On Wed, 31 Mar 2021 18:51:00 +0100, Jeff Layman
wrote:

snip

I got one of those (3Kw) put in our garage after I found the Ariston
under-sink heater left by the previous owner tripped the RCD when I
switched it on.

;-(

It's worked well for 8 years, although in winter when the water feeding
it is very cold, it needs to be on full, and even then the flow is
fairly low.

That's good to learn (for our potential use) as it will be indoors.

It's quite sufficient, though, for washing hands after a
messy job, and the spray head actually helps shift the grime.

Yes, I was thinking that might be the case. My circulating de-greasing
tank works better because of the constant flow washing the debris
away.

We are in
a hard/very hard water area (Ca CO3 level is 281mg/litre), as it comes
from a chalk aquifer under the Downs.

Very posh. ;-)

I've used descaler now and again
on the spray head, but never on the heater itself.

No. We have had a Triton T80 shower for maybe 30 years now and I don't
think I've ever de scaled the guts of that (but have done the
nozzle(s) a good few times). [1]

I find leaving anything like that to soak in a container of suitably
diluted 'Green stuff' moves the calcium very well.

Cheers, T i m

[1] I was there when the guy did some plumbing mods round Mums ex cold
fired, gravity CH/HW system and none of the pipes showed any real
level of furring.