I posted recently asking about "descalers" for combi boilers.

I spoke to my friend who has pretty much decided to get a "Fernox
Quantomat". From what I can see it's suitable for whole house use as
well as protecting the boiler.

What are the advantages to protecting the whole house instead of just
the boiler? Scale build up only occurs on the hot side so is there any
point protecting the cold water circuit?

Obvious disadvantages are that it'll cost more and the family will be
drinking water with phosphates in it.

(fwiw, he's never had any problems with appliances scaling up.)

Unless anyone can see an advantage to whole house protection I'll
recommend fitting it to the boiler only.

sponix