swiggers wrote:

Is this Magna booster a good idea - or a useless gimmick?

The second one, useless gimmick.

We live on the South Downs. The water is harder than in London. THe CH
system has been in place for 25 years with only a change in boiler to
get a more modern unit a few years ago. There's no sludge in the pipes
or radiators. I know because runs of pipework were taken to pieces for
checking when the new boiler was installed.

As others have said, the water in the CH system does not get changed,
hence there's no problem with limescale or sludge.

Ignore Drivel, he really is a drooling retard.