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is it possible to convert a grill from natural gas to propane?

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Just an observation that doesn't make sense:


The current NG orrifice is approximately 1.2mm (caliper visual measurement).


This would be between #56 & #55 on the BTU charts. Which would be 3/64" or 0.0469".


The BBQ is rated for 4.5" WC NG. This orifice would be 6333 BTU per burner for NG according to the charts.


6333 x 6 burners = 38'000 BTU.


This is VERY different from the 75'000 BTU rating.


Any idea why?


Or is there typically 50% extra BTU to accommodate side burners?




A visual caliper reading is VERY inaccurate. I just measured with a toothpick (put permanent market on the orifice and stuck a tapered bamboo toothpick into the orifice until snug then measured where the mark on the toothpick was). It shows as 1.45-1.50mm depending on toothpick rotation.


1.4mm = 0.0551", #54 orifice is 0.0550" and 8709 BTU.


8709 x 6 = 52'000 BTU, leaving 22'000 BTU unaccounted for.


Looking better?

Edited by Koula

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The tag will only carry the BTU rating of the grill as Weber built it. There seem to be different vintages of the 6XXX grills from Weber. Does your model have a rotisserie burner? If so that most likely is accounting for 15K BTU of the rating. The typical Weber grill runs about 10 -12K BTU per burner in my experience BTW.

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No rotisserie, smoker, or side burner. Just 6 identical burners.


I'm inclined to go with a 1.0 mm hole, as it's easy to get this drill bit. This would be approx 11000 BTU at 11"WC LP per burner. 66'000.


Would this be too hot and too difficult to modulate with the NG valves?


Alternatively, I order a smaller drill bit and match the existing NG BTU rating (post above) at 52'000 BTU. LP orifice size 0.9mm or between #65 and #64.

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I am a little stumped. Every conversion I have done has been LP to NG not the other way. But IMO I would go with a #60 and work my way up from there based on grilling performance. I always fine tune. I have a set of drills and I work on the very low end and work up from there. My reasoning is that I don't have the ability to do it with the precision the factory has. I.E. I know my chuck will have slight "runout" and such so my theory is you can always go bigger but you can't go the other way

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