When searching for high-volume, compact air-moving components for HVAC and ventilation equipment, you will likely come across the term "double inlet blower wheel." But what exactly does it mean - and how is it different from a traditional centrifugal impeller?
In this guide, we explain what a double inlet blower wheel is, how it works, and why it is widely used in systems such as fan coil units, air handling units, and inline blowers. We'll also show how it rela
tes to products like our forward centrifugal fans, backward curved centrifugal fans, and EC energy-saving fan modules.
Definition: What Is a Double Inlet Blower Wheel?
A double inlet blower wheel is a type of centrifugal impeller designed with air inlets on both sides of the wheel. As a result, air is drawn into the impeller from two directions (left and right) and then expelled radially outward into a housing - creating a high-volume airflow in a relatively compact footprint.
This design is typically used in double inlet centrifugal fans/blowers, which are also known as double-suction fans.
How It Works
Air Entry → Enters from both sides of the wheel
Impeller Rotation → Accelerates air using centrifugal force
Air Discharge → Exits radially into the scroll housing
Because air is drawn from two sides, the airflow is evenly distributed across the impeller, which increases volume capacity while also reducing shaft load and vibration.
Characteristics of Double Inlet Blower Wheels
| Feature | Benefit |
|---|---|
| Two air inlets | Higher airflow (CFM / m³/h) per wheel size |
| Compact construction | Suitable for slim fan coil units and cabinet blowers |
| Balanced airflow loading | Longer bearing life, reduced vibration |
| Commonly forward-curved blades | Excellent for low-pressure HVAC supply |
Double Inlet vs Single Inlet Blower Wheel
| Item | Double Inlet Blower Wheel | Single Inlet Blower Wheel |
|---|---|---|
| Number of inlets | Two sides | One side |
| Airflow capacity | Higher within compact housing | Lower for same wheel size |
| Typical fan type | Double inlet forward centrifugal fan | Backward centrifugal fan or 400mm EC backward curved fan (single inlet) |
| Application | FCUs, AHUs, wall-mounted blowers | Industrial duct ventilation, exhaust, filtration |
Applications
Double inlet blower wheels are widely used in:
- Fan coil units (FCU) and air handlers
- Commercial HVAC supply and return
- Cabinet blowers and air curtains
- Double-inlet forward centrifugal fan assemblies
- Compact plug-in blowers in ventilation equipment
If higher pressure or cleaner airflow is required, these wheels may also be replaced with single-inlet backward centrifugal fan wheels, such as a 355mm backward centrifugal fan or 400mm EC backward curved centrifugal fan.
Related Fan Products You Can Link To
Here's how you can interlink product pages from this article:
- Forward centrifugal fan: standard double inlet blower fan
- Backward centrifugal fan: higher-pressure single inlet solution
- Backward curved centrifugal fan: premium efficiency alternative
- EC axial fan / 400mm EC backward curved centrifugal fan: EC upgrade version for energy-saving AHUs
Conclusion
A double inlet blower wheel is a centrifugal impeller that draws air from two sides, delivering higher airflow in a compact package. It is commonly used in HVAC fan coil units, air handing units, and other space-limited ventilation applications where high volume but moderate pressure is needed.
Whether you're using a traditional forward centrifugal fan, upgrading to a backward curved centrifugal fan, or moving towards EC axial fan modular solutions, understanding blower wheel structure helps you optimize airflow performance and system efficiency.
