What Is a Desiccant Dehumidifier and How It Works

Desiccant dehumidifiers excel at reducing humidity in cold environments.

September 17, 2025

How to Use

Article Updated on: September 10, 2026

Dehumidifiers are handy for lowering the humidity in basements and attics, in buildings under construction, on restoration projects, and in manufacturing, healthcare and warehouse settings. Refrigerant dehumidifiers are often the default choice, but a desiccant humidifier can be more efficient and effective in cool environments and unheated spaces, and for industrial dehumidification.

What is a desiccant dehumidifier?

A desiccant dehumidifier uses silica gel or another absorbent material to dry out the air. Humid air is drawn into the unit and passed over a rotating desiccant wheel, which traps some of the moisture. A small heater dries out the desiccant material so it can continue to work. A blower sends the dried, slightly warmed air into the space. The hot, wet air coming off the desiccant wheel may need to be ducted to the outside.

What are the types of desiccant dehumidifiers?

There are two types of desiccant dehumidifiers. A portable desiccant dehumidifier, which sits on wheels and is relatively easy to move, is typically a cost-effective way to dry out small and mid-sized spaces such as sheds, garages, attics and crawl spaces.

Industrial or large commercial desiccant dehumidifiers are towable and range in size from 5,000 cubic feet per minute (CFM) of airflow to up to 17,500 CFM. They are suitable for larger spaces, construction drying, warehouses, businesses and industrial dehumidification, such as in food processing facilities.

Most desiccant dehumidifiers run on electricity, but propane, tri-fuel and natural gas dehumidifier models are also available.

How does a desiccant dehumidifier work?

Have you ever tried to dry out a wet smartphone by zipping it into a bag containing silica gel packets? These are the small packets often found in mail-order packages to protect goods such as foods, medicines, and shoes from humidity. A desiccant humidifier works on the same principle of drawing out moisture using silica gel or a similar medium.

Silica gel is made of tiny, porous beads. Moisture is attracted to these beads, which hold it on their surface in a process called adsorption.

Adsorption works well at temperatures below 50°F, which is why desiccant dehumidifiers are best for cooler climates and unheated spaces.

Refrigerant vs. desiccant dehumidifiers

Are desiccant dehumidifiers better than refrigerant dehumidifiers? Both have their advantages. Choosing a dehumidifier type comes down to which will work better for the particular application and environment.

Desiccant dehumidifiers

A desiccant dehumidifier may be an excellent choice for colder areas and unheated spaces with high humidity. This type of dehumidifier:

Is much more energy efficient than refrigerant units at temperatures at or below 50°F
Is better at maintaining very low humidity levels (potentially as low as 1%)
Can work in extremely cold temperatures and in low-humidity environments
Is lighter and has a smaller footprint
Is quieter because it does not have a compressor
Does not have a water discharge tank that needs to be emptied
Is typically the most cost-effective way to prevent mold and fungus from growing in buildings and interior components

Refrigerant dehumidifiers

Refrigerant dehumidifiers come in large and portable models, perfect for drying carpet, drywall and plaster, and suitable for water damage restoration. Another available option is a refrigerant dehumidifier and air conditioning hybrid unit that removes air moisture while providing temperature control.

Refrigerant dehumidifiers use a compressor and a refrigerant to dehumidify the air. Water is collected in a built-in bucket. The bucket is emptied manually or drained through a hose.

A refrigerant dehumidifier:

Is more energy efficient at temperatures above 50°F
Causes a smaller increase in room temperature, making it a better choice when excessive heat is an issue
Does not work in cold temperatures

How much electricity does an industrial dehumidifier use?

Electricity consumption varies widely and depends on the size of the unit, the air temperature, the humidity and how many hours the unit runs during the day. A relatively small desiccant dehumidifier may use anywhere from 360 to 1,500 watts per hour. A larger unit may use 1,500 to 3,500 watts per hour.

Desiccant dehumidifiers are often more energy efficient than refrigerant dehumidifiers.

“Desiccant dehumidifiers are generally more efficient at delivering large amounts of power,” said Justin Kaidel, Region Product Development Manager, Power/HVAC North America, United Rentals. “They remove more moisture per hour per day using less energy.”

Large units used for heavy-duty applications run on higher voltages (such as 460V or 480V), with lower amperage. This means less energy is wasted as heat in the wiring. These units feature 3-phase motors, which are often more efficient than single-phase motors and run more smoothly.

“For typical industrial applications involving larger electrical loads and machinery, a 3-phase system is generally preferred over a single-phase 120V or 240V system,” said Kaidel. “For residential and small commercial applications, single-phase 120V or 240V equipment is common and often more practical.”

Desiccant dehumidifiers are generally more efficient at delivering large amounts of power.
-Justin Kaidel, Region Product Development Manager, Power/HVAC North America

Best uses for desiccant dehumidifiers

Desiccant dehumidifiers are good choices for a variety of applications, including these:

Construction drying, especially in winter (paint, coatings, sealants, drywall, brick, concrete, plaster, hardwoods)
Mold prevention during disaster cleanup (restoration and remediation)
Dehumidifying cold or unheated spaces such as garages, attics, basements, warehouses, food processing facilities, cold storage units, pharmaceutical product and medical equipment storage areas
Dehumidifying data centers and battery production facilities
Dehumidifying industrial tank interiors after sandblasting in preparation for painting
Preparing industrial surfaces for coating
Drying electromechanical equipment such as motor windings during plant shutdowns

Need a desiccant dehumidifier rental?

Many factors go into the choice of a dehumidifier. When you’re renting a dehumidifier, working with a knowledgeable climate control partner will help ensure that you end up with the best model for your application and budget.

United Rentals can provide information to help you choose between a desiccant and refrigerant dehumidifier and size it based on the amount of space to be dehumidified, how quickly you need to remove moisture, what materials you’re drying (some materials, such as concrete, hold more moisture than others), and how many gallons of water per day you need to remove. The United Rentals Power and HVAC team can also advise on dehumidifier placement and ducting needs and supply a ducting kit if needed.

If you have other temporary HVAC equipment on site, such as air conditioners, air scrubbers or blowers, United Rentals can help you optimize the equipment so it works together for the best, most efficient outcome.

Frequently asked questions

What is a desiccant dehumidifier used for?

A desiccant dehumidifier draws humid air over a rotating desiccant wheel coated in silica gel or a similar absorbent material, then sends dried air back into the space. Teams use desiccant dehumidifiers for construction drying, mold prevention, cold storage and industrial dehumidification in environments below 50°F where refrigerant units lose efficiency.

What's the difference between a desiccant and a refrigerant dehumidifier?

A desiccant dehumidifier uses absorbent material and no compressor, making it quieter, lighter and more efficient in cold or low-humidity environments. A refrigerant dehumidifier uses a compressor and works best above 50°F, making it a better fit for water damage restoration in heated spaces. Your teams should choose based on temperature, humidity target and application.

When should I use a desiccant dehumidifier instead of a refrigerant unit?

Choose a desiccant dehumidifier for cold or unheated spaces, low-humidity targets below 1%, or applications where noise and space are concerns. This includes construction drying in winter, food processing facilities, data centers and pharmaceutical storage. Contact the United Rentals Power and HVAC team to help size and place the right unit for your project.

Can a desiccant dehumidifier help with mold prevention during restoration work?

Yes, a desiccant dehumidifier is often the most cost-effective option for preventing mold and fungus growth during disaster cleanup, since it maintains very low humidity levels even in cool, damp conditions.