Plumbing advice · Boilers & Heating
Water Heater Not Working? A Repair Guide
Immersions, multipoints and wall heaters fail in predictable ways.
Immersion heaters
A dead immersion is usually the element or the thermostat, both inexpensive parts. Scalding-then-cold water means the stat; simply cold means the element or its fuse. In hard water areas elements rarely die of old age, they die of scale.
Instantaneous and multipoint heaters
No hot water at one outlet but fine elsewhere points at the heater itself: scaled heat exchanger, failed diaphragm or a flow rate below the unit's switch-on threshold. Units under eight years old usually earn a repair.
When replacement wins
If the repair costs more than a third of a new unit, or the model is obsolete and parts are hunted rather than stocked, replace. We quote both numbers and let the arithmetic decide.
Need it done instead?