Trevi mixer shuts down the water.

[gnnmartin]

We have a Trevi shower which has developed a fault. The water supply suddenly cuts out. If the shower is turned off for a few seconds, and then turned on again, the shower recovers, however it is likely to shut off again after a short while. We have a second shower driven from the same pump which is fine, so there is no problem with the water supply.

My strong suspicion is that there is something in the cold water supply which entirely blocks the cold water at some point close to the mixer. The water then gets very hot briefly and then the thermostat shuts down the hot feed too. This is supported by the fact that if I override the stop on the temperature control and turn the shower temperature much higher, the shower starts again (but too hot to use).

However, when the water flow shuts off it is entirely shut off, which I find surprising. So does anyone know of a possible fault in a Trevi mixer that could cause the water to shut off completely?
Nigel Martin

 

[seco services]

i would check the filters first.
you'll have to remove the thermostatic cartridge for that.

 

[Martini]

Fixed a Trevi Traditional built in mixer today.
It would shut down after running for approx. 10 seconds.
This is the time it takes (in this house) for the hot water to reach the thermostatic cartridge. It then shuts off unless you turn the temperature much hotter than normal. This points to cold water supply failure. Check that isolator valves haven't accidentally been turned off somewhere first but in my case the cold supply 1/4 turn ceramic disc cartridge adjacent to the thermostatic cartridge was not opening. The geared cogs are gripped onto the shaft by tightening a screw. The shafts do not have splines so if the cartridge has got very stiff due to limescale then the gear wheel will slip on the shaft.
You can check this by removing the black plastic cover over the gears and turning the water on (water doesn't actually need to be on). Check that the screws in the end of the shafts rotate in sync with the gear. If the gear moves but the screw does not then the cartridge is jammed!
The hot water cartridge opened but the cold did not. Undo the cartridge and spray it with silicon spray or WD40 to free it up and re-install. Re-assemble everything. Check this possible fault option before removing the Thermostatic cartridge although it is always a good idea to remove it to check the filters at the back of the cartridge.