Increase Water flow - pipe/accumulator

[Cockneydave]

Hi all, looking to solve my clients water flow issues.

5bed detached House in the South East with a combi boiler.

Customer is unhappy with shower flow when running a single shower.

Affinity water have come out with the following measurements:

Water Meter

2.5 bar

Max flow 25l/m

Running pressure.

20L/1.5bar


Garden Tap pressure.

2.5bar

12.5l flow rate at 1 bar dynamic.

The customer is only getting 10L/min at the kitchen sink and 6L/min at the upstairs shower.

Looks to be 20mm MDPE coming into the stopcock but unsure of what’s outside the house (1950s house).

Considering the flow at the meter is only 25L/min, would it be better to put a pumped accumulator in or just changing the supply pipe to 32mm?

I don’t want the customer to spend on the supply pipe and still be unhappy with the flow!

Cheers,

Dave

 

[Chuck]

20mm MDPE has an ID of 15.4mm, which is too narrow for a 5 bed house IMO. I'm not sure, however, that it's the root cause of your specific problem, i.e. low flow at the shower.

I consider accumulators to be a last resort, mainly useful in rural properties where there is plenty of space but a very long undersized supply pipe. (Not everybody agrees with me.)

Tell us a bit more about what's inside the house. Is there a water softener? What model of shower is it? Does it have an 'eco' shower head? How long is the path from stopcock to shower?

 

[Cockneydave]

20mm MDPE has an ID of 15.4mm, which is too narrow for a 5 bed house IMO. I'm not sure, however, that it's the root cause of your specific problem, i.e. low flow at the shower.

I consider accumulators to be a last resort, mainly useful in rural properties where there is plenty of space but a very long undersized supply pipe. (Not everybody agrees with me.)

Tell us a bit more about what's inside the house. Is there a water softener? What model of shower is it? Does it have an 'eco' shower head? How long is the path from stopcock to shower?

1. water softener present however these figures are present when currently bypassed. I would say the flow drops 50% when connected.
2. Shower is a standard shower non eco
3. The path is 18m from the meter to the stopcock.

 

[John.g]

You can calculate the pressure drop (friction loss) here for any pipe once you know its length (18M?) and ID.

Friction Loss Calculator - National Pump & Energy

Calculate your efficiency losses due to friction in your system pipeline with NPE's easy-to-use Friction Loss Calculator.

www.nationalpump.com.au

 

[Chuck]

From tabulated values, I estimate that 6 litre/s through PE 1/2” nominal (15.8mm id) will give pressure drop of ca 0.29 bar / 100m, or 0.05 bar over 18m. This suggests to me that you need to look critically at the pipe sizing and condition between the stopcock and the shower as the supply pipe is not the limiting factor.

 

[John.g]

"Garden Tap pressure.
2.5bar
12.5l flow rate at 1 bar dynamic.
The customer is only getting 10L/min at the kitchen sink and 6L/min at the upstairs shower."

From the above it seems that there is a pressure drop of 1.5bar at 12.5LPM at the garden tap = 0.35bar at 6LPM so theoretically at least = 2.15bar dynamic available to overcome pipe loss + static head + shower&shower head loss. Is this how you see it?.

 

[John.g]

1. water softener present however these figures are present when currently bypassed. I would say the flow drops 50% when connected.
2. Shower is a standard shower non eco
3. The path is 18m from the meter to the stopcock.

What is the dynamic pressure and where are you taking it at a shower flowrate of 6LPM?.

 

[Limecc]

Pardon me but what's wrong with a good old fashioned hot water cylinder, big header tank and shower pump?

 

[Cockneydave]

UPDATE…

Just dug up the to the water meter outside and found it’s the old 15mm lead pipe. The house has been extended so I’m assuming when the new kitchen was put in, they extended the lead pipe using 20mm mdpe to the stopcock.

Having found this new information, shall I just upgrade the whole supply to 32mm MDPE?