Can anyone share a story or advice dealing with a cracked heat exchanger? At the time of inspection, no cracks were visable. Now, some 5 months later, a client is saying I missed it during the inspection. Should I prepare for a lawsuit?

Why are you posting this in two different spots???

Joshua with all due respect - it depends on how and what you reported. As an example did you possibly indicate an approximate % that was visible, and if and how you observed its condition. You indicate no cracks were visible, which in itself may be factual or possibly not indicative of having full view of all of the heat exchanger. Were other tests or tools used to substantiate that statement, or is it based solely on observation?

There are other points that may potentially influence the strength or weakness of your report, such notation of specific limitations, etc.

Just a start to get this topic going.

If you said it was OK , than yes you should.

Heat exchanger evaluation is not part of home inspection for several reasons.
Read the SOP and let me know what you think.
I’ll fill in the blanks.