Why does my water heater pilot light keep going out?
A pilot light that will not stay lit is one of the most common gas water heater complaints, and it is genuinely aggravating: you carefully follow the relighting procedure, watch the flame catch, release the button, and moments later the pilot dies again. The heater is not being stubborn; it is following its safety logic. Every standing-pilot water heater is designed so that if it cannot confirm a healthy, stable pilot flame, it shuts off the gas supply rather than risk releasing unburned gas into your home.
That means a repeatedly extinguishing pilot is almost always a signal that a sensing or combustion component needs attention. For Metro Vancouver and Fraser Valley homeowners, the usual suspects are a worn thermocouple, a clogged pilot, or a draft or venting problem, and the right fix depends on which one it is. Because all of these involve the gas system, this is a topic where knowing the causes helps you communicate with a technician and recognize the important safety cues, rather than a full DIY repair. Here is what is going on and what to do.
The Thermocouple: The Usual Suspect
The most common reason a pilot light keeps going out is a failing thermocouple. This small metal probe sits directly in the pilot flame, and when heated it generates a tiny electrical voltage that tells the gas valve the pilot is burning and it is safe to keep gas flowing. It is a clever safety mechanism: if the pilot goes out, the thermocouple cools, the voltage disappears, and the gas valve closes automatically, preventing gas from leaking. The catch is that when the thermocouple itself fails, becomes dirty, or drifts out of position, it stops generating that voltage even when the pilot is lit, so the valve shuts the gas off and the pilot dies within seconds of you releasing the control knob. The telltale sign is a pilot that lights fine while you hold the button but goes out the moment you let go. Thermocouples wear out over years of heat exposure, and replacement is a routine repair, but because it is part of the gas system it should be done by a licensed, TSBC-certified technician who can also confirm the pilot assembly and gas valve are working correctly.
Dirty Pilot, Drafts, and Venting Problems
If the thermocouple is sound, a dirty pilot or an airflow problem is often to blame. The pilot burns through a small orifice, and over time dust, lint, or combustion debris can partially clog it, producing a weak, flickering, or yellow flame that cannot properly heat the thermocouple, so the pilot keeps failing. Cleaning the orifice restores a strong blue flame. Drafts are another frequent cause: a strong draft from a nearby door, window, or forced-air vent can physically blow the pilot out, and homes with the water heater in a garage or drafty utility area are especially prone to this. More seriously, venting problems can extinguish a pilot. A blocked flue, a bird nest or debris in the vent, or a backdrafting condition can disturb combustion and blow out or starve the pilot, and this category matters most for safety because poor venting can allow carbon monoxide to accumulate. A working CO alarm is essential in any home with gas appliances. If the pilot keeps going out and you also notice soot, odd smells, or a CO alarm activating, treat it as a safety issue and get professional help.
Gas Supply and Valve Issues
Less commonly, the problem lies with the gas supply itself or the gas control valve. If the gas pressure to the pilot is too low, whether from a supply issue, a partially closed valve, or a fault upstream, the pilot flame will be weak and prone to going out. Fluctuations in gas supply can cause intermittent pilot failures that seem random. The gas control valve, which houses the safety magnet that the thermocouple energizes, can also fail internally; when it does, it may not hold the valve open even with a good thermocouple signal, so the pilot dies repeatedly no matter how many times you relight it. Diagnosing a valve fault requires ruling out the thermocouple and pilot first, then testing the valve, which is why a systematic professional approach saves time and frustration. A failing gas valve is also a component you never want to improvise with, because it is the heart of the appliance’s gas safety system. If a technician has confirmed the thermocouple and pilot are good and the pilot still will not stay lit, the gas valve is the likely culprit and should be replaced by a licensed professional.
Safety First, and When to Call HeatLand
Because this is a gas appliance, safety comes before troubleshooting. If you ever smell gas, that classic rotten-egg odour, do not try to relight the pilot: stop, leave the home, avoid using switches or phones inside, and call your gas provider and a professional from outside. Never keep trying to relight a pilot repeatedly over a long period, as that can allow gas to accumulate. For a pilot that keeps going out without any gas smell, you can safely note the pattern, whether it dies the instant you release the button (pointing to the thermocouple) or stays lit briefly then fails (suggesting a dirty pilot, draft, or venting issue), and check whether an obvious draft source is nearby. Beyond that, cleaning the pilot orifice, replacing the thermocouple, correcting venting, and testing the gas valve are all jobs for a licensed technician. If your water heater pilot keeps going out, call HeatLand at (604) 330-3812. A technician will diagnose the exact cause, make the repair safely, and verify the whole gas and venting system is sound so your hot water stays reliable.
Quick Checklist
- Note if the pilot dies the instant you release the button (thermocouple) or after a delay
- Look for nearby drafts from doors, windows, or vents
- Check the pilot flame color: a weak or yellow flame suggests a dirty orifice
- Ensure a working carbon monoxide alarm is installed near sleeping areas
- If you smell gas, leave the home and call from outside; do not keep relighting
- Call a licensed technician for thermocouple, venting, or gas valve repairs
| Symptom | Likely Cause | Action |
|---|---|---|
| Pilot dies when you release the button | Faulty thermocouple | Professional thermocouple replacement |
| Weak or yellow pilot flame | Dirty pilot orifice | Technician cleans the pilot assembly |
| Pilot blows out repeatedly | Draft near the heater | Reduce drafts; technician to verify |
| Soot, odors, or CO alarm | Blocked flue or backdrafting | Stop use; professional venting inspection |
| Random pilot failures | Low gas pressure or supply issue | Professional gas supply check |
| Won’t stay lit despite good thermocouple | Failing gas control valve | Licensed valve replacement |
Frequently Asked Questions
Why does my pilot go out as soon as I release the button?
That’s the classic sign of a failing thermocouple. While you hold the button you’re manually feeding gas to the pilot, but once you release it, the thermocouple must sense the flame and keep the gas valve open. If it’s worn, dirty, or misaligned, it can’t do that and the pilot dies. A licensed technician can replace it at (604) 330-3812.
Can a draft blow out my water heater pilot?
Yes. A strong draft from a nearby door, window, or forced-air vent can physically extinguish the pilot, and heaters in garages or drafty utility areas are especially prone. Reducing the draft source sometimes helps, but if the pilot keeps failing, have a technician confirm it isn’t a thermocouple, dirty pilot, or, more importantly, a venting problem that carries safety risks.
Is a pilot that keeps going out dangerous?
The safety system is designed so that when the pilot goes out, the gas shuts off, which is protective. The concern is repeatedly relighting over a long period, which can let gas accumulate, and the possibility that venting problems are involved. Keep a working CO alarm installed. If you ever smell gas, leave the home and call from outside rather than relighting.
Can I replace the thermocouple myself?
We recommend a licensed technician. While a thermocouple is a relatively inexpensive part, replacing it involves working on the gas system, correctly positioning the probe in the flame, and verifying the pilot assembly and gas valve are safe. A HeatLand technician can also rule out venting and valve issues that a simple part swap would miss, ensuring the repair actually lasts.
Reviewed by the HeatLand Heating & Cooling team — licensed HVAC contractor serving Metro Vancouver & the Fraser Valley since 1999. If you smell gas or your CO alarm sounds, stop, leave the home, and call a licensed technician or 911.