For more than 60 years products from our house ensure the right temperatures. Through path- breaking developments in the field of refrigeration and air- conditioning engineering we have gained worldwide recognition.

Our product range covers unit air coolers, fan coils and finned heat exchangers. We only produce at our company located in Gerlingen near Stuttgart.

Fan Coil Units
Air Coolers
Heat Exchangers

Options FKN

Heat exchangers

Our air coolers are designed for refrigeration applications. Our cooler work efficient in the Standard Condtions according to EN 328, with refrigerants like R404A, R507A or R134a.

If a cooler should be operated outside the limits specified in the catalogues or the selection software, it is possible to adjust the circuiting of the air unit coolers to ensure the operation of the unit.

For different refrigerants e.g. R410A, R407C etc. special heat exchangers are available on request.

Water/ brine heat exchangers

Water connectionUnit air coolers can be equipped with heat exchangers for water or brine operation. Compared to refrigerant heat exchangers the ones for water operation are equipped with threaded fittings, and have an optimised circuiting for water / brine operation. On request the heat exchangers can be prepared for bleeding/ draining.

The maximum allowable pressure for "water" heat exchangers is PS 16 bar.

Regulary used brines are e.g.

  • Ethylene glycol
  • Propylene glycol
  • Temper
  • Tyfoxit

The heat exchanger consists of wide tubes for a minimum of pressure loss, and optimised ciruiting to suit your application.


On our unit air coolers we only use high quality fans of well- known manufacturers designed for application in refrigeration. These fans match typical requirements of cold storage.

Due to that the temperature range of the fans is limited to typical refrigeration applications. 

Higher ambient temperatures, more energy-efficieny, explosion-proof, different voltages are exemplary reasons to change the standard fan.

EC fans

Electronically commutated fans are the latest electric motor technology in the market. Due to their higher efficiency than shaded pole and even AC motors, the waste heat of the component is minimized.

EC fans for usage with FKN are limited to two fan speeds.


Due to frost formation on the fins, coolers have to be defrosted regualary to keep their performance. Frost can be removed in many ways.


T- VersionMost of the Roller air coolers are available as a T- Version. T is the abbreaviation for the german "Tiefkühlung" - low temperature applications. The T- versions differ from the normal air unit coolers in the following ways:

  • Heater rod mounted for optimal defrost of the coil.

The well-thought-out layout of the heaters ensures a uniform and complete defrost operation.

Defrost safety thermostat

Defrost safety thermostatThe defrost safety thermostat terminates the defrost in case of an failure of the defrost control. A wide range of Roller air unit coolers is already prepared for the installation of the defrost safety thermostat.

Technical data:

Fixed break point,
disconnects +25 °C,
connects +3,5 °C
Contact load at 230 V, 50 Hz:
ohmic Imax 25 A,
inductive Imax 5 A,
Protection class IP 44.
Connection cable 2 cores, 75 cm long.

SI flexible heater

SI flexible heaterThe SI flexible heater is designed to heat the plumbing of the condensate drain. It's available in different lengths to satisfy your application. The SI flexible heater is not designed for contious operation.

Hot gas defrost

Hot gas defrostHot gas defrost is an either energy saving possibility to defrost the coil block. It is possible to equip the coil with a preparation for hot gas defrost operation. This includes a T at the distributor and a coil at the bottom sheet of the evaporator.

We recommend to lead the hot gas line first to the bottom coil, than to the collector of coil block and go back to the compressor via the T at the distributor.

As there are several possibilities for defrost control and different conditions at the plant there are probably better solutions of a hot gas defrost design.

Protection against corrosion

If an air unit cooler is defective, corrosion is one of the most possible reasons. That is why in certain cases it makes sense to protect the air cooler from possible damage caused by corrosive environments.

Contents of corrosive environments are for example:

  • Acetic and other organic acids
  • Amines and ammonia compounds
  • Chlorine 
  • Salt
  • Cleaning agents

In corrosive environmets the heat exchanger should be cleaned more often than in neutral environments, depending on the corrosiveness a minium interall of an quarter year is suggested.

Type C

If the complete heat exchanger is varnished by 2 K laquer or powder- coated it's called protection against corrosion type C.

These type of corrosion protection is used at the Co2olers.

Type D

The protection against corrosion type D is a combination of different anti corrosion actions, that lead to sja atisfying result.

First of all the copper tube is protected by a sacrificial anode.

Second the complete heat exchanger ist coated, due to that it is hardly possible for corrosive agents to attack the basic components of the heat exchanger.

The usage of additional material has a negative effect of the performance of the air cooler. When desinging your refrigeration plant, be sure to check the protection against corrosion box in the selection software.

Protection against corrosion type D isn't possible at Co2oler units.

Type E

It's possible to manufacture the complete heat exchanger of copper. This leads to an increse of capacity by about 8 %.

The heat exchanger is then well protected against influences of salt, which is the most common corrosion phenomen at aluminium.

These type of corrosion protection is only possible at fin spacings < 6 mm.

Type F

Fins can be made of prelaquered finstock. Compared to the complete varnished heat exchanger the capacity is a little bit higher, but due to cutting edges the Aluminium is not as good protected as in type C or D.

Type G

Protection against corrosion is a combination of tinned copper tubes, prelaquerd aluminium fins and a varnishing of the two end plates. It is only possible up to a fin spacing of 6 mm.


Different accessories bring the portfolio of cubic air coolers up to a round figure.

Stainless steel casing

Casings of the air unit coolers can be made of stainless steel (V2A, 1.4301, AISI 304). The stainless steel casing is superior robust compared to the Aluminium casing.

If you like pure metalic designs the stainless steel casing may also be an option.

Suspension devices

Suspension devices are available for a wide range of air unit coolers.

The bracket Wand- K1 is a smaller one designed for static loads up to 20 kg per bracket. It 's the preffered choice for:

  • FKN/T 
  • HVS/T x00- x06
  • FHV/T x01- x06
  • FHV/T x11- x14
  • UV/T

The HVS Euro bracket is designed for static load up to 35 kg.

  • HVS/T x07- x14 
  • FHV/T x16
  • FHV/T x21-x23

For gravitiy coils and air coolers for display cabinets there is the W- bracket available as well as different types of suspension angles. 

Drain pan for wall mounted ceiling air coolers.

Ceiling type air unit coolers are in most cases wall- mount able with an additional drain pan. Evaporators can be equipped with the drain pan as an accessory. In case of a water/ brine heat exchanger the intention of a wall mounting should be known in advance to ensure a correct bleeding of the heat exchanger.