Discuss Adjusting the PRV to go to 4 bar..? in the Plumbing Jobs | The Job-board area at PlumbersForums.net
Seriously though test it in various places you’re plunging straight in with what isn’t the answer and will not be told
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.
Take a picture of the stop tap and pressure reducing valve.What would you test first? If it isn't the PRV what do you think the issue is? The pipes were tested and cleaned prior to installation.
Haha, nope. That we can agree onNot the tidiest install is it
Personally I think the install is a bit untidy the flow rate could be improved on by correct pipe sizing is there a dedicated supply straight from the incoming stopcock purely supplying the cold water inlet to the gas saver 22mm minimum without anything else coming off it? there will be Pressure loss as water passes through each piece of equipment and height and length of the pipework needs to be considered. Kop
I agree this is the most worrying aspect of this ideaAlso going above 3bar can impact other things such as the boiler from a safety perspective
Pressure and volume are obviously inter related but in actual fact separate issues , in fact Yorkshire Dave if you pm me we could produce a simple fact sheet to clear up,this issueCan someone please explain to me why plumbers do not understand how flow is a consquence of pressure & bore? Keep the bore the same & increase the pressure & flow increases. Similarly, increase the bore & keep. Pressure the same & flow increases.
The point of a pressure reducing valve is to provide a maximum pressure with 'unduly' limiting flow. All PRVs impeed flow somewhat.
In terms of increasing flow in this instance 'bouncing out of the sink' is zero indication of anything. The only real test is a weir gauge or physically timed test. The real test is looking at the flow rate of a second outlet.
I hope this basic information helps people.
Pressure and flow are two different things, upping the pressure reducer to 4bar will likely have no impact on the flow rate.
Increasing the pressure will certainly increase flow rate as it is proportional to the sq.root of pressure, if the pressure is increased to 4 bar at the tap (by adjusting the pressure reducing valve) then the flow rate should theoretically increase by a factor of (4/3)^0.5 = 1.15 so the flow rate should increase from 10 to 11.5 lpm...that is assuming there is 3 bar at the tap when it was flowing 10 lpm originally, in practice pipe friction losses will reduce this.
Can someone please explain to me why plumbers do not understand how flow is a consequence of pressure & bore?
Can someone please explain to me why plumbers do not understand how flow is a consquence of pressure & bore? Keep the bore the same & increase the pressure & flow increases. Similarly, increase the bore & keep. Pressure the same & flow increases.
The point of a pressure reducing valve is to provide a maximum pressure with 'unduly' limiting flow. All PRVs impeed flow somewhat.
In terms of increasing flow in this instance 'bouncing out of the sink' is zero indication of anything. The only real test is a weir gauge or physically timed test. The real test is looking at the flow rate of a second outlet.
I hope this basic information helps people.
Hi Riley. Sorry are we talking about the heating or DHW circuit here?Also going above 3bar can impact other things such as the boiler from a safety perspective
What bomb are you talking about mate? In Europe we have 5 bar mains incoming cold water and have combi boilers installed never encounter any time bomb hahaha don’t get your point to be fairNo 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
Small update:
Static pressure is 4 bar, dynamic pressure (read from PRV at mains) is 2.4 bar when 1 tap is running and 1.5 bar with 2 taps running. Is this normal?
I still intend to dial up the static pressure and test the flow with a Weir gauge, but likely won't be able to test for a week or so.
Small update:
Static pressure is 4 bar, dynamic pressure (read from PRV at mains) is 2.4 bar when 1 tap is running and 1.5 bar with 2 taps running. Is this normal?
I still intend to dial up the static pressure and test the flow with a Weir gauge, but likely won't be able to test for a week or so.
How long is the new leingth of 25mm plastic pipe? does it go to to a stoptap in the path or road? Is this stoptap turned on fully? sounds to me like there is a restriction somewhere, the new PRV in the house has a filter is this clean, you also have a stoptap in the house is this blocked with debris,as pressure is droping when there is a greater demand
I would expect about 20l/min from the kitchen cold tap at that pressure,and if the mains pipe from the road is only 4M away not a great deal of flow would be lost, does your new 25mm pipe go to the main in the road or is it joined to the exhisting smaller diameter pipe somewhere, ( was it connected by the water company) ?25mm pipe is maybe 4 meters long, yes it does go to a stop tap in the road which is fully open, the stopcock in the house is fully open.
Why do you think there is debris - should I not be losing as much pressure when opening a tap/2 taps from mains pressure?
Is it a shared supply that feeds other houses?I would expect about 20l/min from the kitchen cold tap at that pressure,and if the mains pipe from the road is only 4M away not a great deal of flow would be lost, does your new 25mm pipe go to the main in the road or is it joined to the exhisting smaller diameter pipe somewhere, ( was it connected by the water company) ?
I would expect about 20l/min from the kitchen cold tap at that pressure,and if the mains pipe from the road is only 4M away not a great deal of flow would be lost, does your new 25mm pipe go to the main in the road or is it joined to the exhisting smaller diameter pipe somewhere, ( was it connected by the water company) ?
Is it a shared supply that feeds other houses?
I seem to remember that my kitchen taps have a flow coefficient (Kvs) of something like 0.4 M3/h @ 1 bar which equates to 6.7 LPM @ 1 bar, if the OPs taps are similar then it would require 5 bar to get his expected 15 LPM, his reading of 2.4 bar (one tap) would suggest a flow rate of ~ 10.4 LPM (easy to measure this with a empty milk bottle) the 1.5 bar reading (two taps) would suggest a combined flow rate of ~ 16.4 LPM. The PRV will have its own Kvs which affects flow rate as well plus the differential pressure across it will have a big effect on its output. This Kvs is not known but the manufacturers should certainly know it.
I would suggest (as has been suggested in other posts) increasing the PRV outlet pressure to max with both taps open and then measure both tap flow rates, I would also suggest cleaning the PRV strainer if only to rule it out.
Depending on the above test, to really narrow down the problem I would replace (temporarily) the PRV with a spool piece and repeat the measurements, that will tell a lot IMO.
Conclusion..
We tested the garden tap and it was putting out >20 l/m, the plumber explained that it is the 12mm flexi pipes that came with the tap sets are restricting the flow a great deal. We tested some of the shower taps with and without the nozzles attached and we measured a difference of about 3-4 l/m (going up to 16 l/m).
That being said the plumbing of the boiler wasn't completely finished, with the blending valve being installed a couple of weeks back. The results are a bit odd. Most of the taps still output at 10-12 l/m, however, the bath taps output at near 20l/m with both taps fully open, the shower output is at 16/m which is certainly good enough for what we need.
I'm not sure why there is such variance but it's worked out for the best, I can only assume it's the type of connections used for each tap combined with the fact that the boiler is now a great deal more efficient now that the blending valve is in. We're still at 4 bar of standing pressure.
Shower heads are designed to give a nice spray effect so there is a considerable pressure drop across them so no really big surprises there. You are getting 20 LPM from a bath tap and 10 LPM from the other taps, my bath taps are 3/4", all the remaining taps are ~ 1/2"or even less (metric), my upstairs bath tap flows 12 LPM @ gravity head of 0.25/0.3M, the upstairs bathroom basin tap flows ~ 4 LPM @ the same head.
All in All I think you should be happy enough.
Did you observe the PRV pressure with a flow rate of say 20 LPM?, even assuming a mains PRV upstream pressure of 6/8 bar one would expect a "drooping" in the PRV pressure of (depending on its type & quality) 0.25 bar to 0.5 bar giving 3.75/3.5 bar? @ 20 LPM.
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