If your heating is working but you have no hot water, or your hot water is intermittent, the cause is usually a specific component fault rather than a complete boiler failure. This guide explains the most common causes and helps you decide whether a repair or replacement is the right next step.
The most frequent culprits include a faulty diverter valve (on combi boilers), a broken motorised valve, a failed hot water thermostat or cylinder thermostat, low boiler pressure, or an airlock in the system. Some of these are inexpensive to repair; others — particularly on older boilers — may signal the end of the unit's reliable life.
If the fault is a diverter valve on a boiler that's already 10+ years old, or if this is one of several recent faults, replacement often makes more financial sense than repair. A new boiler gives you years of reliable hot water and heating with a fresh manufacturer's warranty.
From your first message to a working boiler — here's what to expect.
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