Pressure Reducing Valve limiting mains water pressure why?

[ecswtrav]

Hello,


I was hoping someone could answer a query that has puzzled me for a while and nobody has been able to help all that much. I have a new mains water supply coming into the basement which has replaced the old lead version. This new connection is instantly greeted by a pressure reducing valve set at just over 2 bar on the meter. My boiler is an ideal iStor (unvented cylinder bolted on to a condensing boiler) - they don't have a good reputation - but this one has caused me very few problems over the past 3 years as its serviced annually. Up to now it works just fine.
Anyway, my showers and taps aren't exactly bursting with power/flow/pressure/ or whatever the technical phrase is. In fact, its no different to the old lead supply. However, I decided to adjust the PRV with a screwdriver and turn the pressure up to see what happened. Instantly the water comes flying out of the taps/showers with some force etc - just how I'd like it. I instantly brought it back down to 2 bar though.
I Wondering what the purpose of this device was, I read the Ideal istor manual and it says this must be installed as the boiler cannot operate on more than 2bar of mains pressure. In fact, the actual boiler comes with the valve when you buy it so it seems.


Why on earth would anyone want to restrict their mains pressure like this? Is there anything I can do to take advantage of having a new mains supply with extra pressure?


I assumed maybe the meter on the PRV was knackered and not giving the correct reading? It could be set at 1bar but showing just over 2? I did notice it reduced in pressure when a tap is switched on - I assumed it would be a constant 2 bar?


Anyway, any advice I'd be very grateful. Thanks

 

[ShaunCorbs]

In simple terms the pressure reducing valve keeps the cold mains supply at no more than 2bar, the pressure relief valve is set at 6bar on unvented systems leaving 4bar for expansion in to cold water main before 6bar prv blows off into discharge pipework, a expansion vessel rated for the system is also added and normally charged at 3bar to help accommodate this expansion. But lets not forget the main reason that only competent persons install/service/repair is that 1ltr of water is turned into 1600ltrs of steam should hot water vessel fail,
and as for replacing the pressure reducing valve most installers fit unvented systems as kits, as all components are suited for that system, so should only be replaced with the same part that was fitted.

slightly wrong but close all depends on what your system/ boiler is rated to if the cylinder is only rated for 2 bar and the expansion vessel should take any expansion that is needed due to heat up

 

[Unregistered]

That's why I said simple the point I was making was don't mess around, It may not be gas but can cause as much damage if it goes wrong