Desiccant Dehumidifiers

Desiccant Dehumidifiers for Low-Temperature and Industrial Moisture Control

When does a desiccant dehumidifier outperform a refrigerant unit?

Refrigerant dehumidifiers cool incoming air below its dew point to condense moisture onto a cold coil. That process depends on the air being warm enough to hold significant moisture in the first place. Below about 65°F, refrigerant coils begin to frost, efficiency drops sharply, and at sub-freezing temperatures the units stop removing moisture entirely. Desiccant dehumidifiers work on a different principle: a silica gel or molecular sieve rotor absorbs water vapor directly from the air regardless of temperature. The rotor then passes through a heated regeneration zone that drives off the moisture and exhausts it outside. This means desiccant units operate at full rated capacity in cold storage facilities, unheated warehouses, freezer vestibules, and outdoor restoration jobs in winter months where a refrigerant unit would be useless.

The ASHRAE Fundamentals Handbook defines desiccant dehumidification as the preferred method when process conditions fall below 40°F or when target relative humidity must reach below 35% — conditions refrigerant units cannot achieve. Bry-Air and Ebac build industrial desiccant units specifically for these environments, with stainless or coated internals that resist corrosion in humid industrial settings.

What industries rely on desiccant dehumidification and why?

Water damage restoration contractors use desiccant units on winter jobs and in crawl spaces where ambient temps drop too low for refrigerant equipment to function. Cold storage operators use them to prevent condensation on freezer walls and floors, which causes slip hazards and accelerates corrosion. Pharmaceutical manufacturers use desiccant systems to maintain humidity below 20% RH during tablet production, since moisture activates hygroscopic compounds and degrades shelf life. Museums and document storage facilities use them to protect paper, film, and artifacts from humidity-driven deterioration. Any industrial process that involves hygroscopic materials — powdered chemicals, electronic components, food packaging — benefits from the low dew point capability that only desiccant technology provides.

For restoration contractors specifically, a desiccant unit paired with air movers on a cold-weather water damage job meets the structural drying requirements set out in the IICRC S500 standard even when outdoor temperatures prevent running a refrigerant unit at the door for exhaust management.

Related: Commercial Dehumidifiers · Flood Water Extraction Equipment · Air Movers · Air Scrubbers

How do you size a desiccant dehumidifier for a commercial application?

Sizing is based on moisture load, not room volume alone. The key inputs are the volume of air to be processed per hour, the inlet air temperature and relative humidity, and the target outlet humidity. Bry-Air and Ebac publish performance curves for their units at multiple inlet conditions, which allows accurate sizing for cold-temperature applications where standard pint-per-day ratings — calculated at 80°F and 60% RH — are meaningless. A unit rated at 150 pints per day under AHAM standard conditions may deliver only 60 to 80 pints per day at 40°F, while a correctly sized desiccant unit maintains its rated output regardless. For facility managers specifying equipment for a cold storage or manufacturing environment, the EPA moisture control guidance recommends targeting indoor RH between 30% and 50% year-round — a range desiccant units can maintain even through winter.