Simplex 4098-9778


Heat Sensor

Availability: In Stock

Condition: New
Brand: Simplex
Status: Active
SKU: 46861
Manufacturer Part #: 4098-9778


TrueAlarm heat sensors are self-restoring and provide rate compensated, fixed temperature sensing, selectable with or without rate-of-rise temperature sensing. Due to its small thermal mass, the sensor accurately and quickly measures the local temperature for analysis at the fire alarm control panel.

Rate-of-rise temperature detection is selectable at the control panel for either 15° F (8.3° C) or 20° F (11.1° C) per minute. Fixed temperature sensing is independent of rate-of-rise sensing and programmable to operate at 135° F (57.2° C) or 155° F (68° C). The 4098-9734 sensor provides an additional 190° F (88° C) set point.

In a slow developing fire, the temperature may not increase rapidly enough to operate the rate-of-rise feature. However, an alarm will be initiated when the temperature reaches its rated fixed temperature setting.

TrueAlarm heat sensors can be programmed as a utility device to monitor for temperature extremes in the range from 32° F to 155° F (0° C to 68° C). This feature can provide freeze warnings or alert to HVAC system problems.

Additional information

Weight 0.2 lbs

Set via Base

Thermal Rating

135°F, 155°F, Programmable



Detection Method

Fixed Temperature, Rate-of-Rise


Production Status



  • Sealed against rear air flow entry
  • Interchangeable mounting
  • EMI/RFI shielded electronics
  • Selectable rate compensated, fixed temperature sensing with or without rate-of-rise operation


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