Key Features

  • 58°C & 78°C fixed temperature and rate of rise heat detectors
  • Ability to customise the heat thresholds
  • 100% mechanical and electrical backwards compatibility 
  • -30°C to +80°C operating temperature range
  • 10% to 93% relative humidity


System Sensor Addressable Heat Detectors use low mass thermistors and microprocessors to provide fast response temperature sensing. 

System Sensor Addressable Heat Detectors can be configured to provide fixed heat detection at either 58°C or 78°C or as a rate-of-rise detector with 58°C threshold and a rate-of-rise of 10°C/minute.

System Sensor detectors are housed in a modern, white enclosure that includes a tri-colour LED that provides 360° visibility and are available with or without single pole short circuit isolation.



Tech Specs

Operating Voltage Range 15 to 32Vdc
Maximum Standby Current 200µA at 24VDC (no communications)/ 300µA at 24VDC (LED blink enabled, once every 5s)
Led Current Red: 3.5mA at 24VdcGreen: 7.0mA @ 24Vdc   Yellow: 10.5mA @ 24Vdc
Remote Output Voltage  22.5Vdc @ 24Vdc
Remote Output Current  10.8mA @ 24Vdc
Additional Loop Resistance Using The B501AP          Typical 20mohm (max 30 mohm)
Temperature Range-30°C to +80°C †
Humidity10 to 93% relative Humidity (non-condensing)
Heat Detection Performance 52051RE / REI Class A1R – 58°C fixed temperature and rate of rise
Heat Detection Performance 52051E / EI Class A1S – 58°C fixed temperature
Heat Detection Performance 52051HTE / HTEI  Class BS – 78°C fixed temperature
Height61mm installed in B501AP base
Diameter 102mm installed in B501AP base
Weight88g (excluding base)
Max Wire Gauge for Terminals 2.5mm2

† Do not install detectors in locations where normal ambient temperature exceeds 50°C



Eurofyre is an authorised distributor of Honeywell and we support the entire Morley IAS and System Sensor range of products. We offer expert advice and supply all aspects of fire detection systems including excellent before and after-sale support.

Contact us to receive competitive trade discounts or apply online for a credit account.

System Sensor Addressable 58°C Fixed Heat Detector with Base


System Sensor Addressable 58°C Fixed Heat Detector


System Sensor Addressable 58°C Rate of Rise Heat Detector


System Sensor Addressable 78°C Fixed High Heat Detector


System Sensor Addressable 58°C Rate of Rise Heat Detector, Isolator