Checking Actual Heat Output Of A Rooftop Unit Using Testo Smart Probes

***Read First***

My pal Jason Rende has kindly reminded me that the discharge probe should be out of line of site of the heat exchanger if at all possible. The placement of 605i sensor in the supply may have messed with the final result. Although, the method and appliction still remains the same.

Checking actual heat output, in BTU/H, of any system has become very easy to do this day in age with tools like Testo Smart probes in conjunction with the Smart Probes app. In the video, I check system air flow and entire system performance using a 405i and two 605i Smart Probes.

Use this link for preferred Testo pricing at

Listen to the HVAC Know It All Podcast

Visit for articles and tips