Electric Hot Water Not Heating? The 5 Real Causes, and When a Heat Pump Makes Sense

Byron Knight, Licensed Electrical Contractor

QLD Lic. 1511406 · 20+ years’ experience · Gold Coast & SEQ · Updated September 2026

Search “electric hot water not heating” and nearly every result is written by a plumber. That isn’t wrong — plumbers install and service hot water systems every day. But roughly half of what actually goes wrong inside an electric storage tank is electrical work, and most guides blur that line without saying so.

Here’s the version written from the other side of it: the five real causes, which are genuinely ours versus a plumber’s, and what the heat pump conversation looks like once you’re past the repair stage.

Why “call a plumber” isn’t always the right first move

An electric storage system is a tank, a thermostat and one or two heating elements, all wired back to your switchboard. The tank, the pipework, the pressure relief valve and the tempering valve are plumbing. The wiring, the elements, the thermostat and the circuit protecting all of it are electrical.

In Queensland, replacing a heating element or thermostat is licensed electrical work — performed by a licensed electrician or an appropriately licensed plumber, but electrical work either way, governed by the same Electrical Safety Act 2002 that covers every other circuit in the house. Knowing which side your fault sits on gets the right licensed trade to your door the first time.

The 5 real causes

1. A tripped breaker or safety switch

The most common cause of “no hot water at all”. The safe check-and-reset sequence:

1. Find it. At the switchboard, look for a breaker sitting in the middle position, or a safety switch flipped down.
2. Reset it properly. Push it fully off, then back on.
3. Wait an hour. Elements take time to bring a full tank up to temperature, so test again before concluding anything.
4. Stop if it trips again. A breaker that won’t hold is telling you the fault is still live. Don’t keep resetting it.

2. A failed heating element

Most Australian electric storage tanks run two elements — an upper one for fast top-up heating and a lower one doing the bulk of the work. One failed element usually means a noticeably shorter supply before it runs cold. Both failed means nothing at all. Elements have a finite service life, and coastal conditions on the Gold Coast tend to shorten it through accelerated corrosion.

3. A faulty thermostat or high-limit cutoff

Every electric system has a working thermostat and, separately, a high-limit safety switch that cuts power if the water overheats. If that cutoff has tripped it’s usually behind the same access panel as the thermostat — and if it keeps tripping after a reset, the thermostat itself has likely failed and needs replacing rather than resetting.

4. A loose or damaged electrical connection

Less discussed than the first two and genuinely more serious. A loose terminal inside the switchboard circuit or at the element generates heat at the connection point — the same failure mode behind a switchboard that keeps tripping and a board that buzzes. If you notice water pooling near the base of the tank, or smell anything burning near the access panel, switch the circuit off at the switchboard and call immediately. Water reaching an electrical compartment is a genuine shock and fire risk.

5. A plumbing-side fault

In fairness to the plumbers who’ve written the rest of the internet’s hot water content: this one is real and it isn’t ours. A stuck tempering valve blends too much cold water into the outlet even when the tank is heating correctly, producing exactly the same lukewarm symptom as a failing element. Sediment build-up can also reduce efficiency over time. If we test your elements and thermostat and find them working, that’s where we point you to a licensed plumber rather than guess.

What’s safe to check yourself — and what isn’t

The electrical side is covered by our hot water system electrical repairs and checks. Here’s where the line falls.

You can safely check and reset a tripped breaker or safety switch at the switchboard. That’s it. You cannot legally remove an access panel, test an element with a multimeter, or touch any wiring inside the unit — in Queensland that’s licensed electrical work with no DIY exemption, the same principle set out in what you can and can’t legally do yourself.

Element and thermostat testing genuinely is simple for a licensed electrician with the right equipment. But “simple for a professional” and “safe to DIY” are different things when water and 230 V share a compartment.

When repair stops making sense

Not every fault means a new system. As a general rule: if the tank is under 8–10 years old and the fault is a straightforward element, thermostat or connection repair, fixing it is almost always the better investment. Once a system is past that age and showing repeated or multiple faults, or the repair starts approaching a meaningful fraction of replacement, that’s the point where conversion starts to make more sense than patching it again.

Heat pump conversion: what actually changes

A heat pump doesn’t generate heat directly the way a resistive element does. It draws warmth from the surrounding air and moves it into the tank, using a fraction of the electricity an element needs for the same result. That efficiency difference is the entire economic case, and it’s why hot water is usually the first thing we look at when someone asks why their power bill is so high.

The electrical side of a conversion

Most integrated heat pumps arrive factory-sealed on the refrigerant side, so the job splits cleanly between plumbing and electrical. The electrical side is where it quietly goes wrong if it isn’t assessed beforehand.

1. Switchboard capacity. A heat pump draws less than a resistive element but is still a meaningful continuous load. The same assessment we run before an EV charger install applies, and an older board near its limit may need attention regardless of which appliance triggered the check — see what drives a switchboard upgrade.
2. A dedicated, correctly rated circuit, with its own breaker and RCD protection sized to the unit.
3. Off-peak or controlled-load wiring. Connecting a hot water system to a controlled tariff is an electrical decision made at the switchboard, not something wired in with the pipework.
4. Isolation and certification. A proper isolator at the unit, and a certificate of testing and compliance on completion — the certificate that covers installation work in Queensland.

We handle the electrical connection and any switchboard work; a licensed plumber handles the tank and pipework. Split-system heat pumps, where the compressor sits separately from the tank on refrigerant lines, need a refrigeration-licensed technician for that connection as well. A well-run installation coordinates all three, rather than the homeowner discovering the gap on installation day.

When a heat pump doesn’t make sense

• Frequent outages in your area. A heat pump needs electricity and most carry no backup. If hot water resilience during an outage matters, gas continuous-flow is the better fit.
• A cramped, poorly ventilated position. Heat pumps need airflow around the unit to work efficiently. A tight enclosed spot undermines the exact efficiency you’re paying for.
• A near-new system with a simple fault. Replacing a good tank rarely makes sense just to chase a rebate.

On the Gold Coast, specifically

Coastal conditions shorten element life, and the systems we’re called to most often are in older beachside housing through Palm Beach, Currumbin and Burleigh Heads, where the tank and the switchboard are often the same age as each other. Unit and townhouse owners through Labrador and Southport hit a different problem: where the system serves one lot but sits on common property, who arranges the repair is its own question, covered in body corporate vs unit owner responsibilities.