Copper or plastic pipes for mains water?

[Bcp]

I've just had an unvented cylinder installed and have been converted to a pressurised system fed by the mains. At the moment all pipes are copper. My concern is the noise - when the taps run or the loo cistern fills there is quite a noise of the water in the pipe, a typical mains water noise (not hammering). I think someone might have said told me that plastic pipes should be used instead of copper in order to reduce the noise. Is this right or rubbish? I think the pressure I have is about 3-4 bar.

 

[1974stephen]

I'm no expert but have just replaced my central heating with a combi boiler and run all pipe work in plastic. It runs at 2bar and I don't have any noise from pipes at all, compared to a reasonable amount of creaking from the copper that was removed with the old system.

 

[JPC]

the creaking would have been copper pipes expanding when hot and would not occur if they had been wrapped at the joists.
the problem here is a diff problem
i'm not if plastic pipes would reduce the noise from high pressure mains.
can ur unvented run at a lower presure ?
read the m.i. and see.
the hot and cold should be equal pressure by ffitng a pressure reducing valve on the cold before it branches out to the taps.

reducing the pressure on the prv might solve ur noise problem ?
but i'm only new at this...see what other folk say

 

[MANDATE]

Someone will correct me if this is wrong but as I understand it there are two sides when talking of a sealed/unvented system.
The central heating water has its pressure adjusted to about 1 bar. The prv is directly related to this side and opens about 4 bar.
Hot water is basically heated cold water so still at mains pressure.
In the past cold water for taps (other than the kitchen) and for toilet cisterns were fed from the water cistern in the loft and were at lower pressure than the mains supply. So changing to a higher pressure may well be the cause of noise. I believe toilet inlet valves are rated depending on high or low pressure and taps may also be the same.
I would try turning the stop cock down to reduce the flow and see if that improves things. Of course it will not affect the heating side.

 

[JPC]

i was refering to the pressure reducing valve..not release valve.
pressure reducing valve should be fitted on the mains before they t off to cold taps.
unvented should run at predetermined pressures..2-4 bar normally.
you have to fit a prv to the hot water cylinder so that it works to spec...u cant have ungoverned pressure in the cylinder.
if u have fiited the prv after the t" off for the cold u might have higher pressure cold water ie
cold at 7 bar
hot at 3 bar.
this will cause a problem for showers etc
fit the prv ( this is abviously in an ideal world) before and both hot and cold will be similar pressure.
the above has nothing to do with the central heating.
now....back to where i was...if the prv is adjustable try turning it down,,,,but this will affect your water flow performance.. and you need to check the manufactures instruction to check its limitations.
in fact you should not really be touching it...but hey ho (they can be lethal if they go wrong-but dont worry....there are 3 tiers of safety..so u should be alright).....thats what they tell airline pilots aswell !!!!

 

[ChrisR]

pressure reducing valve should be fitted on the mains before they t off to cold taps.

Er not normally, unless you have really high mains pressure.
The Unvented package comes with a pressure reducing valve to protect the uv cylinder. CW output should be taken after that so the shower mixer has balanced supplies.
But other CW outlets like kitchen sink and possibly loos may normally be unreduced. SOmetimes to make the pipework easier almost everything goes through the one pressure reducer.

Anyways, the loo is probably working on 3 bar or so now instead of gravity. Old inlet float valves have to have a part changed to cope, if not the water pressure may overcome the float, but they also make a lot of noise. WIth the right part the noise is not usually a problem. If it IS though, a flexy tap connector could be used to connect the loo which would kill the noise being carried back down the pipe.

If you have really high mains pressure, say over 5 - 6 bar,and it's unreduced for the loo supply, it's getting high for some types of flexy connector so a pressure reducing valve would be a good idea.