Hot Water Pilot Light: How to Relight It & Why It Keeps Going Out

Updated July 2026 · 7 min read · Geelong Emergency Plumbing

A hot water pilot light that goes out is one of the more approachable gas hot water problems — in most cases it's a simple relight, printed in instructions on the unit itself, and the whole thing takes three minutes. The complication arises when the pilot lights and then dies when you release the button, or when it goes out repeatedly over days or weeks. Here's the full picture: how to relight it, what a persistent outage means, and where the gasfitter becomes necessary.

Before You Touch Anything: Safety Check

A pilot light that goes out is not a gas leak — when the pilot goes out, the gas supply to the pilot also stops (the thermocouple shuts it off). You should not smell gas around the unit. If you do smell gas near the unit when the pilot is out, do not attempt relighting. Follow the gas safety steps — ventilate, leave the area, call the gas faults line. A persistent gas smell means gas is escaping through a path other than the pilot flame, which is a different problem entirely.

No gas smell, just a cold shower? Proceed.

How to Relight the Pilot Light: General Steps

Detailed instructions are printed on every gas hot water unit — usually on a label behind the access panel at the bottom. The general sequence across most Australian storage hot water systems:

1. Find the access panel at the base of the unit. Open or remove it (usually held by clips or a quarter-turn fastener).
2. Set the gas control knob to PILOT. The knob typically has settings: OFF, PILOT, and a temperature range. Turn to PILOT.
3. Locate the igniter button (usually a red or grey button near the gas control knob) and the pilot assembly itself (a small copper tube leading to the burner area).
4. Press and hold the gas control knob down — this manually opens the pilot gas valve, bypassing the thermocouple safety.
5. While holding the knob, press the igniter button repeatedly until the pilot lights. You should see a small blue flame at the pilot tube tip.
6. Keep holding the knob for 30–60 seconds after the pilot lights. This heats the thermocouple — the safety sensor that must sense heat before it will allow gas to continue flowing. Releasing too early is the most common reason a pilot won't stay lit on the first attempt.
7. Release slowly and watch the pilot. If it stays lit, turn the gas control to your desired temperature and replace the panel. If it goes out, repeat from step 4 — some thermocouples need multiple cycles to fully heat.

Pilot Lights and Won't Stay Lit: The Causes

If you've held the button for a full minute and the pilot still dies when you release it, the problem is almost certainly the thermocouple. The thermocouple is a safety sensor — a bimetallic probe that sits in the pilot flame and generates a tiny electrical signal when heated, which tells the gas valve it's safe to stay open. When the thermocouple wears out, it doesn't generate enough signal even when heated properly, and the gas valve shuts the pilot off as a safety precaution.

Thermocouple replacement is a licensed gasfitter job in Australia — it involves working on the internal gas components of the appliance. The part itself costs $20–$60; a gasfitter's visit to replace it typically runs $150–$300. This is a worthwhile repair on a system under 10 years old; on a system over 12 years old, the thermocouple diagnosis becomes a conversation about repair vs replacement costs in our system lifespan guide.

Why the Pilot Keeps Going Out (Even After a Successful Relight)

• Draught — external units in exposed positions can have pilots extinguished by wind. If the pilot goes out after windy nights specifically, draught protection is the issue. The unit's cowl or draught shield may be damaged or missing.
• Dirty pilot orifice — a partially blocked pilot orifice produces a weak, unstable flame that doesn't heat the thermocouple reliably. Cleaning the orifice is a gasfitter task.
• Gas supply interruption — LPG bottles running empty, a mains supply interruption, or a partially closed gas valve at the unit. Check other gas appliances to confirm supply.
• Failing thermocouple — an intermittently failing thermocouple stays lit most of the time but goes out unpredictably. Replace it before it becomes a committed no-hot-water situation.
• Faulty gas valve — the gas valve itself failing is less common but produces similar symptoms to a thermocouple failure. A gasfitter can test which component is responsible.

When to Stop Trying and Call a Gasfitter

Stop attempting relights and call a licensed gasfitter when: the pilot won't stay lit after three relighting attempts with proper technique, you detect any gas smell near the unit, the unit is making unusual sounds, or the system is past 12 years old and this is the second component failure. These are either safety issues or cost-effectiveness issues — in both cases, continuing to relight is not the right path.

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