How to choose a silent bathroom extractor

A fan is a rotating machine that puts air in motion. It is therefore capable of transmitting the energy necessary to generate a pressure that maintains a continuous flow of air. Among its components is a drive motor, generally electric, and the control devices typical of this type of motor: starting, speed regulation, polarity switching, etc. The entire assembly is enclosed in a casing with spiral closure walls in the case of centrifugal fans and by a flat frame or tubular wrapping in axial ones. One of the fans most frequently used within a home is the bathroom extractor. Its function is to air and ventilate bathrooms to reduce mold and bad odors. Extraction also prevents condensation and keeps seals, walls, and ceilings in good condition.

Types of extractors

Extractors are electric devices, and therefore need to be connected to the power grid. They should not be placed above the bathtub or shower as regulations do not permit it. It is also not recommended to place them above radiators to avoid heat loss, nor next to doors or ventilation grilles, as a microcircuit can be created that prevents the air from being effectively renewed. Extractors require little maintenance; only periodic dust cleaning of the grille is needed and checking the condition of the internal ducts connecting the intake and exhaust openings to the device. Basically, bathroom extractors can be classified into two main groups:

• Axial: the extractor is placed on the ceiling. They are typically used in installations where the length of the ducts is very short. This group includes the helical models that are installed in windows or on an exterior wall, as they do not require any extraction duct.
• Centrifugal: these are more powerful than the previous ones and are indicated for installations where the exhaust ducts extend over long distances, up to 50 meters.

Properties of a silent bathroom extractor

A extractor must be capable of extracting a flow per hour ten times higher than the volume of the bathroom. To do this silently, vibrations, which are the main cause of the noise typically emitted by an extractor, should be avoided. The primary reason for these vibrations is usually the imbalance caused when the rotation axis of a rotating element (blade or impeller) does not pass through its center of mass (static imbalance) or does not align with the rotor's principal inertia axis (dynamic imbalance). This type of vibration is characterized by its frequency being equal to the rotation speed. Another factor that commonly generates vibrations is misalignments, which occur when two parallel shafts or those forming an angle are not aligned.