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Discuss Water tank too small?? in the Bathrooms, Showers and Wetrooms area at UKPlumbersForums.co.uk.

  1. Kim Wong

    Kim Wong New Member

    Hi All,
    I have just had a bathroom refit with new Mira overhead and handheld shower (Mira Agile ERD by Mira Showers) fitted in place of the old power shower. The pump was kept the same. I now have the problem where I can have a lovely warm powerful shower but only for 5 minutes then the water goes cold. If I put the hot water 'boost' on whilst showering the water will stay hot after the 5 minutes but the pressure drops.
    My bathroom fitter suggested that the hot water tank was too small and was draining quickly due to the power of the new shower. Does this seem likely and what are my options apart from replacing with a bigger tank? I have only electricity in the house, no gas.
    Thanks
     
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    What size tank do you have / if you can put a pic up of the tank / cylinder
     
  3. Kim Wong

    Kim Wong New Member

    I can post a pic later but it is about 3ft tall if that helps?
     
  4. fixitflav

    fixitflav Active Member

    It might be worth checking the supply to the cold water tank - manual valves, ball float valve etc. If it's restricted so the feed can't keep up with the shower flow the flow will fall. But I'd expect in that case the pump would draw in air and you'd notice it coming out of the shower head. How big is the cold water tank? A bigger one would help.
    It must be a hefty shower if it uses all the hot water in 5 minutes. Doesn't the control allow you to turn the flow down? That may be all you need to do,
     
  5. bacon_sandwich

    bacon_sandwich GSR

    worth noting where the take off for the shower is on the tank, they can be 3/4 up which can reduce capacity of hot water, i assume there is an immersion heater somewhere, you could try and increase the thermostat a little, which is located at the head end of the immersion. This may give you a few more minutes
     
    • Disagree Disagree x 1
  6. chris watkins

    chris watkins Plumber

    How long a shower was you getting with the pump on the old shower?
    As soon as the shower goes cold after the 5mins turn it off & check the top hot outlet pipe on the cylinder & /or run a hot tap to see if the there is still hot water in the tank.
    have you 1 or 2 immersions in the cylinder?
    Seems more likely it is cold back feeding into the hot (maybe they different fit the check valves) or its air on the hot side.
     
  7. chris watkins

    chris watkins Plumber

    BMA label seems to suggest it is limited to 12L/M which means you would using approximately 7.2L/M hot X 5mins showering = 36Litres @ approx 60degC (likely to be less this time of the year).
    On the other hand it does claim to give up to 3 times better flow.
    What happens if you just shower with the hand set or slow the flow rate right down?
     
  8. Ric2013

    Ric2013 Plumber

    Easy question. Once the shower has run cold, is the top of the hot water cylinder and the pipe coming out of the middle of the top warm or cold? And do you have hot water at taps?
     
    • Agree Agree x 1
  9. Kim Wong

    Kim Wong New Member

    Thanks for all your replies, so I have just run the shower till cold and the pipe on the top of the tank is cold and there is no hot water coming out of the bathroom or kitchen taps.
    If I use the overhead shower the hot water runs out faster (a minute or so) than the hand held head. I have attached some photos.

    20180803_194506.jpg

    20180803_194458.jpg

    20180803_194502.jpg
     
  10. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Wrong cylinder installed for just electric heating

    Immersion will only heat the top 1/3 of the cylinder

    Also pump is installed wrong / incorrectly
     
    • Like Like x 1
    • Agree Agree x 1
  11. Ric2013

    Ric2013 Plumber

    Also depends on the length of the immersion heater in use. A 27" one will still give more hot water capacity than an 11" one, so if that cylinder has an 11" immersion fitted, a longer immersion heater would be a cheap upgrade, evn if you'll still not get quite a full tank of hot water.

    Agree with Shaun that pump installation is poor in nearly all respects, but it is probably not the main cause of your problem.
     
    • Like Like x 1
  12. Kim Wong

    Kim Wong New Member

    Oh wow ok thanks for the diagnosis. Ill get a plumber in to have a look and hopefully fix the problem asap, cant be having cold showers when winter comes!
     
  13. Ric2013

    Ric2013 Plumber

    Yes, a good idea. Preferably not the same person that installed the pump.
     
    • Agree Agree x 4
    • Like Like x 1
  14. chris watkins

    chris watkins Plumber

    Why not go un-vented ? i.e. off of the mains then you can loose the pump.
     
  15. Kim Wong

    Kim Wong New Member

    Will I still get a good flowrate with an unvented tank?
     
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