Duct Heaters



A Duct Heater is a self-contained heater designed to be installed in the air stream of a duct system, external to the air moving unit. It is designed to be installed in a duct where an adequate flow of air from a separate, interlocked fan or air handling system is insured. Such a heater may be located in a main supply duct of a warm air heating system, in one of the branch ducts, or used as a room heater, at the end of a branch duct.

Electric Duct heaters are an ideal answer for the heating system designer, because of electricity's inherent cleanliness as a fuel, their adaptability for use with other comfort conditioning components, such as humidifiers, de-humidifiers, electronic filters and heat pumps, and their flexibility for use with a variety of control systems to maintain the precise temperature desired. Airflow Duct Heaters to accommodate all applications.


General: Electric duct heaters and air handling coils shall be as manufactured by Airflow Engineering (SI) Ltd. Voltage, size, KW, stages and controls shall be as scheduled. Three phase heaters shall have balanced phases.

Type: Heaters shall be of the following configuration:

For Duct Mounting             Insert, Flanged or Circular Duct Section

For Control Wiring             Bare Terminal, Pre-Wire, and Full Wire

For Solid State Relays       Bare Terminal or Pre-Wire Only

Direction of airflow: heaters shall be interchangeable for horizontal left or right or vertical airflow

Safety devices: a manual reset thermal cut-out shall be furnished for primary over-temperature protection. Secondary protection can be either an automatic cut-out or an air pressure switch. All safety devices are serviceable through the terminal box without removing the heater from the duct.

Wiring diagrams: a wiring diagram with a manual including photos of unit shall be furnished for each heater. A manual is also kept on an electronic file for future use.

Suggested Specification

Electric Duct Heaters shall be finned tubular heaters are made of corrosion resistant Stainless Steel as manufactured by Airflow Engineering (SI) Ltd. voltage, physical size, wattage, number of steps and with accessories as noted on the drawings or specified.  Heater shall be of design for mounting in a horizontal or vertical duct with air flow through heater in either direction. Units shall meet applicable requirements of the latest ASNZS3102 standards.

Provide heaters with a manual reset thermal cutout for primary protection installed in the control, and either an automatic high temperature safety cut out or an Air Pressure Switch. Protection devices shall be serviceable through heater terminal box, without removing heater from duct. (Thermostats Optional)

Heater ducts and terminal boxes shall be constructed of 20 gauge-galvanized steel or heavier. Terminal boxes shall have a removable lid for easy access. Duct sections shall be lined 250mm each side of the elements.