When indoor relative humidity increases, what happens to the temperature split?

When indoor relative humidity increases, the temperature split across an air conditioning system typically decreases. This phenomenon is related to the principles of psychrometrics, which describe the relationships between temperature, humidity, and the physical properties of air.

In HVAC systems, the temperature split refers to the difference between the supply air temperature and the return air temperature. When humidity levels are elevated, the air holds more moisture, which increases the latent load on the cooling system. As the system works to remove this excess moisture, it tends to cool the air less effectively since the cooling process is now more focused on dehumidification rather than just lowering the temperature.

This shift in focus leads to a smaller temperature drop as the air passes through the cooling coils, resulting in a reduced temperature split. Consequently, as indoor humidity rises, the ability of the system to maintain a significant temperature difference is compromised, ultimately demonstrating the inverse relationship between humidity and the temperature split.