termostats

A thermostat is a device that regulates temperature by sensing the environment and switching heating or cooling equipment on or off to maintain a user-defined setpoint. It is commonly used in buildings and household appliances to provide comfort and conserve energy.

Thermostats work by comparing the current temperature to the setpoint. When the temperature drifts beyond a predefined differential, the thermostat activates the appropriate system. The differential, sometimes called hysteresis, prevents short cycling and reduces wear on equipment.

There are several types. Mechanical thermostats rely on a bimetallic strip or other thermal expansion mechanism to actuate a switch. Electronic thermostats use temperature sensors such as thermistors or RTDs and solid-state switches. The range includes non-programmable, programmable, and smart thermostats; multi-stage versions manage heating and cooling in more complex systems.

Power and control vary by design. Some thermostats are line-powered and directly switch high-voltage equipment, while most modern heating, ventilation, and air conditioning (HVAC) thermostats operate on low-voltage 24 V control circuits. Sensing elements determine accuracy and response time, with digital devices typically offering finer resolution and remote control via wireless networks.

Applications span residential and commercial heating, ventilation, and air conditioning, as well as certain appliances and industrial processes. In homes, programmable and smart thermostats enable schedules, remote monitoring, and learning capabilities to improve efficiency.

Safety and standards are overseen by organizations such as UL and CE. Proper installation, calibration, and compatibility with the controlled system are essential for reliable operation and energy savings.