NovelAire DH 55 Industrial
Desiccant Dehumidifier Review

The NovelAire DH 55 is a small, light weight desiccant dehumidifier suitable for use in small areas where valuable and moisture sensitive items are stored or operated and exceptional dehumidification capabilities are required. This unit was originally designed specifically for military applications, particularly those where a very dry atmosphere is required and must be reliably maintained in very low temperature conditions.

Armed forces must be ready to meet unexpected contingencies with little or no notice and require their equipment and stores to be in perfect condition at all times. The standards of reliability specified by procurement agencies are extremely demanding and apply as stringently to dehumidifiers as to any other items in the inventory. The outcome, in the case of the DH55, is a dehumidifier of outstanding performance, with a low probability of failure and exceptional ruggedness.

Many civilian applications are less demanding but some have comparably exacting operating requirements which are as critical to achieving key organizational goals. Examples may be found in the pharmaceutical, food processing, confectionery manufacturing and electronics industries and in cold storage areas, archives and vaults, among others.

novelaire dh 55 industrial desiccant dehumidifier


The NovelAire DH 55 is able to achieve low relative humidity levels and low dew points because it uses desiccant technology to remove water from the air. The majority of dehumidifiers use a refrigeration process to cool a metal surface on to which water vapour is condensed from the air. This technology becomes increasingly inefficient at lower levels of humidity and a typical room dehumidifier, for example, struggles to extract moisture below 50%RH.

More sophisticated (and more expensive) refrigerant dehumidifiers are effective to lower RH levels but the nature of the process imposes limits which only a desiccant dehumidifier can exceed.

A desiccant dehumidifier works using a chemical process. A wheel or rotor consisting of a desiccant (water adsorbing) material, overlaid on another material to ensure an air-flow across as large a surface area as possible, "traps" the water molecules from the air.

A large surface area is important because the desiccant does not absorb moisture, draw it into the body of the desiccant, like a sponge. It adsorbs individual water molecules on to its surface, to which the molecules are drawn by a chemical process. This chemical action will continue to draw water from the air at levels of relative humidity much lower than a refrigerant process which makes this type of dehumidifier much more effective where extreme dryness is required.

The desiccant process is also impervious to the effects of frost. Ice formation on the evaporator coil of a refrigerant dehumidifier degrades its effectiveness and energy has to be expended to heat the coil to melt the ice. At temperatures around the freezing point of water even the best refrigerant units are unable to operate.

A desiccant dehumidifier will continue to perform effectively at much lower temperatures, in the case of the NovelAire DH 55 this is as low as 0°F (-18°C). In addition to extreme dryness the DH 55 is also capable of extremely low temperature operation and is in its element when both features are required.

As the water is adsorbed the capacity of the desiccant to adsorb more approaches its limit. To "reactivate" the slowly turning desiccant wheel a portion of it is passing through a warm air stream at any time during each rotation.

The heat energy releases the water molecules into this air stream, which is vented outside the drying area via ducting. The now "reactivated" portion of the desiccant re-enters the return air stream and adsorbs more water as another "saturated" portion is reactivated in its turn.

The NovelAire DH 55 will extract 26 pints of water per day at AHAM conditions (80°F/27°C and 60% relative humidity). These test conditions are scarcely relevant for this unit as it would only be employed in much lower humidity and/or temperature conditions. A graph plotting water extraction rates under varying conditions is included in the DH 55 Tech Sheet. In the operating conditions for which it was designed the performance of this unit is impressive.

The NovelAire DH 55 is an extremely compact unit with exterior dimensions of just 12.6 x 9.5 x 17 inches. This suits the dehumidifier for use in smaller areas, for which it was designed. The DH55 is portable and weighs only 27lb and is a stand-alone unit although, of course, ducting must be installed to enable operation in any application.

Reflecting its design for military applications the DH55 is a durable unit with tough components enclosed in a robust casing for protection. Desiccant dehumidifiers dispense with the troublesome refrigeration system of a refrigerant dehumidifier and are, therefore, intrinsically more reliable. A humidistat is also incorporated for precise control of the moisture content of the air.


Brand NovelAire
Model NovelAire DH 55 Desiccant Dehumidifier
Application(s) Industrial
Suitable for Smaller areas (up to 143 sq ft)
Portable Yes
Carrying handles No
Wheels/casters No
Weight (lb) 27
Dimensions, inches (WxDxH) 12.6 x 9.5 x 17
Dehumidification process Desiccant
Water extraction (80°F 60%RH) 26 pints per 24 hrs
Water container capacity (pints) N/A
Container full indicator N/A
Auto-power cut off when full N/A
Continuous drainage option N/A
Operating temperature Range 0°F to 110°F
Blower 55 CFM
Anti-frost N/A
Electronic controls No
Humidistat Yes
Variable fan speed settings No
Noise level Not Rated
Power input 115v/935w


Superior performance at low temperature/low relative humidity

Precise humidity control

Energy efficient





No condensate


Initial purchase cost

Requires ducting

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