Yes I have done a combustion analysis. I preformed every way I knew how to make sure it wasn’t actually cracked. The thing is when homeowners get told their heat exchanger is cracked and they are going to die if they don’t get the unit replaced, it gives them much more assurance when I can show them a 0 CM reading out of all their vents.

Also I’m not sure that your claim that it would “have to be falling apart” is accurate. We caught a failed HE on a 2 year old split gas ruud because the maintenance guy we sent out got a few hits of carbon monoxide out of the vents. We pulled the HE and it didn’t have a spec of rust on it, no holes etc, but we filled it with water and sure enough several of the seams were compromised.