Illinois Home Inspector Practice Exam 2025 – Comprehensive Test Preparation

The factor that most significantly affects Delta T, which is the temperature difference between two points or systems, is humidity. Humidity influences the moisture content in the air, which impacts heat transfer and the perceived temperature. When humidity levels are higher, the air can hold more moisture, affecting the thermal comfort level and how heat dissipates from surfaces, thus altering Delta T.

Temperature, while related, primarily affects Delta T directly instead of as a modifying factor like humidity does. Pressure and altitude offer different influences on physical behavior in various systems but are not primary factors in determining Delta T in typical environmental contexts. Therefore, humidity is crucial in understanding and analyzing the variations in Delta T, especially in home inspections dealing with heating, ventilation, and air conditioning systems.