Electric showers - can we do any "better" than our old Mira Vie 9.5kw

[matticus]

Our Mira is 15 years old, and faulty. That's a good innings, in my view, so I'm happy to retire it, but I don't want to replace with something flashy-but-less-reliable.
Having said that, the pressure could be better in winter.

So I'd like more ooomph .. but are there fundamental limits with standard electric showers and british (cold) water supply?

 

[fossyant]

You'll have limits with your water pressure, but be careful going over 10KWh as your electric cable to the shower may not be enough. We had a 8.5kw that lasted probably 20 years, and only replaced it when we re-tiled the bathroom. I went to about 9.5kwh and a fancy looking one, much more compact. But the blimmin thing packed in after about 3 years (or lets say it was less waterproof than it should be), so switched to a Mira of a similar style. Do, however, hunt about on the web for prices, and also note where the cold supply enters the existing unit as you'll want one that has a similar entry - most will go bottom left or right these days.

I was annoyed at having to drill an additional hole in the tiles for the fitment, and 'patch' a drill hole from the previous unit. We chose as close as possible replacement.

The offending unit - looked great, but broke.

https://www.plumbworld.co.uk/triton...WfN0vuQZ_RChMHA3PO5qcdAZkTv4rJJMaAhbZEALw_wcB

Replaced with this, but no trouble, and less heat fiddling - just works.

https://www.plumbworld.co.uk/mira-decor-electric-shower-95kw-warm-silver-65-1274580

 

[lazybloke]

I ran a very chunky cooker cable from the distribution board to my shower as one of the first jobs after moving in 26 years ago. Pretty sure i have a 45 amp mcb, so my electricity meter is more like a gyroscope when anyone's washing.

My mains supply is over 250 volts, so in theory the shower can draw over 11kwatts.

It's still rubbish in a winter cold snap.
A hot tank, a pump and a thermostatic shower would be so much better.

 

[Alex321]

Our Mira is 15 years old, and faulty. That's a good innings, in my view, so I'm happy to retire it, but I don't want to replace with something flashy-but-less-reliable.
Having said that, the pressure could be better in winter.

So I'd like more ooomph .. but are there fundamental limits with standard electric showers and british (cold) water supply?

Yes. It isn't the pressure of the cold water supply that is the issue, but rather the wattage of the shower heater.

It should be on a 45A circuit breaker with 6mm wiring (similar to a cooker), but that gives you a max of 10.8kW power. Most showers will be a bit less than this, so your 9.5kW one is close to the maximum.

You can get them going up to the full 10.8kW though, which will be a little better.
If you like the Mira otherwise, this is one example https://www.screwfix.com/p/mira-spo...tric-shower/305PM?tc=EH6&gStoreCode=EH6&gQT=1

 

[fossyant]

Bear in mind, if you've a teenager/young adult that spends a stupid amount of time in the shower, keep it under the max wattage. I've had to change the wall mains switch to a heavy duty double pole unit as the previous one started to overheat with 'excessive' shower running.

 

[presta]

I had a 10.8kW Gainsborough shower which lasted for 25 years trouble-free until it went bang last January. I've just replaced it with another Gainsborough, which is fine so far. I went for a 10.8kW shower 25 years ago because that's the maximum you can get, and I was fed up with the hopeless 6kW one we had before.

https://www.gainsboroughshowers.co.uk/slim-duo-electric-shower-10.5kw-white
https://www.aqualisa.co.uk/media/amasty/amfile/attach/705928_Gainsborough-Installation-Guides.pdf



View: https://www.youtube.com/watch?v=SNcq9pzypRU

Having said that, the pressure could be better in winter.

So I'd like more ooomph .. but are there fundamental limits with standard electric showers and british (cold) water supply?

In winter the incoming mains water is colder, so you need a greater temperature rise to get the same shower temperature, and to do that without increasing the element power you have to slow the flow rate down. It's not a lack of pressure, it's that the knob marked as a 'heat' control is just a simple water tap to adjust flow rate like the one on your kitchen sink, so when you run the water slower the outlet gets hotter. If you want to be able to use a better flow rate without the water being colder your only option is a higher power, and 10.8kW is your limit.

It should be on a 45A circuit breaker with 6mm wiring (similar to a cooker), but that gives you a max of 10.8kW power. Most showers will be a bit less than this, so your 9.5kW one is close to the maximum.

For a 45A circuit you need 10mm cable:

 

[presta]

Some pix of the old one, you can see the smutty mark where the safety vent blew. An altogether more compact and better looking one than the new one IMV, but as long as it works and is reliable, that's OK.

 

[fossyant]

Our new shower units have been much more compact than the old one.

 

[matticus]

What an amazing set of answers - far better than when I ask about bikes.

(Isn't anyone going to suggest t*beless?!?)

 

[fossyant]

What an amazing set of answers - far better than when I ask about bikes.

(Isn't anyone going to suggest t*beless?!?)

Nah, you don't want that, you'll get gunk all over the bathroom.

Pretty sure our shower cable is 10mm - I checked before I replaced the unit.

 

[presta]

Our new shower units have been much more compact than the old one.

The reason my old one was smaller than the new one is that it wasn't designed to accommodate multiple cable & pipe entry points, which is what wastes all the space.

 

[Dogtrousers]

What an amazing set of answers - far better than when I ask about bikes.

(Isn't anyone going to suggest t*beless?!?)

What do you want a shower for? They're all just marketing fluff. Get a tin bath in front of the fire.