Smoke alarms detect smoke fit them in all rooms where a fire might start. But in smoky or steamy rooms like kitchen or bathroom, a heat alarm is more suitable. These alarms go off when the room reaches a certain temperature.

A heat detector is usually used in rooms where there is excessive dust or fumes for instance, a garage or cellar which a smoke alarm can mistake for dust, soot or combustible elements in the atmosphere. It's also used in rooms where highly-flammable chemicals are stored.

Electro-pneumatic heat detectors contain a diaphragm which moves when there is a change in pressure owing to a shift in the ambient temperature. When the diaphragm moves, an electric circuit is completed, which activates the alarm. Rate of Rise or ROR heat detectors operate using two heat-sensitive thermocouples.