Mains Pressure

Donal Duck

I wonder would someone have a comment on this.

My house is under mains water pressure. The pressure regulator is set at 4 bar. But static mains pressure is often less than this. Today it is 3 bar. When a tap is turned on pressure drops to 1.5 bar. If two taps are turned on downstairs water pressure upstairs is zero - there is no flow. Any comments on the following would be much appreciated:

Should static mains pressure ever be less that the regulated 4 bar?

Is the drop from 3 bar to 1.5 bar normal - at about 6 litres per min, 150 metres of 0.75 inch PVC piping.?

Or should I look for a restriction in the piping from the mains to my house?

Wearb

Static pressure will not exceed mains pressure, so perhaps there's a drop in mains pressure.

John.G

https://www.boards.ie/discussion/2058313566/mains-pressure

You have a huge run of piping at 150M but IF the pipe diameter has a ID of 3/4" which I doubt the the pressure loss will only be 0.2bar at 6LPM. If your pipe is like mine, ~ 21mm OD X 11.5mm ID then the pressure drop will be 1.6bar at 6LPM in 150M of piping. You wil have zero pressure at the end of the end of the pipe at ~ 8.5LPM.

Donal Duck

Thanks, John.

The pipe is 3/4". I looked up the tables and the pipe should not be a problem. I'm hoping that there is an issue with the mains supply that I can take up with the Co Co. But I don't know enough not to be fobbed off.

Dan

John.G

Did/can you measure the outside diameter of the pipe?, if it is 3/4" inside diameter then there could be a stone or gravel in it or possibly a faulty pressure reducing valve, some of these have a strainer.

Donal Duck

Hi John,

Yeah, the external diameter is a little over 1" and I'm satisfied that the pressure regulator is OK. There is a standard water meter at the road. That belongs to Irish Water. I don't know what information can be obtained from that. 8.00 p.m., water demand is low, static pressure is 3.2 bar, suggesting that static pressure out in the mains isn't much more than 3.2 bar. Is that standard? acceptable? I don't know. I would like to be able to put the right questions to Irish Water / Co Co and eliminate an external problem before trying to find a way to check pressure loss in the meter to house pipeline.

If I was to throw out a caution to readers in general, I suspect that having a house water supply under mains pressure is a dodgy option.

John.G

Have you a pressure gauge on the PRV or after it?, if so, then IW shouldnt have any problem in measuring the pressure at their end, both static and dynamic when you open a few taps, that will soon tell them and you where the problem is.

Donal Duck

Looks like it will take a while to talk to someone in IW. Yes, if they will check concurrent pressures at the meter it will tell a lot. (Gauge is on the regulator.) Thanks, John.