The thermocouple is usually the part that has given up
The pilot flame heats a small copper-tipped probe called a thermocouple. While the probe is hot it generates a tiny electrical current that holds the gas valve open. If the pilot goes out, the probe cools, the current stops, and the valve snaps shut so gas cannot pour out unburned. That is the safety system working. The catch is that thermocouples wear out. After years in a flame the tip oxidises and the current weakens until the valve will no longer stay open, and the classic symptom is exactly what you are searching: a pilot that lights fine, runs for a while or dies as soon as you release the button, and goes out again within hours or days.
Causes ranked by what we actually find
| Cause | Typical sign | Who fixes it |
|---|---|---|
| Worn thermocouple | Pilot dies when button released, or within hours | Licensed gas fitter, quote on inspection |
| Draughts and wind at the unit | Goes out on windy or stormy days only | Gas fitter checks flue and location |
| Blocked pilot tube or dirty burner | Weak, yellow or flickering pilot flame | Cleaned during a service |
| Blocked or damaged flue | Sooting, smell, pilot starves of air | Licensed gas fitter, treat as urgent |
| Low gas pressure or LPG running out | Whole burner weak, other gas appliances affected | Check bottles first, then gas fitter |
| Failing gas control valve | Relit pilot drops out randomly, unit is older | Often the point to price a new system |
Relighting it yourself: once is fine, repeatedly is not
Every gas storage unit has relighting instructions printed inside the access panel, and following them once is safe for a householder. Turn the gas control to off, wait a few minutes for any gas to clear, then follow the printed sequence. Two hard rules. If you smell gas at any point, stop, do not relight, do not operate switches near the unit, and get it checked. And if the pilot will not stay lit after one proper attempt, stop there. Repeated relighting of a unit that keeps dropping out means a safety component is failing, and persistence is just deferring the callout while your family runs out of hot water on a schedule.
Wind, weather and where your unit lives
Gold Coast weather is a genuine cause on external units. Storm-driven wind can snuff a pilot through the draught openings, and units installed in exposed positions or with deteriorated draught diverters do it every time the southerly comes through. If your pilot only dies in bad weather, tell us that on the phone, it changes the diagnosis. The fix ranges from a service and minor flue work to relocating or replacing an ageing unit, and we quote it on inspection after seeing the installation.
This is licensed gas work, and the service is cheap insurance
In Queensland, work on gas appliances beyond the printed relighting procedure must be done by a licensed gas fitter. That is not gatekeeping, it is because the failure modes here involve unburned gas and combustion products. An annual gas appliance service runs $150 to $200 as of 2026 and covers cleaning the pilot assembly and burner, testing the thermocouple, checking gas pressure and inspecting the flue. Units that get that service almost never surprise their owners on a cold morning. Ours is a small owner-operator team and the licensed gas fitter who quotes your job is the one who turns up.
When repair stops making sense
A thermocouple on an otherwise healthy unit is a straightforward repair and worth doing. But a gas storage unit past 10 to 12 years with a failing gas valve, rust streaks or a weeping tank is telling you where this ends. Gas storage replacements run $1,800 to $3,200 installed and gas continuous flow $1,900 to $3,500 on the Gold Coast as of 2026, and continuous flow units have no pilot to blow out at all. We will give you both numbers, repair and replace, and let you choose.
No hot water this morning? Call Hills Plumbing & Gas on 0472 657 042. Our licensed gas fitter will talk through what you are seeing, quote a fixed price, and give you an honest ETA on the call. After-hours emergencies run $360 to $560 for the first hour plus the work, and we will tell you honestly if it can wait for a standard-hours visit instead. Details at our hot water systems page.
Sources: Queensland Petroleum and Gas (Production and Safety) Act 2004 gas work licensing requirements; manufacturer relighting and maintenance instructions; Resources Safety and Health Queensland gas safety guidance.