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Water Pressure

Discussion in 'Home and Garden' started by Danger Phoenix, May 18, 2014.

  1. Danger Phoenix

    Soldato

    Joined: Jul 21, 2004

    Posts: 6,337

    Location: Bromley / Uxbridge

    We have recently had a house done up and moved in, but we have found that the water pressure it pretty low. We have twin boilers and a 300l Megaflo system but the pressure is not adequate for 1 shower let alone 4.

    We have had Thames Water come out but they claim it is the piping in the house and refuse to replace anything before the water meter as that would cost them quite a bit.

    A few friends have recommended getting a mains cold water pump to go where the pipe comes up into the house, but ones with tanks look pretty expensive. Plus I am worried that these would be quite noisy.

    Thoughts? :)
     
  2. Django x2

    Capodecina

    Joined: Sep 28, 2008

    Posts: 12,427

    Location: Britain

    It's illegal to pump mains cold water. Ask Thames water for their pressure reading to the property (although they will only give it to you at the pavement / street stop valve and not your main stop valve in the property). Assuming this is in excess of 3bar, you then need to check the pressure at your indoor stop valve. If theres a difference here, then the issue is in the pipework under the house / driveway / etc, which falls under your ownership. If this is old lead pipework, it might be worth the upgrade to 25/28mm pipe, but to dig up that pipework and replace won't be cheap.

    Twin boilers means little here. What is the actual pressure you are receiving and what flow are you getting (measure downstairs and upstairs as both will have different readings).
     
    Last edited: May 18, 2014
  3. Danger Phoenix

    Soldato

    Joined: Jul 21, 2004

    Posts: 6,337

    Location: Bromley / Uxbridge

    Ahh, didn't realise they were illegal... had seen some boosters available online and assumed it was alright. Surely, the ones with a tank are alright?

    All the pipework from the water meter outside to everything inside the house is new. I believe the builder used 22mm piping inside (where ever he could) and from the outside we have a blue plastic tube.

    Thames Water have measured the water at the meter (25l/min), at the back garden (18l/min), and in the first floor bathroom (15l/m). I think they said the pressure from the mains was 2 bars.
     
  4. Participant

    Caporegime

    Joined: May 13, 2003

    Posts: 30,606

    Location: Warwickshire

    The person installing the megaflo for you should have checked the dynamic pressure and flow was adequate before they did so.

    Django's right that you can't pump mains water directly, but you can get something like a grundfoss booster set, which is a large tank that fills up with cold water, then pumps this at 3.5 bar to the whole house. Expensive and potentially noisy, depending on installation site.

    An accumulator might help, but they maintain flow when multiple outlets are running rather than increase it for any given outlet at once.

    What flow rate in l/m are you getting at your outside / garden tap?
     
  5. Danger Phoenix

    Soldato

    Joined: Jul 21, 2004

    Posts: 6,337

    Location: Bromley / Uxbridge

    See above for flow rates :)
     
  6. Django x2

    Capodecina

    Joined: Sep 28, 2008

    Posts: 12,427

    Location: Britain

    By very nature, a good accumulator will help with pressure as some can be "charged" so that the release of the diaphragm gives the impression of a boost in pressure. The water flow and pressure need to be measured at different times of day before ordering a suitable accumulator.
     
  7. Danger Phoenix

    Soldato

    Joined: Jul 21, 2004

    Posts: 6,337

    Location: Bromley / Uxbridge

    I kind of gave up on this before but have come back to it now. The flow and pressure at the mains is 20l/min and 2 bar. Back garden it is 18l/min and 2 bar. Kitchen tap and downstairs shower output about 5l/min, and this drops to 4l/min in the first floor bathrooms and 3l/min in the loft bathroom.

    If one person is showering and a tap is turned on elsewhere then the water flow and pressure drops drastically, which doesn't seem right if we are getting 20l/min coming into the house.

    Getting one of those devices that pump mains water up to 12l/min isn't going to help because we already get more than that. I was looking at this, but I think that it going to actually limit the flow into the house:
    http://www.stuart-turner.co.uk/products/flomate/mains-boost-extra-80/

    Other options are:
    http://www.anglianpumping.com/products/aps-house-booster-1000---mq
    http://uk.grundfos.com/products/find-product/home-booster.html
     
    Last edited: Dec 21, 2014
  8. Maccapacca

    Don

    Joined: Apr 13, 2010

    Posts: 16,430

    Location: Sunny Sussex

    The water companies only have to provide 1bar at the kerb.

    It really sounds like your system design is wrong.
     
  9. Danger Phoenix

    Soldato

    Joined: Jul 21, 2004

    Posts: 6,337

    Location: Bromley / Uxbridge

    How do I go about figuring out what the issue is?
     
  10. iraiguana

    Mobster

    Joined: Aug 24, 2005

    Posts: 2,572

    The issue sounds like it is within your internal plumbing. You are getting a good pressure up to and inside the house.

    How to proceed further will likely require someone with greater knowledge of how the plumbing should have been designed in the first place.
     
  11. Danger Phoenix

    Soldato

    Joined: Jul 21, 2004

    Posts: 6,337

    Location: Bromley / Uxbridge

    If it helps, I think this is what we have (very high level):
    [​IMG]
     
  12. Ronty

    Gangster

    Joined: Aug 17, 2005

    Posts: 270

    Location: Surrey

    Have you checked its not the softener at fault?

    Otherwise it does sound like the pressure and flow rates weren't properly tested before deciding on using a mains pressure system.

    It should be easy enough to add an accumulator in to maintain the 2bar you do have when using more than one outlet, but that's only if you have the space for another cylinder about the size of your megaflow and can connect into the correct place (just after softener)
     
  13. wazza300

    Caporegime

    Joined: Jul 11, 2009

    Posts: 26,772

    Location: BenefitStreetBirmingham

    makesure the stop **** in the street is turned on fully,this happened to us and we put up with poor pressure for months

    was so simple
     
  14. amigafan2003

    Capodecina

    Joined: Jan 18, 2008

    Posts: 14,267

    Location: Fylde Coast, Lancashire

    It'll be the water softener - they are quite restrictive. Open the bypass valve before it and test again - should notice a decent increase in pressure.
    He says he's got 2bar coming into the house.
     
  15. Danger Phoenix

    Soldato

    Joined: Jul 21, 2004

    Posts: 6,337

    Location: Bromley / Uxbridge

    The water company checked the flow and pressure and said everything was good on that front. I have already tried the softener bypass and that hasn't helped. I worked out that I need a flow of 50l/min to provide water to more than one outlet at a time. I'm looking into underground water tanks (2000l) which I can pump from into the existing system.

    Anyone know any decent plumbers in the Uxbridge area because our builder (who recommended what we have and installed it) has no idea why it's so rubbish.
     
  16. RJC

    Don

    Joined: May 29, 2005

    Posts: 28,298

    Location: Kent

    What type of pipe have you got coming from the street to the stopcock in the house.
     
  17. Danger Phoenix

    Soldato

    Joined: Jul 21, 2004

    Posts: 6,337

    Location: Bromley / Uxbridge

    A 28mm blue plastic one.
     
  18. malfunkshun

    Soldato

    Joined: Aug 20, 2003

    Posts: 6,661

    Location: Pembrokeshire

    32mm surely?
     
  19. Danger Phoenix

    Soldato

    Joined: Jul 21, 2004

    Posts: 6,337

    Location: Bromley / Uxbridge

    I thought it was 28mm... most of the copper pipes are that size. Let me double check and get back to you.
     
  20. malfunkshun

    Soldato

    Joined: Aug 20, 2003

    Posts: 6,661

    Location: Pembrokeshire

    hoping it isn't 25mm MDPE into 28mm copper.