What is the off-peak or timer switch on my switchboard?

A controlled load is a separate circuit, usually on its own tariff, that is switched on and off at set times. In many Victorian homes the smart meter does the switching itself. In others you'll see one of these on or near the board: a time switch with a dial or digital display that turns the circuit on at set times, a relay that responds to a signal, or a contactor, a heavy-duty switch the timer or meter uses to carry the hot water's load.

Some boards also have a boost switch that bypasses the timer so the tank heats outside the off-peak hours. If yours is labelled, it's there to use, but switch it back afterwards, because boosting heats at your normal rate.

An off-peak tank heats only during its window, so it has to hold a full day's hot water. It runs short when the household now uses more than the tank holds, when the heating hours changed after a meter or tariff change, or when an older time switch lost time during a power cut and now heats at the wrong hours. A failed contactor or relay means the tank never heats, which can look like a dead element.

Faults in the tank itself, such as a failed element or thermostat, give the same symptom. If the tank is cold, the hot water breaker is on and a labelled boost switch doesn't help, the element, thermostat or switching needs testing.

If the switching happens in the smart meter, the hours are set on the network side, so ask your retailer about changes rather than looking at the board. A failed time switch, relay or contactor on the board is a repair for a licensed electrician. A heat pump usually does better heating in the warmer part of the day, so moving to one can mean changing the timer or tariff, which we look at when we connect it.