Electric Shower vs Mixer Shower

Discussion in 'Plumbers' Talk' started by Marcus Dare, Sep 11, 2017.

  1. Marcus Dare

    Marcus Dare New Member


    We currently have a Mira Isle 8.5kw electric shower. However we have just had all of our heating installed and now have a new Vaillant EcoTec Plus 32Kw Boiler.

    Current shower: https://www.mirashowers.co.uk/showers/electric-showers/mira-isle-85kw/

    I have had BAD experiences before with mixer showers that relied on the Boiler for it's hot water.

    However, because we have a really decent boiler now, do you think it's worth me ripping out the current electric shower and installing a new Mira Agile ERD mixer shower?

    New shower: https://www.mirashowers.co.uk/showers/mixer-showers/mira-agile-erd/

    Also, will a new Mixer shower still require an electric supply or is it totally mechanical?

    Last edited: Sep 11, 2017
  2. terrymac

    terrymac Active Member

    as you already have an electric shower I would keep it ,as when your boiler fails ( as they all do ) you will still be able to shower.
  3. Marcus Dare

    Marcus Dare New Member

    Hi, thanks for the reply. Yes we do worry about this. I might consider just upgrading the electric shower to 11kw. But then this seems wasteful when we have a 32kw gas boiler.
  4. Dr Bodgit

    Dr Bodgit Well-Known Member

    I'm not a fan of combi boilers. You will see an improvement with a 32KW combi over the 8.5KW electric, I don't know how much of the 32Kw is available to heat hot water though and its still a combi so performance won't be as a good as with an indirect system. I'd first want to establish how much (i.e. flow rate) hot water is available at 60 degrees in the winter when mains water is at its coldest. You also have issues if some other demand for hot water kicks in when having a shower. And as terrymac notes, you currently have redundancy.

    Most mixers are purely mechanical although some mixers have an integral pump which obviously requires power.
  5. Devil's Advocate

    Devil's Advocate Well-Known Member

    Hi Marcus.

    You are going to end up more confused after reading this thread :). 'Cos I'm going to say the exact opposite of that above.

    A 32kW combi will use all that power - if needed - for the DHW (it usually runs at a lot less than this for the CH, but in any case it will 'modulate' (adjust) it's output to suit demand). And 32kW will give you an EXCELLENT shower.

    My combi is a 30kW GlowWorm, and that provides a powerful shower akin to a 'power' shower - I usually have to turn the flow on the shower down a bit 'cos full-on is far more than I want (until I rinse off with a full blast...(with apologies for the inevitable involuntary visualisation))

    PROS: Superb shower experience. Instant and constant hot water. Cheaper energy supply from gas, tho' obvious'y you'll be using more of it with a powerful combi over a piddly leccy.

    CONS: Yes, if the combi goes faulty you won't have a shower. But I wouldn't consider that a factor for a nano-second - they rarely go wrong and are usually fixed very quickly; that should not be a consideration imo. Yes, someone turning on another tap/flushing a loo can affect it's performance or temp. But, again in practice, a thermostatic shower (like the one you linked to) should cope with that and prevent freezing/scalding. And in any case, the times this happens is rare. My shower mixer - although 'thermostatic' - has never worked properly at this, so I have had to odd 'ouch' and 'brrrr' occur, but it's surprising how rare this is - and this is in a house with 2 teenagers.

    You have a cracking new boiler - if you love your showers, there is only ONE way this decision should go. :)

    (I've just bought - but not yet fitted - an Aqualisa themo shower mixer to replace my current dodgy one. This one is supposedly designed specifically for modulating combi boilers, but no idea what difference it'll make. It's ugly, tho' - now't like the one you're thinking off :))

    PS. Yes, they are all fully mechanical in operation. The only exception is if it is 'digital' and has remote controls.
    Last edited: Sep 11, 2017
    Marcus Dare and Dr Bodgit like this.
  6. Dr Bodgit

    Dr Bodgit Well-Known Member

    Good advice there by DA. Seeing as though he actually has experience of combi boilers & showers I'd take his advice over my scare mongering.
    Marcus Dare likes this.
  7. Marcus Dare

    Marcus Dare New Member

    Hi DA,

    Thank You for your very long and very informative response. Yes this has definately cleared up matters and so i will installed a new mixer shower at some point in the near future. Yes you are correct our boiler bangs out the 32KW on DHW and around 18KW for the CH.

    Our boiler kicks out a stable 13 litres per min of hot water even at 50-60c, so yes this sounds a lot better than our current electric shower which has a much lower flow rate when the temp is high (around 50c).

    I've managed to find the Mira Agile ERD shower online Brand New for half the RRP price, so it seems worth it i think.

    Yes a nice powerful shower is what we require, so this seems like the right option.

    And thanks, i will be happy to remove the current 10mm 45A electric cable from behind the tiles as i dont like the idea of having a high power electric cable in the bathroom.

  8. diy_nixy

    diy_nixy Member

    Get rid of the electric shower....they are awful and costly to run. Poor shower experience...even worse in winter.
    Dont worry about Combi boilers breaking down, its very rare. I had a very old Vailant boiler. It never broke down in 10 years. Its now very old so I replaced it anyway with a new Vailant 42kW combi. Fab shower.

    Replace your electric with a thermostatic bar mixer shower. They can go faulty but easy to replace. Just screw off the old one and replace with a new one. You can replace yourself for around £60. Don't fit a completely concealed shower valve inside the wall. They are hard to replace when faulty and expensive plumbers bills.

    The Mira Agile you mentioned above is a bar-shower. A good thing. However the fixed-head is very big at the top and will probably need a large-flow rate. It will probably behave more like a drip with a 32kW Combi. Its also expensive at £480.

    My opinion...No need to buy an expensive shower. They all deliver hot water the same. Its more about the shower head you use and matching this with the correct flow rate. A large shower head with large pin holes will cause a poor shower experience (like a dribble). I recommend this Mira Response shower head with a 32kW Combi


    Then buy any mixer-bar shower of your choice.

    (Keep the shower head from your old electric shower, they often work well with Combi boilers as they are designed for low flow rate electric showers. Having smaller pin holes can give a better shower experience - more stronger jets). I've often found it difficult to get shower heads over the years to match lower flow rates.
    Marcus Dare likes this.
  9. jonathanc

    jonathanc Active Member

    why not keep the electric but drop in a ceiling fed digital mixer off the boiler? best of both worlds then?
    Marcus Dare likes this.
  10. Marcus Dare

    Marcus Dare New Member


    Thanks for your reply. I've managed to find that Mira Agile online Brand New for £260, which is a bit better!!,

    Our combi is brand new and has extended Vaillant installer warranty to 10 years, so fingers crossed it should be ok!!

    Also, my combi can provide 13 litres a min at 60c, and my cold supply is more like 20 litres a min, so if the shower was mixing at say 45c, i would hope that the flow rate would be 15+ litres per min.

    IF it was 15 litres a min, would that be enough to power the big shower head on the Mira Agile?

    Good idea though to keep the current fine nozzle shower head from the electric.

    Yes those bar showers do seem easier to replace, also good idea.

    And i wouldn't mind getting a shower with a digital thermostat, however the 10mm 45A cable will be seriously overkill for that and it would only need a 2.5mm 32A cable or even less.

    Devil's Advocate likes this.
  11. Marcus Dare

    Marcus Dare New Member

    True, this could indeed be done. However the current 10mm cable on an independent 45A circuit is seriously overkill for powering a simple thermostat and no heater! I would need to downgrade the cable to 2.5mm or atleast downgrade the MCB at the Consumer Unit to 32A or even 20A, but keep the REALLY overkill cable lol.
  12. The Teach

    The Teach Active Member

    Is the shower to be fitted over a bath or fitted in a shower enclosure ?.

    That mira will give a good powerfull flow via the hand held shower head,the round rain fall shower gives a more gentle shower experience where the water fall is column like.Still ok thou.
  13. diy_nixy

    diy_nixy Member

    I very much doubt your 32kW combi will be able to supply the large shower head on the Mira Agile.

    My cold water supply is 20 litres/min. I have the latest and greatest Vaillant 42kW combi installed two months ago. This gives me 15-litres/min hot supply set at 65-degC on the settings at the boiler stat. I still have to be careful on my choice of shower head. It still can't supply all the nozzles on my Mira Response shower head, which is a general use shower head for most systems. I have to turn the spray pattern so it uses less nozzles on the head to get a reasonable shower experience.

    I expect you would need a pressurised water tank to supply your large shower head. These have massive flow and pressure. My parents have a pressurised tank and its worlds apart from a combi hot water supply. The magnitude of pressure is so big I have to turn down the flow rate at the shower valve otherwise its painful hard jets.

    Just get a mixer shower with a standard sized shower head. And try to make sure the supplied head is not too big. They always seem to be designed for high flow rates. Ideally the heads with plastic pin holes rather than rubber nozzles so you can see the dimensions of the pin holes. I have rarely seen manufacturers state the ideal flow rate for their shower heads. They just write "suitable for all systems" which isn't very useful.
    Marcus Dare likes this.
  14. The Teach

    The Teach Active Member

    iirc these set's are factory designed to deliver water flow of 12 lpm but this can be increased to the available flow rate by simply removing the flow limiter.

    Marcus Dare you can contact Mira technical via their message service or phone.
    Marcus Dare and Devil's Advocate like this.
  15. jonathanc

    jonathanc Active Member

    i think you'd need to keep the supply as is if you keep the electric shower. a seperate digital shower can be fed off an rcd protected 3A supply.

    i have an electric shower as backup but the cubicle also has a combi boiler fed ceiling digital shower - which is what is normally used. electric is there for backup only
  16. Devil's Advocate

    Devil's Advocate Well-Known Member

    If you are DIYing this install, then lose the leccy supply - completely.

    'Digital' is nice on paper, but in reality is an further unnecessary complication. Your call - but I personally wouldn't bother with digital control.

    I have to say I disagree with Dixy, and agree with you, Marcus - your boiler will give a superb flow, and is a mix of hot and cold, so potentially greater than what just the boiler is capable of delivering. I am as sure as a sure thing that your 'rain head' will cascade down on you a'plenty.

    My current shower has a 'Victorian' style handset, so quite large holes - far larger than that on a leccy shower. It honestly fires out at a 'powershower' rate, and I rarely have it on max flow as it can bounce off me 'ead and go over the cubicle.

    If you have any doubts, ask Mira as T'Teach says.
    Marcus Dare likes this.
  17. Marcus Dare

    Marcus Dare New Member

    Hello Everyone,

    Thanks for all of your helpful replies.

    I found this guide to mixer showers by MIRA:


    It's interesting to know that Mira have a limiter on the flow rate of their showers that can be adjusted, I had no idea about this and would definately seek to get the flow rate increased, so i will contact Mira.

    Yes thanks, i personally don't have my showers that hot, so if the water was set to 40c, i would hope that the flow rate would be somewhere between 13 and 20 litres per minute.

    Yeah i agree that there probably isn't any major benefit to an electric thermostat apart from MAYBE keeping the temp even when someone flushed the toilet etc.

    If i did keep the electric, i would keep the same heavy 10mm cable, but reduce the fuse in the Bathroom Isolation Switch down to 3A and reduce the Shower circuit MCB at the CU down to 3A.

    I don't mind the big showerhead over the top being medium pressure, as long as there is High pressure on the smaller hand held shower.


Share This Page