Heating problems can be linked to various complications: The power supply from the DB board may be compromised with a faulty breaker switch, preventing power from reaching the geyser.  The isolation switch could be faulty preventing power from reaching the geyser.  The element could be faulty and cause the breaker on the DB board to trip, indicating a compromised element resulting in no hot water. The thermostat could have an electrical fault causing a disconnect of power to the element.