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).

 

[SimonG]

Whats the dynamic pressure. 2 bar is poor standing pressure imho.

 

[hshah]

Whats the dynamic pressure. 2 bar is poor standing pressure imho.

That I do not know, nor know how to check, sorry.

 

[PlumbBobBob]

to check dynamic pressure you put a pressure gauge on first outlet i.e. outside tap with it on, then turn on another outlet i.e. kitchen tap. this give you an idea of dynamic pressure.

 

[wetdrip]

Thought about viewing the thread, but with 105 replies I decided against it.

 

[Matt06]

previous post it says 2 bar static 1.5bar dynamic

You could ask to check a few of the neighbours properties see what they get

if they are similar then you'll probably have to go the route someone else said ( Break tank, pump etc )

 

[hshah]

Right, so what do people recommend to be the next steps?

Jase is suggesting we go with:

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.

The water meter and outside stopcock is accessible if you have the long turning pole thing (no sure what it is called) so I'm thinking we turn that off and check the flow and pressure just before the house stopcock too. Then do the steps above followed by flushing the system with the temporary pipe, like someone mentioned earlier in this thread.

Make sense? Anything else we should do or haven't considered?

 

[anthonytinkler]

Hi Mate
just been reading through the threads some good advise there
however with a large house and with such a big loss in pressure i would start by
confirming that you have good water pressure at the meter on both sides, if so
1) take pressure reading before stopcock
2)take pressure reading after stopcock ( are there the same ? )
3) check all out lets on ground floor only, and check standing pressures ( is their a difference ? )
4) move on to next floor and repeat stages 1 -3 and so on
keep in mind all taps are closed and you are checking pipe work and standing pressure
my idea been is you will be able to check for lost pressure, once you have found lost pressure you will be able to isolate that area put a temp line in and then check standing pressures again
if you are happy with standing pressure move on to checking working pressures
this time remove excising tap and put a temporary tap in its place and check water flow do this one at a time and check flow rare
I know this is time consuming put it will be a question of eliminating blocked or restricted pipe work and will give you some idea of where the problem is
hope this helps
thanks Tony

 

[Sparkgap]

Hi Mate
just been reading through the threads some good advise there
however with a large house and with such a big loss in pressure i would start by
confirming that you have good water pressure at the meter on both sides, if so
1) take pressure reading before stopcock
2)take pressure reading after stopcock ( are there the same ? )
3) check all out lets on ground floor only, and check standing pressures ( is their a difference ? )
4) move on to next floor and repeat stages 1 -3 and so on
keep in mind all taps are closed and you are checking pipe work and standing pressure
my idea been is you will be able to check for lost pressure, once you have found lost pressure you will be able to isolate that area put a temp line in and then check standing pressures again
if you are happy with standing pressure move on to checking working pressures
this time remove excising tap and put a temporary tap in its place and check water flow do this one at a time and check flow rare
I know this is time consuming put it will be a question of eliminating blocked or restricted pipe work and will give you some idea of where the problem is
hope this helps
thanks Tony

Sorry Tony, standing pressure would be the same throughout the whole system under no-flow conditions! To check for excessive drop you'd need to turn on a couple of taps and leave them running while you checked pressures before and after meter and at incoming stopcock in the house. That would show up if there was a possible blockage in the incoming main or a dodgy meter.

One thing: 25mm PE is about 20mm internal. For 6 beds etc. I'd have been happier with something much larger.
I suppose you could try temp connecting some 32mm from the meter into the house and see if that improves the flow but checking the pressures should give an indication anyway.

 

[Ermintrude]

Well....... Initial awesome flow for 20 seconds then dwindled to a trickle. Removed internal stop tap and it was full of .....

Thank the Lord for the check valve above stop tap.

Newbuild 25mm mdpe laid in pipe bedding!!!

 

[Chalked]

Well....... Initial awesome flow for 20 seconds then dwindled to a trickle. Removed internal stop tap and it was full of .....

Thank the Lord for the check valve above stop tap.

Newbuild 25mm mdpe laid in pipe bedding!!!

Is that from this property?

 

[hshah]

Is that from this property?

It isn't lol!

 

[Ermintrude]

From my last job today.

 

[wetdrip]

Looks Vegan to me.

 

[Ermintrude]

Not really. It's crushed lime stone....... Line stone is sedimentary and contains dead animals. [emoji16]

 

[Ch4 plumbing]

I had one yest, no flow at kitchen tap! Unscrewed the airator and loads of metal Chipping's came out so flushed it and good as new!