Adjusting the PRV to go to 4 bar..?

[dblvkrb]

We've installed a new 25mm water mains in to replace a led mains in and the pressure is so high we've had to put pressure reducing valve on and cap at 3 bar.

The flowrate from the tap is about 10 litres per minute but we're expecting at least 15l/m. The taps/showers are rated to 3bar but I want to find out if anyone thinks there is a great risk in adjusting the PRV to 4bar to increase the flow.

For info, the combi storage boiler is rated for 18l/m and the current Plumbing has been power flushed, no issues. Any advice appreciated?

 

[Aire]

Pressure and flow are two different things, upping the pressure reducer to 4bar will likely have no impact on the flow rate.

 

[Rob Foster]

We've installed a new 25mm water mains in to replace a led mains in and the pressure is so high we've had to put pressure reducing valve on and cap at 3 bar.

The flowrate from the tap is about 10 litres per minute but we're expecting at least 15l/m. The taps/showers are rated to 3bar but I want to find out if anyone thinks there is a great risk in adjusting the PRV to 4bar to increase the flow.

For info, the combi storage boiler is rated for 18l/m and the current Plumbing has been power flushed, no issues. Any advice appreciated?

No never , you might well be creating a pressurised bomb
Combi set ups operate at 1.5 bar
And no more ever. There have been accidents ! With over over pressurised unvented systems
I know it’s my specialist area
Centralheatking

 

[townfanjon]

^^^^^^^^^ sake

 

[townfanjon]

As Craig says very little if any difference, flow is increased by correct pipe seizing .

 

[Riley]

Safety feature NO pressure and flow are not the same

 

[Riley]

Would advise speaking to local water board to see what pressure and LPM you could possibly expect in your road then if that is ok look at the pipework to and from the boiler

 

[dblvkrb]

When the new mains in was originally plumbed without the PRV the water was bouncing out of the sink, so it must be related to the flow to some degree. I absolutely agree about potentially creating a time bomb.

Let me ask this a different way, what flow would you expect on average with good pressure and a high spec combi, what other things can I do to improve the flow rate from the shower or taps?

 

[dblvkrb]

Would advise speaking to local water board to see what pressure and LPM you could possibly expect in your road then if that is ok look at the pipework to and from the boiler

There is a great deal of pressure, this isn't the issue.

 

[Riley]

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-??

 

[Aire]

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.

 

[ShaunCorbs]

When the new mains in was originally plumbed without the PRV the water was bouncing out of the sink, so it must be related to the flow to some degree. I absolutely agree about potentially creating a time bomb.

Let me ask this a different way, what flow would you expect on average with good pressure and a high spec combi, what other things can I do to improve the flow rate from the shower or taps?

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 ?

 

[Riley]

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.

PRV doesn’t affect flow

 

[Aire]

PRV doesn’t affect flow

That's what I thought too but op installed a new water main, had too great a flow rate, installed a prv and now flow isn't so great. If turning the prv up increases his flow to what he classes as desirable then it's an easy fix

 

[Riley]

That’s not how it works