Duct Heater

Duct Heater – Precision Heating for Airflow Systems

Duct heaters are engineered to provide controlled, efficient heating of air in HVAC systems, process ventilation, and industrial drying applications. Designed for inline installation, these heaters deliver uniform thermal output across air streams with minimal pressure drop.

Key Features:

  • High-Performance Heating Elements: Nickel-chromium or stainless steel tubular elements for fast response and long service life
  • Customizable Configurations: Available in open coil or finned tubular designs to suit airflow velocity and temperature requirements
  • Robust Housing: Galvanized or stainless steel casing resists corrosion and ensures structural integrity
  • Integrated Controls: Options include built-in thermostats, thermal cutoffs, SCR/SSR control compatibility, and PLC integration
  • Temperature Range: Supports air temperatures up to 650°C depending on design and application
  • Mounting Flexibility: Flanged or slip-in styles for easy installation into rectangular or round ductwork
  • Safety Features: Overheat protection, airflow interlocks, and insulation barriers for safe operation

We design and manufacture all duct heaters according to customer specifications.

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Description

Duct Heater – Precision Heating for Airflow Systems

Duct heaters are engineered to provide controlled, efficient heating of air in HVAC systems, process ventilation, and industrial drying applications. Designed for inline installation, these heaters deliver uniform thermal output across air streams with minimal pressure drop.

Key Features:

  • High-Performance Heating Elements: Nickel-chromium or stainless steel tubular elements for fast response and long service life
  • Customizable Configurations: Available in open coil or finned tubular designs to suit airflow velocity and temperature requirements
  • Robust Housing: Galvanized or stainless steel casing resists corrosion and ensures structural integrity
  • Integrated Controls: Options include built-in thermostats, thermal cutoffs, SCR/SSR control compatibility, and PLC integration
  • Temperature Range: Supports air temperatures up to 650°C depending on design and application
  • Mounting Flexibility: Flanged or slip-in styles for easy installation into rectangular or round ductwork
  • Safety Features: Overheat protection, airflow interlocks, and insulation barriers for safe operation

HVAC Electrical Duct Heater Overview

Jingang rectangular duct heater are supplied in customized sizes and with an output of up to 200KW. They are used to heat up the inlet air in duct systems, in centralized air handling units and for various industrial processes. Our flexible production enable us to precisely adapt the duct heaters to the intended application. This may concern heaters for air handling units, industrial processes or very harsh environments. This may require electrical insulation, stainless materials, large power requirements and high temperatures.

Our duct heaters consist of finned tubular heating elements that are either flanged or inserted in the duct. Air duct heaters are primarily used in air flowing ventilation systems and comfort heating applications.
Jingang designs and configures your electric duct heaters according to your specifications. Our team is dedicated to development of the latest technologies, while striving to meet every customer’s needs by manufacturing quality duct heaters. Our extensive expertise in developing and manufacturing electric duct heaters make our duct heaters, the most easily adaptable solutions for all air-heating applications.

Key Features

  • Models with duct sizes from 150 x 150mm to 2000 x 2000mm and outputs from 300w to 100kW
  • General purpose terminal enclosure
  • Finned tubular elements, constructed using SUS304 element with SS fin coiled around it which increases the heat transfer surface of the element.
  • Elements supports fitted as standard when duct widths exceed 600mm
  • Over-temperature thermostat fitted (8mm inside diameter thermowell) to shit off heater in the event of an over temperature situation set @ 70 degree Celsius.
  • Voltage 230V – 1Ph only (for output to 2.5KW) or Voltage 400V – 3Ph (2KW and above)
  • 1.2mm galvanized steel body
  • Special sizes, wattages, and materials available upon request
  •  Option:
    • Build in air pressure differential pressure switch
    • SCR controllers
    • Main Disconnect
    • Magnetic Contactors
    • Control transformers
    • Fan interlock relay_ AHU/FCU interlock
    • Pilots’ lights
    • Built stainless steel frames available

Duct Heater Selection

KW Power Supply Duct Size  Min. Air Flow No of Elements Model No Appr. Weight
230V 415V     CFM m³/min Flange Insert KG
1Ø      3Ø mm mm
1 ✓ – 150 150 50 1.4 2 F06x06-01 I06x06-01 7
2.5  ✓ – 150 150 150 4.2 3 F06x06-025 I06x06-025 7
7.5 – ✓ 350 200 390 11 6 F14x08-075 I14x08-075 9
10 – ✓ 350 300 500 14.1 6 F14x12-10 I14x12-10 11
12.5 – ✓ 400 300 625 17.7 6 F16x12-125 I16x12-125 14
15 – ✓ 450 300 750 21.2 6 F18x12-15 I18x12-15 14
17.5 – ✓ 450 350 875 24.8 6 F18x14-175 I18x14-175 16
20 – ✓ 450 400 1000 28.3 6 F18x16-20 I18x16-20 16
25 – ✓ 500 450 1250 35.4 9 F20x18-25 I20x18-25 23
30 – ✓ 600 450 1500 42.4 9 F24x18-30 I24x18-30 25
35 – ✓ 600 550 1650 46.7 9 F24x22-35 I24x22-35 27
40 – ✓ 650 600 2050 58 12 F26x24-40 I26x24-40 32
45 – ✓ 700 600 2200 62.2 12 F26x24-45 I26x24-45 34
50 – ✓ 700 650 2500 70.7 12 F28x26-50 I28x26-50 36
60 – ✓ 750 750 3000 84.9 15 F30x30-60 I30x30-60 43
80 – ✓ 900 800 4000 113.1 15 F36x32-80 I36x32-80 48
100 – ✓ 1050 900 5250 148.5 18 F42x36-100 I42x36-100 59
120 – ✓ 1200 900 6000 170 18 F48x36-120 I48x36-120 68

Construction

Standard Design
The casing is made of Galvanized sheet steel which is corrosion resistant. The heating elements are tubular heating elements made from stainless steel, SUS304. The junction box contains all the terminals required for electrical connection. The casing is available in two different designs. The duct heaters are manufactured with an IP43 degree of protection, but are also available with IP55 or IP65.
The products are customized in terms of size and output.
The heaters are suitable for a maximum outlet temperature of 50 °C, a minimum air velocity of 1.5 m/s and a maximum pressure of 1000 Pa.

The two available heater frame constructions are Flange type and Insert type.

WARRANTY: Under normal use the Company warrants to the purchaser that defects in material or workmanship will be repaired or replaced without charge for a period of 18 months from date of shipment, or 12 months from the start date of operation, whichever expires first. Any claim for warranty must be reported to the sales office where the product was purchased for authorized repair or replacement within the terms of this warranty.

Components of Duct Heater

Finned Tubular

All element consist of Kanthal D heating element (80% Nickel, 20% Chromium), precisely centered in a stainless steel tube which is filled with magnesium oxide. The heater is compacted to maximize heat transfer and dielectric properties of magnesium oxide. A stainless steel fins is helically wound on to the tube to increase its heater transfer surface.
Overtemperature Protections

Duct heaters have built in primary (automatic) and secondary (manual reset thermal cut-out) overtemperature protection.
Airflow Interlocks

Air flow switch must be provided to stop the heater if the air flow switch senses low or no airflow. The flow switch continuously monitors the airflow and switches off the heater if the air velocity drops below 1.5 m/s and thus prevents overheating.
When the air velocity rises above 1.5 m/s the heater is turned on automatically if heating is required.
This implies that heaters with an integrated flow switch meet the requirement for interlocking with the fan/air flow and can be installed without any external interlock.
Overcurrent Protections

For heater drawing more than 48 amps, fuses or circuit breaker will be used.
Disconnection Means

For heater installation/maintenance, a disconnect switch is provided to ensure heater cannot be turn on with the disconnect switch turn off.

Technical Design of Duct Heater

Calculating Power(KW) Requirements
The volume of air that goes through the duct heater is heated according to the following formula:

P = Q X 0.36 X Delta T

P= Output in W,

Q=Air flow in m3/h,

Delta T = Temperature increase in Celsius

 

Ensure a minimum air velocity to prevent over heating of heating element.

The duct heaters are dimensioned by default for a minimum air flow of 1.5 m/s and a maximum operating temperature of 50 °C for the outlet air. The air velocity can be calculated using the following formula:

V=Q/(3600 x A),

V = Air Velocity in m/s,

Q= air flow in m3/h,

A =sectional area of duct heater in (WxH), m2

 

Surface Temperature of Heating Elements
The surface temperature of heating elements is dependent of the air velocity and the heating elements’ surface effect.
The surface effect of the heating elements is approximately 3 W/cm². The table shows the surface temperature of the heating elements when the duct heater’s outlet air temperature is about 20 °C.

 

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