Replacing a shower mixer in the wall:
When an older shower mixer begins to go faulty it is just as easy to replace the entire valve as it is to try and hunt down the correct kit of parts for it to find it is worn out inside anyway.
Remove the old faceplate and see how much of the wallboard has been cut out compared to the size of the plate. It is possible to get a mixer with an oversize jumbo plate cover designed for change over mixer installations like this.
Once you have the new mixer and larger cover plate or the exact same mixer as before but new. Turn off the water as per instructions given at the very start of this book. If the shower mixer cold is feed from a supply tank in the roof space or on the roof you will have to wait until you have drained this down after turning off the supply of water to this header tank out on the street.
Note: A trick of the trade is to tie something around the pipes that are traveling downwards to prevent the loss of a nut inside the wall cavity.
As most situations find no new mixer the same as the old anymore. The easiest way to replace the mixer is to remove the old mixer and place 1-foot (300 mm) flexi hoses onto the pipes in the wall and then onto the new mixer. Then position the new mixer on the mix pipe heading to the spray and screw the mixer back tucking the flexi hoses into the wall as you go. Turn the water back on and test. Fit the cover plate and place handle with Allen key provided.