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Discuss Shower advice needed in the Bathrooms, Showers and Wetrooms area at

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  1. luke990

    luke990 New Member

    Our 8.5KW shower is on its way out and we are thinking of replacing it with a 10.8kw due to current one having such a poor flow rate when heated.

    How much of an improvement would we see by upgrading it to a 10.8kw? As we will need to have the cables changed we are weighing up the options of upgrading vs getting a power shower installed.

    The flow rates are as follows with 8.5kw: - Cold 8 liters per minute - Hot (ideal shower temp) 4.2 liters per minute

    Would the more powerful 10.8KW shower be able to knock out 7+ liters per minutes at a hot temperature or would it only be a small improvement on our current one?

    Also if anyone know roughly what we are looking at to have wiring upgraded from 6mm to 16mm would be great to know.

    Thanks in advance.
  2. Chuck

    Chuck Active Member

    It'll give you 27% more flow (5.3 litre per minute) under like-for-like conditions, i.e. raising the temperature of the incoming water by 29°C. If you aren't happy with your current shower (and it's working correctly) you're probably not going to be delighted by the new one.

    The cost of upgrading the wiring is a 'How long is a piece of string?' question depending on the state of your current system. Get an electrician to give you a couple of quotes.
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  3. JCplumb

    JCplumb Plumber

    You will see a difference between an 8.5 and a 10.8kw shower, a 10.8 should give you 7+litres/minute at lower temps, but will struggle at higher temps.
    The shower head is important too with electric showers, lots of big holes will be a dribble compared to fewer smaller holes. Some shower manufacturers will only honour the warranty if you only use the provided shower head too.
    Glad you're already aware that your wiring needs upgrading, no way to guess a price without specifics. How long is the run, is it in trunking, do floors need lifting etc.
    You'd need to get a sparky or two in for some quotes.
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  4. JCplumb

    JCplumb Plumber

    The following graph is from Mira.
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  5. luke990

    luke990 New Member

    Thanks for the replies that graph is exactly what i was looking for, I think I will be going the power shower route unless its much more expensive
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  6. JCplumb

    JCplumb Plumber

    If you are on anything other than a gravity hot water system then consider a thermostatic mixer shower.
    They run great on combis or unvented systems.
  7. Chuck

    Chuck Active Member

    Another positive thing about not using electric showers is that the energy cost of heating water with gas is roughly one sixth the cost of using electricity. Also, in my experience, electric showers aren't very reliable and need replacing every few years. A good quality mixer, I like Mira, should last a *lot* longer.
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  8. luke990

    luke990 New Member

    I like the idea of this, for years we have been getting burnt in the shower whenever someone uses water elsewhere in the house.
  9. moonlight

    moonlight Plumber GSR

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