Centrifugal Fan Selection Guide: Application and Selection

From air purifiers to large AHU fan walls, different scenarios require different types of centrifugal fans. This article covers four of the most common centrifugal fans to help you quickly find the right solution.

1. Plastic/Galvanized Steel Backward-Curved Centrifugal Fan

Application Scenarios:

Air purifiers, fresh air units, laboratory fume hoods, clean benches, medical equipment.

Core Advantages:

Lightweight impeller, quick start, low noise; low cost, suitable for high-volume OEM applications.

Parameter Range:

Impeller φ190-280mm, airflow 380-1900m³/h, static pressure 50-600Pa, power 40-210W, AC external rotor motor.

Selection Method:

Based on equipment space and system resistance, locate the operating point on the P-Q curve, ensuring it falls within the high-efficiency zone.

2. Double-Inlet Forward-Curved Centrifugal Fan with Volute

Application Scenarios:

Traditional commercial AHU supply/return sections, central air conditioning units, industrial plant ventilation.

Core Advantages:

Double-inlet design delivers 40%-60% more airflow than single-inlet at the same diameter; volute directs airflow to connect directly with rectangular ducts; belt drive allows flexible speed adjustment; low cost, mature technology.

Main Disadvantages:

Low efficiency (55%-70%); belts are prone to wear and require regular maintenance; weak non-overloading capability.

Parameter Range:

Size #2.0-#4.5, airflow 900-19000m³/h, static pressure 300-850Pa, power 0.25-7.5kW, belt drive.

Selection Method:

Select based on required airflow and external static pressure, reserve 15%-20% static pressure margin for final filter resistance.

3. AC Backward-Curved Centrifugal Fan without Volute

It adopts a backward-inclined centrifugal aluminum impeller paired with an AC external rotor motor, features a volute-free structure, and works by being directly embedded into equipment cavities or plenums. It is one of the widely used fan types in the HVAC industry today.

This fan is widely used in AHU fan walls (multiple units installed in parallel and embedded in the plenum), FFU (Fan Filter Units), fresh air ventilators, energy storage cabinet/electrical cabinet cooling, medical clean workstations, and biological safety cabinets. It is especially suitable for space-constrained applications or situations requiring multiple units in parallel for redundancy.

Core Advantages:

01.Direct Drive, Maintenance-Free:   No belt drive, fewer failure points, low maintenance costs Non-Overloading,

02.High Static Pressure:   The backward-inclined impeller has a flat power curve, preventing motor stall during resistance fluctuations; airflow decay is 20%-30% slower than forward-curved fans when filters become dirty

03.Flexible Installation:  Short axial length allows direct embedding into cavities; multiple units can be connected in parallel for N+1 redundancy

04.High Cost-Effectiveness: Procurement cost is 35%-50% lower than EC solutions

Parameter Range:

Impeller diameter φ280-630mm, airflow 2100-14000m³/h, static pressure 100-800Pa, power 130-3000W, AC external rotor pure copper winding motor, voltage 220V/380V, frequency 50Hz/60Hz.

Selection Method (Three-Step):

Step 1: Confirm Operating Point:

Calculate total system resistance, reserve 15%-20% margin, locate the operating point in the high-efficiency zone on the P-Q curve

Step 2: Determine Installation Method:

Space-constrained or requiring multiple parallel units → choose volute-free version

Step 3: Match Electrical Parameters: Confirm voltage, frequency, and protection rating

4. EC Plug Fan use Fan Wall in AHU

EC plug fan is currently the most widely used and in-demand category for replacement in the HVAC industry.

Application Scenarios:

AHU fan walls, FFUs, fresh air ventilators, energy storage cabinet cooling, medical clean workstations.

Core Advantages:

Short axial length for flexible installation; multiple units provide redundancy — one failure does not affect overall operation; uniform airflow distribution; higher cleanliness.

Parameter Range:

Impeller Diameter: φ280~φ630mm

Airflow:           2100~14000m3/h

Static Pressure:   100~800Pa

Power:           130-3000W

Motor:        EC motor + support 0-10V/ PWM/ Modbus, native stepless speed control

AC backward-inclined centrifugal fans feature high cost-effectiveness, direct-drive maintenance-free operation, and non-overloading high static pressure. They are suitable for budget-sensitive, constant-air-volume applications such as FFUs, fresh air ventilators, energy storage cabinet cooling, and AHU fan wall retrofits.

EC Plug Fans feature 30%-50% energy savings, native stepless speed control, and BMS smart integration. They are suitable for high-end projects with long annual operating hours and mandatory requirements for energy efficiency and intelligence, such as hospital clean rooms, data center CRAH units, and VAV systems.

In short: AC is a cost-effective and worry-free basic solution; EC is an energy-saving and intelligent upgrade solution. The former suits constant-air-volume, budget-first projects; the latter suits variable-air-volume projects prioritizing total lifecycle cost optimization.

Shanghai Weima, as a fan manufacturer, offers a full range of centrifugal fan products and supports OEM/ODM services. For wholesalers, we offer annual purchase discount programs. Welcome to contact us for cooperation!

Contact us for a quote