Scale blockage

Reduced or intermittent flow caused by calcium carbonate (limescale) building up inside the boiler, pipes, or solenoid valve.

Why it matters — Scale doesn't just block — it insulates, reducing heating efficiency, slowing response, and eventually damaging elements. In hard water areas, untreated machines fail in years rather than decades.

Good to know

• Prevention is far cheaper than cure. Good water filtration (BWT bestmax class, or equivalent ion-exchange filter) means you'll likely never need to descale.
• If you must descale, follow the manufacturer's exact protocol. Aggressive citric acid solutions can damage boiler seals and copper components.