Heating modes
The maximum heat output shows the capabilities of the device. At the same time, almost all air curtains can adjust the heating mode, thereby reducing power consumption. The reduced power mode is more gentle on the wear of the device and is appropriate for the continuous operation of the air curtain. Which also favourably affects the power supply to which the device is connected.
Fan power
The highest electrical power consumed by the air curtain when operating in ventilation mode, without air heating.
The performance, speed and range of the airflow depend on this parameter (see below). However, this dependence is not unambiguous — units similar in fan power can differ markedly in other specs. But what this parameter directly affects is energy consumption. For water models (see "Type"), as well as curtains that do
not have a heating function at all (see "Features"), it is the power in fan mode that describes the total electricity consumption. And if an electric heater is provided in the design, then the total energy consumption can be derived by adding the power in fan mode and the maximum heat output (see above).
Max. range
The greatest effective range provided by an air curtain, in other words,
the greatest distance that the airflow travels from the device before dissipating and losing effectiveness.
It is worth choosing a device according to this parameter in such a way that it is guaranteed to block the corresponding opening. Of course, one should not forget about other specs, first of all, performance (see above); however, if the range is insufficient, then even the most efficient air curtain will be ineffective.
Number of speeds
The number of speed adjustments provided in the design of the air curtain.
Speed adjustment provides additional options for adjusting the operating mode of the unit to the specifics of the situation. For example, if an air curtain is installed at the entrance to a store, then in the morning and late at night, when there are few people and the door is rarely opened, you can reduce the speed, saving electricity, and increase it during peak hours to prevent heat loss through constantly opening doors.
The more speed adjustments, the more extensive the adjustment possibilities, the more options the user has and the easier it is to choose the best one. The most advanced option is stepless adjustment, which does not provide fixed settings at all and allows you to select any speed value from the minimum to the maximum. On the other hand, such an adjustment affects the cost of the unit.
Noise level
The highest level of noise generated by the air curtain during normal operation.
The
lower this figure, the more comfortable the use of the unit, the better it is suitable for cases where noise is undesirable. When choosing according to specific values recorded in the characteristics, it should be taken into account that the decibel used to measure the noise level is not a linear quantity: for example, an increase in sound power by 2 times corresponds to an increase of 3 dB, 10 times — by 10 dB, 100 times — by 20 dB. Therefore, to assess the noise level, it is easiest to refer to comparative tables, where the correspondence of specific values in decibels to various real sound sources is recorded. In most modern air curtains, the noise ranges from 25 to 70 dB, here is the simplest table for this range:
20 – 25 dB — a weak audible sound, comparable to a whisper at a distance of 1 – 2 m;
25 – 30 dB — intelligible whisper at a short distance, ticking of a wall clock;
35 dB — muffled conversation;
40 – 45 dB — normal human speech;
50 – 55 dB — talking in raised tones, noise in the office;
60 dB — loud conversation at a distance of 4 – 5 m.
70 dB — loud conversation nearby.
Dimensions (WxHxD)
General dimensions of the over-door heaters. The amount of space occupied by the unit during installation depends on the dimensions, but also the dimensions of the space it covers — namely the width of the airflow (or height, if the flow is directed not down, but to the side). Most air curtains have characteristic elongated proportions, and the mentioned width/height corresponds to the largest dimension of the device.
Note that the width and height of the air curtain, in this case, are indicated for the standard installation method (see above): for example, devices installed on top will have a large width at a low height, and side ones vice versa. For models with universal mounting, the dimensions can be indicated in different ways, but it is usually not difficult to evaluate the characteristics of the flow in them if we take into account the elongated proportions described above — the largest dimension is usually the same as the width/height of the flow.
Features of choosing an air curtain in terms of dimensions (and, accordingly, the width of the covered space) also depend on the type of its installation. When mounted above the doorway, the width of the unit must be no less than the width of the doorway (and ideally, a little more, with some margin). If the curtain is installed on the side, it is enough that its height is 3/4 of the height of the opening — due to the peculiarities of the movement of heated air, this will completely cover the required space.
