By how many degrees must the ambient temperature of a ceiling be below the rated value of the heat detector for installation?

For the installation of heat detectors, it is essential that the ambient temperature of the installation environment be lower than the rated value of the heat detector to ensure that the device operates effectively and provides a reliable response to a fire. The general standard in many fire safety codes indicates that the ambient temperature must be at least 20 degrees below the rated value of the heat detector.

This standard is designed to accommodate fluctuations in ambient temperature and to ensure that the heat detector can accurately detect temperature increases indicative of a fire. If the ambient temperature exceeds the specified limit, the sensitivity of the heat detector may be compromised, leading to delayed activation or false readings.

By requiring an ambient temperature at least 20 degrees below the rated value, the system maintains a functional margin that helps prevent nuisance alarms while ensuring that fires can be detected in a timely manner.