Have an old electric shower - at least 10 years. No idea of its power
rating but it's always worked well enough in the summer - didn't use
it in the winter as it couldn't get the water up to a decent temp.
Anyways - having aquired a significant other, suddenly it's getting
maoned about. First question is - is it worth replacing - in the last
10 years have electric showers got better. Second question - how easy
is it likely to be to replace - the pipe into the existing shower
seems to be the same width as all the other pipes in the house and
I've done odd bits and pieces on them over the years with 'standard'
fittings - the electric cable comes in via an external switch to
isolate it. Could I resonably expect a new show to fit where the old
one was without a lot of trouble?
Finally - any particular recomendations - guess I''ll get a 9.5kw
version - but all these showers come with a range of whistles and
bells and huge range of prices - what whistles and bells are worth
having and what r just a waste of money??
The (considerable) energy required to raise a given volume of water through
a given number of degrees hasn't changed ;-) And this is the basic limit
for electric showers. What mfrs seem to have done is to introduce
increasingly beefy elements to get more energy into the water - so, 10
years ago ratings of 7.2kW - a 30A supply - seemed to be common; now you
see showers around the 10kW mark (40A and more needed) quite commonly.
As I'm sure you'll appreciate, you can't just fix up a higher-power
shower and blithely re-use the existing wiring; it's unlikely (though
not impossible) that what was installed has an extra 40% safe current
carrying capacity. Putting in a new cable run (maybe in 10mmsq to replace
an existing 6mmsq) will vary in PITA factor from minor to huge depending
on your particular house layout. The water supply is unlikely to be a
problem - I don't think there's any set standard on where the units
expect their cold water connection, but getting the supply to the new
unit isn't going to need more than a couple of new bits of pipe and
joints at the outside.
The other thing the mfrs seem to have done is to improve the controls
in both useful and less obviously useful ways. Elementary control
theory seems more often applied in current designs, so they seem to
compensate better for changes in the supply pressure and temperature
(as you use up the ambiently-heated water which had been sitting in
the pipes and onto the colder stuff waiting underground, for example).
And if you and your SO have differing ideas over the "right" temperature,
electronic controls (or even, Gawd help us, multiple preset memories!)
can keep tempers smoother than crude mechanical adjustments or the
simplistic "1, 2, 3" power-input-only controls found on earlier models.
I'll leave recommendations on particular models to others, but will
watch with interest - one of our 'lectric showers is out of commission,
and the round tuits to replace with another are closer to hand than
waiting for the new-boiler-convert-DHW-to-mains-fed-and-get-custom-
tank-with-spare-heat-exchanger-for-solar-gain-heating-too which lurks
in the back of the Zabic conciousness...
They are better, but probably won't be a straight swap, unless it happened
to be wired in 10mm cable, which is unlikely for a 10 year old one. Most
showers from this period use 6mm cable, which probably won't do for a
typical modern shower.
However, if there are bath taps nearby, it would be far superior to install
a power shower instead. These use the hot and cold supplies and pump them to
give much better water flow. They don't attempt to heat the water
themselves. Exactly what form of shower and repiping is required will depend
on your current water supplies and whether they are mains or gravity etc.
The flow rate of such a shower will be many times that of a puny electric
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