K Circular Duct Fans

High Quality radial fan for circular ducts

  • Available with AC and EC motors

  • Indoor and outdoor installation

  • Reliable and airtight

  • Mounting bracket included

  • Noise and energy optimized impeller


The K fans are intended to use for supply or extract air, designed to be installed in any position. This ensures that the fans can be used in a variety of commercial and domestic applications.


The unit’s airtight casing and corrosion resistance permits outdoor and indoor use. The combination of reliable casing and motor construction ensures, to minimize the need for maintenance of the fans and allows long continuous operation.


Sound optimized radial impeller together with high efficient external rotor motor are designed to ensure high-level performance to minimize power consumption and maximize efficiency.


K fans can be selected together with variety types of accessories as fast clamps, heaters, filters, dampers, etc.

Systemair Accessories – the perfect match!

Save time in design and installation while ensuring the most optimal ventilation solutions for your project.

Featured accessories for your K-fan

FK, Mounting clamps for circular duct
Mounting clamps for circular duct
ECBasic, Controller series with 0-10V analog output signal
Controller series with 0-10V analog output signal
LDC, Easily-fitted silencer for circular ducts where noise reduction is paramount
Easily-fitted silencer for circular ducts where noise reduction is paramount


Casing made of galvanised sheet steel, corrosion class C3 is fully air tight class C according to EN1751. The fans are equipped with an external terminal box with protection class IP55.


K fans use backward curved radial impellers. These are from lightweight, hard-wearing fiberglass reinforced polyamide, dynamically balanced and paired with corresponding external rotor motors.


Depending on type, K fans are equipped with AC or high efficient EC external rotor motors. All motors are suitable for 50Hz and 60Hz.

Motor protection

Fans with AC motors have integrated thermal protection with manual (electrical) reset. Size 100 and 125 has an impedance motor protection.

Fans with EC motors have an integrated electronic thermal protection including locked-rotor protection and soft-start.


EC motor with built-in potentiometer to adjust working point can be also controlled by external signal 0-10V.

AC motor can be controlled by 5-step or stepless speed regulator.


K fans can be installed in any position indoor and outdoor by included mounting brackets . All models have a spigot with 25 mm length which is perfectly designed to connect circular duct by fast clamps preventing vibration to the duct.

Installation can be combined with filter boxes, sound attenuators, and other mechanical accessories from recommended list.