Another indirect CO2 reading using a combustion analyzer is to hold it near the floor and read the O2. If it drops much below the 20.9% norm, you have to ask yourself is this CO2 displacing O2 as it settles near the floor. Now, if you ambient O2 is dropping, you will start getting incomplete combustion and making Bad Stuff, which the analyzer will pick up. Just goes to part of the whole picture.

Sniffers are notorious for false positives. I've picked up a hit that turned out to be formaldehyde offgassing from wet insulation. I have also found a CO leak when it picked up on the aldehydes so I ran and got my analyzer and sure enough, CO! Most sniffers will hit on soap bubble test solutions so sniff then bubble (non-corrosive only).

BTW, analyzers are pumps that draw in room air from several feet whereas sniffers must be placed into the vapor cloud or it will give a false negative. I agree w/ David that Bacharach's Training Room is a good primer.
HTH
Bob

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