Where is the sensor for an outdoor ambient thermostat typically installed?

The outdoor ambient thermostat sensor is typically installed in the entering air stream to the outdoor coil. This location is crucial for accurately measuring the temperature of the air that the heat pump will be using for heating or cooling. By placing the sensor here, the thermostat can respond effectively to the changes in outdoor temperature, allowing the heat pump to operate efficiently and adapt its performance to prevailing weather conditions. This precise monitoring is essential for optimizing the system's operation and ensuring comfort in the conditioned space.

The other placements are less effective because an indoor air return duct would not accurately reflect outdoor conditions, while placing the sensor on the compressor unit or inside the electrical panel could lead to incorrect readings and potentially hinder the overall performance of the heat pump.