Shower mixer not shutting off

[DIYspanner]

Used the shower and now the water's not shutting off. I've taken the cap off and the valve spindle is turning but not shutting the water off although the flow does reduce.

Can this type of mixer be repaired from the front?

No isolator valve as far as I know and the mixer is set in a cavity wall, the rear faces a cupboard.

 

[terryplumb]

Don't recognise the shower valve ,but suspect replacement parts can be replaced from the front ,providing you can source the parts .How old is it ?

 

[oldbuffer]

It looks to me like a Trevi Boost shower. The rest of this response assumes this is correct.

1. Yes, it can be repaired from the front.
2. Both hot and cold supplies will need to be shut off. If there are no isolation valves you will need to shut off the cold at the main stopcock.
3. How you isolate the hot will depend on the system you have. If a gravity fed from cold water storage cistern (CWSC) in loft to hot water cylinder (HWC) in airing cupboard, turn off cold feed from CWSC to base of HWC. If a combi boiler, or an unvented hot water cylinder, turning off the cold main will also cut off the hot. You will need to open lower level taps to let residual water drain out.
4. The spindle you turn rotates a shaft, which has a gear on the end of it. This gear engages with two other gears, one on each of the hot and cold water inlet valves.
5. You will probably need valves for the hot and cold, and may wish to change the spindle and gears at the same time.
6. Its a fiddly job, but with care and patience not too difficult.
7. Be prepared for a shock at the prices. Have a look at https://www.showerdoc.com/trevi-therm-pre-1997-red-override-button

 

[DIYspanner]

Installed when the house was built in '92.

What I've done is taken the shower hose off and inserted and rubber disc in the hose connector to isolate the water at the outlet.

 

[terryplumb]

May be time to explore the possibility of fitting a new shower valve. The wisdom in repairing 28 year old valves is questionable.

 

[HERTS P&D]

I love the timber shelf in the shower.

Andy

 

[DIYspanner]

I'll have to look at options.

 

[Mottie]

Used the shower and now the water's not shutting off. I've taken the cap off and the valve spindle is turning but not shutting the water off although the flow does reduce.

It looks like a Trevi therm to me. I have one the same. That spindle has a gear assembly on it that operates the hot and cold flow through a pair of clutches and it seems like one or both of your valves are sticking. Remove the chrome plate and the plastic valve cover and you can then remove the spindle/shaft. That connects to two clutch wheels that are fitted to the hot and cold flow valves. New clutch wheels will probably temporarily cure it but it’s best to replace both valves at the same time too. They are cartridges and just unscrew but make sure your water is turned off first! You won’t believe the difference in operation it makes - silky smooth and light as a feather. I’ve replaced the clutches and valves on mine several times in the last 20 years or so.

With the cartridges removed, you may be able to strip, free off and lubricate them though.

 

[DIYspanner]

I contacted showerdoc.com, sending them the photo above.

They replied confirming its the Trevi Therm - Pre 1997 (Red Override Button)

Looks like its the spindle, clutches and valves to replace.

 

[DIYspanner]

On with the job now.

Have taken the front panel off and the only bother is one of the on/off valves is stiff and a very slight drip when I turned it on. The the gears, both spindle and valve are in good condition so looks like just a pair of valves needed.

 

[DIYspanner]

I'm intrigued.

If the the two valves are the same part number and the gear spindle turns them in opposite directions, surely one valve is being closed when the other is being opened?

 

[oldbuffer]

The intermediate gear attached to the knob rotates one way. Both the engaged gears therefore rotate in the opposite direction to the intermediate, but in the same direction as each other.

 

[DIYspanner]

The intermediate gear attached to the knob rotates one way. Both the engaged gears therefore rotate in the opposite direction to the intermediate, but in the same direction as each other.

Indeed!
I tripped myself up with my own confusion. Its gears that are meshing directly that are opposite.

By the way, which is best, lithium, ceramic or red rubber grease to coat the gears?

 

[Burnerman]

I only use a silicone grease when I’m stuck into jobs like this......got my tube from Amazon.
Then, a bloody mouse chewed into it
John

 

[HERTS P&D]

Must taste nice John.

Andy