What color should a furnace flame be? Blue
Blue. A gas furnace flame should be steady and blue with maybe a small tip of yellow, like the row in this photo. Mostly yellow, orange or a flame that lifts and dances means the burners aren’t getting the air they need, and that’s when a furnace can start making carbon monoxide.
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From one of our jobs
A row of blue burner flames inside a furnace
Right now: Look through the small window in the furnace door while it runs. Blue and steady is good; yellow, orange or lazy flames, turn the heat off and call.
Each flame here sits right on its burner and burns clean blue. Next to them you can see the igniter wires and the little window where the control board’s light blinks its status. The flame sensor sits at the far end of the row: if it can’t feel a flame, it shuts the gas off a few seconds after the burners light.
Rust flakes, dust and a dirty burner are the usual reasons a flame turns yellow. Don’t take the burner door off to look. The Heating Check covers the burners, the flame sensor and a carbon monoxide test, and you see what we see.
Quick answers
What people ask about furnace flames
Why is my furnace flame yellow or orange?
The burners aren’t getting enough air, usually from dirt, rust or a cracked part. A yellow flame burns dirty and can make carbon monoxide, so have it checked before you keep running it.
What is a furnace flame sensor?
A thin metal rod that sits in the flame. It tells the board the burners lit. When it’s coated, the furnace lights, runs a few seconds and shuts off, over and over.
Why does my furnace light and then shut off?
A dirty flame sensor is the most common reason. Cleaning it is a quick repair, and we check it on every Heating Check.
What does the blinking light on my furnace mean?
It’s the control board’s status code. Count the blinks and match them to the chart inside the furnace door, then call us with the number.
Who checks gas furnaces in Northern Virginia?
Call SwiftPro at (703) 997-9757. We check, repair and replace gas furnaces across Northern Virginia, carbon monoxide test included.
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SwiftPro Heating, Cooling & Plumbing
4230 Lafayette Center Dr N, Chantilly, VA 20151
44679 Endicott Dr, Suite 211, Ashburn, VA 20147
SwiftPro Plumber & Water Heaters
4200 Lafayette Center Dr, Suite N, Chantilly, VA 20151
Virginia Class A contractor license #2705192276