System boiler - low water pressure

Dipak

Hi All,
Hope you're all keeping safe and well 
I'm hoping someone is able to help me find out what is causing the low water pressure in my System boiler. The boiler (Worcester) and cylinder (Joule) were installed back in 2016, since then i've had low water pressure on and off. I noticed it more if upstairs shower is running and someone opens the tap in the kitchen. The upstairs water pressure in the shower drops considerably and im pretty much getting small amounts of water. Similarly if upstairs shower is running and downstairs shower is running then downstairs shower will get most of the water and upstairs would get small amounts. I had a system bolier installed on recomendation as i have 2 showers in my house. I have contacted the waterboard whose confirmed the pressure coming into my house is normal. The boiler and tank are located on the ground floor.

When i had the new boiler installed it needed more water so i also had a new blue pipe installed which takes the water from the mains direct to my bolier. I therefore know that the boiler is getting a direct supply of water. I have followed the blue pipe and checked for leaks too and none found. No water patches have appeared anywhere over the few years that i've noticed. Has anyone come across this issue? Please note my boiler is not a combi but a system boiler. I'm not a plumber myself by i need ideas on what i can do to find out whats causing this low water pressure in my house.

Stay safe all!!
D

nofoollikeold

1. You need to know the following:
1a. The static pressure of the cold water coming into your house.  This is measured using a pressure gauge with no taps or other outlets running.
1b. The dynamic pressure.  As 1a but with 1 other cold tap running, preferably the kitchen cold or an outside tap, but a tap with as few restrictions between it and the incoming mains as possible.
1c. The flow rate of the open tap used in 1b.  Can be measured by filling a bucket to the 10 litre mark and timing it. Tap (and main stopcock) fully open.
2. If the dynamic pressure is less than 1.5 bar, and / or the flow rate is less than 20 litres per minute then you won't be able to run two outlets at the same time, or at least not without one affecting the other.  
3. If the pressure and flow rate are equal to or greater than the figures in 2. above, then most likely there is some restriction in the pipework to your unvented cylinder.  

Dipak

nofoollikeold said:

1. You need to know the following:
1a. The static pressure of the cold water coming into your house.  This is measured using a pressure gauge with no taps or other outlets running.
1b. The dynamic pressure.  As 1a but with 1 other cold tap running, preferably the kitchen cold or an outside tap, but a tap with as few restrictions between it and the incoming mains as possible.
1c. The flow rate of the open tap used in 1b.  Can be measured by filling a bucket to the 10 litre mark and timing it. Tap (and main stopcock) fully open.
2. If the dynamic pressure is less than 1.5 bar, and / or the flow rate is less than 20 litres per minute then you won't be able to run two outlets at the same time, or at least not without one affecting the other.  
3. If the pressure and flow rate are equal to or greater than the figures in 2. above, then most likely there is some restriction in the pipework to your unvented cylinder.  

For 1a and 1b is that something i can do or would you suggest getting a plumber in to do it? I'm not clear what you mean by dynamic pressure sorry!! can you explain please?

Moss5

https://www.screwfix.com/p/monument-tools-mains-water-pressure-test-gauge/82412
This gauge would allow you to measure incoming pressure.
Static pressure exists when no water taps are running.
When a tap is turned on, the pressure will fall to a lower (dynamic) pressure.
Your unvented hot tank (Joule) will have a pressure regulator fitted to prevent over-pressure from the mains supply and a pressure relief device to vent excess pressure caused by overheating.
These devices can only be tested/adjusted by a qualified plumber.
Your new blue pipe is providing the pressure/flow-rate to the Joule tank, not the boiler.
Once the system boiler/radiators have been charged to the desired pressure (say 1 bar), and air has been bled, that system becomes sealed and not influenced by mains pressure.

southcoastrgi

You keep mentioning your system boiler but this has absolutely nothing to do with your incoming water supply or your showers