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Heat Detector
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Heat Detectors for Harsh Environments

Heat detectors monitor ambient temperature changes or rate-of-rise to provide early fire alarms. Ideal for dusty, steamy, or smoky environments where smoke detectors may cause false alarms.

Our FHD1100, FHD912, and FHD751 heat detectors use stable and reliable thermal sensing technology, delivering fast response, strong interference resistance, and easy installation and maintenance. Widely applied in industrial plants, warehouses, and equipment rooms, they ensure dependable fire detection for fire protection systems.

Fire Detector PDF
Heat detector on white background
Working Principle

Heat detectors monitor ambient temperature changes or reach a preset threshold to identify fire conditions and send an alarm signal to the fire alarm system.

Core process: Temperature rise → sensor activation → circuit response → alarm signal output.

Heat detector on normal condition
Normal Conditions

In normal conditions, air expanded by asmall amount of heat is allowed to escape from the vent.

#
Heat detector sensing temperature rise
During Fire 1

Heated up suddenly in a fire.

#
Heat detector activated
During Fire 2

After a certain rise in temperature,the expanded air will push the diaphragm up and close the contact, sending a signal.

Category
  • FHD1100
  • FHD912
  • FHD751
FHD1100 Heat Detector
Technical Specifications
  • Sensitivity: A1R or A1S
  • Operating Voltage: 10 to 33 VDC
  • Standby Current: 70 to 100 μm
  • Standard: EN54-5: 2010
  • Alarm Indicator: Red LED (Steady on)
  • Reset Voltage: < 5 V
  • Reset Time: < 2 s
  • Operating Temperature: -10 °C to + 50 °C
  • Humidity: 0 to 98% RH, non-condensing
  • Weight: 91 g (with base)
  • Dimensions: Ø106 mm × 35 mm (H), with base
  • Alarm Current:
    • FHD1100-A1S/A1R: 35 mA ± 2 mA @ 24 VDC
    • FHD1101-A1S/A1R: 32 mA ± 2 mA @ 24 VDC
  • Classification:
    • FHD1100-A1S / FHD1101-A1S: Fixed temperature, 60 °C
    • FHD1100-A1R / FHD1101-A1R: Rate-of-rise, > 8.5 °C/min
FHD1100 heat detector on white background
Features
  • Two-wire heat detector.
  • Wide voltage range with stable output.
  • Easy installation and maintenance.
  • Intelligent temperature compensation, low false alarm rate.
  • Durable sensor, no replacement required.
  • Compact and aesthetic design.
  • Cost-effective with high performance.
Dimensions
FHD1100 heat detector dimensions drawing

FHD1100 heat detector dimensions drawing

Product Range
Table 1: FHD912 Product Range
FHD912-2 2-wire heat detector
FHD912-2L 2-wire heat detector with remote LED output
FHD912-4 4-wire heat detector (12/24 VDC)
FHD912-4B 4-wire heat detector with buzzer (12/24 VDC)
FHD912-4AR 4-wire heat detector with auto reset (12/24 VDC)
FHD912-4ARB 4-wire heat detector with buzzer & auto reset (12/24 VDC)
Parameters
Table 2: FHD912 Product Parameters
Model 2/4 Wire Voltage DC Standby
Current
(Max.)		 Alarm
Current
(Max.)		 Surge
Current
(Max.)		 Star-Up
Time
(Max.)		 Permissible
Current
(Max.)		 Frequency Alarm Contact
FHD912-2 2 10~33V 45 μA 50 mA 100 μA 30 seconds 80 mA 1-3 seconds –
FHD912-2L 2 10~33V 45 μA 50 mA 100 μA 30 seconds 80 mA 1-3 seconds –
FHD912-4 4 12/24 V 45 μA 30 mA 100 μA 30 seconds – 1-3 seconds form A
FHD912-4B 4 12/24 V 45 μA 30 mA 100 μA 30 seconds – 1-3 seconds form A
FHD912-4AR 4 12/24 V 45 μA 30 mA 100 μA 30 seconds – 1-3 seconds form A/auto reset
FHD912-4ARB 4 12/24 V 4 5μA 30 mA 100 μA 30 seconds – 1-3 seconds form A/auto reset
FHD912 Heat Detector
Technical Specifications
  • Response Temperature:
    • Fixed Temperature: 57 °C
    • Rate-of-Rise: Class 2 (EN 54-5) or 8 °C/min (UL 521)
  • Ceiling Spacing: 50 ft
  • Reset Voltage: < 1 V
  • Alarm Indicator: Red LED (steady on)
  • Remote Output: 25 mA max., diode gated
  • Operating Temperature: -10 °C to +50 °C
  • Max Current: 80 mA
  • Humidity: 0 to 95% RH, non-condensing
  • Alarm Contacts (4-Wire): NO/NC, form A, 1.0 A @ 30 VDC / 0.5 A @ 125 VAC
  • Dimensions: Ø100 mm × 46 mm (H), with base
  • Weight: 120 g (with base)
FHD912 heat detector on white background
Features
  • Available in 2-wire or 4-wire models.
  • Advanced detection and discrimination algorithms.
  • Easy installation and maintenance.
  • Slim, low-profile design.
  • Durable sensor, no replacement required.
  • SMD PCB technology for reliable performance.
  • Relay output selectable NO/NC.
  • Auto Reset (AR) function for 4-wire models.
  • Detector base options standard or schottky diode.
Dimensions
FHD912 heat detector dimensions drawing

FHD912 heat detector dimensions drawing

Product Range
Table 1: FHD912 Product Range
FHD912-2 2-wire heat detector
FHD912-2L 2-wire heat detector with remote LED output
FHD912-4 4-wire heat detector (12/24 VDC)
FHD912-4B 4-wire heat detector with buzzer (12/24 VDC)
FHD912-4AR 4-wire heat detector with auto reset (12/24 VDC)
FHD912-4ARB 4-wire heat detector with buzzer & auto reset (12/24 VDC)
Parameters
Table 2: FHD912 Product Parameters
Model 2/4 Wire Voltage DC Standby
Current
(Max.)		 Alarm
Current
(Max.)		 Surge
Current
(Max.)		 Star-Up
Time
(Max.)		 Permissible
Current
(Max.)		 Frequency Alarm Contact
FHD912-2 2 10~33V 45 μA 50 mA 100 μA 30 seconds 80 mA 1-3 seconds –
FHD912-2L 2 10~33V 45 μA 50 mA 100 μA 30 seconds 80 mA 1-3 seconds –
FHD912-4 4 12/24 V 45 μA 30 mA 100 μA 30 seconds – 1-3 seconds form A
FHD912-4B 4 12/24 V 45 μA 30 mA 100 μA 30 seconds – 1-3 seconds form A
FHD912-4AR 4 12/24 V 45 μA 30 mA 100 μA 30 seconds – 1-3 seconds form A/auto reset
FHD912-4ARB 4 12/24 V 4 5μA 30 mA 100 μA 30 seconds – 1-3 seconds form A/auto reset
FHD751 Heat Detector
Technical Specifications
  • Response Temperature:
    • Fixed Temperature: 57 °C
    • Rate-of-Rise: Class 2 (EN 54-5) or 8 °C/min (UL 521)
  • Ceiling Spacing: 50 ft
  • Reset Voltage: < 1 V
  • Alarm Indicator: Red LED (steady on)
  • Remote Output: 25 mA max., diode gated
  • Operating Temperature: -10 °C to +50 °C
  • Max Current: 80 mA
  • Humidity: 0 to 95% RH, non-condensing
  • Alarm Contacts (4-Wire): NO/NC, form A, 1.0 A @ 30 VDC / 0.5 A @ 125 VAC
  • Dimensions: Ø102 mm × 43 mm (H), with base
  • Weight: 125 g (with base)
FHD751 heat detector on white background
Features
  • Available in 2-wire or 4-wire model.
  • Advanced detection and discrimination algorithms.
  • Quick and easy installation and maintenance.
  • Modern, sleek design.
  • Durable sensor, no replacement required.
  • SMD PCB technology for high reliability.
  • Selectable relay output NO/NC.
  • Auto reset (AR) function for 4-wire models.
  • Detector base options standard or schottky diode.
Dimensions
FHD751 heat detector dimensions

FHD751 heat detector dimensions

Product Range
Table 3: FHD751 Product Range
FHD751-2 2-wire heat detector
FHD751-2L 2-wire heat detector with remote LED
FHD751-4 4-wire heat detector (12/24 VDC)
FHD751-4B 4-wire heat detector with buzzer (12/24 VDC)
FHD751-4AR 4-wire heat detector with auto reset (12/24 VDC)
FHD751-4ARB 4-wire heat detector with buzzer & auto reset (12/24 VDC)
Parameters
Table 4: FHD751 Product Parameters
Model 2/4 Wire Voltage DC Standby
Current
(Max.)		 Alarm
Current
(Max.)		 Surge
Current
(Max.)		 Star-Up
Time
(Max.)		 Permissible
Current
(Max.)		 Frequency Alarm Contact
FHD751-2 2 10 to 33 V 45 μA 50 mA 100 μA 30 seconds 80 mA 1-3 seconds –
FHD751-2L 2 10 to 33 V 45 μA 50 mA 100 μA 30 seconds 80 mA 1-3 seconds –
FHD751-4 4 12/24 V 45 μA 30 mA 100 μA 30 seconds – 1-3 seconds form A
FHD751-4B 4 12/24 V 45 μA 30 mA 100 μA 30 seconds – 1-3 seconds form A
FHD751-4AR 4 12/24 V 45 μA 30 mA 100 μA 30 seconds – 1-3 seconds form A/auto reset
FHD751-4ARB 4 12/24 V 45 μA 30 mA 100 μA 30 seconds – 1-3 seconds form A/auto reset
Application
Heat detectors in kitchens

Catering Kitchens

Boiler room interior

Boiler Rooms

Parking garage interior

Parking Lots

Heat detectors in industrial plants

Industrial Plants

Warehouse interior

Warehouses

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