I am Nate Certified Heat Pump & Gas Hydronics. I am also RSES CM. We need some standardized certifications in our industry. Most other professionals have to pass some sort of test to get a license. Would you want a Doctor who could not pass his licensing exam but was "still a good Doctor"?
You need both practical knowledge and book smarts in this industry, especially on complicated systems like Infinity. It sounds like someone already did the easy stuff when they installed it. Now you need some book smarts to make it work properly.