Dehumidifiers: They expel moisture, shield health


Three typical types of dehumidifiers are used in the market and are now basic household and professional equipment: with compressor, zeolite or thermoelectric function.

* By Mr. Kyriakos Talekoglou

The dehumidifier is a device that removes moisture from an indoor space.

It is used in places with humidity above 65%, because if the humidity is regulated to the desired level, great energy savings are achieved, the cost of heating is drastically reduced and the ideal conditions are ensured.

Humidity is measured in several ways, the most common of which is the measurement of relative humidity, the ideal average value of which ranges between 50-60%.

At this level of humidity the person feels comfortable and lives in an ideal environment, which prevents the occurrence of allergies, colds and bone pain. At the same time, an average humidity of 50-60% helps to protect and maintain the materials that exist in the space, such as walls, plasterboard, wooden floors and furniture, while clothes in the closets are also protected.

So when the humidity in a room is much higher than these levels, then it is recommended to use a dehumidifier either occasionally or permanently. This is because there are places that may have a humidity problem only at certain times of the year, but also places that have humidity all year round (such as the bathroom) or places that are not heated and properly ventilated, even in summer.

There are also times when humidity is an individual problem, in a room of the house, in an area where there is no insulation or in places with construction errors or defects.

There are three main types of dehumidifiers: a) the compressor dehumidifier, b) the thermoelectric dehumidifier and c) the zeolite dehumidifier.

Below we refer to each type in detail.

1. Dehumidifier with compressor

The principle of operation of compressors of this type is similar to the operation of air conditioners: The liquid air passes through the cooling element of the dehumidifier, which condenses the moisture in its special cold device, thus removing water from the air.

This water is collected in a container of the device, while the rest of the air passes through a heating element where the temperature rises to the desired levels, and then returns to the room.

The advantages of this type of dehumidifier are:

- Direct result.

- Economy during operation in areas that are normally heated.

The disadvantages are:

- There is an impact from the ambient temperature. (For this reason, this dehumidifier is not recommended in places where the temperature drops below 12-15οC).

- The compressor gives more volume and weight to the device.

2. Thermoelectric dehumidifier (Peltier)

The principle of operation of this dehumidifier is similar to that of the compressor dehumidifier, but it is based on the Peltier thermoelectric effect, from which it took its name.

In the Peltier effect, electric current flows through two different materials that join at a point, and depending on the direction of the current, that point is either heated or cooled. In the thermoelectric dehumidifier, liquid air enters the appliance and is cooled to eliminate water vapor and water, and then returns warmer to the room.

The advantages of this dehumidifier are:

- Its portability.

- Silent operation (because it is small in size).

- Lack of moving parts or compressor.

In addition, the construction of the thermoelectric dehumidifier is simple, while its basic components are economical.

Its disadvantages are:

- The small fan, which may require frequent replacement.

- The possibility of use only in small spaces, because most models in this category remove only 0.5 - 0.8 liters of moisture per day.

3. Dehumidifier with zeolite

Zeolite is a natural drying material with a wide range of uses. It is placed in the dehumidifier, in a special disk which rotates at low speed and through which the air of the space passes. During the passage of air, the zeolite retains moisture and is then heated by an internal thermal resistor and removes moisture, directing the water into a container and delivering the dry-hot air back to the room.

The advantages of the zeolite dehumidifier are several:

- Its performance remains constant regardless of the ambient temperature.

- During its operation it emits dry and hot air, which also helps to heat the space.

- The zeolite drying material does not wear out and does not need to be replaced.

Its disadvantage is the higher power consumption compared to compressor dehumidifiers.

Dehumidifier selection

There are several dehumidifiers with a built-in ionizer, which releases ions helping to neutralize bacteria, dust, odors and smoke. Calculating the dehumidification capacity is difficult and depends on several factors. Therefore, before choosing a dehumidifier, the following should be taken into account:

a) The dimensions of the space we want to cover. We have to calculate the space in cubic meters, in order to choose the dehumidifier taking into account how many times a day the dehumidifier will refresh the air of the space.

b) The thermal insulation of the space, the age of the building, as well as any problems.

c) The humidity of the area, the orientation of the building and the altitude at which the building is located.

d) The area to be dehydrated (bathroom, storage, north room).

As it is understood from the above, the correct calculation of our needs and the correct planning will help us to choose the right product for our space, without additional charges.

* Mr. Kyriakos Talekoglou is a teacher (of the branch PE82), Head of Mechanical Engineering at the Civitanideio Public School of Arts and Professions.

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