Reliance pressure reducing valve running

14 Dec 2017
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United Kingdom
Hi guys

I have a water system installed as below. This is fed by pump attached to a reservoir also in the basement. The water is run through a Reliance 3 bar pressure reducing valve with a 4.75 bar pressure release.

When the system was about 3 years old water from the pressure release outlet started dripping and this only seems to happen when the hot water is is being heated.

I have tried replacing the pressure release valve of the multibloc but the problem remains.

I have also checked that the water is not actually coming from the tank pressure release outlet.

I'm now thinking about replacing the whole multibloc now but I wanted to see if you guys would recommend anything else.


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Recommendation. Get it looked at by someone who is G3 qualified.
As stated above, work on these unvented cylinders requires a plumber with the "G3" qualification.

You might however try removing the black plastic cap from the top of the expansion vessel. This should reveal a Schrader valve, like a car tyre valve. Depress the central pin of this very briefly. Then:

1. If water comes out it is likely that the expansion vessel membrane has ruptured, meaning there is nowhere for the expansion of the water heating to go. If this is the case you will probably need a new expansion vessel, although some can have new membranes fitted.
2. If no water comes out, try measuring the pressure using a car type pressure gauge. If the pressure is low (say 0.5 bar or less) the expansion vessel may need pumping up. This should be done by a G3 person who will know the correct pressure to inflat to.

These systems are meant to be serviced every year.
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Thanks for stopping me making a mistake, guys.

Thanks especially old buffer for that information. I'm a bit disappointed with the installer for not telling me that I needed to get this regularly serviced.

I'll call in a pro.

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