On Sat, 10 Mar 2018 14:08:41 -0800 (PST), Jon Parker
wrote:

So. I'm fed up with scale everywhere. I'm thinking water softener.

I don't want to faff about filling it with salt every 5 minutes.

Most Ion Exchange systems need filling about once a month.

It's there an idiots guide somewhere which explains the different systems?

Yes - Ion exchange water softeners work.
Phosphate dosing systems partially work - they reduce the problem of
pipes getting clogged but don't stop marks on taps, sinks etc.
Permanent magnet systems don't work in domestic environments.
"Electronic" ones such as the one you linked to do not work at all.

This one for example seems to good to be true. Which probably means it's total ********...

Correct.

https://www.easyh2o.co.uk/product/4-...em-rrp-239-105

Can anyone with a system installed comment please?

Some years ago during a very long running discussion of these devices
I cobbled together a test rig to measure the scale deposition in a
heated pipe. A kind Irishman who used to sell permanent magnet
systems donated a couple to try. An electronic one came from a
neighbour, a local plumber gave me phosphate dosing system and an Ion
Exchange system I already had.

Using tap water (hard around here) the results were as above. The
permanent magnet system actually worked a bit but only when the same
water was re circulated very many times through it (which is common in
industrial cooling systems where permanent magnets are sometimes found
but irrelevant for domestic use where water only passes once.)

The electronic system had no measurable effect at all whether the
water passed it once or many times.

The phosphate dosing system prevented scale build up on the test
pipe..

The Advertising Standards Agency say " The ASA understands that no
universally accepted theory about how these devices operate and no
evidence to support the contention that the devices can inhibit scale
formation generally exists."

https://www.asa.org.uk/advice-online...t-devices.html

http://www.chem1.com/CQ/magscams.html

and

https://www.csicop.org/si/show/magne...01/powell.html
are worth reading.