Type 9NN: Small size air duct square heaters, for incorporation, 400 to 1200W.

Typical Applications

Thin and compact air duct heaters, designed to be used in industrial or commercial air conditioning systems. Their design allows to mount them at the end of 125mm dia. air duct on existing circuits.  One of their applications is to allow, without costly work, to boost air/air type heat pumps whose power is insufficient in extreme weather conditions. They are intended to be used by integrators in ventilated air ducts.

They are made of a stainless steel sheathed tubular heating element, mounted on an electro-galvanized steel or stainless steel frame. They can be supplied with or without electrical connection box.

They are supplied with 2 levels of temperature overheat protection.


Main features

Frame: Galvanized steel sheet or 304 stainless steel

Safety thermostat N°1: automatic reset, open at 50°C, reset at 40°C

Safety thermostat N°2: Open at 95°C. Manual reset

Heating element: 8mm diameter sheathed tubular heating element, stainless steel 304L. (Other features, see page 7)

Power vs Heater surface loads and minimum flow *:

– For 400W the surface load is 1.2W/cm², and minimum air velocity must be 0.5 m/s, i.e. a rate equal to or greater than 28m3/h in a dia. 125mm duct.

– For 600W the surface load is 1.8W/cm², and minimum air velocity must be 1.5 m/s, i.e. a rate equal to or greater than 84m3/h in a dia. 125mm duct.

– For 1200W the surface load is 3.6W/cm², and minimum air velocity must be 2.5 m/s, i.e. a rate equal to or greater than 140m3/h in a dia. 125mm duct.

* Indicative values. Calculated so that the surface temperature of the heating elements does not exceed 300°C. It is up to the integrator to perform the appropriate checks and flow and temperatures reached in the application, so that they conform to the regulations and safety standards.

Voltage: 220/240V, 50/60Hz (110-120V on request)

Connection box(in models supplied with it): IP40 with M20 cable gland in  PA66

Connection: ceramic terminal block 3×2.5mm²

Mounting: on flat surface, with 8 screws. Also allows the mounting on a 125mm dia. metal duct with a collar lip diameter 144mm to 150mm. (See accessories hereunder)

Options: other surface load, other thermostats set point temperatures (MOQ apply)


2D&3D Drawing

Main references

References with zinc plated steel enclosure

References with SS304 enclosure

Power (W)

Connection box

Surface load (W/cm²)

Surface load (W/in²)



9NNL128423400BJ0 400 No 1.2


Bracket and collar tube for 125mm dia. duct

(zinc plated steel)




9NNL188423600BJ0 600 No 1.8



9NNL368423A20BJ0 1200 No 3.6



9NNL188423600BJC 400 Yes 1.2



9NNL368423A20BJC 600 Yes 1.8



9NNL188423600BJC 1200 Yes 3.6