In article ,
stuart noble writes:
I'm on my second electric shower in 25 years, and the first one didn't
fail due to scale, despite being in a moderately hard water area. Seems
odd that a market leading shower can't cope with hard water

It will depend on the surface area of the heater.
Heating water up to showering temperature doesn't cause any build-up
of scale. The problem will arise if the heater surface area is small
such that it heats a small proportion of the water up much hotter
(60C) to be mixed later in the flow with cold water which missed
the element. That will cause the element to scale up. So it all
depends on the design of the heater.

--
Andrew Gabriel
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