Yes, your pilot light should stay on most of the time—but there are safe exceptions
A pilot light should burn continuously on gas water heaters, furnaces, and gas fireplaces during the seasons you use them. The flame stays lit so the appliance can ignite the main burner when you need heat or hot water. If your pilot light goes out, the system cannot start, and you will have no heat or hot water until you relight it.
The only time it is safe to turn off your pilot light is during months when you will not use that appliance at all—typically summer for a furnace, or year-round for a gas fireplace you do not use. Even then, many homeowners leave it on because relighting it takes time and carries a small risk of gas buildup if done incorrectly.
Key Takeaways
- Your pilot light should stay on during any season when you might need the appliance, because it is the ignition source for the main burner.
- Turning off a pilot light saves a small amount of gas—roughly 10 to 15 dollars per month on a water heater—but most homeowners leave it on year-round for convenience.
- If your pilot light goes out on its own, the thermocouple (a safety sensor) may be failing and should be checked by a technician.
- Relighting a pilot light yourself is safe if you follow the manufacturer's instructions exactly, but if you smell gas or the light will not stay lit, call a professional instead.
Why pilot lights stay on during heating season
A pilot light is a small, continuous flame that sits near the main burner. When you turn up the thermostat or turn on the hot water tap, the pilot light ignites the main burner, which produces the heat you need. Without the pilot light already burning, the system has no way to start the main burner.
On a furnace, this means you need the pilot light on from fall through spring, whenever outdoor temperatures drop and you might need heat. On a water heater, many people leave the pilot light on year-round because hot water is needed every day. On a gas fireplace, you only need the pilot light on if you use the fireplace during that season.
The cost and safety trade-off of turning off your pilot light
Leaving a pilot light on does consume gas continuously—roughly 10 to 15 dollars per month on a water heater, depending on your gas rate and the appliance's age. Over a full year, that adds up. Some homeowners turn off the pilot light during months they know they will not need the appliance, such as turning off a furnace pilot in late spring and relighting it in early fall.
The trade-off is convenience and the small risk of error. Relighting a pilot light requires you to follow the manufacturer's steps exactly: usually turning a valve to "Pilot," holding down a button to release gas, lighting the flame with a long lighter or match, and holding the button for 30 to 60 seconds while the thermocouple heats up. If you rush this process or do not hold the button long enough, the light will go out again as soon as you release it.
If you smell gas at any point during relighting, stop when ready, leave the area, and call your gas company or a technician. Do not try again.
When a pilot light that should be on keeps going out
If your pilot light goes out on its own during a season when you are using the appliance, something is wrong. The most common cause is a failing thermocouple, a small sensor that detects whether the pilot light is burning. If the thermocouple is worn out or dirty, it stops sending the signal that tells the gas valve to stay open, and the pilot light shuts off.
Other causes include a draft blowing out the flame, a clogged pilot tube that does not deliver enough gas, or a gas valve that is failing. You can try relighting the pilot light once following the manufacturer's instructions. If it goes out again within a few hours, or if it goes out repeatedly, call a technician. A thermocouple replacement is inexpensive—usually 150 to 300 dollars including labor—and a technician can diagnose the real problem quickly.
How to safely relight a pilot light yourself
Relighting a pilot light is a task most homeowners can do safely if they follow instructions carefully. Start by locating the control panel on your appliance—it is usually on the front or bottom of a water heater, or inside the furnace cabinet. Look for a dial or knob labeled "Pilot," "On," and "Off."
Turn the dial to "Off" and wait five minutes to let any gas clear. Then turn it to "Pilot." Press and hold the ignition button (or the dial itself, depending on the model) while you light the pilot opening with a long lighter or long match. Hold the button down for 30 to 60 seconds after the flame appears—the manufacturer's manual will specify the exact time. Then release the button. If the flame stays lit, turn the dial to "On." If the flame goes out, wait five minutes and try again.
If the pilot light will not stay lit after two attempts, or if you smell gas, stop and call a technician or your gas company. Do not keep trying.
Seasonal pilot light management for water heaters and furnaces
On a water heater, most homeowners leave the pilot light on year-round because hot water is used every day. The gas cost is small, and you avoid the hassle of relighting it. If you want to turn it off during summer months when you use less hot water, you can—just turn the dial to "Off" and relight it in fall.
On a furnace, you should turn off the pilot light only if you are certain you will not need heat for several months. In most climates, that means turning it off in late May or early June and relighting it in late August or early September, before the first cold snap. If an unexpected cold spell hits and you need heat, you will have to relight the pilot before the furnace can run. Some homeowners leave the furnace pilot on year-round to avoid this risk.
On a gas fireplace, turn off the pilot light if you do not use the fireplace during that season. Many people turn off the fireplace pilot in spring and relight it in fall, saving gas during months when they do not need the extra warmth.
Signs your pilot light system needs professional attention
Call a technician if your pilot light exhibits any of these problems: it goes out repeatedly even after you relight it, it burns yellow or orange instead of blue, it produces a smell like rotten eggs or sulfur, or you see water pooling around the base of the appliance. A yellow or orange flame usually means incomplete combustion, which can produce carbon monoxide. A smell may indicate a gas leak or a problem with the appliance's venting.
You should also have a technician inspect your appliance if you have not had it serviced in more than two years. Annual or biennial maintenance on a furnace or water heater keeps the pilot light system clean and catches small problems before they become expensive repairs.
Frequently Asked Questions
Is it bad to leave a pilot light on all summer?
No, it is not bad for the appliance. Leaving a pilot light on continuously uses a small amount of gas—roughly 10 to 15 dollars per month on a water heater—but does not damage the system. Many homeowners leave pilot lights on year-round for convenience and to avoid relighting them.
Can I turn off my furnace pilot light in spring?
Yes, if you are certain you will not need heat until fall. Turn the dial to "Off" and relight it in late August or early September, before cold weather returns. If an unexpected cold snap hits, you will need to relight the pilot before the furnace can run.
What does it mean if my pilot light keeps going out?
A pilot light that goes out repeatedly usually indicates a failing thermocouple, a clogged pilot tube, or a faulty gas valve. Relight it once following the manufacturer's instructions. If it goes out again within a few hours, call a technician for diagnosis and repair.
Why is my pilot light flame yellow instead of blue?
A yellow or orange flame usually means the burner is not getting enough air or the gas is not burning completely. This can produce carbon monoxide. Stop using the appliance and call a technician to inspect and clean the burner.
Do I need to turn off the pilot light before I leave for vacation?
No. Leaving the pilot light on while you are away is safe. If you will be gone for several months and want to save gas, you can turn it off, but there is no safety reason to do so.