New Water Main..Poor Dynamic Flow still

[bravefish]

Hi Team

Firstly, I have done my best to read and get some understanding (with plumbers and across forums). I'm stuck and could use some help.

- Victorian property, was on a shared supply. 15mm feeding my maisonette (one ground below).
- New 25mm MDPE fitted with one 90degree elbow and 2 then rise to 1st floor, under the floorboards. One 25-25MPDE through connection and a 25->15mm connection into the existing copper pipes. Up pipe from downstairs capped.
- From what I see, stopcock is an isolating valve in kitchen behind dishwasher (flathead screw type), I have checked, this is open but cant tell if it's full bore.
- Harvey water filter, 15mm pipe. Bypass fitted
- Currently one toilet - flexi, one sink 15mm cold hot with two tails to one mixer, kitchen sink (can't see) and boiler (15mm). Bath has hand shower and Victorian mixers which I believe to be 3/4BSP fed by 2 flexis coming from 22mm (looks like).
- Run of MDPE is not large. 3m boundary to inside, up 3m, across 8m (my side of stopcock)
- Old Worcester 24cdi 9l/m CB

Now. The issue I had is that before, I couldn't take a shower if down and up taps/dishwashers were on. That has been resolved. Pre change, this was a massive issue, and one tap open, the other tap complete dribble/stops the other tap.

Didn't have a Weir but could think that I was 10ish l/m bathroom tap.

Issues/Questions:

1. Should I route the 25-15mm to 25-22 (new 22 copper) to the kitchen and then back to the bathroom, and potentially to the boiler to reduce to 15mm?
2. Dynamic flow is still quite poor. One tap open, reduces the other by quite a lot but I have no way of measuring.
3. With the water softener on I can get 14/15ish l/min to bathroom tap (Weir. plumber), but only 12l/min to kitchen tap. Softener bypassed - bathroom can be 18ish l/min and kitchen stays the same. Any idea of why the difference, would this most likely be internal plumbing?
4. Are the numbers expected? would 15-17 with a new 25mm supply be acceptable.
5. Flexis are old small bore I guess, would removing these help, as well as the potential isolating small bore?
6. My ultimate question is that I don't know what I should be expecting. This affects the boiler choice I need. 20 quotes. One says 30kw for 12l/min. Others 35 for 14-15 and some 40 for 16/17. But I am worried about the dynamic flow reduction.

Just confused - Can't find a plumber who will just help me. And don't mind doing what needs to be done, including upgrade from 15-22 as the run from entry to the bathroom/kitchen is quite small.

Thank you for anyone who can help here.

Far

 

[Gasguru]

You need to measure the static pressure (ie. the pressure in the main outside with no water flowing) and dynamic pressure (ie at various flowrates).

 

[bravefish]

Thank you for the response. hmmmm - not quite sure how to measure pressure and flow outside, nor inside re pressure (obviously flow rates I can do). Do I need to cut and insert some kind of pressure sensor on the MDPE pipe?

Far

 

[CBW]

You can usually use a pressure gauge connected to garden tap, or washing machine valve. https://www.toolstation.com/mains-w...MIrOPdpLau6AIVx4jVCh0U2AoTEAQYASABEgKZqfD_BwE

 

[bravefish]

Thanks. This could give me a pressure rating internally. I see that there is a connection for washing machine with a small bore isolation valve. The cold seems to be coming from a sink circuit but behind kitchen cupboards. Would the small bore skew results? I guess I could get dynamic too by opening a tap as well.

For main MDPE flow, how would you go about that. I think that's the way I can isolate it to internal or just the street.

Best
Far

 

[Gasguru]

Connect the gauge anywhere for now (downstairs best) just to give you the static pressure in the street...we need to know the pressure out there first.

 

[bravefish]

Ok sure, have ordered a gauge and will report back. I presume as it is going up one floor and has one elbow that it will lose some pressure, but the flow seems low to me. Will come back here with an answer. Thanks so far

Far

 

[Madrab]

All you need is the pressure gauge connected to a WM valve. Doesn't matter about how narrow it is as that won't alter the water pressure reading. Once that's fitted then open one and then 2 outlets and notice the drop in pressure from static to dynamic and report back.

Up one floor then it will drop by the height it has to rise - 0.1bar drop per 1m.

Measuring flow - time filling a bucket over a minute, then measure how much water you have - that will give you L/Min. Do this alone and with another water tap open and measure the difference.

Elbows/Bends/tee's/stop taps/flexi's etc will reduce flow and pressure due to resistance and that will be more apparent as the pressure drops.

 

[bravefish]

Should get the gauge today and will report. I'll do flow and pressure with and without softener. Be in touch shortly. Thanks

 

[bravefish]

Sorry for the delay, getting a gauge has been quite tough!
Will come back to the thread.
Far