low water pressure in flat

[Andrew Smith]

Hi,
I am a newbie in this forum, so my apology if I posted my question in the wrong forum.

The water pressure in my flat has dropped to very low pressure, which allows for only one tab at a time to be operational.
It happened end of July and is continuous low 24h.

There seems to be no obvious leak as the water meter is running not at all if all tabs are closed and the little wheel is very slowly, if I open a tab and stops immediately when the tab is closed.

The pressure is so low that only one tab (hot or cold) only can be operated at any one time.

The mains water pressure pump for the building in the garage seems to be working fine (@ 4.3 bar) and neighbouring flats do not experience the issue I have.

I checked the main valve and the ball valve separating the hot water supply to the immersion boiler in my flat (even though I never touched them) and they are fully open.

In 2018 the same happened. First the water pressure dropped in July 2018 and then the water pressure was back to normal in October 2018 without any intervention being done. As there was some building works going on at the same time I assumed it was related to it. But I also recall that the works finished way before the pressure went back up again in 2018.

The water pressure did not show any issues at any time between October 2018 until July 2019.

What could be the possible cause for this strange behaviour?

Many thanks.

 

[Stigster]

Do you have an unvented (pressurised) hot water cylinder or is your water heated some other way e.g. an older style open vented cylinder with header tank or a combi boiler?

 

[Andrew Smith]

Do you have an unvented (pressurised) hot water cylinder or is your water heated some other way e.g. an older style open vented cylinder with header tank or a combi boiler?

Hi Stigster,
I have a Prostel unvented hot water storage tank with two immersion heaters (one on a daily timer and one is a booster).
Hope this helps.
Many thanks.

 

[Stigster]

When all taps have been closed for a while and you open one up, either hot or cold, does it give an initial burst of good pressure/flow and then die off to a trickle or is it poor flow from the moment you open the tap? I'm just trying to understand the symptoms so we might figure out where the problem lies.

 

[Andrew Smith]

Hi,
Thanks for checking on the symptoms.
It shows reasonable pressure for about 3 seconds. Then it dies down to be a very poor pressure. The initial pressure burst is not as good as the normal pressure was a month ago.
I hope this helps. Many thanks for your help.

 

[Stigster]

Hi,
Thanks for checking on the symptoms.
It shows reasonable pressure for about 3 seconds. Then it dies down to be a very poor pressure. The initial pressure burst is not as good as the normal pressure was a month ago.
I hope this helps. Many thanks for your help.

The problem is likely to be with the Group Inlet (AKA combination valve) at the unvented cylinder. Unfortunately you need to be what they call "G3" registered to work on them so you will need a plumber with this certification to repair it. Anyone who is qualified to work with unvented cylinders would almost certainly recognise the symptoms and know what to do. This is not something you can DIY I'm afraid. It's a very common issue with unvented cylinders that have not been serviced for a long time.

 

[Andrew Smith]

Thanks for the great advice. I will do. But is it common that it fails after 2 years? The cylinder was installed 2 years ago by a G3 registered plumber.

 

[Stigster]

Thanks for the great advice. I will do. But is it common that it fails after 2 years? The cylinder was installed 2 years ago by a G3 registered plumber.

Firstly as I'm sure you are aware some things do just break before their time. There are also factors that are beyond your or the manufacturer's control like work being carried out on the water mains somewhere in your area introducing debris into the supply.