Heating repairs and power flushing

Check the switch is on and the circuit breaker hasn't tripped. If power is reaching it, the element or thermostat has probably failed. A failed element is common in hard-water areas, where limescale builds up and makes it overheat. Both parts can be replaced without replacing the cylinder.

Lifespan varies a lot with water hardness and use. In London and Hertfordshire, where water is hard, limescale on the element is the main reason they fail early. Setting the thermostat sensibly rather than at its maximum helps. Signs it's failing include slow heating and crackling noises.

Signs include radiators that are cold at the bottom, some radiators heating while others stay cold, a boiler that bangs or gurgles, and black water when you bleed a radiator. If bleeding and balancing the radiators doesn't help, sludge is the likely cause.

Most homes take most of a day, depending on how many radiators there are and how dirty the system is. The heating is off while we work. We flush each radiator in turn until the water runs clear, then refill the system with fresh water and corrosion inhibitor.