Pressure Reducing Valve- Am I about to drown??

[sparky3659]

Hi,
Hopefully one of you can put my mind at rest. I live in a block of flats, and I have a very high water pressure rate which I guess is good. I have a pressure reduction valve fitted after my stop clock under the kitchen sink. It has a gauge on it with an apparently self moveable red line set at 3bar, and a black line which moves itself.

Now.. I have just started on refitting my kitchen, so have noticed this gauge when I have been turning the water on and off. My issue is that when i turn the mains on and have no taps running, the black line just keeps going up and up (like off the gauge into 8+ bar). Is this right, as I am concerned my pipes are going to blow up. When I run a tap, even very slightly, the black line drops to somewhere around the red line. So, is this the sign of a perfectly normal valve, or should that black line not be going off the gauge? As a precaution, I have closed the mains valve, and only turn it on when I need water.

Thanks in advance

 

[Boilerman2]

The PRV may need setting up. sometimes there is an adjustment nut on toip of the unit winding the screw in will increase the pressure winding out will decrease, however you may not have an adjustible one fitted in which case you should find a label with it's rating, usually 3.5 bar.
PRV's can creep a bit, but yours sounds like it needs some TLC or replacing

 

[sparky3659]

Thanks for your reply. I have had found a blue twisting knob on the side which does seem to increase or decrease the pressure, however, no matter where we set it, as soon as we turn the hot water on and then off, the pressure just increases until its off the scale. I am starting to think that its a faulty gauge.

Can you just confirm that, when the taps are off, the black line should be near to where the red line is set, or should it only be near that red line when i am running water?

 

[Boilerman2]

The Gauge wont be wrong, because it is rising & falling I suspect your PRV is letting by and this is why pressure is rising when the taps are orf!
sounds like it's time to fit a new PRV

 

[sparky3659]

Then it shall be done. Thanks for your help sir!!

 

[Master of None]

If it is after the hot tap is turned off could it not be the water in the heat exchanger expanding in the closed system after the tap is closed. Check valve fitted at stopcock? No mini expansion vessel fitted?

 

[sparky3659]

Well that intrigued me... I looked for an expansion vessel as suggested, and assumed that it would be somewhere under my combi boiler, and I cant see one. However, Ive just tried the test with cold water only, and the pressure is still rising...

When either tap is running, I can turn the valve knob and get the black line whereever i want it, so Ive put it on the 3 bar area where my red indicator line is. Its just when I turn the tap off, the pressure keeps rising, and the black line goes off the clock and almost starts going around again. Ive found a little trick is to keep a tap turned on very slightly so it is dripping. This makes the pressure how I set it, but this obviously isnt a long term solution.

 

[Boilerman2]

As per my previous post NEW PRV