zip pressure reducing valve operation

[redbarnman]

Thought I had a problem with an Ariston 30L water heater in a village hall whereby the hot water flow has steadily reduced to almost nothing over a period of a year. When you open the hot water tap you get a burst of water then it slows and stops after only a small amount has come out. Suspected blocked filter or outlet but all OK. Next suspect is what looks like a Zip pressure reducing valve (nominal 3Bar) with filter. Checked filter, clear and OK. Have not done a static pressure test yet on incoming cold but it may be less than 3 bar in the day. Does a 3 bar pressure reducing valve need more than 3 bar to flow or should it pass water and gradually shut off as the pressure increases to 3 bar. I can only get this one to flow by increasing the pressure setting well above the nominal 3 bar factory set point and that seems counter-intuitive.

 

[ShaunCorbs]

No they don't need a min of 3 bar to operate they just won't reduce the pressure

Are you G3 registered?

 

[snowhead]

If you put 2 bar through a P.Reg.V. set to 3 bar you'll get almost 2 bar through it. (minor internal losses)

 

[Best]

Anything over 15 litre unvented needs G3 ticket, so hope you have it and a public building even more important

 

[ShaunCorbs]

Anything over 15 litre unvented needs G3 ticket, so hope you have it and a public building even more important

Any water heater now mate

 

[Welder]

Blimey Shaun, I never knew that and I only renewed my ticket 10 mths ago. When did that happen?

 

[ShaunCorbs]

Blimey Shaun, I never knew that and I only renewed my ticket 10 mths ago. When did that happen?

About 3 years ago I think

 

[fixitflav]

Thought I had a problem with an Ariston 30L water heater in a village hall whereby the hot water flow has steadily reduced to almost nothing over a period of a year. When you open the hot water tap you get a burst of water then it slows and stops after only a small amount has come out. Suspected blocked filter or outlet but all OK. Next suspect is what looks like a Zip pressure reducing valve (nominal 3Bar) with filter. Checked filter, clear and OK. Have not done a static pressure test yet on incoming cold but it may be less than 3 bar in the day. Does a 3 bar pressure reducing valve need more than 3 bar to flow or should it pass water and gradually shut off as the pressure increases to 3 bar. I can only get this one to flow by increasing the pressure setting well above the nominal 3 bar factory set point and that seems counter-intuitive.

The pressure reducing valve is meant to maintain downstream pressure of 3 bar, irrespective of higher upstream pressure, within limits of design pressure, and maximum flow determined by size of valve. If the upstream pressure is below 3 bar it goes wide open, and flow falls off as the upstream pressure falls. Your symptoms look a bit peculiar.