In which location should thermostats not be installed?

In which location should thermostats not be installed?

• A. On a wall away from direct sun.
• B. In direct sunlight.
• C. Near return air grilles.
• D. In a shaded closet.

Answer: (B)

Direct sunlight on a thermostat exposes its sensor to radiant heat, making it read a higher temperature than the actual room air. That leads the system to think the space is warmer and either delay cooling or run longer, wasting energy and reducing comfort. The thermostat should sense the true room temperature, so it belongs on an interior wall away from sun exposure and other heat sources. That’s why direct sunlight is not a suitable location. Nearby return air drafts or restricted airflow in a shaded closet can cause their own issues, but the primary problem this item tests is avoiding radiant solar heating on the sensor.

Direct sunlight on a thermostat exposes its sensor to radiant heat, making it read a higher temperature than the actual room air. That leads the system to think the space is warmer and either delay cooling or run longer, wasting energy and reducing comfort. The thermostat should sense the true room temperature, so it belongs on an interior wall away from sun exposure and other heat sources. That’s why direct sunlight is not a suitable location. Nearby return air drafts or restricted airflow in a shaded closet can cause their own issues, but the primary problem this item tests is avoiding radiant solar heating on the sensor.