No hot water? A checklist before you call a plumber
Some hot water problems are a tripped switch or an empty gas bottle; others need a licensed plumber or gasfitter straight away. Work through the checks for your type of system, and stop at any sign of danger.
Written by Cassel’s Plumbing & Gas, Bli Bli. Facts checked against the official sources listed at the end. Updated 11 October 2026.
Stop and call if you see any of these
Don’t keep troubleshooting if water is leaking from the tank itself, the relief valve is pouring out hot water and won’t stop, you can smell gas, there are scorch marks, soot or a burning smell, or the safety switch trips again after you reset it.
Turn the unit off at the switchboard (electric) or at the gas isolation valve (gas), then close the cold water valve into the tank. If you smell gas, turn off the gas at the bottle or meter, don’t use switches or flames, open doors and windows, move away and call a licensed gasfitter. If you can still smell gas after the supply is off, call 000.
Which type do you have?
Electric storage: a tank with a power supply and no flue. Often on an off-peak tariff.
Gas storage: a tank with a flue on top and a gas control near the base. On the Sunshine Coast it usually runs on LPG.
Gas continuous flow: a wall-mounted box with no tank. It runs on gas but also needs power.
Heat pump or solar: a tank with a fan unit or roof collectors. Check the power supply first, then call.
Electric storage: checks
Switchboard. Look for a tripped circuit breaker or safety switch labelled hot water. Reset it once. If it trips again, leave it off and call: that usually means an element or wiring fault.
Power point or isolating switch. Some units have one beside the tank. Make sure it’s on.
Off-peak timing. On Energex Tariff 31 the unit only gets power for about 8 hours overnight (roughly 10pm to 7am), so a big day of showers and washing can empty the tank until the next night. Tariff 33 supplies at least 16 hours a day, usually outside 4pm–9pm.
Lukewarm water with the power on usually means a failed thermostat or element. These are live electrical parts behind the cover, so leave them to a licensed tradesperson.
Gas storage: checks
Is there gas? Try the cooktop or another gas appliance. If nothing works, check the bottles: both may be empty, or the valve on the full one may be closed.
Isolation valve. Make sure the gas valve on the line into the water heater is open.
Pilot light. If the unit has a pilot, follow the lighting instructions on the unit’s label. If it won’t light or won’t stay lit, stop and call. A thermocouple, gas control or gas pressure fault is likely.
Weak heating on LPG, especially with low flames on the cooktop too, can point to a failing regulator. Regulator work is gas work for a licensed gasfitter.
Gas continuous flow: checks
Power. These units need electricity to ignite. Check the power point and the circuit, and remember a power cut stops hot water too.
Error code. Look at the controller in the kitchen or bathroom. Write the code down: your owner’s manual explains it, and it tells a technician where to start.
Gas supply. Check the bottles and the gas valve, as above.
Flow. Turn a hot tap on fully. These heaters need a minimum flow before they fire, so a trickling tap or a blocked shower rose may not start them.
The relief valve: what’s normal
Storage water heaters have a temperature and pressure relief valve that releases water as it heats and expands. Dux’s guidance is that a small amount of water during heating is normal, but more than a full bucket over 24 hours is not; a plumber may need to fit a pressure limiting valve or replace the relief valve.
Never plug, cap or block the relief valve or its drain line.
Never fit a relief valve with a higher pressure rating than the one specified for the unit.
Hot water streaming from the valve without stopping is a fault: turn the unit off and call.
Queensland temperature rules
At least 60 °C storedHot water in a storage system must be heated to at least 60 °C to control bacteria such as Legionella.
No more than 50 °C in the bathroomA temperature control device keeps water to bathroom taps, showers and baths at a maximum of 50 °C to reduce scalding.
Tempering valve on every replacementA temperature control device must be fitted to all new and replacement hot water systems, so expect one on a like-for-like changeover.
Source: Business Queensland, hot water systems.
Repair or replace?
A rough rule of thumb:
Repair when the tank is sound and the fault is a replaceable part: thermostat, element, relief valve, gas control, thermocouple or regulator.
Replace when the tank body is leaking (it can’t be repaired), the unit is past its cylinder warranty and the repair is a large share of the cost of a new one, or you want to change to a different type of system.
How long a tank lasts varies a lot with water quality, salt air and maintenance. The cylinder warranty on the unit’s label is a fair guide to what the maker expects. A replacement also brings a tempering valve if one isn’t already fitted. See hot water repairs and replacement, or for a leaking tank or a household that can’t wait, emergency plumbing.
What customers say
★★★★★
Clayton Cassel came and repaired a faulty gas regulator at very short notice on a Saturday morning, so that we could have hot water over the weekend. Thank you Clayton!!!
Kerry Pengelly · Google review
★★★★★
We have used Cassels Plumbing for a number of years. Clayton has done the Plumbing in our bathroom renovations & replaced our gas hot water system.
Why is there no hot water when the cold water works?
On an electric unit, check the switchboard, any power point or isolating switch beside the tank, and off-peak timing. On gas, check the bottles, the gas valve and the pilot or error code. If those are fine, the fault is likely a part such as a thermostat, element or gas control.
Is it safe to reset the hot water safety switch?
You can reset it once. If it trips again, leave it off and call a licensed tradesperson, as it usually points to an electrical fault in the element or wiring.
Is a dripping relief valve normal?
A small amount of water while the unit heats is normal. More than a bucket over 24 hours, or hot water running constantly, is not and should be checked.
Do I need a tempering valve if I replace my hot water system?
Yes. In Queensland a temperature control device must be fitted to all new and replacement hot water systems so bathroom water is delivered at no more than 50 °C.
