Desiccant Dehumidification

The energy efficient choice

All desiccant dehumidifiers operate on the same principle. Moist air passes over a desiccant material, which grabs the moisture, releasing dry air to be recirculated back into a room or building. The desiccant is then heated to remove the moisture from the dehumidifier and the moisture is then released outdoors.

The difference between desiccant dehumidifier designs is in the type of desiccant used and the way in which it is introduced to the moist air.

Regardless of the design, natural gas desiccant dehumidification is an energy-efficient way to keep large areas feeling dry and comfortable, even on the hottest most humid days.

Desiccant dehumidification is ideal for buildings:

  • Which require low indoor humidity at a dew point of 10 C or less.

  • Where the latent load is greater than 25% of the total cooling load.

  • Which have a high fresh air intake or are in humid climates.

Rotating dry desiccant wheels

Dry desiccants collect moisture on their surface and hold it, a process known as adsorption, not absorption.

Some common dry desiccant materials are silica gel, titanium gel, dry lithium chloride, natural zeolites and activated alumina.

Whatever type is used, it is formed into a wheel with a large surface area. Moist air passes over the surface area and is dried by heating it. A properly maintained desiccant wheel will last anywhere from 5 to 10 years.

Liquid desiccant systems

Liquid desiccants work on the principle of chemical absorption of water vapour from the air. The moisture is pulled out of the air and absorbed by the liquid desiccant.

Over time, the water extracted from the air will dilute the liquid desiccant. To maintain its prescribed concentration, the desiccant is fed through a regenerator where it is heated to release the moisture. The water is exhausted outdoors and the regenerated desiccant is cooled and reused.

Liquid systems are the ideal solution where biologically uncontaminated air is required, in places such as healthcare facilities or sensitive industrial applications such as pharmaceuticals. The liquid desiccant kills bacteria on contact, and there are no cool surfaces on which bacteria could grow.


Routine maintenance is required for either a dry or liquid desiccant system. Air streams must be filtered, and filters should be checked regularly to ensure they are clean.

Ventilation Air

In humid climates, it’s a good idea to mix incoming air with existing air in the space being cooled to avoid introducing overly humid air into the system. Mixing indoor and outdoor air in this way will keep indoor humidity levels down.