What is the difference between a heat alarm and a smoke alarm?

Smoke alarms are triggered by smoke particles in the air — they're ideal for living rooms, hallways, and bedrooms where a fire would produce smoke before flames. Heat alarms don't react to smoke at all — instead they trigger when the temperature rises above a set level (usually 58°C) or rises very quickly (rate-of-rise detection). This makes them perfect for kitchens, where cooking steam and toast can set off a smoke alarm dozens of times a week. Heat alarms are also used in garages (car exhaust fumes) and lofts (dusty environments where smoke alarms false-alarm). The downside of heat alarms is that they respond more slowly to a developing fire than smoke alarms — a fire must already be generating significant heat before a heat alarm triggers. So never use a heat alarm in a living room or bedroom. Use smoke alarms where you sleep, heat alarms in high-false-alarm areas.