It is also a good idea to do a flow and BTU check on these systems. I work with one of the Engineers over at APS (local power company) that does this type of work for APS. I will find out exactly how they do it. I am pretty sure he just does it with a BTU/flow meter.
Well let us know what you find out
They use an ultrasonic tester that also does temperature. With the flow number and the temperature number it then calculates BTUs. It cost in the $13,000 range…OUCH! Here in AZ it is required as a test out procedure in order for the system to qualify for any type of rebate to the end user.