Dehumidifiers – which is best suited for my requirement?

Which dehumidifier is best suited for my requirement?  Desiccant or Refrigerant?

Dehumidifiers are designed to extract moisture from the air. CAS-Hire currently provides two types which use very different methods to achieve this aim. Option One is the Desiccant dehumidifier and Option Two is the Refrigerant dehumidifier.

Desiccant dehumidifier

The desiccant version functions by drawing damp air through a rotor wheel containing special moisture absorbent material.

DehumidifierOnce the moisture is extracted from the air, the dry air is re-circulated back into the enclosed area or room continuing to increase the drying process.  The water collected within the absorbent material rotor is then released using heat to create condensation vapour which is directed by ducting from the desiccant dehumidifier to a suitable ventilation point usually outdoors.

The absorbent material used within the dehumidifier to create this procedure is usually a porous granules of silica gel.  This material can absorb water by drawing it in with each individual granule. As this part of the process is completed the introduction of heat releases the moisture by evaporating the damp vapour out of the material leaving the dry material ready to repeat the process and extract further moisture from the affected area.

Refrigerant dehumidifiers

The refrigerant type of dehumidifier functions by drawing damp air through a cold evaporator coil filled with refrigerant gas sealed within the dehumidifier which cools the damp air below its dew point temperature creating condensation.

The condensation drips are then caught in a container which can either be emptied manually or by an inbuilt pump which allows the water to be pumped away from the dehumidifier to a suitable drainage point. The dry air is then passed through warm coils increasing the temperature before being released back into the affected area or room thus enhancing the drying procedure.



Temperature Performance comparison

Extraction of moisture in cooler temperatures
Desiccant dehumidifiers operate better than refrigerant models at cold temperatures due to the fact that they use silica gel filled absorption material which performance is unaffected by fluctuation of temperature. Refrigerant dehumidifier performance levels fall dramatically when used at lower temperatures as the condensation dew point is more difficult extract from the air.

Extraction Performance comparison

Refrigerant dehumidifier models generally outperform desiccant dehumidifiers during the initial stages of air saturation especially when material within the area require to be dried quickly. We would highlight that mindful consideration must be taken regarding the extraction rates as performances are also dependant on the appropriate refrigerant dehumidifier sizing within the affected area.

Running Costs

Refrigerant dehumidifiers use less electricity therefore are more affordable to run.


Whilst the refrigerant dehumidifiers are more common place in the UK and extremely compact in size they generally are heavier units that the desiccant models. Many of the desiccant units are supplied with flexi ducts that require to be directed to a suitable nearby ventilation point so that the moisture can be removed which can be restricting compromising manoeuvrability to and from some affected damp area locations.
As the refrigerant dehumidifiers use compressors to complete the refrigeration cycle within the dehumidifiers they are generally noisier that desiccants models however noise levels are generally acceptable in most applications.

We are only too happy at CAS-Hire to discuss and assist offering guidance with your dehumidifier choice based on your application criteria.

Equipment available nationwide call 0800 525082 today for further assistance!

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