In hard-water regions – true for much of Switzerland – limescale builds up especially fast. On the heating element it acts like an insulating layer: the boiler takes longer and uses more electricity to heat the water. Lime sludge also collects on the tank floor, reducing the usable volume and potentially promoting corrosion. Regular descaling therefore lowers electricity use and noticeably extends the appliance's life.
During the service the boiler is first disconnected from power and drained. The plumber opens the service flange, where the heating element and protective anode usually sit, removes the lime sludge mechanically from the tank, cleans or replaces the heating element and checks the magnesium sacrificial anode. This anode protects the steel tank from rust and is itself a wear part – if largely consumed, it is replaced. Finally the flange is closed with a new gasket, the boiler is filled, vented and checked for tightness.
How often to descale depends on water hardness and the set temperature. As a rule of thumb, a service every three to five years is advisable; with very hard water, more often. The protective anode should be checked at the same time – many firms combine both in one service visit. The job takes about one to three hours depending on boiler size and scaling.
As a guide, descaling a boiler including an anode check costs around CHF 200 to 450, depending on boiler size, accessibility and material for the gasket and any anode replacement (no guarantee). That is far cheaper than a boiler destroyed prematurely by scaling, whose replacement quickly costs several thousand francs.
What to watch for: the service belongs in professional hands because the tank is under pressure and the anode must be assessed correctly. If the protective anode is neglected, the tank rusts through – the most common reason for a total loss. A well-maintained boiler works more efficiently and often lasts 15 years or more.