Flame out of Air Mixer Holes on Vented Pan Burner

Written by Rett Rasmussen

Updated at July 27th, 2024

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Here are the potential causes of a flame coming out of the air mixer holes:

The pan is filled with sand, which creates too much back pressure for the gas to push through the sand, so it takes the path of least resistance by exiting out the air mixer holes. Any pan burner with the air mixer should only be filled with volcanic ash.
The pan may be filled with volcanic ash, but the same type of issue as in #1 above is occurring. The volcanic ash has settled, become laden with debris or for whatever reason is preventing the free flow of gas through the pan media. I recommend removing all of the volcanic ash from the pan, then refilling the pan (preferably with new volcanic ash). While the pan is unfilled, inspect the burner ports (holes, which face downward) to ensure they are open. If they have closed from corrosion, the burner pan should be replaced.
An orifice was not installed in the brass fitting at the inlet side of the air mixer. The orifice (small hole) speeds up the gas so that it pulls in the air through the air mixer holes, allowing the air to mix with the gas. Without an orifice, the gas travels too slowly to properly mix with the air, and spills out the air holes.
There is an obstruction in the air mixer that is blocking the total flow of gas to the burner, spilling some of it out of the air mixer holes.

burner vents air flames

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