Low pressure/low flow

[Simon Read]

where is the prv fitted if on incoming main i would remove it

Hi, yes it’s between the main stopcock (inside the house) and the rest of the house? Why would you suggest removing?

Thanks,

Simon

 

[aqualogic]

the prv is probably the problem this will test it

 

[Jim Goodenough]

@Simon Read have look at DAB Esybox and Esytank, 480ltr storage and modulating 3bar pump - I've installed a few and they've worked well. Not cheap unit with be around £1300.

 

[John.g]

Hi, yes it’s between the main stopcock (inside the house) and the rest of the house? Why would you suggest removing?

Thanks,

Simon

Your electric shower will only flow ~ 4 LPM to give a 40C showering temperature, if the mains/PRV cannot supply this, then the PRV is suspect, as above.

 

[moonlight]

Is your pressure reducing valve an adjustable one? a Worcester boiler can have up to a maximum of 10 bar incoming cold water pressure. So adjusting yours up to test might be worth a try first. Make sure all the other appliances can take an increased pressure first.

 

[SJB060685]

I would be cautious about adjusting an adjustable PRV on your incoming mains. Although I can't find a maximum inlet pressure figure in the boiler manual, from personal experience I can say some combis don't react well to a high static or dynamic pressure (I've replaced enough fibre washers and other parts due to failure).
As Brambles and I said, its more likely to be what we've discussed.
A PRV only affects the pressure, one might argue it would reduce the flow rates slightly but doubtful. If you really wanted to be sure though you could isolate the cold mains into boiler and remove the PRV and replace with a short bit of pipe, if your flow rates on cold improve then ok but you would still need a PRV into boiler and then the system won't be balanced anyway.

 

[John.g]

Is there no pressure gauge on the PRV??

Should have read post #1, there is.

 

[Brambles]

Hi,

to get to the to the root cause you need to know the dynamic pressure and flow rate from your unrestricted incoming mains. To do this, isolate your incomming mains at the meter / external stop tap, remove your PRV and insert a pup piece.

Thereafter, measure the dynamic pressure ( when flowing) and flow rate at various times of day ( 9am, noon, 3pm, 6pm and midnight).

That will then give you the base data to develop a solution. If your static pressure (not flowing) is greater than 7 bar then I would reinstate the PRV, if not I would leave it out of the system. If you do have the luxury of a high incoming static pressure - spend plenty of time checking and monitoring the system (particularly compression joints)

My guess is that your incoming mains is the issue and that the PRV is not restricting either the dynamic pressure or flow rate.

There are occasions where high static pressures deliver deliver low dynamic pressure and low flow rates, but usually only on sub 20mm MDPE incommers

 

[Ric2013]

I have had a pressure reducing/regulating valve fail to open properly. It had been fitted in a holiday chalet and seen very little use, so it may have become partially seized for that reason.

The owner of the building had set it to around 1 Bar IIRC and it shut-off correctly at the set pressure, but it would not open up sufficiently to allow any kind of reasonable dynamic pressure. In fact, it even took several seconds to allow the pressure to recover after all taps had been shut.

The solution was to replace the valve and the problem was solved. I did, however, take the old valve home, and was eventually able to free it off. Untested, but it probably would work perfectly now.