Steve coughed up some electrons that declared:

Hi. This is a bit complicated so please bear with me.



My incoming water pressure is quite high (about 7 bar - just measured it).
The info' on the new tap I have says it will handle 5 bar max. - above
that, the guarantee isn't valid.



I can currently get about 20 litres/minute flow rate, which, I have read,
is
the minimum to run a Combi boiler. I want to install one sometime in the
future.



If I fit a pressure reducing valve (PRV) on the cold supply now, I can use
the tap and also protect the (push-fit) plumbing system from the somewhat
high pressure. But - and this is the actual question - will the PRV have
the unwanted affect of reducing the flow rate, which could prevent a
future Combi from working properly?



And, related to this, are there any PRVs which limit the pressure but not
the flow rate too much.



Thanks



Steve


You missed my post this very day.

I just went into this in some detail ("MDPE copper unions?" thread).

Firstly: My water pressure is 7.5 bar and no, pushfit doesn't explode - I've
had a bit of JG in service for months and it's been OK.

However, 7+ bar is a bit violent on the tap user and seems to destroy garden
hoses. And your taps do state 5 bar max...

I just ran a bit of 25mm MDPE into the house, jointed to the 1/2 inch
polythene outside. Then a full bore 22mm lever valve, then an Altecnic PRV,
22mm (see the MDPE thread for details, or the G1/4 thread)

Meaurements previously indicated 30-40l/min flow rate.

Now I've thrown 2m of 1/2" pipe away, as well as a manky silly stop cock, I
can now get 50l/min out of the 22mm pipe after the PRV, at any pressure
setting between 2-6 bar. I still have about 15m of 1/2 inch clean bore PE
pipe between me and the road.

That should answer your question. See the mentioned thread for a link to the
PRV I used - you want this one... See also the "Sealing G1/4 pressure gauge
into water pressure regulator" thread for some side fun.

As to your flow - you should get more than 20l/min at 7 bar unless your
incoming pipe is crudded to buggery or your valves or road stopcock are
constricting the flow.

Can you do as I did and swap the incoming parts to full bore valves and
bigger pipe?

See here for mine:

http://photos.dionic.net/v/public/bu..._0019.jpg.html
http://photos.dionic.net/v/public/bu..._0016.jpg.html
http://photos.dionic.net/v/public/bu..._0017.jpg.html

HTH

Tim