If you have a gas water heater, the small blue pilot flame is essential. It starts the burner and keeps hot water flowing. When the pilot light goes out or will not stay lit, your water heater cannot work.
In the Greater Toronto Area (GTA), ignition problems are very common, especially with water heaters that are more than 8-10 years old. Cold winter weather can make things worse. Strong winds and cold air can enter through the vent pipe and blow out the pilot flame, even if the unit worked fine before.
The good news is this: some pilot light problems are simple and safe to check on your own. Others are warning signs that you should call a licensed technician. This guide helps you understand the difference.
Prefer to skip the troubleshooting and book a pro? Visit our Repair Service page: Water Heater Repair – Mas Air Home Comfort or Call us at 1-855-795-1199.
Step 1: Safety First – Can You Relight the Pilot Light?
Before you touch anything, safety comes first. Gas appliances must be handled carefully.
Stop immediately and call a professional if you smell gas at any time.
How to Relight a Water Heater Pilot Light
Follow these basic checks before assuming something is broken:
- Do the sniff test
Stand near the bottom of the water heater. Smell the air normally. If you notice a gas smell, do not relight the pilot. Leave the area and call for emergency service. - Check the control knob
Look at the gas control dial on the front of the heater. If it is set to OFF or PILOT, the main burner will not turn on. Set it to your normal temperature and wait a few minutes. - Look through the inspection window
Many water heaters have a small glass window near the burner. If you see a steady blue flame, the pilot light is on. In this case, the problem is likely the main burner, not the pilot. - Try to relight the pilot
Follow the instructions printed on the tank. In most cases:- Turn the knob to PILOT
- Press and hold the igniter button (or use a long match)
- Keep holding the knob for 30-60 seconds after the flame lights
- Slowly release the knob
If the pilot stays on, turn the knob to your desired temperature.
Important: If the pilot light goes out after 2-3 attempts, stop trying. This usually means a part has failed.
Step 2: Why the Pilot Light Won’t Stay Lit
If relighting does not work, the problem is usually one of these two parts.
Thermocouple vs. Gas Control Valve
| Symptom | What It Usually Means | Professional Fix |
|---|---|---|
| Pilot lights but goes out when you release the knob | Faulty thermocouple | Replace the thermocouple |
| Pilot stays lit but burner never turns on | Failed gas control valve | Replace the gas valve |
What Is a Thermocouple?
A thermocouple is a small metal sensor that sits in the pilot flame. It creates a tiny electrical signal that tells the gas valve the flame is present. If the signal stops, the valve shuts off the gas for safety.
Over time, thermocouples can fail due to:
- Age and wear
- Dirt or carbon buildup
- Incorrect positioning
When this happens, the pilot flame goes out as soon as you let go of the knob. This is one of the most common water heater repairs in the GTA.
Water Heater Thermocouple Replacement: What to Expect
A licensed technician can usually replace a thermocouple in one visit. The repair is quick and does not require draining the tank or turning off your home’s water supply.
Step 3: What You Can Do Yourself — And What You Shouldn’t
Not all ignition problems need a service call. But gas repairs have clear limits.
Safe DIY Checks (Green Zone)
You can safely:
- Follow the relighting instructions on the tank label
- Adjust the temperature or control knob
- Gently clean visible dust around the burner area (with the unit off)
Call a Professional (Red Zone)
You should not attempt to:
- Replace a thermocouple or burner part
- Open a sealed combustion chamber
- Adjust gas pressure
- Continue relighting when the pilot will not stay on
In Ontario, gas appliance repairs must be done by a licensed technician. This protects your safety and your home.
Need Hot Water Fast in the GTA?
No one plans for cold showers. If your pilot light won’t stay lit or your water heater will not ignite, our licensed technicians can help, often in one visit.
At Mas Air Home Comfort, we offer same-day service across Toronto, Mississauga, Vaughan, Brampton, and the surrounding GTA.
Water Heater Repairs & Emergency Service:
📞 +1 (855) 795-1199
New Water Heater Installation Estimates:
📞 +1 (647) 360-6623
You can also book online to request a free estimate or service visit.
Related Reading (Keep Troubleshooting Smart)
Don’t let a minor fault turn into a major breakdown. Explore our expert guides to identify other common water heater issues in your GTA home:
- No Hot Water — icy surprises or stone-cold taps.
- Inconsistent Hot Water — fluctuating between perfect warmth and an ‘icy spike’.
- Water Heater Leaking — water pooling at the base or seeping from the tank body.
- Strange Water Heater Noises — popping, rumbling, or banging sounds while heating.
- Low Hot Water Pressure — hot water flow is a weak trickle compared to cold taps.
- Smelly or Discolored Water — water smells like ‘rotten eggs’ or looks rusty.
FAQs
If the pilot lights but shuts off as soon as you release the control knob, the thermocouple is likely failing. It is designed to stop gas flow when it does not sense a flame.
Most replacements take less than one hour. It is a routine repair for trained technicians.
Yes, as long as you follow the instructions on the tank and do not smell gas. If gas odor is present, stop and call a professional.
Cold air and strong winds can enter through the vent pipe. This can disturb or blow out the pilot flame. If this happens often, a technician should inspect the venting system.
