Type 9NF: Medium power duct heaters, with finned stainless steel heaters, 3.5W/cm², for air speed≥2m/s

Main applications

These medium duct heaters are mainly used in air ducts, upstream vents, for heating industrial premises, in closed hot air circuit (recirculating air) or open circuit, with a mini air speed of 2m/s.
They are also used for drying, for heat treatment, dehydration, or cooking, in industrial processes.
They can be used on square or rectangular ducts. They consist of finned stainless steel heating elements, mounted on a stainless steel flange. Their installation in existing pipes requests cutting a 140x110mm rectangular hole, and drill 8 holes for 6mm dia. screws. The electrical connections are made in an IP65 aluminum housing. These devices are equipped with a 3 pole manual reset failsafe limiter.

Main features

Assembly: The finned tubes are oriented at 45 ° from the axis of the mounting bracket, thereby it is possible to position the duct heater along or perpendicular to the duct upon available spacing.
Ducts minimum sizes:
170mm heating element references: 200 x 170 mm
320mm heating element references: 350 x170mm
420mm heating element references: 450 x 170mm
Duct opening: 140x110mm rectangular hole, plus 8 holes for dia.6mm screws (or equivalent size).
High limit thermostat: 3 poles, failsafe, manual reset, capillary thermostat, calibrated at 120°C (other values ​​on request). Bulb mounted inside a waterproof pocket.
Connection box: in gray epoxy paint aluminum housing, IP65, 160 x 124 x 92mm, fitted with two M25, PA66 cable glands.
Minimum air velocity: ≥ 2m / s
Mounting bracket: 304 stainless steel, 150 x 235mm, 1.2 mm thick, with 8 holes for M6 screws (undrilled version on request). IP65 sealing between the heating elements, connection box and bracket
Heating elements: 3 or 6, non-removable, finned heaters, surface load 3.5W/cm ², 304L stainless steel, with internal connection on M4 screw terminals. The power of each element is 250 watts in 170mm, 500W in 320mm and 700W in 420mm (Other features, see page 8)
Voltage: 230V, 50/60Hz (110-120V on request).Wiring is possible in 230V single phase, or in 400V three-phase with neutral.
Power, surface load, air flow:
See for information, in the technical section at the end of this catalog, the temperature charts recorded ​​on standard models. However, it is up to the integrator to perform the appropriate checks of flow and temperatures reached in the application, and insure that they comply with the local regulations and safety standards.


2D&3D Drawing

Main references

3 finned heating elements

6 finned heating elements


Total power (W)

Length L


Total power (W)

Length L


750 170 9NFL170C231506NC 1500



1500 320 9NFL320C233006NC 3000



2100 420 9NFL42C234206NC 4200