Why Won't My Water Heater Pilot Light Stay Lit?
If you relight the pilot on your gas water heater and it goes out again a few seconds or a few hours later, something is preventing the safety system from keeping the gas valve open. This is a common problem with clear causes. This guide explains how a pilot works, the most likely reasons it keeps going out, which checks are safe to do yourself, and when to call a licensed technician.
How a water heater pilot works
Older gas water heaters use a small, steady flame called the pilot to light the main burner. A thermocouple sits in that flame and produces a tiny electrical signal while it is hot. That signal tells the gas control valve that it is safe to keep gas flowing. If the flame goes out or the thermocouple cannot sense it, the valve shuts off gas to prevent unburned gas from escaping.
Newer heaters often use a hot-surface or spark igniter and a flame sensor instead of a standing pilot, but the idea is the same. If the system cannot confirm a flame, it shuts down.
The most common causes
These are the issues our technicians find most often when a pilot will not stay lit:
- A worn or bent thermocouple that no longer sits in the flame
- A dirty pilot tube that makes the flame weak or yellow
- A failing gas control valve
- Poor combustion air or a blocked flame arrester screen
- Venting or draft problems that pull the flame away
- Low gas pressure or an issue with the home's gas supply
Safe checks you can do
First, make sure there is no gas smell. If you smell gas, do not try to relight anything. Leave the house and call your gas utility from outside. If there is no smell, read the lighting instructions on your heater label and follow them exactly. Hold the pilot button down for the full time stated, often about a minute, so the thermocouple can heat up.
Look at the flame through the viewing window. A healthy pilot is mostly blue and wraps around the tip of the thermocouple. A small, yellow or flickering flame usually points to dirt, a draft or a supply problem. Check that the area around the heater is clear of stored items, lint and dust, because many modern heaters have a flame arrester at the bottom that clogs and shuts the heater down to prevent fires.
When to stop and call a technician
If the pilot goes out more than once, it is time for a professional inspection. Thermocouples, igniters, flame sensors and gas valves are safety parts, and replacing them correctly requires the right parts and testing. Repeated outages can also be a sign of venting problems, which can allow combustion gases into the home. A technician will check the draft and make sure the heater is venting properly.
If your water heater is older or has other problems such as leaks or rust, replacing the pilot assembly may not be the best investment. We will explain both repair and replacement options. For pricing on either, call for a free quote.
Preventing pilot problems
Keep the space around the heater clean and free of stored items, especially in garages where dust and lint collect. Make sure doors and closet vents are not blocked so the heater gets enough combustion air. Annual maintenance lets a technician clean the burner and pilot assembly, inspect the venting and catch weak parts before they fail.
Local help in Fullerton and Orange County
The Water Heater Warehouse repairs pilot and ignition problems on all major brands, including Rheem, A.O. Smith, Bradford White and Rinnai. Our trucks carry common thermocouples and parts, so many pilot repairs are finished in one visit. Call us to get your hot water back safely.
Related service
Learn about our water heater pilot and ignition repair, or see our water heater repair in Fullerton.
Frequently asked questions
What does a bad thermocouple look like?
It may be bent, discolored or not sitting in the flame. Often it looks normal and has to be tested, which a technician can do quickly.
Is it safe to keep relighting the pilot?
Relighting once by following the label is fine. If it keeps going out, stop and have the heater inspected.
Can wind or drafts blow out my pilot?
Yes. Strong drafts or venting problems can pull the flame away. A technician can check the draft and venting.