Your boiler is providing central heating for your radiators as normal, but is failing to heat your hot water tank or taps.

No HW But CH Ok

What causes this fault?

This fault occurs when the boiler's internal components or external controls fail to signal that the hot water needs heating, even though the central heating for your radiators is working fine. The most common reason is a faulty motor or sensor that prevents the heat from being diverted away from the radiators and toward your hot water cylinder.