Replacing shower "flow valve"

[dave22]

I have a Mira Fino shower (the "exposed controls" version), and need to change the flow valve as it is getting harder to turn off the shower completely.

I have acquired the relevant spare parts - new flow valve and new on/off lever, including all relevant washers.

The instructions warn me only to use a silicone-based lubricant when assembling, but they don't mention where it should go. There's a very small, sealed polythene packet in the box about the size of an AAA battery containing what I assume is the relevant lubricant. Should it be applied:

(1) around the threads of the screw joints
(2) where the on/off lever connects to the flow valve
(3) around the washers
(4) somewhere else...?

Also, any general tips on replacing shower flow valves appreciated - I'm a complete novice when it comes to plumbing.

Thanks,
Dave

 

[Beerlover]

The silicon lubricant is to stop the o rings being snagged when fitting, no drama really. Isolate the supplies to the shower and put an old towel in the bath shower tray/bath to protect it from dropped tools and vital bits going down the plughole.

Just remember if it anything doesn't come apart easily, check it is not being held in by anything else before forcing it. Grub screws are easily missed.

 

[JohnD]

If yours is hard to turn it probably has limescale in it. I found it helpful to soak mine in descaler overnight.

If it won't come apart, put the whole thing in. If it will come apart, dismantle and immerse the parts. Polish up the brass and remove any remaing scale and dirt using a green nylon kitchen scourer (this will also remove any thin film of copper if the acid dezincs the surface). Clean out the grooves that O rings go into.

As well as using the silicone grease on the O rings and their seats, I think it is useful to put it on any sliding or rotating parts. I also like to put PTFE tapes on any threads to prevent them seizing in future, and round the spindle shaft. This might be a bit too fussy for some.

Have you got the exploded diagram showing how it comes apart?

http://www.shower-spares.co.uk/mira/mira_fino_shower.htm or similar

 

[dave22]

Thank you both for your helpful replies. I do have a diagram of how it comes apart, but thanks for the link all the same.

Regarding descaler, the only thing I have in the house that can remove limescale is "OxKleen Bath Power" - any good for this sort of job? If not, which brand do you recommend that is easily available?

Dave

 

[Whitespirit66]

White vinegar can work wonders if left overnight. Isn't to harsh for plated surfaces either.

 

[dave22]

Thanks, but I've tried that before on my kitchen tap, leaving a little bag of white vinegar tied round the limescaled end of the tap for a few hours. It started to strip off the chrome plating .

Perhaps the vinegar I tried was particularly strong. Anyway, I'll try an official descaler - any recommendation welcome if "OzKleen" isn't a good idea.

Dave