Electric hot water system not working: what to check first
Four faults cover most dead electric systems. Two you can rule out at the switchboard. The other two sit behind a cover you must not open.
An electric hot water system that has gone quiet is rarely a mystery. Most of the time the fault is one of four things: no power reaching the unit, a protective device that has tripped, a failed heating element. Or a thermostat that has stopped doing its job. Two of those you can check from the switchboard. The other two are licensed work.
The useful question is not "how do I fix it?" but "which of the four is this?". The answer decides whether you wait, reset something, or ring a plumber.
| What you notice | What it usually points to | Who deals with it |
|---|---|---|
| Stone cold, no sound, no warm pipes | No power: breaker, safety switch or a dead supply | You can check the switchboard |
| Breaker trips again as soon as you reset it | An electrical fault in the unit or its wiring | Licensed tradesperson |
| A short burst of hot water, then warm | A failed lower element | Licensed plumber or electrician |
| Warm from the first second, all day | Thermostat drift | Licensed plumber or electrician |
| Hot only at certain hours | Off-peak or timer control | You can read the setup, then ask your retailer |
Is the power actually reaching the unit?
Start at the switchboard. Find the circuit marked for hot water. It may be a separate breaker, and in some homes it sits on its own off-peak circuit.
Check that the breaker is on and that no safety switch (RCD) has dropped. If one has, switch it back on once. If it stays on and the water heats over the next few hours, you have a one-off trip, probably from a storm or a power flicker.
If it trips again, leave it off. A unit that trips a safety switch repeatedly is telling you there is a fault, and a wet enclosure with mains voltage inside is no place for guessing.
Is it on an off-peak or timer circuit?
Many electric systems in Australia heat only at set hours. That is deliberate, and it means "no hot water at 5pm" can be normal after a heavy morning. If you were away or changed retailer or meter, the schedule may have changed with it.
Read about how off-peak hot water works before you assume something has broken. A system that heats overnight and runs out by evening is a sizing or tariff question, not a fault.
A failed element looks like a short supply
An electric storage system heats with one or two elements. When the lower one fails, the upper one still heats the top of the tank. You get a few minutes of properly hot water, then warm, then tepid.
That pattern is worth reporting word for word. It points the plumber at the element before they arrive. The element replacement guide sets out what fails and who may replace it.
When the thermostat is the problem
A thermostat that has drifted stops heating too early. The water is warm at every tap, from the first draw of the morning, and it never gets better. If that is you, the lukewarm hot water guide separates a thermostat from a tempering valve in a few minutes.
Do not turn up a setting to compensate. Storage temperature is set to keep bacteria down in the tank, and delivery temperature is set to keep people from scalding.
Age is a fair suspect
If the unit is old, a repair may not be the smart spend. Elements, thermostats and the tank itself wear on the same schedule. Check how long hot water systems last before paying for a second repair on a tired tank.
The checks that are yours to make
- Look at the switchboard. Is the hot water breaker on, and has a safety switch dropped?
- Feel the pipes. Warm pipes above the unit mean it has been heating recently.
- Time the hot. Hot then warm and warm from the start are different faults.
- Check the schedule. Is the unit on off-peak or a timer, and did that change recently?
- Look for water. Any pooling around the base is a leak, not an electrical fault. See a leaking hot water system.
What to tell the plumber
Four facts save a second visit:
- Did the breaker or safety switch trip, and did it trip again after a reset?
- Hot then warm, or warm from the start?
- Is the unit on off-peak or a timer?
- How old is the unit, and has it been repaired before?
How far can you take this yourself?
Reading the switchboard and the schedule is yours. Everything inside the unit is not. Replacing an element, a thermostat or a cut-out, and any fix to the wiring, is licensed work. And your state or territory plumbing regulator is who licenses and inspects it. The licensed work pillar sets out where that line falls.
Frequently asked questions
Why has my electric hot water system stopped working?
Most dead electric systems come down to no power reaching the unit, a tripped breaker or safety switch, a failed heating element, or a drifting thermostat. Check the switchboard first. If the breaker is on and the water is still cold or only warm, the fault is inside the unit, and that is licensed work.
Can I reset my electric hot water system myself?
You can switch a tripped breaker or safety switch back on once at the switchboard. Do not open the cover on the unit to reach a reset button, because that is mains voltage in a wet enclosure. If the breaker trips again, leave it off and call a licensed tradesperson.
Why do I only get a few minutes of hot water from my electric system?
A short run of hot water followed by warm water usually points to a failed lower element. The upper element keeps heating only the top of the tank. A system that is too small for the household can look the same, so note how long the hot lasts before you call.
Could my electric hot water be on a timer or off-peak circuit?
Many Australian electric systems heat only at set hours. Running out in the evening can be normal after heavy use. Check whether your unit is on an off-peak circuit or a timer, and whether that changed after a move or a meter or retailer change.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- Australian Government, energy.gov.au. Hot water systems — types, installation and energy performance
- NSW Fair Trading. Plumbers, drainers and gasfitters — licensing