Adjusting the PRV to go to 4 bar..?

[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.

 

[rpm]

Seen 6bar static pressure reduce to 0.6bar dynamic pressure along with the sort of flow you would expect from 0.6bar.

 

[rpm]

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.

View attachment 36032

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.

View attachment 36032

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.

View attachment 36032

Those valves supposed to be closed guys?

 

[dblvkrb]

Those valves supposed to be closed guys?

So.. I could test increasing the static (PRV) pressure to see if the dynamic pressure improves the flow, have I understood this right?

I'll pass on whether the valves should be closed (I did not install the boiler) - but it is working as expected and the hot flow is similar to the cold mains flow.

 

[Aire]

Yes you can increase the pressure, as I said your boiler is rated at 5 bar, stick below that and you'll be fine.

And no those valves aren't supposed to be closed, but then the hot feed coming from the top of the heat store should also feed the boiler through a blending valve mixed with the cold main. Whoever installed the boiler hasn't finished it.

 

[Riley]

If that’s a heat store then what pressure is that safe up to??

 

[dblvkrb]

Yes you can increase the pressure, as I said your boiler is rated at 5 bar, stick below that and you'll be fine.

And no those valves aren't supposed to be closed, but then the hot feed coming from the top of the heat store should also feed the boiler through a blending valve mixed with the cold main. Whoever installed the boiler hasn't finished it.

Thanks - I will definitely check out the boiler setup with the installer, the blending valve should be somewhere. The boiler is rated to 5 bar, just worried about the taps being rated to 3, but I think I may have to test this anyway to see exactly how much the flow rate is effected.

 

[Riley]

Dear lord why risk leaks and damage swap out the prv also what is the cold inlet pipe size to the hot water Store.

 

[Riley]

My suspicion is it’s a piping issue exacerbated by the restriction of a prv

 

[Riley]

Seriously though test it in various places you’re plunging straight in with what isn’t the answer and will not be told

 

[Aire]

If that’s a heat store then what pressure is that safe up to??

It's rated upto 5 bar, the boiler, flue gas recovery and heat store all come together. The heat store is pressurised by the heating water not the mains, it has a coil going through it which comes off the flue gas and back into the cold feed to the boiler, at least it should do but as I said, it's not finished. And I just want to point out to you again that I don't disagree with anything your saying and op has gone the wrong way about reducing his flow rate but for the sake of adjusting the pressure and how long it will take it's worth a try.