Low Water Pressure - Except When Attic Tank Refilling

bunit

Hi all,

Hoping to get some insight on a water pressure issue Ive been having.

Moved into a new property a year ago which has a cold water feed direct from mains supply. Cold water pressure at the kitchen was crazy high (>6 bars) and was causing lots of issues with water hammer and vibrating pipes while the attic tank refilled.

Got the a plumber out to install a pressure reducing valve under the kitchen sink at the stopcock and took the pressure down to ~ 2 bars, also installed an outside tap as well while he was there. All was well and good then for about 10 months.

Then our cold water pressure started to decrease. However, whenever the cold water attic tank is refilling (after toilet flushing or running hot water taps) the cold water pressure from the kitchen tap returns to what is was before (~2 bars). I called the the County Council water supply people who came out and checked the water pressure going into the house and they said its all fine (~6 bars). I cant figure out why an increased draw on the cold water system while the attic refills would lead to an increase in water pressure (surely an increase draw from the attic tank refilling would only decrease water pressure from the sink tap?).

Racking my brain trying to troubleshoot this. Any suggestions would be welcome!

Curious_Case

I wonder is that pressure reducing valve, spring operated? Could the spring have become weak and the increased flow to attic is opening it further ??

Alternatively, if the reducing valve is a simple narrow bore arrangement, then the attic flow might be temporarily moving debris from it, thus allowing normal flow ??

10-10-20

Is it a static or adjustable pressure reducing valve? Did you try adjusting it? It does sound like a flow issue within the value.

https://techblog.ctgclean.com/2012/04/valves-pressure-reducing-valves/