Motor power
The power of the hood at maximum speed.
The more powerful the device, the more performant it is, usually. However, there is no rigid dependence here, and hoods of the same power may differ in actual performance. So it is worth evaluating power consumption in terms of power first of all: the lower this indicator, the more economical the device. And when evaluating performance, you need to look not so much at power as at the directly claimed flow of the air (see below).
Max. noise level
The level of noise produced by the hood in the loudest mode of operation. Usually (but not necessarily) it is the maximum power mode. It affects the comfort during operation of the device, so
quiet hoods will be more preferable, but also more expensive.
The decibels in which the noise level is measured are non-linear units, so it is easiest to use comparison tables to estimate a specific value. Here is the simplest table for the values relevant in this case:
— 35 dB. The volume of a conversation in an undertone (but not a whisper). The lowest maximum noise value in modern hoods. Devices with such characteristics are almost guaranteed not to cause inconvenience: such noise is often blocked by other sounds, for example, the background noise of the street in an open window.
— 40 dB. The volume of a normal conversation. The maximum noise level allowed in a residential area during the day. If the hood is bought for home use, and it is supposed to be turned on often and for a long time, the noise level in the selected device shouldn't exceed this indicator.
— 50 dB. Conversation volume at medium tones.
— 60 dB. Raised conversation.
— 70 dB. Sound background on a busy street, in a crowd of people talking loudly, the sound of a vacuum cleaner motor at a distance of 2 – 3 m.
— 75 dB. Scream or loud laughter at a distance of about a metre.
— 78 – 79 dB. Loud mechanical alarm clock, motorcycle o
...r truck engine. The highest level in modern consumer-grade hoods.
Note that the actual comfort of using the device depends not only on the volume but also on the timbre (tonality) of the noise: for example, a low, even rumble is generally perceived easier than high frequencies with clanging notes. If the hood installation is unsuccessful, the actual noise level may be higher than stated in the specifications. For example, additional noise can be caused by the hum of air in the ducts or rattling from the contact of the vibrating body with the wall. However, when choosing, it is worth focusing on the noise level claimed in the specifications.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.
Duct diameter
The duct diameter characterizes the size of the hood outlet to which the ducts are connected. The standard is either
120 mm or
150 mm. In many cases, an adapter from one diameter to another can additionally be included with the device. However, when replacing the hood with a new one, it is still better to operate with the existing pipe diameter and not use adapters.
