Pressure reducing valve - is this normal?

[Ric2013]

Hi. Just been shown a job by an engineer friend who likes to mess around with things. He's fitted a pressure reducing valve to the supply pipe to a heated outbuilding. The mains pressure is 5 Bar, the valve has a gauge on it showing 2 Bar when taps are closed.

He helps me out, so I don't mind helping him out.

Open a tap and pressure gauge drops to zero after a few seconds and flow reduces to a dribble.

His suspicion is partial freezing of underground supply which I very much doubt. I'm suspecting the valve is at fault and he did eventually admit it was a used one I'm thinking it's probably stuck in some way.

Can anyone confirm that a pressure reducing valve would normally keep the pressure reasonably constant in normal flow conditions? I've never had to use one myself, so I lack the practical experience to judge whether this is normal or not.

 

[Welder]

Hi. Just been shown a job by an engineer friend who likes to mess around with things. He's fitted a pressure reducing valve to the supply pipe to a heated outbuilding. The mains pressure is 5 Bar, the valve has a gauge on it showing 2 Bar when taps are closed.

He helps me out, so I don't mind helping him out.

Open a tap and pressure gauge drops to zero after a few seconds and flow reduces to a dribble.

His suspicion is partial freezing of underground supply which I very much doubt. I'm suspecting the valve is at fault and he did eventually admit it was a used one I'm thinking it's probably stuck in some way.

Can anyone confirm that a pressure reducing valve would normally keep the pressure reasonably constant in normal flow conditions? I've never had to use one myself, so I lack the practical experience to judge whether this is normal or not.

It does. That's it point Ric. Sounds beggared to me.

 

[Scott_D]

Why was it fitted?

 

[ShaunCorbs]

fecked easy way to test remove prv and see if any water come out at 5 bar ish

 

[Welder]

fecked

Welsh for discombobulated ?

 

[ShaunCorbs]

Welsh for discombobulated ?

hammer time

 

[chris watkins]

Blocked filter / strainer mesh ? Remove cartridge & check.

 

[Welder]

Blocked filter / strainer mesh ? Remove cartridge & check.

If it's 'that' bad, you'll not get it out Chris surely? Well I never have (without breaking them...)

 

[chris watkins]

Does depend how old & which type but if it does then they will know that was the likely problem.

 

[Ric2013]

Why was it fitted?

It's a farm...

Mostly because my friend was concerned that the multipoint water heater in the building was not designed for 5 Bar.

 

[Stigster]

It's a farm...

Mostly because my friend was concerned that the multipoint water heater in the building was not designed for 5 Bar.

It's behaving the same way as an unvented cylinder with a blocked strainer in the group inlet. You get that initial burst of decent pressure then the supply can't keep up with the demand and it slows to a dribble.

 

[oz-plumber]

Return a favour - go buy a new valve, install it for him and charge him for it.
See if that resolves the issue.

Engineers: The more you charge them the better they feel about the job being done right.

 

[Last Plumber]

Hi. Just been shown a job by an engineer friend who likes to mess around with things. He's fitted a pressure reducing valve to the supply pipe to a heated outbuilding. The mains pressure is 5 Bar, the valve has a gauge on it showing 2 Bar when taps are closed.

He helps me out, so I don't mind helping him out.

Open a tap and pressure gauge drops to zero after a few seconds and flow reduces to a dribble.

His suspicion is partial freezing of underground supply which I very much doubt. I'm suspecting the valve is at fault and he did eventually admit it was a used one I'm thinking it's probably stuck in some way.

Can anyone confirm that a pressure reducing valve would normally keep the pressure reasonably constant in normal flow conditions? I've never had to use one myself, so I lack the practical experience to judge whether this is normal or not.

I presume you tried adjusting this valve?

 

[Ric2013]

I presume you tried adjusting this valve?

Not yet, but the static of 2 bar is fine, so does sound like a blockage as others have suggested, or perhaps the valve is unable to open up properly when the pressure drops. Just looked at it in passing last night, and it wasn't the time to be buggering about.

I'm not charging him - he's going to help me fabricate a stainless bracket for my washing machine, thus saving me over £400 on spare parts.

He does have some new valves, I just wanted confirmation from others that the existing one isn't working properly before I made an assumption - and in front of someone who likes my approach of never assuming (the first principle of engineering, you know).

 

[TMHM]

Shirley the gauge should be reading 5 bar when taps are closed as there is no flow and it should be reading system static pressure?

It sounds, to me, like there already is a drop in pressure to the outbuilding.

 

[Ric2013]

I thought pressure reducing valves affected the standing pressure too, and that the gauge was on the outlet (reduced pressure) side? Am I wrong?

 

[johnduffell]

His suspicion is partial freezing of underground supply which I very much doubt. I'm suspecting the valve is at fault

Based on the described symptoms, either of you could be right, or both. it could be either a partial blockage of the supply or a restriction in the prv so as per the previous posters start to dismantle and see what flow you get through the upstream pipe

 

[Ric2013]

UPDATE Took the Comap valve out today. The filter was not clogged though there was some gunk it it and the piston bit seemed reasonably stiff to move up and down. Will have a play with it another day and find the exact cause, but replacing it seems to have cured the problem. Weirdly the filter seems to be a bit too small: designed in such a way that I'd expect dirt to be able to get past the filter.

New cheapest Screwfix valve was preset to 3 bar standing and dropped to 2 bar with taps fully open. Reset new valve to 2 bar standing and dropped to just 1 bar with taps fully open, which is much better than having the pressure drop to 0.1 bar.

Told my friend that if his builder is doing any more plumbing, can he ask him to please leave a few inches clearance around the valve instead of plumbing it in hard against two elbows, otherwise it makes maintenance very awkward.