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Discuss Poor flow and pressure issues? in the Plumbing Forum | Plumbing Advice area at PlumbersForums.net

macka09

Plumber
Gas Engineer
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1,117
Hi guys.

I replaced an electric shower for a family member recently and on completion noticed how poor the pressure was. It wasn’t like this the week before when I initially looked at it. Apparently Severn Trent were in the area the following week to do some work. She’s now saying that the shower is too hot and she thinks it’s the poor flow. I’ve asked what it was like on the eco setting which apparently is too cold. Other than maybe checking the mains tap in the street is all the way open and the house stop tap, what other checks would you recommend? On installation I noticed that the internal stop tap was only a quarter turn open, which was odd I thought. Apparently the poor flow/pressure only occurred between my initial visit and installation visit.
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
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30,341
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1
Need to have the stop tap open fully minus 1/4 turn the old shower has been failing for a while and to compensate they’ve turned the stop tape closed
 

king of pipes

Esteemed
Plumber
Gas Engineer
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5,551
Electric showers have a mesh filter in the small inlet pipe, it doesn't take much to get restricted and stop the shower from operating as it should, as Shaun said the stop taps needs to be fully open the turned back 1/4 of a turn check your flow rate with a wier cup and and pressure gauge you can do this with the shower head removed on its hose and then compare your findings at a suitable tap . Kop
 

WC1

Esteemed
Plumber
Gas Engineer
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1,246
Is there pressure / flow data or is this based on what they feel has happened?
 

macka09

Plumber
Gas Engineer
Messages
1,117
Thanks for the advice guys. When I initially completed the shower swap and opened the stop tap fully, I went upstairs and opened up the bath and basin taps which were very poor flow/pressure. At one point the bath tap stopped completely, which surprised me. I then asked what has happened since my last visit to the water, she replied, “it’s gone bad in the last week, but Severn Trent are doing work in the street next week”. I assumed the supply would return to normal once they’d completed there work. Obviously I’m taking the family member at there word.
 

WC1

Esteemed
Plumber
Gas Engineer
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1,246
Need to have the stop tap open fully minus 1/4 turn
The British standards people should insist this be cast into the body of the tap. Easily done and save us all grief and save customer money.
 

John.g

Messages
2,793
Thanks for the advice guys. When I initially completed the shower swap and opened the stop tap fully, I went upstairs and opened up the bath and basin taps which were very poor flow/pressure. At one point the bath tap stopped completely, which surprised me. I then asked what has happened since my last visit to the water, she replied, “it’s gone bad in the last week, but Severn Trent are doing work in the street next week”. I assumed the supply would return to normal once they’d completed there work. Obviously I’m taking the family member at there word.

Turn the temperature (flow) control to fully cold and measure the flow rate, should be ~ 8LPM, do ditto with the control to fully hot, should be ~ 2.0/2.5LPM, carry out both tests with power control setting on 0.
Presume both the old and new showers were/are direct from the mains, some, known as pumped electric showers have their own internal booster pump but can only be fed from the cold water storage tank.
 
Last edited:

macka09

Plumber
Gas Engineer
Messages
1,117
A bit of an update folks. The house is getting 1bar standing pressure but only 5.5lpm at the kitchen tap. Replaced the internal stop tap and made sure the one in the street was open fully. It’s a shared mains that comes in to the house in 15mm.
 

John.g

Messages
2,793
A bit of an update folks. The house is getting 1bar standing pressure but only 5.5lpm at the kitchen tap. Replaced the internal stop tap and made sure the one in the street was open fully. It’s a shared mains that comes in to the house in 15mm.

Re Shower: Mains supplied electric showers require a minimum of 0.7bar (ish) maintained pressure at the shower so yours only borderline but something not quite right, in post #1, shower too hot on full power and too cold at Eco power, it is very unlikely IMO that it cannot be controlled via the temperature contol (flow) to give a comfortable showering temperature of 40C albeit with a poor flow of ~ 2.5LPM from a present mains temp (here) of 12C, if the temperature control cannot reduce the flow rate to achieve this then maybe shower cover not installed/lined up properly so maybe worth having a look at this.
In the long run, a (integrally) pumped electric shower fed from the CWST is probably the only guaranteed way of running the shower on full power.
 

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