Do you know the 4 operating modes of a DX Make-Up Air Unit with Hot Gas Reheat? Most of us have worked with these systems, but breaking it down on the psychrometric chart really shows how they behave under different outdoor conditions. Here’s a quick walkthrough. For this example we are designing for a 75F DB SAT that is below a 55F dew point set point. Dehumidification Mode – When it’s hot and humid (e.g. 95°F DB / 78°F WB), the air is above the dew point set point. The DX coil cools the air be