As a results-oriented mechanical engineer with much experience in data logging and control systems, I agree with your assessment.
Hell, I can guess THAT close! LOL
Engineering should be easily able to get to 10
%. With some gained knowledge, thought and experimentation in the field, 1% is generally quite economically achieved.
I'm just a silly EE with 23 yrs under my belt in R&D. If I delivered a product to my boss that had a critical component like temperature with a +/-20% accuracy - I wouldn't have a job today.
I mean, I can understand 5% accuracy - but they go on to suppose how the entire unit gets warm. How much heat is lost to the unit cooling? He doesn't have a clue. Where is the placement of this heat? No idea. Why make steam, when you can simply be a heat exchanger and remain in the linear region of the water heating tables?
I think he's on to something; but this continual refusal to provide accurate data is hurting him.