Some Experience When Choosing Dehumidifier

may hut amCurrently the need of humidity treatment becomes a matter of concern not only in the technical sector but also in commerce. It is not simple to choose an optimal method among various methods of dehumidifying. Therefore, in this article we will compare these dehumidifying methods so that we can have an overview to know which is the most efficient and economical.

Nowadays, using dehumidifiers becomes popularly. In addition, maximizing effectiveness of using dehumidification equipments almost relies on designers’ experience. There are some technologies of moisture treatment. It is difficult to determine performance, power consumption or reliability of each type if we do not know its application. Therefore, the application of appropriate method in each particular case is very important to save three main costs: initial cost, installation cost and operation cost.

After selecting the appropriate equipment, the cost of installation and operation will be the main issue for investors and suppliers together with the initial cost:

– Installation cost: The initial cost is quite small in comparison to the installation cost of the system. Thus, the investment cost of dehumidification equipments is less important than the cost of installation.

– Operation cost: The operation cost is quite higher than the installation cost.  Dehumidifiers often consume a lot of energy for heating and cooling to adjust temperature of air inlet. When designers can utilize other cheaper energy sources instead of the electric power, this may reduce the operation cost.

Each dehumidifier is different adequately to each application. If suppliers, designers and contractors can understand comprehensively functions of dehumidifiers, this will take risks out of end users and increase reliability and longevity of the equipments. Various dehumidifiers would has been installed in various ways. Therefore, contractors must understand and experience  various installation methods to reduce the risks during construction and operation of the system.

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Cooling-based Dehumidifiers

By reducing temperature of supply air to dew point, vapor in the air condensates on the surface and is removed from the humid air.

Desiccant Dehumidifiers

Desiccants attract moisture from the air by creating an area of low vapor pressure at the surface of the desiccant.


In many practical situations, cooling-based dehumidification system and desiccant dehumidifiers are the same function to make the air drier. However, we would wonder which type of methods should been used for our purpose. Actually, no exact answer to this question, for particular case, we should consider the reference following:

– It would be better if cooling-based dehumidification system combined with desiccant dehumidifiers. Desiccant dehumidifiers only operate effectively when the temperature left purge section as low as possible. However, operation of desiccant dehumidifiers is not limited by the dew point temperature of air inlet as cooling-based dehumidification. Thus, the two systems support each other, the strengths of this one will complement the other’s weaknesses and vice versa.

– For specified projects, we would compare electric power cost with thermal energy cost to determine which system should be used; desiccant dehumidification or cooling-based dehumidification. If the cost of thermal energy is cheaper than electric power cost, the former would be selected and vice versa.

– Normally, cooling-based dehumidification is more economical than desiccant dehumidification in normal temperature and humidity. However, the former can not operate well in an environment with dew point temperature lower than 40°F (4.4°C ). In this condition, snow would has been appeared on coils which reduces the efficiency of dehumidification equipment.

– Using dehumidifier to handle fresh air for air conditioning system combined with ice storage tank is very effective. Because the dew point of distribution air in the air conditioning system using ice storage tank is very low range 40°F~ 45°F (4.4°C ~ 4.5°C), return air mixing with fresh air will cause very large condensed water. Therefore, we have to dehumidify primary fresh air before mixing with return air to reduce installation cost for PAU system and to save initial cost of fan and pump gone along with the PAU.

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