Guide to window fans
Window fans are used for ventilation of rooms and belong to the family of smaller ventilating systems. They remove unpleasant scents and prevent the foundation of mould. That is why the motor-operated devices are predominantly used in damp rooms with limited options for de-airing. They can be found in canteen kitches or generally in the gastronomy sector and have become more and more popular over the recent years. However in the course of increasing demands for eco friendliness in renovated or new houses, which are usually implemented through measurements of heat insulation,
fans are a great alternative when it comes to ensuring a balanced indoor climate.
- Differences between models
- Benefits of window fans
- Applicable standards
- In comparison with other kinds of fans
Generally, fans are labelled as technical stream machines, that are constantly transporting air and gas. Powered by electric motors, the energy that is being created is transferred onto the medium by a rotor. When it comes to designs, the main types that can be are differentiated are axial-flow fans and centrifugal fans. However, there are subtypes such as semi-axial flow or semi-centrifugal fans a well. In any case it is important that the device can deliver the best possible efficiency, so that costs for energy can be kept at a minimum.
axial-flow window fans
Window fans are mostly built to comply with the axial-flow design, that is usually used in case of low pressure in combination with a high amount of air. Therefore, heating or cooling are also some examples where they are applied, apart from de-airing and ventilation. Axial-flow construction means, that the rotor is parallel and axial respectively to the direction of the air, which can be compared to propellers of planes. The fan sucks in air from all directions of the room and, with the help of the blades of the rotor, releases it back in the axial direction.
Note: As ceiling fans ensure that air is lead outside or inside the room, it is necessary to implement a separate, additional ventilation system for air supply so that the air pressure in the room can stay even. This can be realised in several different ways, for example an additional (reversed) fan, a ventilation grille or window fold fan. In the end, it always depends on individual architectural conditions and requirements.
Installation of the devices
The main reason why window fans are quickly gaining popularity is the relatively easy installation. However, the setting up actually does require mechanical skills, so mounting the device should always be done by a professional. These are roughly the most important steps:
Attention: As the installation of these appliances requires working with electricity, it is crucial to employ the services of an electrician or expert.
Place of installation
Gastronomy has already been mentioned before, but the devices can be put up in a number of different types of rooms, including for example:
- Living room
- Conference rooms
- All types of common rooms
Basically, window fans can be used at any place that requires an extensive exchange of air; be it because of bad air quality because a lot of people in the room or because of smells that are a created in canteen kitchens, for example.
Differences between models
When choosing a window fan, the type and build of the existing window and the type of control that will be applied are important factors. These two aspects should be taken into consideration as well, on top of the requirements for the ventilation.
types of windows
Before the purchase of the right window fan, it should definitely be checked if the window is even suitable for the device. Many models for example, are not suitable for mounting in hinged double-pane windows. Should that be the case for you, there is no need to despair. Special system accessories are available as well, which allow installation in double-pane windows, for example. Generally speaking, however, these devices can be mounted in almost every type of window, including roof windows.
types of controls
Basically, we can differentiate between two types of controls for window fans, manual control and automated control with sensors.
The relatively easy installation is just one of the many benefits of the systems. Taking factors such as air exchange, noise level, costs, effort put into cleaning or flexible handling into account, there are quite a few advantages the use of these fans has. Yet, all in all the device has to fit the requirements of the user’s premises, so that it can realise its maximum efficiency. In order to constantly provide fresh air in the room, it is usually necessary to not only use one fan, but rather to use combination of several fans. The calculation of air volume is one of the core measures that need to be taken when drafting a ventilation concept. To name an example, the requirements of air volume in big canteen kitchens is far greater than in a meeting room.
The exchange of air is essential in many places, to prevent mould or remove unpleasant scents, like body-odours or the smell of toilets. However, in the end window fans alsoallow a constant supply of fresh air, which is a central factor for efficient working and studying in offices or classrooms, for example. Furthermore, ventilation systems, such as window fans, can also help to save energy as long as the chosen fan is suitable for the premises which is realised by the efficiency of each model.
Window fans generally operate on a low noise level, which promotes its use in living quarters. That means the devices can also be used in nursery schools or even in bedrooms, without any sounds that result in harm to the body.
The appliances are known to be a reasonably priced option for supplying premises with fresh air. However, it is not only the acquisition costs that are kept at a minimum, but also maintenance costs are marginal. The biggest cost factor are actually the costs for energy after years of use, which can be considerably reduced by using energy-efficient models.
The fans are easy to clean, in most cases the housing has a click system. Normally, the devices are maintenance-free, which also has positive effects on the expenses.
On one hand, easy installation and assembly make window fans very flexible devices, as they can be mounted to different types of windows and therefore in various places in side the room as well. On the other hand they play a major role for an extensive ventilation concept when combined with other fans.
There are many different standards and guidelines that should be taken into consideration when it comes to designing ventilation systems with window fans. A central standard of ventilation systems in apartments and arrangements of several rooms for example is the standard DIN 1946-6 that requires the compilation of a ventilation concept and ultimately picks up guidelines for the so-called fan supported ventilation. In this connection the DIN 18017-3 is to be mentioned as well, as it also includes rooms without windows, such as internal bathrooms, kitchens or toilets, which the DIN 1946-6 does not take account of. Both standards were updated in 2009 in order to comply with European guidelines. For instance the energy saving regulations EnEV §6 states that a certain minimum value of air density needs to be present, along with a minimum value of air exchange. The minium exchange of air can be calculated with the ventilation concept recorded in DIN 1946-6. In this context window fans are an option for ventilation, as they provide an exchange of air in accordance with certain standards.
In comparison with other kinds of fans
Particularly the commercial sector requires not only window fans, but often a combination of different devices in order to realise the ideal ventilation concept. This can turn out to be very helpful for de-airing and supply air, as all parts of the room are covered.
Like the same suggests, this kind of fan is put up predominantly in bathrooms and other small rooms, usually in bathrooms without windows. In contrast to window fans, it is mounted to the wall and primarily supposed to prevent humidity and unpleasant smells. However, overall both models are quite similar, because a bathroom fan with an appropriate add-on kit can be converted to a window fan as well.
Central ventilation units
This describes complex ventilation appliances with a system of air ducts that allows extensive ventilation of several rooms at the same time. This category has a difference between devices with central exhaust air and decentralised supply air, as well as devices with central exhaust and supply air. Essentially, a window fan is a possible option for decentralised ventilation, because this type only ventilates a certain room, and does not have any impact centrally on several rooms.
This fan type is primarily used for de-airing and ventilation in the commercial and industrial sector. Just like window fans, wall fans are quite easy to assemble compared to other systems, as there is no need for elaborate installation work of ventilation shafts and air ducts. However, their dimensions are much bigger than models for windows, but their installation also only requires a single opening on the outer wall. Wall fans are directly transporting air to the outside.
This fan’s name is also quite obviously indicating where it is supposed to be installed – on the ceiling. It is a conventional, classic option for creating a pleasant indoor climate. The rotation of the fan blades circulates air inside the room, which helps to save heating costs in winter. It should be pointed out though that ceiling fans cannot exchange air and only circulate the air that is already present, unless there is an open window.
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