A heat alarm is designed to detect heat instead of smoke, the alarm contains a thermistor which is set to respond to temperatures above 58°C.

When a fire breaks out hot air from the fire will rise and enter the sensor chamber.

When temperature inside the chamber reaches 58°C a signal is sent to the integrated circuit which causes the alarm to sound alerting the occupants to the fire.

Heat alarms can be situated in the kitchen and the garage, because heat alarms don't react to smoke they are not prone to false alarms from cooking and exhaust fumes.

View our other guides to find out how different types of smoke and heat alarms work.