Adjusting the Pilot Flame Step by Step Guide
Adjusting the Pilot Flame
If the pilot is weak, oversized, or not enveloping the thermocouple/thermopile tip, a small adjustment on the valve’s pilot screw usually fixes it. The ideal pilot is steady and mostly blue, with a small yellow tip, and should fully heat the sensor tip so the main valve stays open reliably.
Safety and preparation
- Shut off gas: Turn the appliance off and close the local gas shutoff valve. Let the unit cool completely before touching components.
- Ventilation: Ensure good airflow and no drafts into the combustion area; drafts can cause a “dancing” pilot that won’t heat the sensor properly.
- Tools: Use a small flathead screwdriver and a flashlight. No power tools.
Tip: Most pilot adjustment screws are brass and sit on the gas control valve, often labeled “Pilot” or “Set.” If unlabeled, consult the unit’s documentation to confirm the correct screw before turning anything.
Identify the pilot assembly and adjustment screw
- Locate components: Find the pilot burner, thermocouple/thermopile, and gas control valve behind the lower access panel or near the burner tray.
- Find the pilot screw: On the gas control valve, look for a small brass screw marked “Pilot” or “Set.” This screw controls pilot gas flow, changing flame size.
- Confirm flame target: The pilot flame should contact and envelop the sensor tip (thermocouple/thermopile) for reliable heat sensing
Re-light and observe the current flame
- Light the pilot: Follow the appliance’s lighting instructions to relight so you can watch the flame while adjusting.
- Evaluate flame quality: Healthy pilot = steady, mostly blue, slight yellow tip; too small = weak/unstable; too large/yellow = wasteful and can soot components.
Adjust the pilot flame (quarter-turn increments)
- Start small: Turn the pilot adjustment screw in quarter-turn increments.
- Clockwise: decreases gas flow, smaller flame.
- Counterclockwise: increases gas flow, larger flame.
- Let it stabilize: After each tweak, wait 30–60 seconds and observe the flame and sensor coverage.
- Aim for ideal: The flame should be predominantly blue, steady, and fully envelop the sensor tip. A tiny yellow tip is acceptable; avoid long yellow, lazy, or sooty flames.
If the flame won’t tune correctly
- Clean the pilot orifice: A dirty pilot tip can cause weak, split, or yellow flames. Turn the gas valve to OFF and gently clear the tiny orifice with a fine pin or a single wire from a wire brush, then relight and reassess.
- Check sensor position: Ensure the thermocouple tip sits in the flame; if it’s too far, it won’t heat enough to keep the valve open.
- Eliminate drafts: Resolve any air leaks that make the pilot dance; replace the cover and retest.
- Consult documentation: If the screw isn’t identified or the valve layout differs, verify with the specific valve/appliance manual before proceeding.
Final checks
- Stable operation: Pilot holds steady, stays lit for several minutes, and the main burners ignite reliably when called for heat.
- No soot or odor: Flame remains clean and blue; no excessive yellowing or carbon deposits.
- Secure panels: Replace access covers and confirm safe, draft-free operation
Darin DeVries
HVAC Part Store LLC
Coleman HVAC Parts
Technical Service Advisor
Author, entrepreneur, e-Commerce