Why Your Water Heater Pilot Will Not Stay Lit

A water heater pilot that refuses to stay lit can be frustrating, but the cause is usually one of a few specific issues. The pilot flame heats a safety component called a thermocouple. The thermocouple produces a tiny electrical signal when it is heated. This signal tells the gas valve that the pilot flame is present and it is safe to keep gas flowing. If the thermocouple becomes weak, dirty, bent, or misaligned, it cannot stay hot enough to produce the signal. This is the most common reason pilots go out.

Another cause is a weak or dirty pilot flame. If the pilot orifice is clogged, the flame can shrink or lift away from the thermocouple. Even if the pilot lights, the flame may not make enough contact to heat the thermocouple properly.

Gas control valves can also fail with age. Inside the valve is a magnet that holds open when the thermocouple sends a signal. When this magnet wears out, the pilot will light but shut off as soon as you release the control knob.

Some modern heaters have a thermal cutoff switch that shuts down the pilot if the combustion chamber overheats or becomes restricted. Dirty flame arrestors or poor airflow can cause this switch to trip.

A pilot that repeatedly goes out is a sign that a part is failing. If your pilot has become unreliable, we can inspect the system and recommend the best repair.