I'm seeking some insight, information, advice, etc. from the professionals here with more knowledge and experience than I.

I'd typically begin with the identification of the item in question: specific manufacturer, model number, age and any other relevant details but, for certain reasons, I'd prefer to keep this general, if possible.

I have a modern, computer-controlled, natural gas-burning appliance the manufacturer of which dictates must be re-calibrated after any changes to, cleaning or replacement of the gas valve. They further state the only way this can be done properly is by using a combustion analyzer, an expensive, industry specific device to which only a service technician would have access.

Of course, proper adjustment makes sense and, if available, the use the combustion analyzer would be "ideal". However, ideally I'd set engine timing with a timing light, etc. but I can also get it to run its best by adjusting it until the engine sounds what I know to be "just right".

Ideally, I'd tune a musical instrument using a stroboscopic, electronic, or digital tuner but, by listening and playing along with another instrument, we can get it close enough. The list could go on and on. Many things require adjustment, fine-tuning, calibration, synchronization, etc. and --in addition to whatever is considered the ideal method –assuming a certain degree of experience, knowledge or information– there also exists other less exacting methods that work sufficiently well.

But this company insists that it is absolutely 'critical' that it can ONLY be adjusted properly with the use of a combustion gas analyzer. It isn't made clear whether this is presumably for reasons of efficiency or safety (which, I supposes are ultimately, one in the same). I'm wondering whether this insistence even involves functionality, practicality or if it only concerns business (think auto dealership vs. independent mechanic) or as is so frequently the case these days, if it is more due to most decisions and actions being determined by lawyers because of liability issues.

For decades --before CO2 analyzers, gas analyzer, carbon monoxide detectors, etc. existed -- gas burners were adjusted by observing the flame, ensuring that it was strong, straight, pointed, consistent --not flickering or faltering-- and that the color was not yellow nor orange but blue; ideally all blue with a brighter blue triangular section at its base. I suspect that, when the analyzer's displays the right numbers, this is still exactly what one will observe.

Are modern appliances' adjustment that much more critical with smaller tolerances?

..or is this more a sign of the times?

In this day and age where people no longer understand how to give or take directions, and don't know the difference between left/right versus East/West but must rely solely on GPS units is it simply because it's fallen out of fashion for humans to be expected to actually 'know' something ..other than how to access some electronic device or another.

I'll mention that I can understand that the use of the gas analyzer may be necessary on a boiler or similar in which there is no visual feedback. In this case, there is a flame viewing window.

So in a nutshell, what I'm asking is, as long as I can adjust the flame to appear as described, what has traditionally been considered correct, can I rest assured that it's burning efficiently, cleanly, safely?

Hypothetically, how much improvement over this might be realized if a gas combustion analyzer were utilized? 1%? 3%?

Thanks for your input