When my security system was installed they also installed two heat detectors. One in the garage and one by the furnace (we already have wired smokes, so I’m not sure why). They have labels on them that say “Not a life-saving device”. I don’t understand what a heat detector would be used for if its not life-saving???
I think it says that because heat detectors are better suited for protecting property instead of people. A heat detector may not activate fast enough to help save lives, hence the wording “not a life safety device.”
In a fire, what ends up incapacitating a person is the smoke from a fire, not necessarily the fire or heat itself. You can have a small smoldering fire that will fill the area with smoke long before you have any significant heat. And the purpose of a fire alarm system is for early warning of a fire to give occupants time to get out of the building. Heat detectors will not detect smoke and may not give that early warning necessary to get people out if the building - there are some smoke detectors that have integrated heat sensing elements but that’s for another discussion. So as The Big Green stated, heat detectors are more for property protection (sounding the alarm to call the fire department) than for life safety.
Heat detectors can also be used as supplemental protection in system that already meets the minimum code. In your home, you should have the minimum one smoke detector per floor and/or outside all bedroom areas, and one some detector in each bedroom. A typical 3 bedroom, two story home with basement would need 6 smoke detectors. You can add heat detectors in “high hazard” areas that would be out of the operating range of a smoke detector or in an area where placing a smoke detector may cause false alarms - as long as you still are meeting the minimum code with the smoke detectors. These areas can include garages, laundry rooms, kitchens (you NEVER want to place a smoke detector near cooking appliances), heater rooms, or attics for example. There are heat detectors for 12/24VDC alarm systems - the typical Chemtronics or System Sensor style, and there are heat detectors that will work with the 120VAC smoke alarms more commonly found in homes - these are rare but can easily be found on the internet these days.