Low Flow/Pressure

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Low Flow/Pressure

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H

hshah

We have the following system (very high level):
plumbing.png


However, we are finding that if the shower is on upstairs and someone else turns on another tap downstairs then the shower is drastically affected. Even with any of the showers (upstairs or downstairs) when turned on on their own, the flow and pressure are pretty bad. I would have expected that with a 300l Megaflo and two boilers, all provided by a 25l/min mains, it would be far better.

This is a 6 bedroom (4 shower) property, so if you can't have more than one outlet on at the same time then it is quite a big problem.

I am assuming that I will need an expert to come in and look at the system, but before I do that does anyone have any idea where the issue could lie?
 
Water softener not causing a restriction,

the question they have is if taps only produce 8l/ min, why can't they feed 2 x taps at once, surely 18l/min, split into 2 should be able to provide 2 x 8l/min taps!!

and surely it doesn't matter what's coming in as each tap only produces 8l/min maximum so surely 18 l/ min should be plenty to feed 2-3 outlets at the same time shouldn't it?

the only thing I can think is the poor outlets are causing mega issues?
from 18l/min down to 8 is a massive restriction!!!
 
And even more onto that, if the pressure was increased to say 30l/min the outlets would still only produce 8 l /min so why and how would increasing it make a difference?
 
Chalked said:
Very poor water main for that size of house. Plus restriction through water softener and various restrictions in high pressure suited taps.
two fixes.
1 replace complete water main to street ( only if standing pressures are good)
2. Install break tank and pump set after the water softener.
Click to expand...

Water main has been replaced 25mm all the way back to meter!!
 
Working pressure on mains 1.5 bar,
working pressure on outlets, around 0.5 bar by my calculations!!
 
That's what I did, definetly taps causing issues
 
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What have you got at the showers and bath?

Any inline strainers on the taps and showers?....you know the rubber washer type.

If the taps are restricting flow then there shouldn't be a reduction when another is opened.

Have the taps got diffusers on the outlet as this is always a crap catcher and often overlooked.
 
Toxic Ted said:
What have you got at the showers and bath?

Any inline strainers on the taps and showers?....you know the rubber washer type.

If the taps are restricting flow then there shouldn't be a reduction when another is opened.

Have the taps got diffusers on the outlet as this is always a crap catcher and often overlooked.
Click to expand...

6l/min at showers and baths, 0.4 working pressure
No strainers anywhere
Taps all clean, Checked all strainers, Filters etc, no dirt in pipes or taps
Same pressure on taps with filters and taps without.
 
Jase, did you bypass the softener and test.
Unless it's a hiflo type softener you can easily lose a bar there !
 
BLOD said:
Jase, did you bypass the softener and test.
Unless it's a hiflo type softener you can easily lose a bar there !
Click to expand...
Yes and tested before and after water softener and as said before, not loosing any pressure through water softener, hi flow kit fitted on the water softener
 
As Jase mentioned earlier, we have 18l/min just after the stopcock, after the water softener and just before the pipe connects to the taps (after ISO). The fact that the taps have a reduced flow of 8l/min and lower pressure isn't such a big issue because we wouldn't really want more from those taps. However, with 18l/min into the property we should be able to have 2-3 outlets open at the same time, but with 2 taps open the flow drops to about 4l/min out of each tap.

That is our main issue, because whilst someone is showering no one else in the house can use any taps or have the washing machine / dishwasher on.
 
Most modern basin taps are restricted to 6 litres, so nothing wrong there.
 
These are what they are:
taps&showers.png


The only exception is the utility room tap which is a random one from Wickes.
 
Last edited by a moderator:
2 bar standing pressure at garden tap ? how many floors has the house got ? did you measure the dynamic pressure ?
 
BLOD said:
2 bar standing pressure at garden tap ? how many floors has the house got ? did you measure the dynamic pressure ?
Click to expand...

Dynamic pressure question is for jase, but I can answer the floors one... 3 floors including ground floor (one shower on ground, two on first and one on second).
 
Ok. Pipe work right sizes? Have u checked that pipe isn't inserted too far into a tee? Or cheap ISO fitted?

Had one where branch on tee obstructed 95% of main pipe.

Not piped in 10mm is it? Sounds very much like an obstruction. 25mm mdpe restricted? Pebble?

Fit a tee on mdpe. Measure flow rate and dynamic pressure.
 
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