"Richard, it's not just the burner, it's the whole burner/mixer tube/jet package. Think about it:
- at the bottom of the mixer tube, the pressure inside is less than atmospheric and so air is sucked in thru the bottom holes
- at the top of the mixer tube, the pressure inside is more than atmospheric, so gas/air is forced out thru the holes in the burner"
Stuart, quite correct. Most gas burners we use simply use a series of holes around the base of the jet to adjust air inlet. Pretty obvious that air at 15000' will NOT contain as much oxygen as air at sea level. One of the lacks, for flame temperature and CO/CO2 prodiction is a simple air regulator. For those that worry about CO production, it is easy enough to simply file out the holes letting more air into the premixed gas for burning.
In practice, this means it will perform better at high outputs at sea level and better at High Altitudes on lower settings. Or, simply open the inlet holes (minding the distance to the jet (usually somewhat below midpoint) and making a sleeve adjustment for yourself out of brass shimm stock with matching holes in them. A quick and dirty adjustment for air inlets.
Idealy, a change in jet pressure will need a slight adjustment to air, also. This is usually complicated by the matter that two controlls makes it difficult for many people to use...like your gas stove at home. Adjusting gas, then adjusting air. They don't bother, usually simply supplying a sleve than is set with a screw. You do NOT normally need to change this, except if you do mostly high heat cooking, or, mostly low heat cooking, or, live at some high altitude (over 3000'.) A camp stove is about the same, but CO emisions can be greatly reduced by simply over sizing the inlet ports. The flame distance has a little to do with it, but, more importantly, it is the initial combustion mix that determines the byproducts.
Fettling this stuff is really easy.