We have a new shower rose installed. When starting a shower we have to turn it onto full hot (we have a mixer), then move it slightly towards cold to get it about right. 1mm left or right it is too hot or cold. Because it is at the hot end, the water pressure is not great. Our water tank is in the ceiling and the shower is 2 floors down.

  • Welcome, Colin. You might revise a bit to ask an actual question. We can surmise that you'd like temperature control to work differently, but you should be specific.
    – isherwood
    Nov 20 '19 at 18:33
  • Where are you located? What type of shower valve do you have? And, you should probably take our tour so you'll know how best to participate here. Nov 20 '19 at 19:04
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    Is the water pressure both for hot and cold low, or does one affect the other? Are the pipe diameters coming into your bathroom the same size? Did you check any consumer reviews before purchasing your particular mixing valve? Nov 20 '19 at 19:05
  • diy.stackexchange.com/questions/175279/… is relevant
    – Phil G
    Nov 20 '19 at 20:13

The mixer needs to be replaced. I had the same issue a year and half ago! Find out the brand and get a compatible mixer- youtube instruction of you have not done this before but I will say its very straightforward. Remember to turn the water off!

  • This may be true, but the OP did say it's a new installation, in which case it should be returned as defective. Nov 21 '19 at 19:25
  • Probably not defective, just the wrong valve. Returning it will depend on who specified that particular valve..
    – SiHa
    Apr 20 '20 at 10:07

It sounds very much like your cold water pressure is significantly higher than your hot water pressure, and the mixer valve can't cope.

Presumably this is because the cold is at mains pressure (probably 2-4bar, or even greater), but the hot, coming from the header tank is at about 0.6bar (assuming 20ft height differential from tank to shower).

Most mixers require hot & cold to be at the same pressure. You need to either achieve this by running a cold-feed from the same header tank, or replace the mixer with a suitable type.

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