Do You use a Gas Detector?

I’ll try to answer some of your questions.

My CO measurement instrumentcost $1800 and my combustion gas sniffer was $350. I would not recommend that anyone rely upon a $150 piece of equipment other than a flashlight, perhaps, for this kind of inspection.

There is a specific protocol to use in applying these measures and people who are BPI certified have been trained and tested (including a field examination) to ensure that they are doing it correctly. You will not get this training from an online course and, depending upon where you go for your certification, it will cost between $1500 and $2000 by the time you finish the training and testing.

Yes, one of the steps is to insert the CO detector probe in the undiluted exhaust.

If you will Google CAZ (combustion area zone) testing, there are a bunch of videos and white papers that describe the process.

It is not something you should do and I don’t think anyone is insisting or pressuring you to incorporate this into your inspections. However, I don’t understand why you are being critical of those who are trained, certified and who do perform these tests.