14 / 03 / 2017

How to choose the right dehumidifier?

How to choose the right dehumidifier?



Dehumidifiers is a necessity of our everyday life. Its main purpose is to reduce the level of humidity in the air, for health and comfort reasons. A dehumidifier will help you reduce heating costs, since they could increase room temperature up to 2-3°C.

Temperature sense

The temperature equivalent perceived by humans, caused by the combined effects of air temperature, relative humidity and other factors. During winter months, high humidity levels creates a sense of more cold temperature. For instance, if a room has 23°C and 80% humidity the feeling will be more unpleasant than if the same room has 20°C and 50% humidity. Managing ideal indoor humidity with a dehumidifier will provide more comfort and healthy conditions.

Choosing the best dehumidifier

Choosing the right dehumidifier generally depends on the amount of moisture extracted from the air in a 24-hour period. This capacity is measured in liters (lt/24h).The exact calculation of the dehumidifier we need is not an easy case, and depends on many factors, for this reason a specific calculation formula, cannot be given.

- Usually the size of the room you need to dehumidify will determine the size and the and capacity of the dehumidifier needed. This could be only right if the height of the place is to 2.8-3 meters. An alternative way is to choose based on the volume of the room. The volume is calculated by multiplying the square meters of the surface with height. Calculating cubic meters of our space we can put another parament to our dehumidifier, the air supply. Air supply dehumidifier should be able to collect the air as many times could in 24 hours. To understand the calculation, see the example below:

There is a room with 60m² and 3m height so the total volume is 180m³. If we choose a dehumidifier with dehumidifying capacity 20lt/24h has air flow 170m³/h. So in 24h will have total air flow 4080m³/24h. This result can pass the room air 4080 / 180 = 22,6 times though the device. If we choose a dehumidifier 12lt/24h with air supply 120m³/h for the same room, we will scan 16 times. Therefore we recommend for an efficient, faster and cheaper result, the times that passes the air of our space through the dehumidifier is not less than 20 times within 24 hours.

- Humidity levels in the area. For instance, near the sea or a lake which the humidity is high or in areas with low humidity.

- Thermal insulation and waterproofing of our space. For instance: Do we have humidity problems in some walls or rooms?

- The temperature of those rooms

- The frequency of the use of those rooms and how often ventilated.

As a consequence of the above and to avoid ending up with a dehumidifier that is not suited to what you need we would like to suggest the following indicative table with the dehumidifier per square space and average humidity level.

Surface are with average humidity 50-60% (m²) Surface are with average humidity 70-80% (m²) Efficiency dehumidifier (lt/24h)
Up to 30 Up to 20 8
30 to 45 20 to 30 12
45 to 70 30 to 45 16
70 to 90 45 to 60 20
90 to 120 60 to 80 25
120 to 150 80 to 100 30

Attention to the following observations:

1. The dimensions given, referred to single rooms

2. If there are any significant humidity problems, it could be better to be chosen a larger model than this which corresponds to the square meters of the room.

Types of Dehumidifiers

There are two types of dehumidifiers in the market. The dehumidifiers with compressor and those without compressor which used as a desiccant zeolite.

Dehumidifiers with compressor

Dehumidifiers with compressor cover a very wide range of performance depending on their power. To remove humidity, they draw air from the room over a filter and then pass it over cold coils, water then condenses on the coils and drips into the water tank. They are claimed to be better-suited in higher temperatures. For this reason it is not recommended for use in rooms with temperature below 13-14 °C.

Dehumidifiers with Zeolite (Desiccant)

Zeolite is a natural desiccant material that has a large range of uses in different sectors. In dehumidifiers is placed a special disk though which passes the air of the room and retain the moisture. Zeolite can absorb water from the air and then it is heated so that the moisture drips into the water condenser. The main advantage is that the performance remains stable regardless of the room temperature and is highly recommended for rooms with poor heating. On the other hand, they have higher energy consumption compared with dehumidifiers with compressor.

Noise Output

The noise output of a dehumidifier is an important aspect, especially when we have to use the dehumidifier in a bedroom. Therefore, it is significant to take under consideration the noise levels before choosing a dehumidifier. For small rooms the noise should not exceed 38 to 42dB at its lowest speed. Higher power dehumidifiers may have a noise level 44 to 54dB.


The ionizer is a useful accessory which should also be included in dehumidifiers. It helps eliminating the bacteria, dust and odor by generating ions that produce energy, this energy minimizes various odors, dust and smoke, creating a cleaner and healthier atmosphere. The improvement of atmosphere is important in areas with smoke and in places with sensitive people such as infants or elderly people suffering from allergies.

Continuous drainage

One added feature that each dehumidifier should have is the continuous drainage which allows the dehumidifier to operate continuously without being necessary to empty the condensate tank. This is highly recommended in cases where the dehumidifier is installed in places with high humidity problems because the tank will fill up very often or in places where there is no constant supervision.


The proper maintenance and cleaning of the dehumidifier is very important. Usually, the dehumidifiers are placed on the floor so they absorb all the dust lying on it and clog the filter resulting in a reduction of the efficiency of dehumidifier. This leads to an increased energy consumption and it may cause problems in the proper operation of dehumidifier. So, the filter of dehumidifier must be cleaned at least once a month to maintain a proper function.