Hudson Reed Shower Mixer Valve Non Return Valves

[Pete the Feet]

I just recently drained down my Ariston cylinder in order to repair a leak on the immersion connection. The installer hadn't fitted an isolation on the cold feed and hot water supply. My plan was to drain it off and fit an isolation valve on the cold feed then I could turn on the cold water supply whilst I buggered about with the cylinder. It took ages to drain, even with one of those drill assisted pumps, which did speed things up considerably. Turning on the cold water supply I took my eye off the ball and had a bit of a flood. Nothing too serious, but the cylinder was filling up even with the new isolation valve turned off. The culprit would be the failure of the non return valve in the concealed shower mixer valve. The valve is about 20 years old and I'm not sure of the model. Its a thermostatic mixer with the option of running the flexible hose and the fixed head at the same time if required. Therefore rather than disturbing the existing installation, I think two external isolation and non return valves is the preferred way to go. I'll leave it until the New Year as I don't want to spend the festive season showerless or worse should an incident occur with the cylinder.