Low Flow/Pressure

[hshah]

We have the following system (very high level):

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?

 

[hshah]

I would suggest that's not for open forum, but that's just my opinion.

Jase can just text me a quote

 

[dancinplumba]

This is what I am thinking!

step 1, disconnect mains and connect new mains to outside, do dynamic pressures and flow rate with open outlet
step 2, reconnect mains with new pipe from meter (if accessible) to house
step 3, do dynamic pressures on mains with system connected
step 4, check every single outlet (that is accessible) for dynamic pressure, flow before and after taps.
step 5, buy one tap and replace in several places to see if this makes a difference
step 6, breaker tank and pump

Obviously if it any of the above fixes it then we know the issue.

I believe it is the mains for these reasons:

The flow may be good but the pressure can be bad, due to reduced pipework size.
For instance if you put your hand over a hose pipe, you think the water is coming out really fast (flow or L/min), however if you were to measure it, it is actually really low (Bar/ Dynamic pressure)

So a blockage could be giving a good flow rate but the pressure is low.
This in turn would hit the taps and the taps would then restrict it even more.

For example if you were to run a hose and twist it a little in the middle, you will still get a reasonable flow, however if you were to kink it twice it would barely dribble out.

Hope this explains it well!! someone might be able to explain it better.

Just out of curiosity, did you fall out with the builder at any point?

Think about this jase, a blockage would give reduced flow rate

 

[hshah]

Think about this jase, a blockage would give reduced flow rate

So that would explain the drop from 24l/min to 18l/min, but I still don't get why I can't have two outlets on at 8l/min.

 

[kris]

I'm with dancing on this. Nighmare jase .You can change taps and youl still have the same issue i think as because multiple outlets are poop flow you need to trace back to where it's better . There will be one problem that's causing many poor outlet flow rates. I know it's not easy but replacing taps won't really help . Not good to do but it's process of elimination. Tees need to be cut in certain bits if accessible n gauges put on or valves to measure different points ... Like ermi said earlier a tee in too far with a certain fitting it's just finding it. Good luck bud and patience n perseverance.

 

[kris]

24 lam at the mains is poor to start with and if only 18 at the softner then that would indicate to me that the problem is outside. Not inside.

 

[kris]

Also I'd disconnect the non return valve that should be near the mains and try it without it.

 

[hshah]

24 lam at the mains is poor to start with and if only 18 at the softner then that would indicate to me that the problem is outside. Not inside.

Whilst it may be poor, why can't I have two taps on at 8l/min with 2l/min to spare?

 

[dancinplumba]

If nrv on main then exp vessel is a must

 

[kris]

Hi there hshah the tests you guys done to get these figures did you do the checks a couple different times to see if any variation In results. Stick presdure gauges on get your bar reading at stopcock and open outlets and check if gauge drops dramatically. . What was your bar reading on incoming main ?

 

[jase158]

Think about this jase, a blockage would give reduced flow rate

Yeah which is hopefully how I explained it!! Reduced flow to 18 l/min but when faced with the taps, the pressure isn't there to help with the flow which is why it reduces down to 6l/ min?
i am not very good at explaining principles of plumbing.

 

[jase158]

24 lam at the mains is poor to start with and if only 18 at the softner then that would indicate to me that the problem is outside. Not inside.

Provided water board are telling truth and not covering their own backsides.

 

[jase158]

Also I'd disconnect the non return valve that should be near the mains and try it without it.

No NRV, no drain valve, pretty sure the pipe wasn't flushed and probably left in trench for few weeks whilst other work was done with nothing on the ends of pipes.

pretty sure it is mains inlet but only one way to find out, problem is the main is in centre of house, all newly tiled floors.

 

[Toxic Ted]

If you are going to run a temp pipe to an outlet further on, then use it to "blow back" into a large tub to flush back anything that could possibly be in there and do the same with the MDPE with the stopcock removed and being controlled from the street in short bursts.

 

[Matt06]

i would check this if there a water meter fitted ? turn all off in the house (stopcock) and see if meter still spins (possible leak outside if does )

2bar is low for standing pressure

I had similar problem a few months ago but was a shared main someone bodged a section with little bits of copper and some pushfit crap

 

[hshah]

Affinity Water had cut the main before the meter to test the flow and pressure there... they recorded 24l/min and 2 bar.

We are seeing 2 bar after the stopcock and water softener, so all that is being lost is the flow (from 24l/min to 18l/min).