Comparison WetAir WAD-B25L vs Midea MDDF-20DEN7

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.

Power consumption of the dehumidifier in normal operation.

From a practical point of view, this characteristic is secondary — manufacturers select power in such a way as to provide the necessary operating parameters (performance, air flow, etc.), and when choosing, you should focus primarily on these parameters. However, certain practical points also depend on the power consumption. Firstly, only models of less than 3-3.5 kW can be connected to ordinary household outlets; higher power consumption will require either a 400 V supply (see Power supply) or a direct connection to the panel. However, even power of more than 2 kW is rare in modern dehumidifiers — for most of these devices, the energy consumption is in the range from 500 to 1000 W or from 1000 to 2000 W, and in the most modest models it does not exceed 500 W at all. Secondly, power data may be required to calculate the load on the power grid. Such a need arises mainly for the selection of additional equipment — circuit breakers, AVR, UPS, etc.

Also, note that models with similar performance may differ in power consumption. However, a more economical dehumidifier often costs more, but with regular use, this difference pays off by reducing energy costs.

The area of the room for which the device is designed. It is the maximum area that this model can effectively handle: the use in smaller rooms is quite acceptable, but the device simply does not have enough performance for a larger space. Also, note that the area is indicated based on a ceiling height of 2.5-3 m — the standard value for residential premises; with a higher ceiling height, the effective area decreases, and it can be recalculated using special formulas.

When choosing by area, it is worth taking a certain margin, but it should not be too large — otherwise, the device will be unnecessarily powerful, bulky and expensive.

The type of control provided in the design of the dehumidifier.

The type of control determines how external control elements (buttons, knobs, sliders) interact with the hardware of the unit. There are two options here:

— Mechanical. Systems in which the control elements act directly on the individual parts of the dryer. For example, fan speed adjustment (see "Features") in such systems can be carried out using a slider that directly changes the resistance of the resistor in the fan power circuit; the shutdown timer (see ibid.) is a rotary knob with a clock mechanism, etc. The mechanical control is simple and reliable, it is suitable for all basic functions of the dehumidifier and at the same time, it is inexpensive. On the other hand, such systems are inferior in accuracy to electronic ones, and besides, they do not allow many additional features (remote control, display, etc.). Therefore, although this type of control can be found in all categories of dehumidifiers, there are fewer such models on the modern market than electronic ones.

— Electronic. Control is carried out through a special electronic circuit: each user action (pressing a button, turning a knob, etc.) is processed by this circuit, and from it control signals are sent to the working elements of the dehumidifier. Such systems are more functional and advanced than mechanical ones. Electronic control is conveni...ent and allows you to use various additional functions — for example, displays and remote controls; and individual parameters can be controlled with very high precision and small adjustment steps. The disadvantages of electronic systems are considered to be higher cost and lower reliability than mechanics, as well as repair difficulty. At the same time, these shortcomings are not so often critical: for example, differences in cost are usually almost imperceptible against the the overall price of devices, and the probability of failure in modern electronics is still very low. Nowadays, it is the most popular type of control among dehumidifiers of all categories. And it can be implemented either by buttons or by touch panel. The second option gives the device a solid look.

The ability to remotely control the dehumidifier from a smartphone, tablet or similar gadget with a special application installed. The connection in this case is via Wi-Fi.

This feature allows you to control the device from a distance and often gives you more options than the classic control method.

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.

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.

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").

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.