Axial vs Centrifugal Fans in Dehumidifiers: What Is Different?

The fan's role in a dehumidifier

Every dehumidifier contains an air-circulating fan as part of its construction, according to the U.S. Department of Energy (DOE) definition of a dehumidifier. The fan pulls room air through the intake grille, over the cold evaporator coil where moisture condenses, and then over the warm condenser coil before discharging the dried air back into the room. The airflow path is compact and includes filters, coils, and possibly a duct, which creates resistance to the air movement.

Because of this restricted path, the fan must be able to generate enough static pressure to maintain airflow. Static pressure is the resistance the fan must overcome to push air through the components. The two main fan types, axial and centrifugal, differ in how they handle this pressure. To understand the full air path, see the article on how dehumidifiers work and airflow direction.

How axial fans work

An axial fan moves air parallel to its rotational axis, like a propeller or a household box fan. It is excellent at moving large volumes of air when there is little resistance, but its ability to work against static pressure diminishes quickly. In a dehumidifier, the filter and coil add resistance, so an axial fan would need to spin very fast to maintain airflow, which increases noise and reduces efficiency.

Axial fans are sometimes found in very small thermoelectric dehumidifiers, where the airflow path is short and unobstructed. They are also used in some portable units that vent directly through a large opening. For most compressor-based dehumidifiers, axial fans are not the preferred choice because they cannot handle the pressure required.

How centrifugal fans work

A centrifugal fan, also called a squirrel cage or blower wheel, draws air into the center of the wheel and discharges it radially outward through a scroll housing. This design builds up static pressure, making it well suited for pushing air through the coils and out of the unit. The air path is more indirect, but the fan can maintain a steady airflow even as the filter loads with dust.

Centrifugal fans are the standard in residential dehumidifiers. They tend to operate at lower rotational speeds than axial fans for the same airflow, which can make them quieter. The multiple blades slice the air more smoothly, reducing the turbulent noise that axial fans produce.

Airflow and static pressure

The airflow a fan delivers is measured in cubic feet per minute (CFM) at a given static pressure. A centrifugal fan will deliver a higher CFM when the dehumidifier's coils and filters restrict the flow, compared to an axial fan of similar size and speed. This matters because the dehumidifier's moisture removal rate depends on how much air passes over the coil. If airflow drops, the evaporator may ice up or the unit will simply remove less water.

For sizing, you do not need to match CFM precisely; the manufacturer rates the unit for a specific capacity in pints per day. That rating already reflects the fan's performance within the intended airflow path. Instead of focusing on fan type, you can compare capacity and energy efficiency, as explained in the pint rating and IEF articles. A general comparison of the two fan types is shown below.

Noise and efficiency

Noise from a dehumidifier comes from the compressor, the fan, and the airflow itself. Axial fans can be noisier because they generate more turbulence when pushing against resistance. Centrifugal fans, with their bladed impeller, produce a lower and more even sound. Many manufacturers list a decibel rating; you can compare models using the noise level guide.

Energy efficiency is influenced by the fan motor and the compressor. ENERGY STAR certified dehumidifiers use "more efficient refrigeration coils, compressors, and fans," as stated on the ENERGY STAR website. A well-matched fan reduces the electrical load, which contributes to a higher integrated energy factor (IEF). The IEF explainer shows how this metric is measured.

Choosing the right fan type for your needs

For almost any household dehumidifier, the fan type is already determined by the design, and you do not have to choose it yourself. When comparing models, focus on the pint capacity rating, energy efficiency, and features like a built-in pump or continuous drain. The fan type matters most in how it affects noise and performance, but you can infer that a compact unit with a bucket and a grill that exhausts upward likely uses a centrifugal fan.

If you prioritize quiet operation, look for models with a decibel rating and choose one for bedrooms or bathrooms. For large spaces like basements, a higher capacity unit with a robust blower is advisable, as shown in the basement guide. For energy efficiency, select an ENERGY STAR certified model from the energy star guide.

What to pick for your use

Questions

Do all dehumidifiers use centrifugal fans?

Most compressor-based dehumidifiers use centrifugal fans because they generate the static pressure needed to move air through the coils. Some very small thermoelectric units may use an axial fan, but they are less common and generally for small spaces.

Which fan type is quieter, axial or centrifugal?

Centrifugal fans tend to be quieter at the same airflow because they move air more smoothly and at lower rotational speeds. Axial fans can generate more turbulence and noise when they have to push against the resistance of a dehumidifier's internal components.

Can I replace a centrifugal fan with an axial fan in my dehumidifier?

No. The fan is selected by the manufacturer to match the static pressure requirements of the unit. An axial fan will not move enough air through the coil and could lead to poor performance or ice buildup.

How does fan type affect the pint rating of a dehumidifier?

The fan's ability to move air over the coil directly influences how much moisture is removed per hour. A unit with a centrifugal fan can maintain airflow under load, which helps it achieve its rated pint capacity. Manufacturers test the complete system, so the pint rating already reflects the fan performance.

Does the fan type matter for energy consumption?

The fan motor consumes a small portion of the total electricity. The compressor and the overall design determine most of the energy use. ENERGY STAR models use more efficient fans as part of the package, so look for the ENERGY STAR label for lower running costs.