Note there is *no* requirement for softening - only scale
inhibiting. Any phosphate dosing system will do that at
much lower cost. (and no doubt the various interested
groups will wangle their electronic / magnetic / magic
rock placebos in there as well



True (as ever). And one or two of the boilers I've looked
at do have an option to fit just such a system.

What surprised me was that the stuff I've looked at for
(among others) Worcester and Vaillant boilers still just say
in both user and technical literature (to take one example):
"The temperature in the domestic hot water heat exchanger is
limited by the boiler control system and it is not necessary
to install a scale reducer on the cold mains to the boiler.
However, in areas that get exceptionally hard water, a scale
reducer may be fitted to prevent scale formation in the hot
water system pipes."

I find that hard to reconcile with the scale of water
supplies at 200+ ppm according to
http://www.dwi.gov.uk/consumer/faq/hardness.htm But perhaps
the manufacturers haven't bothered to change their
literature - after all, it might be a good way for them to
get out of a warranty claim.

--
Robin