Mains Water Pressure

sie1uk · 11 Dec 2019

Please can anyone tell me what the Pressure valve on my incoming mains water should be set at both when not being used and what it should drop to during use.

I have a high pressure hot water system, in a new house.

Thanks

Madrab · 11 Dec 2019

Depending on the make of the unvented then the Reducing Valve could be set anywhere from 1.5bar up to 3 bar.

What it drops to when being is used is determined by the dynamic mains pressure being delivered through your mains and how many outlets are open.

What does it drop to and what's drawn your attention to it, is there a problem?

Avocet · 7 Feb 2020

Just resurrecting this thread. I'm just trying to buy some bathroom taps. We have no water tank in the loft, it's all mains pressure. I've just been out and stuck a pressure gauge on my garden hose and was surprised to see just under 6 Bar! (About 85 PSI for anyone who prefers old money). That surprised me somewhat. OK, I'll lose a bit of that by the time I get upstairs to the bathroom (say 0.5 Bar?) but that still seems like an awful lot? I've checked the gauge against my son's fancy bike pump, and they agree pretty well. I guess the taps that Mrs. Avocet liked (where the website says "suitable for medium pressure 0.5 - 0.9 Bar") won't really cut it?

Madrab · 7 Feb 2020

What is the gauge you used actually for? Is it a water pressure gauge? The reason I ask is that you wouldn't really be able to check a water pressure gauge against an air pressure gauge I wouldn't think. Did you also test it with more than one outlet running at the same time?

If your pressure is actually that high then I'd be more than tempted to fit a pressure reducing valve as that's is too high IMO and can cause no end of issues with boilers and other pressure sensitive valves.

Jackrae · 7 Feb 2020

Madrab said:
The reason I ask is that you wouldn't really be able to check a water pressure gauge against an air pressure gauge I wouldn't think.

Why not ?

Madrab · 7 Feb 2020

Just assumed they would be calibrated to read different things as air can be compressed where water cant but now that I think about it again I guess pressure is just pressure regardless?

Avocet · 7 Feb 2020

Hi all, thanks for the replies so far. Yes, "pressure" is just "pressure", regardless whether it's oil, water, steam, hydraulic fluid, gas, etc. I think the only confusion arises when the material the gauge is made from is not suitable for prolonged contact with a particular flud (e.g. seawater) and it might corrode the gauge. For short measurements, any old gauge will do though.

I don't know if there's a pressure-reducing valve for the boiler (it's 25 years old though and still seems to work OK). This is just part of a bathroom re-decoration. In any case,since I posted this, the Mrs. has found some taps that she likes, and the online datasheet suggests that they're good for 7 Bar, so I'm feeling a bit happier now!

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Mains Water Pressure

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