Check valves and mixer taps

[swingthelead]

I noticed that the mixer tap was making the sound of running water when the main valve was open but the tap and the spray attachment was closed. I theorised that cold water was running into the hot pipe, as it is much higher pressure. I went online and concluded that the solution was a check valve.

I bought one, fitted it ... and I still get the sound.

Is it the cold supply going into the hot pipes? If not, what is it - and if so, why didn't the check valve stop and what should I do?

Thanks for reading.

 

[Welder]

Pictures pls

 

[swingthelead]

Pictures of what?

 

[Welder]

The tap, the pipework & the check valve in situ.

 

[swingthelead]

Can't manage that right now.
If it helps, this is the tap:
this is the check valve
and it's fitted 3 inches or so below the tap tail on Hep2O 15mm pipe running about 12" from a connector with the old copper pipe.

 

[Harvest Fields]

Nope we need to see it in situ.

 

[swingthelead]

I'll try to sort it out for tomorrow evening.

 

[Burger]

Judging by the tap, being the kitchen sink it could be a burst water main. Turn your stopcock off and see if it still make the noise but only louder, this should confirm a burst. If not did you fit the check valve on the hot?

 

[Riley]

Well the way to be sure is turn off your internal stopcock and see if your water meter still turns

 

[Burger]

Well the way to be sure is turn off your internal stopcock and see if your water meter still turns

If there is a meter

 

[Welder]

Judging by the tap, being the kitchen sink it could be a burst water main. Turn your stopcock off and see if it still make the noise but only louder, this should confirm a burst. If not did you fit the check valve on the hot?

Hence the request for images. Supposition sucks

 

[swingthelead]

Here's the pictures.
It's a communal hot water system in a block of flats; heated in a single boiler and then circulated through all the flats. The noise only happens when a) the main tap valve is more or less central (ie, hot and cold flow) but b) both the adjustable tap and the spray head are off.

 

[Burger]

View attachment 37124 View attachment 37125 Here's the pictures.
It's a communal hot water system in a block of flats; heated in a single boiler and then circulated through all the flats. The noise only happens when a) the main tap valve is more or less central (ie, hot and cold flow) but b) both the adjustable tap and the spray head are off.

Have you tried turning that cold off at iso valve and see if still makes noise?

 

[swingthelead]

Have you tried turning that cold off at iso valve and see if still makes noise?

Yes. No noise.

 

[swingthelead]

New facts.
Turned the main selector to Hot; turned on the tap and left it open until the water ran hot. Turned the selector to the mid-point and heard the 'water rushing in pipes' noise. The water coming out of the tap turned cold - not warm, not cool, but full cold. After turning the selector back to Hot, the tap ran cold for several seconds before warming up to the previous hot temperature.
It must be the cold water running into the hot pipe, surely? The check valve isn't working. Should I replace it?