I recently observed a home inspection done by one of the larger national franchised inspection companies local inspector. I was not surprised to see him take out an non-contact IR pyrometer - but I was surprised to see how he used it. he pointed it first at the return (filter) grid, took a reading. Then he pointed it at a register plate both were metallic - one painted, other anodized. On two different systems he got the same results - only a 10 or 11 degree F differential. This was done on a cool, dry day at 60F as well.
I then did what I consider as a more proper method for this simple test - I put a new digital stick thermometer into the plenum above the evaporator in the path of the airflow, took a reading after it settled, then put the same thermometer in through the filter at the return.
Interestingly, the thermometer yielded a differential 5 degrees greater than that measured by the IR tool.
I then took out my own IR pyrometer and repeated the test his way - and got exactly the same results he did - a much lower differential.
The inspector was pig-headed and wrote his report up describing a below-standard differential.
While I realize that the differential temps are only one simple way to measure the true performance of a cooling system, I also realized that this one flawed test would cause anywhere from thousands of wasted dollars in further inspections and repair/replacement work to possibly even cancelling a perfectly good real estate transaction at the cost of two families and two licensed real estate professionals.
I am curious as to whether or not others have seen this same convenient, but unprofesional method used by home inspectors before, and just how often this is done.
If this is common practice these days, don't we as an industry have a responsibility to attempt to correct this?
What say ye?