Britannica
Sources used in this answer
How does a thermostat use feedback to maintain a set room temperature?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
automation
At the top of the machine is a stack of punched cards that would be fed into the loom to control the weaving pattern. This method of automatically issuing machine instructions was employed by computers well into the 20th century.
A thermostat maintains a constant room temperature by functioning as a closed-loop feedback control system. This process relies on five core components: an input, the process being controlled, an output, sensing elements, and a controller with actuating devices.1
- Input: The desired temperature setting (set point) chosen by the user.1
- Process and Output: The heating or cooling unit is the process, while the actual room temperature is the output being measured.12
- Sensing Elements: These devices monitor the room temperature. Traditionally, this was a bimetallic strip that flexes as it expands or contracts with temperature changes; modern units typically use thermistors.13
- Controller and Actuator: This mechanism compares the measured room temperature to the set point. If the temperature falls below the set point, the controller triggers the heater; if it exceeds the set point, it shuts the system off.12
By continuously comparing the actual output to the desired input, the system automatically adjusts to minimize any difference, ensuring the environment remains stable.1