Fitting mira excel shower

[dp]

I'm fitting a mira excel shower but I'm confused. The instructions say a drop tight pressure reducing valve (PRV) to be fit if the supply exceeds 5bar maintained. I suspect that my pressure is quite high (it comes out of the cold tap a lot faster than the hot tap) the hot tap is fed by a worcester 25si which I understand provides hot at 2.5 bar.

The shower instructions also say the shower works best if the two supply pressures are equal.

Does a PRV allow you to set the output pressure to a certain setting?

Alternatively I've seen some pressure equaling valves here:

I try one of these instead?

Any advice / Experience of Miras appreciated.

Thanks.

[chris French]

In message , dp writes

I had similar installation. I decided to install in and see how it went. After installation the shower 'whistled ' sometimes - usually in the summer. Which is the symptom of to high a pressure.

I put a PRV in the cold feed. It wasn't calibrated in anyway. just set the adjusting screw to midway, it all worked ok so left it at that.

>

[Antony]

> Should I try one of these instead?

A pressure reducing valve is a good thing to have in any installation where there are high static pressures. It should increase the life of valves in washing machines, water softeners, combis, etc. The term "pressure _reducing_ valve" is a bit misleading, as they are really static pressure _limiting_ valves. They are usually adjustable, but in any case are normally set to around 3.5 bar. You install it just after the stop c*ck on the incoming mains supply. e.g.

item you linked to is a pressure equalising valve. It contains a diaphragm that automatically maintains equal pressures in the hot/cold feeds (within reason - it's not really intended to be used where you have mains cold and gravity hot, for example).

The hot water is bound to have a lower pressure than the cold, as it has been through the narrow pipes of the heat exchanger in the combi. You may find that part closing the cold service valve for your shower improves things a bit, without the expense of an equlising valve.

-Antony

[Antony]

> Should I try one of these instead?

A pressure reducing valve is a good thing to have in any installation where there are high static pressures. It should increase the life of valves in washing machines, water softeners, combis, etc. The term "pressure _reducing_ valve" is a bit misleading, as they are really static pressure _limiting_ valves. They are usually adjustable, but in any case are normally set to around 3.5 bar. You install it just after the stop c*ck on the incoming mains supply. e.g.

item you linked to is a pressure equalising valve. It contains a diaphragm that automatically maintains equal pressures in the hot/cold feeds (within reason - it's not really intended to be used where you have mains cold and gravity hot, for example).

The hot water is bound to have a lower pressure than the cold, as it has been through the narrow pipes of the heat exchanger in the combi. You may find that part closing the cold service valve for your shower improves things a bit, without the expense of an equlising valve.

-Antony

[Christian McArdle]

The combi boiler won't affect the static pressure of the water. The fact that the hot tap comes out slower than the cold tap tells you precisely nothing about the pressure. For that, you need a pressure gauge. If the cold is above 5 bar, fit a PRV.

> Should I try one of these instead?

Your shower should have one of these. They are frequently part of the shower valve. If not, fit one, whether you have a PRV or not. It will significantly reduce the effect of water use elsewhere in the house on the occupants of the shower.

Christian.