required will need to be 15mm compression x 1/2" BSP (not
3/4) and it should be a proper bent tap connector with a swivel nut
rather than comp to FI which he appears to have at the moment.
Since he's replacing the valve anyway, cutting through the old one may
be the easiest way of getting it apart - it doesn't need to be done
It look to me as if the wrong sort of brass fitting has been used. I'm
pretty sure that you've got one of these:
whereas you should have one of these:
With the proper tap connector, the nut which screws onto the ball
valve's inlet pipe rotates on its shaft, and a spigot fits inside the
ball valve pipe, and a seal is made with a fibre washer.
With the wrong sort, the female threaded part is integral with the
elbow, and cannot be rotated independently. This would be a bodge, and
would probably have been sealed with PTFE tape or goo of some sort. The
only way to unscrew this would be to disconnect the compression joint at
the bottom first, and then rotate the whole fitting.
But since you're replacing the valve anyway, it will be easiest just to
saw through the valve inlet pipe and then disconnect the compression
joint. Then replace the ball valve *and* fit a proper bent tap connector
in place of the existing elbow. [If you're lucky, the existing olive and
compression nut may fit the new fitting - and can be re-used without
disturbing the olive,]
It looks to my eyes as if a male to female elbow has been used, so the
only way to unscrew the elbow, is to first release the nut between
copper pipe and elbow, then unscrew the entire elbow from the plastic
Or release the outer plastic nut a little then rotate the whole valve
(removed the float arm first) to unscrew it from both outer nut and brass
elbow. Remembering to turn off the water supply first!
I would then replace that elbow with a service valve 90 degree tap
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