Heating and hot water not working: check what they share
Two failures at once usually mean one cause. Here is how to find the shared link, and where to stop.
When heating and hot water fail together, the cause is usually something they share: power, gas supply or a combined unit. Check the shared supply first. A tripped switch or a gas supply problem explains far more of these than two separate faults do.
| What you notice | What it usually points to | Who deals with it |
|---|---|---|
| Everything dead, lights too | Power cut in the street or at the switchboard | Your electricity distributor |
| Only the heater and hot water are dead | A tripped safety switch or circuit breaker | You can reset it once |
| Gas stove and gas heater both out | Gas supply interruption | Your gas distributor |
| Hot water works, heating does not | A heating-side fault, not a shared one | A licensed plumber or gasfitter |
| One combined unit shows a fault code | The unit has shut itself down | A licensed plumber or gasfitter |
Start with the switchboard
Look at your switchboard. If a safety switch or breaker has dropped, flick it back on once. If it trips again straight away, leave it off.
A switch that keeps tripping is telling you something is wrong with the appliance or its wiring. That is a job for a licensed electrician, not another reset.
Is anything else out?
Check a light, the fridge and the stove. If they are all dead, you have a power cut, not a plumbing fault. Look at your electricity distributor's outage page on your phone.
If the lights work but the gas stove does not light, the gas supply is the shared link. Do not investigate the pipework. Ring your gas distributor.
One system or two?
Many Australian homes have separate systems: a hot water unit and a different heater. If both fail on the same day, they probably share a supply. If only one fails, they do not, and you are looking at one fault, not two.
Some homes run both from a single combined unit. If yours is one of them, the fault is almost certainly in that unit. Our no hot water checklist covers the hot water side in order.
Read the display, do not open the unit
Many units show a light or a code when they shut down. Write it down exactly, or photograph it. A plumber can often tell what failed from that code alone, before they arrive.
Do not press reset buttons repeatedly. A unit that locks itself out is protecting you, and forcing it to restart hides the fault.
Warmth while you wait
If it is cold, wear layers and close doors to one room. Do not use a gas stove or oven to heat a room, and do not bring an outdoor heater inside. Both can fill a home with carbon monoxide.
For hot water, a kettle will do for washing. Do not run the hot tap for long if the unit is sounding odd.
What to tell the plumber
- Did both fail at the same moment, or did one go first?
- Is it gas, electric or a combined unit, and how old is it?
- What does the display say? Give the exact code or light pattern.
- Did a switch trip, and did it trip again after one reset?
How far can you take this yourself?
The checks are yours: switchboard, display, other appliances, a call to the distributor. Everything inside the unit or on the gas side is not. The licensed work pillar sets out where the line falls.
Frequently asked questions
Why have my heating and hot water both stopped working?
They usually share a supply, such as power, gas or a single combined unit. Check the switchboard for a tripped switch, see whether other appliances work, and read any display on the unit. If you cannot find the shared cause, call a licensed plumber or gasfitter.
Can I reset a tripped switch myself?
You can reset a safety switch or breaker once. If it trips again straight away, leave it off and call a licensed electrician, because something is faulty.
What should I do if I smell gas?
Leave the house straight away and call your gas emergency line from outside. Do not switch anything on or off. Gas work is licensed work in every Australian state and territory.
Is it safe to heat a room with the gas oven?
No. A gas oven or stove can produce carbon monoxide in a closed room. Use layers and close doors to one room until a licensed tradesperson has fixed the heating.
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