A yellow, wavering burner flame can indicate incomplete combustion, but never open a furnace solely to inspect the flame. If you already see yellow flame, soot, or a carbon monoxide alarm sounds, turn off the equipment if you can do so safely, move everyone into fresh air, and call for emergency help.
What to do right now
If a carbon monoxide alarm sounds, move everyone—including pets—into fresh air and call 911. Do not re-enter until responders say it is safe. If you smell gas or a rotten-egg odor, leave immediately without operating switches, thermostats, lights, or phones indoors; call 911 or the gas utility from a safe location.
If you see soot, smoke, a yellow or unstable flame, or scorching and there is no immediate gas-leak danger, turn the furnace off without opening panels and call for service. Seek medical care for headache, dizziness, nausea, confusion, weakness, chest pain, or breathing trouble.
What furnace flame color can indicate
On equipment where the burner flame is visible through a manufacturer-provided viewing port, a steady blue flame is generally associated with more complete combustion. A persistently yellow, lazy, lifting, or wavering flame can indicate a combustion, fuel, airflow, burner, or venting problem. Flame appearance alone cannot diagnose the cause.
Do not confuse a brief orange flicker caused by airborne dust with a persistent yellow flame—but do not dismiss an abnormal flame either. A trained technician must test combustion and venting with appropriate instruments.
Why carbon monoxide requires a working alarm
Carbon monoxide is colorless and odorless. You cannot confirm its absence by looking at a flame, smelling the room, or feeling normal. Working carbon monoxide alarms provide the essential warning. Follow the alarm manufacturer’s placement, testing, battery, and replacement instructions.
A silent alarm does not make soot, repeated ignition trouble, or an unstable flame safe. Those signs still require the furnace to remain off until inspected.
Never attempt these furnace fixes
Never bypass a limit, rollout, pressure, or door switch; adjust a gas valve; drill or clean burners; modify venting; tape over an alarm; or operate equipment with a panel removed. Do not use an oven, grill, or unvented outdoor heater to warm the home.
Reduce risk before Big Country heating season
Test alarms, replace the furnace filter as needed, keep combustion-air and vent areas unobstructed, and arrange furnace maintenance before sustained cold weather. Review the guide to a burning smell at heater startup. For suspected equipment trouble without an active emergency, request heating repair in Abilene.
Frequently asked questions
Does a yellow furnace flame mean carbon monoxide is present?
A yellow or unstable flame can indicate incomplete combustion and deserves immediate professional inspection, but flame color cannot confirm carbon monoxide levels. Only proper testing and working carbon monoxide alarms provide useful detection.
What should I do when a carbon monoxide alarm sounds?
Move everyone and pets into fresh air immediately and call 911. Do not silence the alarm and remain inside, and do not re-enter until emergency responders say it is safe.
Need help with your heating system?
Wright Choice serves Abilene and nearby Big Country communities.