What adjusting a pilot light means and when you need to do it
A pilot light that is too high or too low will either waste gas or fail to ignite the main burner reliably. Adjusting it means turning a small screw on the gas control valve to make the flame taller or shorter. Most gas fireplaces have a pilot adjustment screw located on the front or side of the valve itself—it looks like a flathead screw and is often labeled with a small flame icon or the word "pilot."
You may need to adjust the pilot if the flame is barely visible (too low) and won't light the main burner when you turn the fireplace on, or if it is so tall that it's licking up the sides of the burner assembly (too high). A properly adjusted pilot should be a steady blue flame about half an inch to one inch tall, with the tip just touching or nearly touching the thermocouple—the small metal rod that senses the pilot heat.
Key Takeaways
- The pilot adjustment screw is on the gas control valve itself, usually marked with a flame icon, and turns with a flathead screwdriver.
- A correct pilot flame is blue, steady, and about half an inch to one inch tall, with the tip near the thermocouple.
- Turn the screw clockwise to lower the flame and counterclockwise to raise it, making small quarter-turn adjustments and waiting 10 to 15 seconds between each one.
- If the pilot won't stay lit after adjustment or the main burner still won't ignite, the thermocouple or gas valve may need professional service.
Locating the pilot adjustment screw on your valve
Before you touch anything, turn off the gas at the control knob and wait at least five minutes for any residual gas to clear. The pilot adjustment screw is on the gas control valve, which is the brass or metal box mounted on or near the fireplace burner assembly. Look for a small flathead screw on the front or side of this valve—it will often have a tiny flame symbol printed next to it or the word "PILOT" stamped nearby.
If you cannot find it, check your fireplace manual or the manufacturer's website for your specific model number. The location varies slightly between brands. Some valves have the screw on the front face, others on the side. Once you locate it, you have found your adjustment point. Do not confuse it with the main on/off knob or the thermostat dial—the pilot screw is much smaller and recessed slightly into the valve body.
How to turn the screw and what to expect
Use a flathead screwdriver that fits the screw snugly—a screwdriver that is too large or too small will slip and strip the screw. Turn the screw in quarter-turn increments only. Clockwise lowers the flame; counterclockwise raises it. After each quarter turn, wait 10 to 15 seconds and observe the pilot flame to see if it has changed height.
You should see the flame respond within a few seconds of each adjustment. If you turn the screw and nothing happens, you may be turning the wrong screw, or the valve may have a safety lock. Some newer models require you to hold the knob in the "pilot" position while adjusting. Refer to your manual if the flame does not respond to your turns.
Getting the flame to the right height
The goal is a blue, steady flame that is about half an inch to one inch tall. The flame should be touching or nearly touching the thermocouple—the thin metal rod that sticks up from the burner assembly. If the flame is yellow or orange instead of blue, that usually means incomplete combustion and is not a pilot adjustment problem; call a professional to check the gas supply or valve.
If the flame is too low and won't ignite the main burner, turn the screw counterclockwise in small increments until the flame rises. If the flame is too high and is licking up the sides of the burner or extending well above the thermocouple, turn the screw clockwise to lower it. Once the flame looks right, turn the fireplace on and watch to see if the main burner ignites smoothly. If it does, you are done.
Testing the pilot after adjustment
After you have adjusted the pilot, turn the gas control knob to the "on" position and try to light the main burner. The pilot flame should ignite the burner within a few seconds. If the main burner lights and stays lit, the adjustment was successful. If the main burner does not light, wait 30 seconds, turn the knob back to "off," and try again—sometimes the burner needs a second attempt.
Let the fireplace run for a few minutes to make sure the flame is stable and the burner is not making unusual noises. If you smell gas, turn everything off when ready, open windows, and call your gas company or a licensed technician. Do not attempt further adjustments if you smell gas.
When to stop adjusting and call a professional
If you have adjusted the pilot screw through its full range and the flame still will not stay lit, or if the main burner refuses to ignite even with a healthy-looking pilot, the thermocouple or the gas valve itself may be faulty. These parts require professional replacement and are not adjustable. A thermocouple typically costs $50 to $150 to replace, depending on the model, and a gas valve replacement runs higher.
Also call a professional if the pilot lights but goes out as soon as you release the knob, or if you smell gas at any point during or after adjustment. These are signs of a deeper problem that adjustment cannot fix. A licensed HVAC technician or gas fireplace specialist can diagnose the issue and replace parts safely.
Frequently Asked Questions
Which way do I turn the screw to make the flame bigger?
Turn the screw counterclockwise to raise the flame and make it bigger. Turn it clockwise to lower the flame and make it smaller. Make quarter-turn adjustments and wait 10 to 15 seconds between each turn so you can see the change clearly.
What if I turn the pilot screw and nothing happens?
You may be turning the wrong screw, or the valve may require the control knob to be in the "pilot" position while you adjust. Check your manual for the exact procedure. If the screw turns freely but the flame does not change, the valve may be stuck or faulty and will need professional service.
Can a pilot flame be too small to see?
Yes. If the pilot is turned down too far, the flame may be so small it is hard to spot in daylight. In that case, turn the screw counterclockwise slowly while looking closely at the burner. You should see a small blue flame appear as you turn it up.
Is it safe to adjust the pilot myself?
Yes, adjusting the pilot screw is safe as long as you turn off the gas first and wait five minutes. The screw controls only the gas flow to the pilot, not the main burner. If you are uncomfortable working with gas appliances, or if adjustment does not solve the problem, hire a technician instead.
How often do I need to adjust the pilot?
A properly adjusted pilot should not need adjustment again unless something changes—such as a change in altitude, a repair to the valve, or a seasonal shift in gas pressure. If you find yourself adjusting the pilot repeatedly, the thermocouple or valve may be wearing out and should be inspected by a professional.