Where should temperature sensors be placed for accurate control and why?

• A. In representative zones away from heat sources, drafts, or direct sun, typically near the occupied space throat or supply air return path.
• B. In the mechanical room.
• C. Right next to the exterior wall.
• D. Random locations throughout the building.

Answer: (A)

Measuring temperature where occupants experience the most consistent conditions is essential for accurate control. The sensor should be placed in representative zones away from heat sources, drafts, or direct sun so the readings reflect the actual space that the system is serving rather than local anomalies. Placing it near the occupied space throat or in the supply air return path helps the controller respond to the air that will enter the rooms, improving comfort and energy efficiency.

If the sensor sits in the mechanical room, it picks up the equipment’s heat and ventilation effects, giving a biased reading that can cause the system to overcompensate. A sensor placed right next to an exterior wall can be affected by solar gain or outdoor temperature, not reflecting the room conditions. Random locations lead to inconsistent data and unpredictable control.