Which device is primarily used to control temperature in electric heating systems?

In electric heating systems, the thermostat is the primary device used to control the temperature. It functions by monitoring the ambient temperature and regulating the operation of the heating system to maintain a desired setpoint. When the temperature drops below the setpoint, the thermostat signals the heating elements to activate, allowing the space to warm up. Once the desired temperature is reached, the thermostat detects this and turns the heating elements off, ensuring consistent comfort and energy efficiency.

The other devices listed have distinct roles in the context of HVAC systems. A contactor is an electrically-operated switch used to control power to various components, but it does not measure or control temperature directly. A furnace is the unit that generates heat, but it requires a thermostat to regulate when it operates. A compressor is typically associated with refrigeration and air conditioning systems rather than electric heating, as its function is to compress refrigerant and facilitate heat exchange in cooling processes. Understanding these distinctions highlights the essential role of the thermostat in controlling temperature in electric heating systems.