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 wasn't digging mate it was just a reply to an earlier post.

And no offence was taken

 

[dancinplumba]

What about hosepipe on outside tap and use to bypass parts of the install to isolate the problem ?

 

[hshah]

What about hosepipe on outside tap and use to bypass parts of the install to isolate the problem ?

Sorry, I don't get what you mean? The outside tap gets 18l/min and branches off after the water filter. How could we use that to isolate parts of the system?

 

[dancinplumba]

After the filter ? . cut pipework near a bathroom and connect hosepipe there, connect direct to unvented cyl ?

 

[Chalked]

Sorry, I don't get what you mean? The outside tap gets 18l/min and branches off after the water filter. How could we use that to isolate parts of the system?

Your outside tap shouldn't be filtered or softened,

 

[hshah]

After the filter ? . cut pipework near a bathroom and connect hosepipe there, connect direct to unvented cyl ?

Sorry, I lie. It branches off the kitchen line, which is before the softener.

All the pipework is in the walls/under the floor and is near impossible to get to. I don't see what this would prove, since we do have two outlets very close to the stopcock (one about 75cm away and one 4m away) and we experience the issue where is the second tap is turned on the flow is halved in the first (both to 4l/min).

 

[hshah]

Your outside tap shouldn't be filtered or softened,

Sorry, I was wrong. See post above please.

 

[Chalked]

So
24 lpm at mains ( so water board say!)
18 from before softener, 6 lpm lost ( this might be all you can get through that tap at your pressure)
12 at outlets (probably restricted by softener, hoses and valves.)

therefore when running two outlets you get 6 lpm .

 

[dancinplumba]

Sorry, I lie. It branches off the kitchen line, which is before the softener.

All the pipework is in the walls/under the floor and is near impossible to get to. I don't see what this would prove, since we do have two outlets very close to the stopcock (one about 75cm away and one 4m away) and we experience the issue where is the second tap is turned on the flow is halved in the first (both to 4l/min).

Am not onsite so

 

[PlumbBobBob]

is there enough room for jase to take the stopcock off the imcoming main to double check what flow you have before it? obviously linking up back to outside so as not to flood the place

 

[jase158]

So
24 lpm at mains ( so water board say!)
18 from before softener, 6 lpm lost ( this might be all you can get through that tap at your pressure)
12 at outlets (probably restricted by softener, hoses and valves.)

no 18 at outlet of iso before tap, 6l/min from outlet of tap, when its on its own, no other outlets running.

2 outlets reduces flow to 4l/min

 

[hshah]

is there enough room for jase to take the stopcock off the imcoming main to double check what flow you have before it? obviously linking up back to outside so as not to flood the place

There is space if we move the water filter out of the way, which is fairly easy to do.

I was also thinking, if we think its the mains pipe that could be the issue, can we temporarily put another one from the meter to the stopcock (run it through the house). Then we can see how everything behaves?

 

[jase158]

There is space if we move the water filter out of the way, which is fairly easy to do.

I was also thinking, if we think its the mains pipe that could be the issue, can we temporarily put another one from the meter to the stopcock (run it through the house). Then we can see how everything behaves?

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?

 

[hshah]

We haven't fallen out with him but towards the end of the work (interior decorating) he started asking for more money. That was after all the plumbing was done so he couldn't have done something to it. We actually came to an agreement a few weeks ago to give a little more money and that is when he came back to do the utility room sink etc.

So for the above, how much would steps 1 to 5 cost me?

 

[Ch4 plumbing]

We haven't fallen out with him but towards the end of the work (interior decorating) he started asking for more money. That was after all the plumbing was done so he couldn't have done something to it. We actually came to an agreement a few weeks ago to give a little more money and that is when he came back to do the utility room sink etc.

So for the above, how much would steps 1 to 5 cost me?

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