Choosing a quality bathroom fan is actually more important than it might seem at first glance. So how not to make a mistake?
The bathroom left its shadowy existence as a purely functional room decades ago. Instead, in addition to its function for personal hygiene, it is becoming increasingly important as a feel-good and relaxation area. As a result, users’ demands on this central space are also growing.
One issue that should not be neglected is ventilation.
For while recreation rooms are always positioned on exterior walls with windows, bathrooms still regularly have to make do with interior positions, despite increased requirements. Bathroom fans promise an alternative to window ventilation.
However, in practice, not every ventilation device is suitable to actually represent an equivalent replacement.
See also: How to Buy the Best Whole-House Fan
What are bathroom fans?
Bathroom fans are a simple form of mechanical ventilation. Unlike centralized ventilation systems, these small room fans do not require a mechanical room or large central components. Instead, the actual fans can be placed directly in the associated air duct.
They are characterized by the fact that they have neither a separate supply air nor a heat exchanger, as is common today with central ventilation units. Instead, they “only” ensure that the room air present in the bathrooms is removed and conveyed outside. In most cases, fresh air is then drawn in through the door gap or special air vents from the rest of the apartment or house.
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Why do you need fans in the bathroom?
The bathroom differs from all other rooms of an apartment by a very special peculiarity: in it are carried out almost exclusively activities that involve a large amount of water.
Showering and bathing, in particular, create extreme humidity, which leads to the familiar images of fogged mirrors and shower stall walls. If the moisture is not removed, it settles in furniture, wall and floor coverings and all existing textiles.
There, for example, mold spores from the room air or other bacteria and pathogens find optimal development opportunities.
The only effective way to eliminate this humidity is ventilation. However, since bathrooms are regularly designed indoors and without windows, bathroom fans have to take over this task. At the same time, the fans also ensure that the air exchange that is more or less inevitable in other rooms is artificially created and that a minimum air quality is guaranteed.
What is important in bathroom ventilation?
Because of their space-saving design, small-room fans in particular do not have an unlimited capacity. Therefore, it should be clear from the outset what requirements are placed on the fans in order to ensure optimum ventilation in the damp room.
After all, the optimum interaction of the various parameters results in a system that meets the requirements in all aspects despite its small design.
The performance of the bathroom fan
In the first place is usually the power of the fan or, more precisely, the electric motor driving the ventilation. More power means a greater volume of air and therefore more moisture that can be extracted from the bath.
Closely related to the actual motor power are the impeller and the duct. They must be matched to the drive to ensure high air turnover in the overall package without creating unwanted flow noise. Due to their frequent location near children’s bedrooms and bedrooms, low noise combined with the necessary power is an absolute must in order to combine air exchange with the comfort expected from living spaces.
One of the main purposes of bathroom fans is to remove the humidity created by the use of the room. From the bathroom’s point of view, this task is completed as soon as the humid room air has passed through the ventilation system.
However, this does not solve the problem of mold and bacteria growth in the warm, humid environment. This is because moisture can naturally condense in the ducts of the exhaust air system as well, providing the same conditions that were skillfully avoided in the damp room by the fans.
An important step to avoid condensation in the exhaust air duct is a good and above all continuous as well as gapless insulation of the duct. If the walls remain warm, the moisture will not condense until it passes out of the duct into the usually much cooler outside air.
It is also advantageous to route the pipes as straight as possible without unnecessary curves or kinks. This is because these interfering points additionally swirl the moist air and promote condensation.
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The control of the bathroom fan
Although bathrooms are becoming increasingly “important” and of higher quality, they are still only used temporarily. The situation is different when it comes to the critical humidity that needs to be removed via the fans. It is true that this only arises with use, i.e. showering, for example.
However, it remains in the room far longer than the users.
And even with functioning ventilation, it takes some time for all the humid air in the room to be removed and exchanged for drier air. A control system is therefore indispensable for bathroom ventilation. This can either be activated independently, so that, for example, a predefined runtime is activated after a switch is pressed.
However, coupling to the light switch is also widespread. When the light is switched on, the ventilation is activated at the same time.
Run-on times through ventilation control
An important component of the control system for bathroom ventilation are so-called run-on times. If the ventilation is activated via the light switch, for example, this defines the start time.
However, the time until leaving the room is not sufficient to carry out the air exchange completely.
For this reason, the control system usually sets a run-on time, i.e. a period of time for which the exhaust air system continues to run after the users have already left the bathroom again and switched off the light.
There are technical possibilities to control ventilation systems by measuring the air humidity. However, the high effort involved means that the standard is now implemented using timers with overrun times.
With correspondingly long time periods, moisture removal is reliably ensured even during intensive use.
When is ventilation worthwhile in addition to bathroom fans?
The question is rightly raised time and again as to whether bathroom fans should not also be provided with supply air in the same way as other room ventilation systems. In fact, the air quality within the room would be improved by installing supply fans with appropriate ducts.
However, the effort required for this is enormous. Instead, in “normal” bathrooms, it is sufficient to supply room air from the adjacent areas via air vents or somewhat larger door gaps.
Controlled supply air would make sense if the wet area were highly frequented and used permanently. This is the case, for example, in indoor swimming pools, wellness areas or fitness studios. In the domestic environment, however, such conditions are rarely encountered.