Pressure reducing valve

[skinrl]

Hi Guys,
I had a combi boiler installed a few months ago. Now having a thermostatic bar mixer shower installed (no shower in the house before this). Looking at the instructions for installation it says a 'drop tight pressure reducing valve MUST be fitted if the supply pressures exceed 5 bar running'.

Firstly, the Greenstar 30si combi I have comes with a pre plumbed pressure relief valve. Is this enough or does the cold water pipe also need one. I don't know the water pressure at the moment. Also, where would the pressure reducing valve go? As close to the shower as possible or just after the stop tap?
When I flush the toilet there is a loud clunk noise shortly after, has this got anything to do with water pressure or just dodgy pipes!?

The boiler also has an expansion vessel, will this be enough to keep my shower in tip top condition and protect it from excess pressures too.

Thanks for any help posted

Rachel

 

[TicklyT]

Pressure RELIEF valves and pressure REDUCING valves are different devices serving different purposes.

The pressure RELIEF valve and and expansion vessel incorporated into your boiler are part of the heating circuit, not the hot water circuit.

Water pressure varies considerably according to local geography amongst other things. It is not indicated by the pressure gauge on your boiler. That only relates to the heating circuit, which is isolated from the hot water supply.

If you do need one, a pressure REDUCING valve can be fitted to the rising main near the internal stopcock to regulate the pressure of both hot and cold water.

The clunking after flushing a toilet is probably just the float valve closing after re-filling the cistem. Most do to some extent. Some valves are worse than others, but the noise can be transmitted further through poorly supported pipework.

Sometimes installing a shock arrester can help. They look similar to a miniature expansion vessel, but serve a different purpose.