System Sensor 5621 135F Dual-Circuit Heat Detector
Overview
The System Sensor 5621 is a 135°F fixed/rate-of-rise heat detector engineered for conventional fire alarm systems operating at 35VDC. The dual-circuit architecture allows deployment in both conventional and addressable system configurations, eliminating the need to stock separate detector types across mixed fleet installations. Fixed-temperature detection at 135°F addresses moderate-temperature indoor environments, while rate-of-rise functionality triggers on rapid temperature increases — critical for spaces where ambient heat buildup is gradual but fire signatures demand immediate response. This combination reduces nuisance alarms while maintaining detection reliability in general commercial and light industrial spaces.
Compatibility
The 5621 integrates with conventional fire alarm control panels operating at 35VDC and supports dual-circuit wiring schemes common in retrofit and new construction deployments. System Sensor conventional detection systems — including legacy addressable hybrids — accept the 5621 without protocol conversion or relay interfaces. Verify your panel's voltage and loop configuration (conventional vs. addressable) before selection; the dual-circuit design accommodates both, but wiring topology must match your installed base.
Installation Notes
Mount in areas where temperature setpoints of 135°F are appropriate — corridors, storage rooms, mechanical spaces, and general-purpose zones. Avoid mounting directly above heat sources (HVAC vents, incandescent fixtures) that may trigger rate-of-rise on non-fire events. Ensure 35VDC loop power is properly fused and supervised per NFPA 72 requirements. The detector requires standard E-series mounting bases compatible with System Sensor conventional lines; confirm base availability in your project specifications before ordering.
