A heat detector is a device that is used to warn people of a possible fire. These alarms are designed to go off when a certain temperature is met or when the temperature in a room rises at a certain rate. Kitchens and closets are areas that can benefit from the installation of a detector, as smoke detectors are not appropriate for these types of spaces. Though they are not meant to replace smoke detectors, heat detectors are a useful supplemental form of fire detection.
One type of detector is the rate-of-rise heat detector, which detects a sudden rise in temperature. These detectors are particularly useful if a fire grows rapidly or explosively. If the temperature in the room rises quickly, this type of alarm will be triggered.
Rate-of-rise heat detectors can be set to detect different rates of temperature change, depending on what is required for the situation. Many modern rate-of-change heat detectors are also designed to ignore a change in temperature that passes quickly, such as would be caused by opening an oven door. These detectors work well in cold areas. Slowly growing fires, however, may not set off this type of alarm system.
The other type of detector, which is called a fixed-temperature heat detector, works by detecting the temperature in the room and setting off an alarm when a certain temperature is reached. A metal component on the detector is designed to melt at a certain temperature, causing the alarm to sound. The melting temperature of this component is set at 117 degrees Fahrenheit (47 degrees C) or higher, and the device is designed to work without a power source. A lag in time exists between when the temperature in the room reaches the melting point of the alarm trigger and when the temperature in the detector causes the device to melt. This type of fire safety device is most useful in warning against slowly developing fires.
A heat detector is not designed to be used as the only fire warning system in a building. The vast majority of fires are detected more quickly with smoke detectors than with heat detectors. A combination of the two types of devices can provide the most reliable fire warning system for a home or other type of building.