No hot water: do you need an electrician or a plumber?

It depends on what kind of unit you have, and the dividing line is cleaner than most people expect.

• Electric storage tank, no hot water at all. Usually electrical. Element, thermostat, a tripped breaker, or the off-peak supply not switching. Electrician.
• Gas, no hot water. Ignition, pilot or gas supply. Plumber (gas-fitting licensed).
• Water on the floor, a dripping relief valve, or no water pressure. Plumber, whatever the unit runs on.
• Heat pump or solar hot water. Could be either. Start with the manufacturer or installer — these have controllers and boosters that are their own specialty.
• Lukewarm rather than cold, or hot water that runs out much faster than it used to. On an electric tank that is the classic signature of one of two elements having failed. Electrician.

We do the electrical side. If it turns out to be a leaking tank or a gas fault we will tell you that on the phone rather than charge you to come and say it.

These take five minutes, cost nothing, and regularly save a call-out fee.

1. Look at the switchboard. Find the breaker labelled hot water, water heater, or HWS. Is it off or mid-position? If it has tripped, that is information: something caused it. You can reset it once. If it trips again, stop and call — a failed element commonly takes the circuit out with it.
2. Check the safety switch. On many boards the hot water sits under an RCD shared with other circuits. If that RCD has tripped, everything under it is dead, and a cold shower may be the first thing you notice.
3. Check the isolator near the unit. There is usually a switch on the wall beside the tank or in a nearby weatherproof enclosure. They get knocked off during other work far more often than you'd think — after a renovation, a service call, or a tidy-up in the garage.
4. Work out whether it is on a controlled load. This is the one nobody checks, and it explains more "faults" than anything else on the list.

A lot of NSW electric hot water runs on a controlled load — the old off-peak tariffs, still widely used. Your retailer sells the energy at a much lower rate, and in exchange the network decides when the tank is allowed to heat, usually overnight.

That arrangement works quietly for years, and then produces a very specific symptom: plenty of hot water in the evening, none by morning, or none for a few days after unusually heavy use. Nothing has broken. The tank simply ran out and is not permitted to reheat until tonight.

Three things commonly go wrong with it:

• The switching isn't happening. The meter or the contactor that energises the circuit overnight has failed, so the tank never heats at all. Looks identical to a dead element from inside the house.
• The household outgrew the tariff. Controlled Load 1 heats for a shorter window than Controlled Load 2. A tank sized for two people on CL1 will not keep up with a family of five and two teenagers, and no repair fixes that — it is a tariff or tank-size question.
• A meter change or solar install moved the circuit and it was never put back on the controlled load properly.

If you have had no hot water since a meter upgrade, a solar installation or a switchboard change, start there. It is the most likely explanation by a wide margin.

On an electric storage tank, two components do nearly all the failing.

The element heats the water. When it fails you get cold water, and often a tripped breaker or safety switch at the same time — a failed element frequently leaks to earth as it goes. Larger tanks have two elements; when only the lower one fails you get a much smaller amount of hot water than usual rather than none, which is why "the hot water runs out after one shower now" is a diagnosis in itself.

The thermostat decides when to stop. A failed thermostat gives you cold water, or water that is dangerously hot, or a tank that cycles constantly and costs a fortune to run.

Both are electrical components and both are routine to replace — the job is usually a fraction of the cost of a new unit. What matters is knowing which it is before anyone starts quoting you a replacement tank.

Worth knowing when to stop spending. Most electric storage tanks last 10–15 years. If yours is at that age and the element has just gone, replacing the element can be good value or it can be money spent on a unit that will leak within a year. The tank's age is on the compliance plate, and it should be part of the conversation.