Capacity
The nominal capacity of the dehumidifier is the maximum amount of moisture that the unit can remove from the air per day.
For efficient operation, the capacity of the dehumidifier must be no less than the amount of excess moisture that accumulates in the room during the same time. This amount can be calculated using special formulas or calculator programs. However, the results of such calculations are quite approximate, but they can be used in the selection, and for a full guarantee it is worth taking a performance margin of at least 10–20%. If desired, this margin can be more; but note that high performance significantly affects the price, dimensions and energy consumption of the dehumidifier.
As for specific values, entry-level models for small spaces provide
less than 25 L/day. Indicators of
26 – 50 L/day can be called average,
51 – 75 L/day — above average; there are also many powerful professional units with a capacity of
more than 75 L/day.
Air flow
The maximum amount of air that a dehumidifier can pass through in an hour.
The choice for this parameter depends on the size of the room. It is believed that for effective operation, the dehumidifier must drive through itself an amount of air in an hour that exceeds the volume of the room by 3-4 times; and you can determine the volume of the room by multiplying the area by the height of the ceiling. For example, a 12 m² room with 2.5 m ceilings will hold 12*2.5=30 m³ of air; accordingly, for efficient operation in such a room, a dehumidifier with a capacity of 30*3=90 m³/h, and preferably 30*4=120 m³/h, is required. It is quite possible to choose a unit with a margin for airflow — unless you need to take into account that an increase in performance affects the price and energy consumption. But a too-low value of this parameter is undesirable: such a dehumidifier simply cannot effectively cope with its task.
As for specific figures, relatively low-power models produce
up to 250 m³/h, equipment for
251–500 m³/h and
501–750 m³/h can be attributed to the average level, and many units are capable of processing
more than 750 m³/h.
Dehumidifying operating range
The range of relative humidity (RH — relative humidity) of the ambient air, in which the dehumidifier is guaranteed to be able to cope with its task and at the same time perform at the level claimed by the manufacturer.
The wider this range — the more versatile the unit, the less likely it is to be in emergency conditions. At the same time, when choosing, it is worth considering the specifics of the application of the dehumidifier. Thus, dehumidifiers are initially designed for high humidity, but the ability to work at 100% relative humidity is not always required. For example, in the cold season, the air coming from the street is "drier" by itself when heated indoors (due to the increase in temperature, the relative humidity drops, although the actual amount of moisture in the air does not change), and even in wet weather, a dehumidifier with a limit of 80-90% may be enough. And the lower dehumidification limit directly depends on the tasks facing the device. If we are talking about living quarters, offices and other places where you need to create conditions that are pleasant for people, then you need to take into account that the most comfortable values for a person concerning humidity are 40-70%. Therefore, for such conditions, it makes no sense to specifically look for a device with a lower limit of less than 40%. But for specific tasks such as drying rooms during repairs, warehousing, etc. lower humidity levels may be needed.
Note that many model...s are quite capable of working outside the operating range, except that the performance may decrease. However, it does not hurt to clarify such an ability according to the official documentation.
Operating temperature range
The ambient temperature range in which the dehumidifier can operate normally. The wider this range, the more versatile the dehumidifier is, and the more diverse the conditions in which it can be used. Note that, in contrast to the humidity range (see above), going beyond the operating temperatures is fraught not only with loss of efficiency but also with serious malfunctions and even breakdowns. Therefore, it is worth choosing a unit according to this parameter in such a way that it is guaranteed to block possible fluctuations in the temperature of the air with which the dehumidifier is to work.
Note that most modern models are designed to operate at positive temperatures, with the lower limit being on average about 4–5 °C. The only type of dehumidifiers that can operate at temperatures below zero are
adsorption dryers(see "Suitable for").
Condensate tank volume
The volume of the tank for collecting condensate (moisture removed from the air), provided in the design of the dehumidifier.
The larger the condensate tank, the slower it will fill up and the less often it will have to be emptied. It is especially important for high-performance units (see above). On the other hand, the volumetric tank has the appropriate dimensions, which affects the dimensions of the entire dryer. When evaluating the relationship between tank capacity and dehumidifier performance, note that the device rarely operates at full capacity. See "Dehumidification capacity" for more on this; here we note that if, for example, a dehumidifier with parameter of 24 L/day has a tank of 4 litres, this does not mean that the tank will necessarily be filled to the top every 4 hours. An alternative to tanks is the use of permanent condensate drainage systems; see "Features" for details.
Noise level
The maximum noise level produced by the dryer during operation. The lower this number, the more comfortable the use of the unit will be; this is especially true for residential premises. For workshops, warehouses and other similar places, the noise level is not so critical — this type of climate control equipment is often installed in places where there are almost no people, or in the vicinity of such noisy equipment, against which the noise from the dehumidifier can simply be lost. However, for non-residential premises, data on the noise can be useful — for example, to assess the need for special ear protection and other labour protection measures.
Note that this parameter is measured in decibels, and this is a non-linear value: for example, a change of 3 dB approximately corresponds to an increase/decrease in power by 2 times, by 10 dB — by 10 times, etc. Therefore, to assess the noise level, it is easiest to use comparative tables. Here is a simplified table for the range that most modern dehumidifiers fall into.
35 dB — muffled conversation;
40 dB — quiet conversation; the maximum noise level allowed in residential premises during the daytime;
45 — 50 dB — conversation in a normal tone;
55 dB — background sound in the office without special noise sources;
60 dB — loud conversation;
65 dB — city street with average traffic intensity;
70 dB — a conversation of several people in raised tones.
Display
The display provides the user with additional information about the operation of the dehumidifier: it can show various current settings (hygrostat, shutdown timer, etc.), data from indicators (for example, tank filling or filter replacement), error messages, etc. Thus, the control of the device is more convenient and intuitive. This feature is only available for electronically controlled models (see above).
