Gas furnace not lighting all burners

This one covers a gas furnace not lighting all burners and dropping out on flame safety. This video is part of the heating and cooling series of training videos made to accompany my websites: and to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome.
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits.

26 Replies to “Gas furnace not lighting all burners”

  1. Great video. Simple and straightforward explanation of what’s supposed to happen and what’s preventing it. I’m going to remove mine and clean it now that cooler weather is here and I’m getting this issue. Thanks!!!

  2. I didn't have a long enough extension to reach the bolts on my far right one on hand and mine would only light on one burner for the first trial or two. Usually on the third trial it would light off all of them but would be kind of "explosive" in doing so. Just to get it working good for now, I took a Dremel brush wheel, bent some of its wires, and was able to work them back and forth through the cross lighters (crossways or whatever they're called). Fires up all the burners good now. Thanks GrayFurnaceMan!

  3. Thank you sir! Used this today… saved me a service call. I appreciate you sharing your knowledge! Getting the burners OUT of the unit was the toughest part.

  4. old video but this was my exact problem, was trying to diagnose it for a while, didn't know exactly how the flame jumped, this was a great explanation

  5. Thank you for the suggestion of watching the burners light. I was starting to look for the temp sensor and saw the last burner was not lighting. I cleaned the last two and it resolved my problem.

  6. Ive found so many videos talking about the gas manifold orphises being dirty being the issue but this is the first one ive seen talking about the spreaders being a potential issue. Great video man, thx!

  7. this seems like it maybe my issue as well, the ignitor comes on but the first burner wont light. I think its clogged, now I know how to take it off and what to expect thank you.

  8. Thank You ! Same exact scenario on AM Standard Freedom 90 – just enough – not much rust to restrict the travel of gas . Gently Used a utility knife blade to remove rust.
    And did the trick.Thanks Again

  9. Thanks for this. In my case, the metal of the flame spreader was pinched in a way that blocked the gas to the last burner. Pried it open with a putty knife, thanks to this video.

  10. For the past 20 years I've worked in the HVAC industry every summer when I got laid from a seasonal job. I made crazy money doing this. This changed over the past year & I'm doing HVAC all year long. It took me hours earlier today to figure out clogged crossover tubes. I've been dealing with things like this all season. It feels like I'm 18 again. Thanks for the video

  11. This really helped me tonight. I live in Tampa Florida we mostly deal with heat pumps electric heat strips so I was stuck for about an hour. Thanks again for the help great video.

  12. This video just fixed what was wrong with our furnace after replacing 3 different parts … thank you very much for sharing we now have heat after 3 weeks of nothing..we just needed a finger nail file to open the flame spreaders…

  13. Thank you for the video! This was my problem and after a quick wire brush treatment it works great!

  14. This is exactly what is going on with my furnace wish me luck going to try to clean it and fix it myself

  15. One of my 4 burners was not igniting well by watching it. I removed some dust with tissue paper from the top. I tapped on each burner spreader with a screw driver from the top a few times. I used a small vacuum attachment to vacuum some in the area. Turned on the furnace and this last burner now spread flames better and the furnace would stay on. Before I had a furnace installer look at it and he replaced the blower motor for $600 but said one burner was not coming on well and did not fix this. Thanks great tip.

  16. Thank u so much for this video. YouTube is awesome and so are u. Fixed my heater that has been giving problems forn3 years now. Changed limit and pressure switch. And sure it was only hot surface ignitor the whole time!! U rock man. Thank u soooooo much

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