Hi, I am thinking of buying Fiedpiece Instrument HVAC Guide. I would like to know in order to check super heat data required is DB for out door and Return WB. One of videos highlights the same on youtube where the wetbulb probe is place in return air duct of AHU. Confused why return wet bulb temp is required,where i presume the temp of the suction pipe near the exit of the evapoartor is to be recorded after the TXV bulb. Hence, what is the importance of return wet bulb temp.