Mixer Shower

Hot water from the combi will also be at mains pressure so there would be no balancing issue.

Neil

Have you measured your static pressure? If it is within the spec of the mixer (usually between 3 and 6 bar max) then you don't need the PRV. Measure at several times during the day. The static pressure is usually highest at night, but not if the water company reduces overnight pressure to reduce leakage.

Christian.

I would have thought that the need for a pressure reducing valve would be to equalise the pressure "if" you had a gravity based hot water system. However, I thought in that case that both supplies should come from a tank.

But as you've got a combi, then both supplies should be at mains pressure, so I wouldn't have thought a reducing valve would be required unless there are significant differences in the hot/cold water pressure.

I have a combi boiler (Grant) and have a mixer bar shower with direct hot and cold feeds.... works great, more like a jet wash than a shower!

Andy

You are getting confused between a pressure equalising valve and a pressure reducing valve. A pressure equalising valve does as you state and is often incorporated into the shower mixer, although standalone versions are available.

A pressure reducing valve is used to reduce the static pressure. It is only required if the incoming mains pressure is too high and could damage the fittings.

Christian.