Would you like to seal up your factory door comfortably?
Why do you benefit of THERMOVENT air curtains?
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
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
The air curtain can be installed by trained workers. We have several installation teams and assemble air curtains around the world.
What characterizes THERMOVENT air door systems?
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.
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.
- Preferably mounting the system centrally the door opening by the two consoles.
- The unit must be pushed on the consoles with the blowers towards the door.
- 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.
- 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.
- 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.
- 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.
- Don‘t install air curtains in combination with strip curtains or swing doors.
- 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.
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 !
The air velocity is too high.
Ineffective and disruptive air turbulences are incuring.
Reduce air speed!
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.
Rear wall assembly with variable console distance
Side mounting with mounting on the side walls
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.
Order directly from us
Directly to the right contact person
Alfons Lütke Dreimann
Austria and Switzerland