Bill is right: new bolier Potterton Suprima HE fitted 3 yrs ago to old system (old radiators). System was power flushed at the time. When asked to service boiler just now, plumber recommended expensive power flush again, saying sludge would damage bolier otherwise. I thought MAgna Clean Filter was just to prevent that. What to do??
In my opinion power flushing is one big rip off.As most of the gunge is actually in the radiators,it will be cheaper to buy new ones and so easy to fit.after fitting and refilling ,top up with a rust inhibiter and you'll have no trouble with sludge for years.
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