A perfect combination for effectively dispersing accumulated heat and saving energy

Unit heaters are THE indoor warm air solution for a wealth of applications. The units are fitted with continuously variable EC single-phase, sickle-blade rotor fans, which run smoothly, even at high power. Due to the EC technology used, they are only operated in the performance range that is required.

Unit heaters are very well suited for countering a phenomenon that occurs frequently in industrial sheds: accumulated heat under the ceiling. Kampmann uses its KaMAX diffuser (Kampmann Multi-Air-Mix), which reduces accumulated heat, especially in high halls and sheds, and thus prevents energy losses.

How is the KaMAX diffuser designed and how does it work?

The fins in the KaMAX are arranged in a circle. A control lever is used to adjust the fins to the required angle externally. Alternatively, the KaMAX diffuser can also be controlled remotely by a plug-in motor combined with a switch.

The swirl of the discharged air, that is its rotation, can be changed so that both horizontal and vertical air streams with variable induction properties and penetration depths can be generated. This prevents high temperature differences between the floor and ceiling. Heat that accumulates under the ceiling is drawn in and entrained in the air circulation. The precise setting of the KaMAX ensures that even large volumes of pleasantly heated air reach the occupied zone draught-free.

Which fin position is best for which hall height?

Below we describe three possible setting positions of the KaMAX fins at different ceiling heights and the respective effect on the diffuser.

Hall height of 3 to 5 m

Horizontal position

  • The fins are horizontal, almost at right angles to the air flow.
  • The narrow air outlet gap between the slats is equally wide open.
  • Air is distributed horizontally under the ceiling with a high swirling effect and flows in a circular air stream around the KaMAX.
  • Floor and ceiling air is entrained. Pockets of heat under the ceiling are dispersed.
  • Even air movements occur.
  • Only low air speeds in the occupied zone
  • No draughts
  • Outstanding comfort is achieved

Hall height of 5 to 10 m

Slightly vertical position/centre position

  • The fins are inclined more towards the occupied zone.
  • The air outlet gap between the fins increases.
  • The fins are now positioned slightly vertically towards each other. This increases the inductive effect of the escaping air flow and thus the induction air content directly at the KaMAX diffuser. Accumulated air is dispersed.
  • The volume of air in the room is largely drawn into the air exchange through a strong swirling movement.
  • A direct primary air stream cannot be felt in the occupied zone.
  • As air is inducted, the outlet air temperature falls.
  • The air speed is greatly reduced when it reaches the occupied zone.
  • Intensive mixing of indoor hall air at low air speed with minimal temperature stratification.
  • This produces greater comfort and energy savings.

Hall height up to 20 m

Vertical position

  • The air is discharged predominantly vertically.
  • In their maximum vertical position, two slats effectively form a nozzle with each other.
  • A diffuser-like cavity thus forms between each nozzle-forming pair of slats.
  • Air is inducted from all sides, the outlet air temperature significantly falling. Pocket of heat under the ceiling are dispersed
  • Twice the volume of air is moved around 2 metres below the KaMAX diffuser.
  • High volumes of air are moved at a low temperature and speed, increasing the penetration depth by up to 30 %.
  • This produces greater comfort and energy savings.
  • This discharge position is ideal for cost-effective heating, even with very high-ceilinged spaces.

KaMAX ensures the systematic mixing of indoor air, bridges thermal lift and thus prevents the formation of unwanted accumulated heat underneath the ceiling:

  • Transmission heat losses are minimised
  • Energy costs are reduced
  • Comfort is enhanced in the occupied zone

Example of a design with a KaMAX diffuser

KaMAX in a vertical position

Our example shows a high-ceilinged industrial hall with a floor area of 3,200 m2 (40 m wide and 80 m long). Its height of 10 m produces a room volume of 32,000 m3 (3,200 m2 x 10 m).

The unit heaters are to be operated at low water temperature LPHW:

  • Supply temperature 45 °C
  • Return temperature 40 °C
  • Room air temperature 20 °C

Based on a maximum installation height at medium speed, size 7 TOP unit heaters are selected with KaMAX diffusers in a vertical position.

At a control voltage of 8 V, the volumetric air flow of the size 7 unit heater is 5,910 m³/h.

Result of the unit heater performance data calculation.
The KaMAX diffuser in a vertical position was selected as an accessory.


The following is calculated to achieve a minimum of 1.8 times the air circulation rate in the hall:
Room volume 32,000 m³ x 1.8 1/h = 57,600 m³/h total air volume flow to be moved.

Comparison of the effective volumetric air flow of different diffusers with regard to the maximum mounting height (in this case, size 7 TOP unit heaters)

The number of units is calculated as follows: 57,600 m³/h / 5,910 m³/h = 9.7 rounded up to 10 units.

10 TOP unit heaters with KaMAX in a vertical position are therefore required to ensure sufficient air circulation throughout the entire hall. The entire air volume of the hall is entrained.

The heat output of the selected unit is 24.7 kW. This results in a total heat output of 247 kW (24.7 kW x 10 units) for the hall.

We provide our unit heater calculation program online, which also takes thermal influences into account for correct design. Calculate the heat outputs and other technical data with just a few clicks.

The benefits for you: At the end of the calculation, download the appropriate data sheet containing a lot of other information (shown here the result of our design example) or the specification wording. Use the wish list to save your individual product configuration including gross price, also including accessories if you wish. You have the option of managing entire projects by setting up a customer account.

The type of unit heater selected in our example can be operated in the design case at medium speed with 8 V control voltage. Thus, there are sufficient reserves even in special situations, e.g. at extremely low outside temperatures or if necessary for ultra-rapid heating-up in the morning.

As a rule of thumb, the higher the hall, the larger the size of unit heater.

The design and planning of unit heaters depends on more than just the heat load calculated. The maximum installation height needs to be considered with the ceiling installation of unit heaters! In addition, the necessary air circulation, structural and acoustic conditions, as well as unit-specific properties, such as the permissible sound level, also need to be considered.

Useful tip: We recommend designing with several smaller units, as the temperature is distributed more favourably here, the air speeds are slower, and lower noise can be expected.

Do you have questions about planning and design? No problem! Simply get in touch with us. We can support you in your project.