Heat Detector Spacing Calculator

Calculate heat detector layout and spacing requirements per NFPA 72 National Fire Alarm Code.

Detector rating must be at least 20F above max ambient

NFPA 72 Height Reduction Table

Ceiling Height Reduction Factor
Up to 10 ft1.00
10-12 ft0.91
12-14 ft0.84
14-16 ft0.77
16-18 ft0.71
18-20 ft0.64
20-22 ft0.58
22-24 ft0.52
24-26 ft0.46
26-28 ft0.40
28-30 ft0.34

Heat Detector Types

Fixed Temperature

Activates when element reaches rated temperature. Available in various ratings (135F-500F). Most common type.

Rate-of-Rise (ROR)

Activates when temperature rises faster than 12-15F per minute. Provides earlier warning for fast fires.

Linear Heat Detection

Continuous sensing cable. Ideal for cable trays, conveyors, and areas requiring linear coverage.