Would you like to seal up your factory door comfortably?

Thermovent air curtains are specially designed for factory doors. Reduce heating costs by avoiding hot air losses and prevent the entry of cold air. The remaining free door opening ensures an unhindered transportation of goods.


Why do you benefit of THERMOVENT air curtains?

Energy savings

Significant reduction in heating costs by avoiding warm air losses at open gates.

Smooth operation by unhindered transport of goods

Convenient and fast, the goods can be transported through the free door opening. Swing doors and strip curtains are no longer necessary.

Hygienically safe

All hygiene requirements of the food industry are met. Contamination of the products by swinging doors or strip curtains is impossible.

Accident prevention

See and be seen is made sure. A dangerous free movement of goods through the air curtain is always guaranteed. Unrestricted view.

Protection against insects

No ingress of insects through doors, which are protected by air curtains. The inflow of dust and smoke is reliably prevented.


The THERMOVENT air curtain system is located above the door and out of the transport area and cannot be damaged by fork lifts mechanically.

Without air curtain


Open door without air curtain

If you open a door of a warehouse or factory gate, cold and heavy air from the outside penetrates at the lower part of the door opening. Warm air escapes to the outside at the upper part of the door.

With air curtain​

fig. 2

Open door with air curtain

Thermovent air curtains create an unique air barrier, in order to avoid, that warm air escapes and cold air infiltrates in the building.


How do air curtains work?

A door of moving air.

An air curtain system is a device that prevents an exchange of air through a wall opening, without any physical barrier.

There is an air curtain blower with an air collection box and a discharge nozzle. A door out of moving air. The systems are equipped with a particular air rectifier in the outlet nozzle. There are hundreds of small blowpipes.

The air flow generated by the radial fans is directed through the blow tube rectifier. It is completely laminar, homogeneous and free of turbulence. The beam is narrow and extends far. This jet of air is blown at right angles to the inflowing air, or surrounding. The air jet must be so strong that it reaches to the floor and tears the incoming or adjacent air with it.

Core beam and sub-beams​
at the correct setting.

Core beam and sub-beams

The blown air forms a core beam. The entrained air forms on each side of the core beam a sub-beam. The air volume of the secondary beams are larger than the air amount of the core jet.

The central stream and the secondary beams hit the ground and divide, so that the air volumes of the core jet and the entrained air quantity of the secondary beams will stay where they came from. The air volumes of the inner side beam remain inside and the air volume of the outer side beam outside. The air volumes of the core beam remain within the range in which they were drawn.

It is important that the core beam is laminar and turbulence-free. Then the air of the secondary beams can not mix with the core jet. Thus, the entrained air volumes in the secondary beams of each other remain separate and the air curtain can be as fully effective.

The neighboring air volumes, air currents or the greater weight of the air, for example, with cold air (air of a freezing chamber is up to 20% heavier than normal air) can push aside the air jet of the system. To correct this, the blow-off nozzle is pivotable such that the discharge angle of the air jet can be pivoted up to 15° to both sides.

Air curtain: Execution and Technique​

Composite material. Both sides lacquered aluminum with a core made of solid polyethylene. Standard white or red aluminum surface. Housing of stainless steel on request.
Ball bearing energy saving blowers with electronically commutated DC motors made in Germany. The fans are quiet, easy to control, have an extremely low power consumption and a very long lifespan.
The slide-in electronic with mains filter prevents reliable power disturbances in the power grid. The Thermovent air curtain is activated automatically when door operation on and off. This is ensured by a waterproof proximity switch 24 volts DC, which is equipped with a watertigth screw contact for the connection with the socket electronics. Wear-free switching operations are guaranteed by non-contact power relays. The variable adjustment of Thermovent-air volu- me and speed ensures an electronic controller.
Stabile consoles of stainless steel to mount the system above the door. We offer consoles for fixing at brickwork or with a clamping plate for fixing at walls made out of sandwich panels. The air curtains up to a length of 8 meter are cantilevered. They can be mounted without suspension. So the Thermovent air curtains are particularly suitable for installation above sectional doors, sliding doors and large hinged doors.
Thermovent air curtain system, two stainless steel brackets, stable wind turbine as an adjustment and proximity sensor with cable and screw. Stainless steel mounting hardware for mounting on a terminal panel wall or alternatively material to fasten on masonry. Windmill to adjust the system.
The air rectifier in the outlet nozzle smoothes the airflow and makes it tighter and more sufficient. In the pressure chamber of the outlet nozzle the air becomes compressed, so that it is uniformly distributed over the entire discharge nozzle. Behind the pressure chamber the air stream passes hundreds of small blowpipes. They rectify the air stream and eliminate all air turbulences. The result is a homogeneous, turbulence-free air curtain with increased penetration and a stable flow. In this way a particularly effective functioning is guaranteed.
To avoid damage during the transport, the packaging is done in sturdy cardboard boxes.

The air curtain can be installed by trained workers. We have several installation teams and assemble air curtains around the world.

You can adjust the setting of the Thermovent air curtain with the help of the provided windmill. For adjustment of the air curtain the windmill must be placed on the threshold of the door. The outflowing cold air lets the impeller rotate. The air velocity and the discharge angle of the nozzle must be adjusted, so that the impeller rotates no longer or only slowly. The stopped impeller of the windmill prooves that the air curtain system is set correctly. Now you can absolutely be sure, that there is no disadvantageous air interchange anymore.

Special features

What characterizes THERMOVENT air door systems?

The housing of the air curtain system can be mounted cantilevered over a distance up to 8 meters. During assembly, the system is placed on two brackets, which are mounted next to the door opening. On the brackets, the air curtains can be pushed in an optimal position to the door ope- ning. So the Thermovent is particulary suitable for extra-wide door openings with overhead doors, sliding gates and rolling doors. These doors can move freely behind the air curtain system.
All systems can alternatively be equipped with energy-saving EC fans with electronically commutated electric motors. The EC motors are the result of a very complex development. These motors work with an extremely low power consumption. They are very simple and very suitable for continuous operation and characterized by a very low operating noise. The power consumption at full load is only half as high as of normal motors. When the speed of the blowers is regulated down, the power consumption falls further analogous to the speed.
Whenever the door is opened, a proximity switch activates the air curtain just when the door is removed from the switch. So the fans are already powered up when the door is fully opened. This is a special switch. It is completely sealed without any moving parts. It is totally waterproofed and works with an operating current of only 24 volts. It is a security switch, which cannot cause any electrical accidents.
Thermovent air curtains can be installed on the warm or cold side of the wall above the door. We suggest the installation on the warm side. The blowers draw in warm air from the higher indoor range and blow it through the outlet nozzle with the air rectifier down. This rectifier is made out of hundreds of small blowpipes. In this way a turbulence-free particularly homogeneous air stream is generated. The air stream is sufficient with the large Thermovent type S to reach up to six meter far to the ground. Heating of the air stream for a good function is not neccessary.

The system is controlled electronically.
There is a slide-in control with the electronics and all critical components, such as:

  • The control of the fan speed.
  • The circuit of the fan by contactless relays.
  • The generation of the safety current –
    24 Volt DC – for the proximity switch.
  • The waterproof connector for this switch.


In case of failure, this slide-in control can be pulled by the operator and exchanged with a new one quickly. This eliminates time-consuming troubleshooting and allows a quick repair. So a global fast service is available.

The system is made corrosion-resistant and sound-insulated. The outlet nozzle and the housing consists of a modern sandwich, core material – plastic with painted aluminum surfaces. Very good properties with respect to insulation, corrosion and stability. The blowers have the protection class IP 44 and are galvanized. The remaining Thermovent parts are produced from solid polyethylene – the consoles and all screws – are made from stainless steel. Very long service life, quiet, maintenance-free and reliable.


Assembly of air curtains

The Thermovent is preferably mounted inside or outside above the door opening.

An internal arrangement provides the advantage that warm air is sucked from the upper part of the space and then blown down. Thus, the useless heat of the upper space region in used to heat the lower part of the room.

Outdoor installation may be necessary for reasons of space. It is also possible to mount two systems laterally of the door opening – one air curtain inside and one air curtain outside. This is the best way to protect a door opening.

The unit consists of:

  • Nozzle with fans and control unit.
  • Two stainless steel brackets.
  • Watertight proximity switch with cable and connector.
  • Fixings for clamp mounting at a panel wall or alternatively fixing material for mounting at masonry.
  • Windmill for functional testing.
  1. Preferably mounting the system centrally the door opening by the two consoles.
  2. The unit must be pushed on the consoles with the blowers towards the door.
  3. The proximity sensor turns the system on, when the door moves away from the switch. The sensor must be placed so, that the blow- ers of the air curtain start to run, when the door moves to open.
  4. The nozzle must be adjusted so that the air flow meets the floor in front of the door at an angle of 5 to 10 degrees.
  5. The air flow is to be set with the potentiometer so that it just reaches the ground. The speed must be kept low, because otherwise the air flow mixes with the outside air.
  6. The Thermovent air curtain is optimally adjusted, when no outside air enters and when no warm air escapes. To check this, the windmill must be set in front of the threshold of the door directly under the air flow of the air curtain. When the system is switched off, you can see how the impeller of the windmill is turning moved by the inflowing cold air. If you switch on the air curtain and turn up the potentiometer you can see the impeller rotating more slowly until it finally stops. When the impeller stops, the nozzle and the air speed are correctly adjusted.
  7. Don‘t install air curtains in combination with strip curtains or swing doors.
  8. The nozzle of the air curtain should be about 10% wider than the door opening.

In the corporate sign on the right cap of the plant is the plug adapter for the hand switch or for the proximity switch and the rotary knob to control the air volume and air velocity.

The knob is secured on some models, so you can adjust it using only a screwdriver.

By turning the knob you can adjust the air speed continuously.

The amount of air flows at a speed of about 15 m / sec from the nozzle.

The speed slows down the more the air flow approaches the ground.

If the air speed is too low, the air flow does not reach the ground.

Air flow of an air curtain system

If the air speed is too high, it collides heavily on the ground, which leads to disturbing turbu-

The air flow must be regulated so that it extends to the ground.

When air curtain is switched off, the wind turbine rotates.

At operating doors it is powered by cold airflowing into.

If you turn on the system and increase the air speed, you will see that the wind turbine will slow down and eventually stop.

If the wind turbine stands, it is guaranteed that it is also in the weakest area of the air flow – namely, on the ground – there will be no more air exchange.

If the discharge angle of the system is set incorrectly, the air is blown into the room, which needs to be sealed, or will be drawn from this space.

As a result, the air pressure changes in the room.

At short intervals there are pressure equalizations in the weakest area of the air curtains that is just above the ground.

You can observe this well, because in this case the windmill alternately turns at short intervals – right and left.

The wind turbine does not reach the rest position.

It changes its direction of rotation with the always alternately for pressure equalization flowing air.

To set the system optimally, the discharge angle must be changed until the Windmill reaches the rest position.

The central stream of the air curtain system widens the further it approaches the ground.

To prevent that the core stream blows into the sealed door opening, the outlet nozzle is pivotable.

In the normal position, the outlet nozzle is so positioned that it is blown at an angle of 7.5 ° to the outside.

If this angle is insufficient, the system may be swung.

For this, the air curtain system is pivotally stored in the consoles.

By carefully loosening a cap nut in the connection pads on the two end caps the system can be moved so that the discharge nozzle can be infinitely rotated by approximately 15 ° to the inside or outside.

Wrong setting

The air speed is too low. The airflow does not reach the ground.
Cold air flows in. Warm air flows out.

The air speed must be increased !

Wrong setting

The air velocity is too high.
Ineffective and disruptive air turbulences are incuring.

Reduce air speed!

Correct setting

The impeller of the windmill does not move.
The air velocity and the discharge angle are optimal.

Warm air cannot escape, cold air cannot enter.

Assembly variants

Rear wall assembly with normal construction width

The THERMOVENT will be mounted with two stainless steel panels with solid polyamide blocks on the warm side of the wall above the door opening. This is the normal type of installation.

Rear wall assembly with reduction of the construction width

The THERMOVENT will be mounted with two stainless steel brackets on the wall above the door opening. These consoles take up less space in the construction width – but need more space in the height.

Rear wall assembly with variable console distance

The THERMOVENT is mounted with two stainless steel brackets with solid polyamide blocks on the warm side of the wall above the door opening. If you can not mount the brackets in the right distance, it can be corrected by shifting the angle brackets below the polyamide blocks.

Ceiling mounting with mounting under the ceiling

The THERMOVENT will be mounted with two stainless steel brackets under the ceiling above the door opening.

Side mounting with mounting on the side walls

The THERMOVENT will be mounted with two stainless steel panels with polyamide solid plates on the side walls and in front of the door opening. This type of installation is often used in corridors that are sealed off by air curtains against warm air loss.

Cost savings

Saving of costs with THERMOVENT air curtains

Warm air is up to 20% lighter than cold air. It flows through the upper part of the door opening at a speed of about 1m/sec to the outside. Cold air enters at the same time through the lower door area.

At a factory gate (5x5m clear opening) and an outside temperature of 0°C 12.5 m³ warm air per second is flowing outside.

In two minutes, there is a loss of 1,500 m³.

The same amount of cold air 1,500m³ is flowing in at the same time and must be energyintensive reheated.

1 liter of oil is required to heat this cold air from 0° C up to 20° C.

This is the formula for the calculation of the energy required for heating air:

Q = m x c dt
Q = energy MJ
m = mass of air 1,239 Kg/m³
x = airflow m³
c = constant heat of the air 1.005
dt = 20 ° C temperature difference
39 MJ = 1.293 x 1500 X 1.005 X 20
35 MJ = 1 ltr. heating oil

One door opening, described above, costs at an unprotected gate in winter about 1 euro.
– In the summer of 0.5 euro.
With daily 25 door openings, the cost of warm air losses amount to about € 5,000 per year.

80-90% of the hot air leakage can be prevented by the use of THERMOVENT air curtains.


Catalog air curtain systems for factory doors

THERMOVENT air curtain systems for door heights up to 800 cm

An 24-page booklet that shows the use of THERMOVENT air curtain units of warehouse doors and factory gates. On a calculation example, the significant cost savings shown that is possible through the use of these facilities.

Facilities are available for door heights up to 8 meters and door widths up to 6 meters.


Photos of our air curtains


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Directly to the right contact person

Alfons Lütke Dreimann

Sales Germany North

Pietro Mattana

Sales Germany South,
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