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?

 

[Welder]

STL
1 - The tap you have purchased needs non return valves in both lines as the supplies mix within the tap body. Unfortunately, it is not a WRAS approved tap otherwise those would have been included. If your supplies are not perfectly balanced then without those NRVs it is not safe to install due to what you are currently experiencing.
2 - The data on the installation sheet is completely incorrect too. As a high pressure tap requiring a minimum of 0.5bar to operate it means you need a MINIMUM distance of 6 metres from the underside of your loft tank to the highest point of your tap for it to flow reasonably. The, so called, instructions say 2m.

What you've bought is 'not very good', contravenes water regulations as fitted and has caused you these problems. Unfortunately UK law means they are able to sell this rubbish with impunity. YOU however become the law breaker by fitting it.

My advice. Go buy a tap that is WRAS approved by a reputable manufacturer. Sorry.

 

[swingthelead]

There is no loft tank. Mains comes straight into the flats.
I recognise the problem, but I'm not about to pay to replace the tap until I understand the why this is happening. Problem solving requires identifying where the problem is, because if you assume where it is, you probably end up solving several non-problems before you solve the actual problem.
It seems the problem is with the check valve.
I'm not opposed to putting a check valve on the cold supply, but that's not going to stop the cold pushing into the hot supply, surely?
So the question remains: how come cold water is going through the check valve in the wrong direction?

 

[Welder]

There is no loft tank. Mains comes straight into the flats.
I recognise the problem, but I'm not about to pay to replace the tap until I understand the why this is happening. Problem solving requires identifying where the problem is, because if you assume where it is, you probably end up solving several non-problems before you solve the actual problem.
It seems the problem is with the check valve.
I'm not opposed to putting a check valve on the cold supply, but that's not going to stop the cold pushing into the hot supply, surely?
So the question remains: how come cold water is going through the check valve in the wrong direction?

The 'problems' you have are two fold:
1 - you have a tap unfit through both performance & regulation for UK plumbing
2 - you choose not to listen
Patently however you know better. It must have been pure chance that you landed at a plumbing forum asking questions. Crack on pal. I hope it's only your own you end up poisoning.
I'm out.🙄😡

 

[Burger]

It could be a faulty check valve yes.

 

[chris watkins]

I am with Dave on this one.
No help or advice from me apart from go find a Plumber who has their Water Regs.
Public health should not be left to some Swing er who wants to problem solve after the event, next they will be leaving that hose in a sink full of dirty water.
I pity the others in that communal block of flats!!!