Non return valve failure?

[mrstevejm]

Hi there,

All was good until one day the hot water suddenly started running quite a lot cooler. Putting my hand on the output at the boiler it's still hot there so I'm guessing there's a problem with cold water feeding into the hot water somewhere along the line. I have mixer taps on two bathroom sinks and in the kitchen, plus a shower with a mixer.

I'm guessing that it's one of these that's at fault.

Here's my question – is what's happening that the cold is getting into the hot line even though the tap itself is closed? Mixing through the mixer? And if the answer is yes, what is the best way of working out where the problem is coming from?

Thanking you experts in advance

Steve

 

[ShaunCorbs]

Will be the shower normally easy to test if it’s a bar mixer

 

[mrstevejm]

Will be the shower normally easy to test if it’s a bar mixer

Thanks, Shaun, I'll start there. Steve