What is the correct spacing of a heat detector listed for 25 feet when mounted at a ceiling height of 25 feet?

The correct spacing for a heat detector can be determined by considering the manufacturer’s specifications and applicable codes or standards, which generally provide guidance on installation based on the detector's listed spacing. When a heat detector is rated for 25 feet, this means it has been tested and approved to provide effective detection of heat within a 25-foot radius under certain conditions.

In this scenario, when the detector is installed at a ceiling height of 25 feet, the effectiveness of its heat detection may be influenced by the distance between the detector and the area it is meant to cover. Typically, the effective coverage area often diminishes or requires adjustments when installed at higher elevations.

To optimize detection while adhering to safety protocols, the standard practice is to reduce the coverage radius proportionally as the mounting height increases. Therefore, the distance of 11 feet 6 inches is derived from an accepted calculation that halves the spacing because the height reaches the maximum rated level. This allows for effective heat detection while accommodating for the altered dynamics at an increased elevation.

This is the rationale behind selecting the spacing of 11 feet 6 inches for the heat detector installed at a ceiling height of 25 feet.