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Duct Heaters

High efficiency, compactness and ease of installation make the utilization of a Forced-Air Duct Heater an ideal solution in applications where fan-forced heating is required. Two designs are available based on the operating temperature;

  • Medium performance duct heaters, for up to 750°F outlet temperatures
  • High performance duct heaters, for up to 1100°F outlet temperatures

The heat source is a set of tubular elements that are arranged in an optimum configuration to minimize the pressure drop.

CFM Temperature Rise (°F)
50 100 150 200 250 300 350 400 450 500 550 600
Kilowatt estimation at standard conditions with 20% safety factor
100 2 4 6 8 10 12 14 16 18 20 22 24
200 4 8 12 16 20 24 28 32 36 40 44 48
300 6 12 18 24 30 36 42 48 54 60 66 72
400 8 16 24 32 40 48 56 64 72 80 88 96
500 10 20 30 40 50 60 70 80 90 100 110 120
600 12 24 36 48 60 72 84 96 108 120 132 144
700 14 28 42 56 70 84 98 112 126 140 154 168
800 16 32 48 64 80 96 112 128 144 160 176 192
900 18 36 54 72 90 108 126 144 162 180 198 216
1000 20 40 60 80 100 120 140 160 180 200 220 240
1100 22 44 66 88 110 132 154 176 198 220 242 264
1200 24 48 72 96 120 144 168 192 216 240 264 288

Recommended protective devices of Duct Heater

  • Air-flow switch: Installed on the inlet side of the duct heaters, air-flow switches prevent the energizing of heaters when there is no air flow.
  • Over temperature Protection: A type “K” high limit thermocouple attached to one of the heating elements monitors the temperature. The thermocouple is attached to a controller that has a manual reset.
  • Fan interlock: To prevent heater from energizing when the fan is not running, the fan starter circuit is interlocked with the heater controls. A time delay can be incorporated in order to keep the fan running after the heater gets de-energized.
Duct Heater - Electric Duct Heater

Typical Heating Applications OF DUCT HEATER:

  • Paint Drying
  • Industrial Ovens
  • Dehumidification
  • Batch-Heating Ovens
  • Forced-Air Drying/Curing
  • Heat-Treating, up to 1100°F (570°C)

Standard construction for medium temperature duct heaters

(Outlet temperatures up to 750°F)

  • Incoloy sheathed heating elements
  • General purpose terminal enclosure (NEMA 1)
  • Mild steel mounting plate, keeper plate and support hardware

Standard Duct heaters for outlet temperatures up to 750°

Cat. No. KW A (in) B (in) C (in) Approx. WT (lbs)
FHIL6 6 6 16 4.5 15
FHIL12 12 9 16 7.5 30
FHIL18 18 12 16 10.5 44
FHIL24 24 15 16 13.5 62
FHIL30 30 18 16 16.5 76
FHIL36 36 21 16 19.5 90
FHIL42 42 24 16 22.5 106
FHIL48 48 27 16 25.5 118
FHIL54 54 30 16 28.5 137
FHIL60 60 33 16 31.5 152

Standard construction for high temperature duct heaters

(Outlet temperatures up to 1100°F)

  • Incoloy sheathed heating elements
  • Reduced watt density on tubular sheath
  • General purpose terminal enclosure (NEMA 1)
  • 2" mineral wool insulation under the mounting flange
  • Stainless steel mounting plate, keeper plate and support hardware

Standard Duct heaters for outlet temperatures up to 750°

Cat. No. KW A (in) B (in) C (in) Approx. WT (lbs)
FHIH6 6 6 20 4.5 16
FHIH12 12 9 20 7.5 31
FHIH18 18 12 20 10.5 46
FHIH24 24 15 20 13.5 64
FHIH30 30 18 20 16.5 78
FHIH36 36 21 20 19.5 93
FHIH42 42 24 20 22.5 109
FHIH48 48 27 20 25.5 122
FHIH54 54 30 20 28.5 141
FHIH60 60 33 20 31.5 156

  • Air-flow switch: Installed on the inlet side of the duct heaters, air-flow switches prevent the energizing of heaters when there is no air flow.
  • Over temperature Protection: A type “K” high limit thermocouple attached to one of the heating elements monitors the temperature. The thermocouple is attached to a controller that has a manual reset.
  • Fan interlock: To prevent heater from energizing when the fan is not running, the fan starter circuit is interlocked with the heater controls. A time delay can be incorporated in order to keep the fan running after the heater gets de-energized.

Features of DUCT HEATERS

  • Weatherproof terminal enclosure (NEMA 4)
  • Airtight sealed joint between element and mounting flange
  • 3" mineral wool insulation inside the terminal box (Box height will increase to 7”)
  • Air-flow switch
  • Stainless steel terminal enclosure
  • Process control thermocouple
  • High-limit thermocouple