Know Your Water Heater – Relighting the Pilot Light

Posted By: Bruce Davis Sr. Education,

Every now and then a bit of wisdom rises to the surface. And when it has to do with an appliance that involves a flame and natural gas in your home, it’s definitely worth repeating. 

Where we live, water heater outages tend to be more frequent in the wintertime. The winds are higher than normal, and can blow out a pilot on a gas water heater. Often during a water heater service call, we end up doing nothing more than relighting a pilot. Sometimes a homeowner will actually know that their pilot is out and will ask us to walk them through relighting the pilot over the phone. These requests are more frequent in rental homes where the occupants are more likely to call property management first, rather than investigate any issue at the tank.

What is a Pilot Light?
A standing pilot is a small flame that stays lit day and night. It is located at the bottom of the tank in the burner chamber, and when lit can be seen through the sight glass or hole. Its purpose is to light the gas released to the main burners when there is a call for heat. It is as much a safety device that shuts down the gas going to the burners, as it is a means to provide an ignition source for the main burner. This pilot light is common in all atmospheric vented water heaters. It is the most common burner ignition system on water heaters, but not all water heaters have them. Typically, the water heaters that won’t have a standing pilot system are water heaters that need power to operate. Simply by identifying if your water heater is plugged into the wall or not will tell you if you have a standing pilot ignition system. 

The other giveaway that a water heater has a standing pilot ignition system are the instructions on the water heater on how to relight the pilot. In fact, when we get the call to relight a pilot on a water heater we will often instruct the home owner to follow the instructions given by the manufacturer. These are step-by-step instructions posted right on the metal jacket of the tank. Each manufacturer will have slightly different instructions for relighting the pilot.

Relighting the Pilot Light
When relighting the pilot, it is important to follow the manufacturer’s instructions and take the necessary safety precautions. The typical relight will ask you to turn a knob to “pilot” and press that knob in while lighting the pilot. What you are actually doing is manually opening a valve that sends gas to the pilot assembly. You can follow the copper thermocouple line or the smaller pilot tube to find the pilot assembly inside the combustion chamber. While holding down the knob the pilot can be lit. Where most people will make a mistake is releasing that knob too soon. The pilot flame is heating a thermocouple that will generate a small amount of voltage (millivolts) to charge a magnet that will then keep the pilot gas valve open. This is a safety feature. If the pilot were to go out as the thermocouple cools down, the valve becomes de-energized and closes preventing both the pilot and the main burner from getting gas.

More recent water heater models will have a combustion chamber that the homeowner is not meant to access. There will be a sight glass to view the pilot. Instead of using a barbecue lighter or long match to light the pilot, pressing the button on a piezo lighter, like what you see on a gas barbecue, creates a spark at the pilot to light the pilot gas. 

Safety Tips
A couple of safety tips to follow when relighting a pilot:

•    Always follow the manufacturer’s instructions
•    Turn the water heater valve to the “off” position and wait 5-minutes before attempting to relight.
•    Be aware of your surroundings.

o    Look for signs of flame roll out (flame leaving an appliance). There may be other issues going on besides the pilot being out.

•    DO NOT attempt to light your pilot if you smell gas outside your appliance.
•    Turn the burner temperature setting all the way down before lighting the pilot.
•    Keep yourself clear of any openings to the combustion chamber where the burner sits on initial fire off of the main burner as a precaution to avoid any flame roll out.
•    Set the temperature back to normal and not in excess of local codes to reduce potential scalding.

If you don’t feel comfortable lighting the pilot to your gas water heater, or have never lit one yourself, call a professional. When that person is on site take the opportunity to let your licensed plumber or HVAC technician show you how to do it so you can decide if it is something you are comfortable doing in the future.

Bruce Davis, Sr. is a Licensed Journeyman Plumber, Licensed Electrician, HVAC/R Electrical Administrator, HVAC/R ,and Certified WA State C.E.U. Instructor. Day and Nite Plumbing and Heating, Inc has been in Lynnwood serving Snohomish and N. King County for over 68-years, and Bruce Sr. has been President and working at this family-owned business for 36-years. Bruce can be contacted at: Email: and Nite Plumbing and Heating Inc. 16614 13 Ave. W., Lynnwood, WA 9803, (800) 972-7000.