Low / High Water Pressure problem

mazza

Hi,

I suspect this is a job for a plumber, but just in case anyone could put me on the right track as to what's up with the water pressure in our house...

Here's a quick description:

- House is divided into two with a single mains water pipe in which splits to feed a granny flat and the main house. Much of the plumbing in the house is quite old (30+ years) and isn't really up to modern water pressure, leaks a bit etc.

- The granny flat has its own stopcock which switches the water on / off, seperately from the water in the main house.

- When I nearly close this stopcock, the water pressure is very low, nearly un-usable. However, when I close the taps the pressure seems to build up over the course of 30 seconds and then all the taps start whistling with air escaping, dripping etc - obviously under too much pressure. When I open a tap, the water pressure is CRAZY for about 20 seconds and then dies down to the very low level again.

I thought by nearly closing the stopcock, the water pressure would be low and _stay low_, but clearly this is not the case? Is this because the higher pressure water beyond the stopcock is increasing the pressure, even though the stop cock is nearly closed?

Am I doing the right thing trying to control the water pressure with a stopcock at all or is it intended to only be used for switching water on / off?

If so, do I need some kind of new valve or pressure limiting device in place of the stopcock to switch water on and off and stop the pressure increasing? As mentioned, the plumbing is old, so it could well be something completely different is needed now....

Any diagnosis or advice most gratefully received!

Many thanks in advance,

Maz

311

It sounds like your not happy because there is too much pressure on the mains...
If that is the case ,I'll just spell out a few things that I know about mains water.
Basically most mains pipes are routed to a kitchen sink ,then elsewhere in the house .
When you open a tap in a low water pressure area ,what happens is the water in the pipe from the tank upstairs sometimes comes back down through the kitchen sink(the gush of water)
In your case ,you are still getting probably about 2 bar pressure ,but when you open your tap and let the pressure out (the gush of water) ,your releasing the pressure and left with the flow restricted a little.
Most common noises in houses from water pressure are whats known as water hammer.
It's actually more common in ex council houses from the 30' and 40's around cabra and crumlin.
Theres a few cures for water hammer ,if thats what your problem is.

PS. I know I don't post in this forum a lot ,but I'm still out of work due to an injury .
Sorry for barging in here if I'm not welcome.:o

mazza

Cheers for the reply, _Brian_.

Yes, I'm not happy with the high pressure, as you say. The problem isn't water hammer though (I'm familiar with this an have sorted elsewhere).

My problem is that the plumbing in the flat can't stand up to the water pressure its coming under. Hence, leaking worse than it should be and one specific value blowing to let off water pressure, soaking everything.

Everything in the flat is fed off the mains (strange I know these days), so there's no water tank involved.

Thanks anyway and get better soon!

311

There are valves ,pressure reducing valves available costing about 60 euro.
You can set the pressure you want on these ,I've never had to use one on mains feeding a house before though.

EDIT :- heres a link that describes the valve ,http://www.watts.com/pro/divisions/watersafety_flowcontrol/learnabout/learnabout_wprv.asp#whatiswprv