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How does a thermostat work?
Quick answer
A thermostat works by sensing the room's temperature and switching heating or cooling on or off to keep it near a set target. It is a feedback loop: when the room drifts from the setpoint, the thermostat turns the system on until the temperature returns.
Step by step
- It compares the measured temperature to your chosen setpoint.
- If the room is too cold (or too hot), it switches the heating (or cooling) on.
- When the target is reached, it switches the system off — a continuous feedback loop.
- Older units used a bimetallic strip that bends with temperature to flip a switch; modern ones use electronic sensors.
- Smart thermostats add schedules and learning to anticipate your needs and save energy.
People also ask
What is a setpoint?
The target temperature you choose. The thermostat works to keep the room close to it by switching the system on and off.
How did old thermostats sense temperature?
Many used a bimetallic strip — two metals that expand at different rates — which bends as it heats or cools and trips a switch.
How do smart thermostats save energy?
They learn your routines and adjust automatically, avoiding heating or cooling an empty home and trimming waste.
How does a thermostat control temperature?
It senses the current temperature and turns heating or cooling on or off to keep the room at your set target.
What is a smart thermostat?
One that connects to the internet, learns your habits, and can be controlled remotely to save energy.
Why does my heating cycle on and off?
The thermostat switches it off when the target is reached and back on when the room cools, keeping it steady.
Part of the guide: Everyday Machines →