Flow of air (extraction)
The performance of the hood in extraction mode at maximum speed shows the real possibilities for air purification. Since this parameter is several times less than the motor performance (maximum performance), not all manufacturers indicate this value, trying to present large and beautiful numbers. A similar situation can be observed among other devices. For example, in vacuum cleaners, the total power is many times greater than the suction power; in acoustics, mediocre brands prefer to list peak power instead of nominal power. Therefore, motor performance and extraction performance can not be compared. However, high-performance motors will also give high performance in extraction mode. And it may well be that the conditional Bosch with an extraction performance of 300 m³/h will be better than another hood with a maximum motor performance of 500 m³/h.
Number of motors
The number of motors provided in the hood.
For most modern models, one engine is enough — this is enough even for fairly high performance.
Models with two motors are somewhat less common — usually, these are powerful performant hoods. One of the advantages of this design is that only one motor can be used at low speeds, and the second one can be connected only when maximum power is required. It has a positive effect on the minimum noise level (see above); on the other hand, the maximum noise level can be quite high, and such devices are usually more expensive than single-motor ones.
It is technically possible to use more than two motors. However, such models are single exceptions.
Filter indicator
The presence
of an indicator signaling the clogging of the filter and the need to clean/replace it. Both grease and carbon filters can be equipped with such an indicator (see above for the filters themselves). One of the options for such an indicator is a pattern applied to the filter surface itself, and a signal about the need for replacement may be the disappearance or, conversely, the appearance of the pattern. A more advanced option is a timer that tracks the total operating time and gives a signal when the filter resource is exhausted.
Sleep timer
A timer that automatically turns off the hood after a predetermined time. With such a system, you do not need to wait until the completion of ventilation and turn off the device manually — just set the timer, and you can safely leave the kitchen on your own business; the hood will turn itself off at the right time.
Display
The hood has its own display. Usually, this is the simplest
LCD screen for two or three characters, sometimes with additional indicators. However, even such a screen makes device control more convenient and visual: it can display the current operating mode, information about the sleep timer (see Sleep timer), the status of filters (see Filter indicator), etc.
This function rarely is used in inexpensive hoods with the simplest functionality. Therefore, the display is usually a sign of an expensive and advanced model.
Height (max)
The height of the entire hood structure is from the lower edge to the upper part of the body (the point of connection of the external air duct). For hoods with an adjustable design that allows you to change the height of the case, the maximum height is the size of the device in the unfolded state; in the case of non-adjustable hoods, this means a correspondingly constant overall height. When choosing a hood in height, it is worth proceeding from two points:
1. The optimal height of the air intake above the hob is 60-80 cm. This height allows the hood to capture kitchen fumes effectively and, at the same time, gives enough space to work with the hob.
2. Between the hood body and the ceiling, a clearance is required for connecting an external air duct.
