I have a MIRA Sport electric shower, the highest rating one they do (11.5kW?). It's fine.
The water pressure you can get in the loft will be as big a factor in whether or not it's any good i'd have thought.
I had a competitor's (almost) equivalent model and it wasn't as good, though was £100 less.

The water pressure you can get in the loft will be as big a factor in whether or not it's any good i'd have thought.

as I pointed out in my sums on the last page, supply pressure isn't much of an issue, as a 9kW shower can only make about 5L of hot water a minute. The design of the shower head may influence how that feels.

simon you are correct only if you are looking at flow rate in regards temp have you taken the ambiant cold wate temp ie winter +5ish and in summer +20 as this will make a big change in flow/temp rates,
Now water pressure is a big factor becouse of the pressure switch on an electric shower ie 8/9kw unit on averidge will need 14psi and 9.lts of water to activate the switch a 10kw unit will need 21psi and 11.lts to activate the pressue switch and these are running pressures not static so if you fit a no termostatic shower you temp will go up and down if the incoming pressure is not constant.

If your water pressure is high enough go electric

You're a discerning man, so get an Aqualisa power shower. They are to showers what B & Q are to hi-fi. No temperature fluctuations when mrs turns the tap on, constant flow of water, not dependant of height of water, loft layout or any of the other reasons why an electric shower doesn't work. They work first time, every time. Not cheap, but don't ever go near a MIRA one.

coffeeking – do you have an old boiler?

No, brand new (18 months ago).

And I've never heard of this time to heat up with an elec shower, of which you talk, the one at my parents (10kW) is at temp within 10 seconds. The only drawback I ever find with elec showers is the turned it off, missed a bit of soap, turn it on – AHHHHHHHHHH hotter than the surface of the sun! – moments!

I have never used an electric shower – even the latest most powerful ones that come anywhere close to the shower on my combi boiler.

If you have a combi I can see no reason for using an electric shower

I'm sure someone on here can work out the amount of energy needed to raise water from 4 deg C to say 38 deg C at the right flow rate (6 litres per min) and will tell you that even at 10,000 watts (joules per second) you can just never reach that flow. Electric = dribble.

C

34C * 6000ml * 4.2 J/cal / 60 sec = 14280 J/sec = 14.28 kW 🙂

I make it 5.6l/min at 38C from a 9kW shower and an inlet temp of 15C. Or 6.5l/min from a 10.5kW job.

I make it 5.6l/min at 38C from a 9kW shower and an inlet temp of 15C. Or 6.5l/min from a 10.5kW job.

yeah, well, ChrisE had a much lower input temp – possibly unrealistic unless it's coming from local surface water in midwinter 🙂

Re OP, can't bar the poss easier to fit/cheaper/can have shower if boiler packs up.

New leccy shower 10.5 kw thing in spare bedroom en suite earlier in year and now new combi fed shower in new bathroom downstairs.

Ok water pressure between upstairs/downstairs may have a part to play but the combi shower walks all over the leccy one, heats up as quickly, much more powerful and probably cheaper to run.

The leccy one is like being in a facsimilie of a shower, it looks like the real thing and does an ok job but sometimes only having the original copy will do.

With a mixer valve on a combi it is always recomended to fit 8.lt flow limiters to the hot/cold inlets so the combi can modulate correctly.Mains water hot stored systems like megaflows ect do not need to be resticted.

Mixer electric you choose what best fit your requirements a bit like broadband some want it mega fast others just want to connect to the outside world.

Mira or Triton you takes your pick no good rubbihing a product without first telling us the faults you had.

Biggest problem i get with electric showers are 1,incorrect water pressure 2,blocked showerhead 3,scaling of heater and the 4th people buying the wrong product and then trying to say it is faulty.

Yes they are more prone to breakdown but 8 out 10 service calls are due to a site condition

I have never heard of that showerman – 8l min limiter on a combi. My combi produces 20l / min