Adjusting the PRV to go to 4 bar..?

[Aire]

Flow is impacted by correct pipe sizing, obstruction or restriction in the pipework and can also be controlled by reduced lpm sanitaryware

Yes I know that, and I'm not trying to argue with you about the difference of flow and pressure.
Read op's post, he says after installing a new water main, his flow was that good that water was bouncing out the sink. So to correct this, he installed a pressure reducer (I know this technically shouldn't change anything). Since installing the pressure reducer, his flow rate has dropped, again I know this technically shouldn't happen, but if he has a high working pressure it could be interfering the pressure reducers function. Basically if the pressure reducer is set to 3 bar and his working pressure is 3 bar or slightly higher then the valve may be opening and closing repeatedly as the pressure required by the prv will be constantly achieved. Sorry if that sounds confusing, in my head I know what I mean, it's just hard writing it 😕

 

[Riley]

I would be looking for an obstruction clearly something has changed but it won’t be the PRV purpose that has caused it

 

[Riley]

Also going above 3bar can impact other things such as the boiler from a safety perspective

 

[Riley]

to be honest it could be something as simple as some muck from the new mains install getting trapped in the new PRV and affecting flow

 

[dblvkrb]

As we’ve said though flow and pressure are different. Alright ignore pressure ask the water board what you should expect. If you are a way off that it’s time to start testing.
Is the strainer filter on the prv blocked?
If you rig up a tap or pipe straight after the stopcock what do you get then flow wise??
What does the incoming reduce to after the stopcock, 25-??

The PRV is brand new, is it likely the filter would already be blocked? I haven't experimented with running a tap straight off the mains stopcock but it's a good idea.

After the stopcock it reduces to 10-11 l/m, up to 12l/m if running purely off of the cold mains.

 

[ShaunCorbs]

The PRV is brand new, is it likely the filter would already be blocked? I haven't experimented with running a tap straight off the mains stopcock but it's a good idea.

After the stopcock it reduces to 10-11 l/m, up to 12l/m if running purely off of the cold mains.

any pics of the install?

 

[dblvkrb]

The water bouncing out the sink shouldn't have been affected by installing a pressure reducer as technically these restrict standing pressure, not working pressure (or at least thats my understanding of them). Basically the standing pressure of your system will be exactly the same as before you installed your new water main so you don't have anything to worry about regarding tap rating etc. I'd turn your pressure reducer up to max, then run the tap and slowly turn the valve down until you achieve your desired flow rate.

Well this is exactly my point, thank you! I've heard "pressure and flow are not the same things" about a hundred times, and I understand they are definitely not directly related, but you can't deny the flow was way too high if anything before installing the PRV.

Do you not think it would be risky to simply turn the valve down (increasing the pressure) until I have 15l/m? I know plenty of people who "overclock" their systems and don't have any issues for years, but then I've heard the other kind of story where it all goes wrong..

 

[dblvkrb]

Off the stop tap to the prv what size pipe

Also what size is the prv 15mm

Pipe size off the prv to the boiler ?

15mm for both - the distance from the stopcock to the boiler is maybe 3/4 metres.

 

[ShaunCorbs]

15mm for both - the distance from the stopcock to the boiler is maybe 3/4 metres.

you sure its not a 20mm main ?

what make of prv are you using

 

[Riley]

You will not increase the flow by increasing the pressure. If that’s what you’re intent on doing you might as well remove the PRV. The PRV could be defective. In terms of what does it reduce to I meant what pipesize is it coming out of the stopcock. Do you notice this reduced flow at all outlets

 

[dblvkrb]

any pics of the install?

Of the new mains, stopcock and PRV I assume? No, but I may go and take a look tomorrow and take some pics. I have a picture of the boiler setup (Alpha Flow Smart, 50l) if that would help at all.

 

[Riley]

What is the cold inlet and hot outlet on the boiler

 

[Riley]

Yes boiler pic

 

[dblvkrb]

you sure its not a 20mm main ?

what make of prv are you using

It's a newly installed 25mm main as I mentioned in my original post, I meant 15mm pipe running from the stopcock.

 

[dblvkrb]

You will not increase the flow by increasing the pressure. If that’s what you’re intent on doing you might as well remove the PRV. The PRV could be defective. In terms of what does it reduce to I meant what pipesize is it coming out of the stopcock. Do you notice this reduced flow at all outlets

15mm coming off the stopcock - the flow rate is the same on the 1st floor and in the loft conversion, almost no loss the further up the house you go.

It might be a defective PRV - would this definitely not reduce the flow rate if it were working effectively?

 

[Riley]

Honest opinion I’d be tempted to change the PRV

 

[dblvkrb]

Yes boiler pic

Not the greatest pic, but hopefully gives you an idea of the boiler - the hot flow is only 2 l/m less than off the cold mains, I doubt it is the issue.

 

[dblvkrb]

It's a newly installed 25mm main as I mentioned in my original post, I meant 15mm pipe running from the stopcock.

Also completely forgot make of PRV, will check though.

 

[dblvkrb]

As Riley and others have said pressure and flow are not the same thing. A PRV could have sorted out the splashing tap but will not have affected flow.

As an example:

If we have two taps both with a flow rate of 15 lpm where tap no1 has 6bar pressure and tap no2 has 3 bar pressure, both will fill the sink up in the same amount of time. But when taps are turned on tap no1 will splash much more violently off the surface of the sink due to the much greater pressure than tap no2. i.e. its the same amount of water but coming out with more force, turn the pressure down and water hits the sink with less force so doesn't splash/bounce but its exact same amount of water per minute hitting the sink.

I understand this, and I'll caveat by saying I didn't personally test the flow rate before the PRV installation but it's obvious it has reduced both the flow rate and the pressure. I'm guessing where we may be getting to is possibly a defective/clogged PRV?

 

[Aire]

As much as i appreciate why everyone is saying increasing the pressure of the prv won't do anything, turning it up and seeing if it improves isn't going to hurt, even by half a bar, the boiler is rated up to 5bar anyway so it's not going to hurt. And if it doesn't work atleast you've ruled it out.