There are two primary HVAC fan types, there are axial and centrifugal fan. These fans vary in terms of design, efficiency, application, and maintenance requirements.
Proper maintenance and cleaning of various HVAC fan types are essential to ensure the fan operates efficiently and has a long service life.
HVAC Fan Types: Axial
Axial fans are HVAC components with blades that rotate around a central axis, similar to propellers. This type of fan is typically in applications that require low pressure and high airflow. You will commonly find axial fans in cooling towers, exhaust systems, and small ventilation systems.
Axial fans are particularly effective at moving air over short distances. Before cleaning, ensure you turn off the power supply to the HVAC system. Then, follow these cleaning and maintenance steps:
Visual Inspection
Perform a visual inspection to check for dirt, dust, or debris around the fan blades and motor. Clean the blades using a soft brush or microfiber cloth to gently wipe them. You can also use a vacuum cleaner with an additional brush attachment to remove dirt and debris.
Motor and Bearing Cleaning
Check the fan motor and bearings for proper lubrication. If necessary, apply lubricating oil to the motor and bearings according to the manufacturer’s recommendations.
Air Duct Cleaning
Ensure the air ducts connected to the axial fan are free from obstructions. Clean the air filter to prevent dirt buildup on the fan. If needed, replace the air filter.
Perform a complete cleaning of the axial fan every 3-6 months. If you live in a dry and dusty area, consider cleaning it more frequently.
Simple ASCII Style Axial Fan
Simple ASCII Style Axial fan
HVAC Fan Types: Centrifugal
Centrifugal Industrial Fan
Centrifugal fans are one of the HVAC fan types found in duct, air handler, and blower HVAC systems. Air enters along the fan axis and then moves toward the fan exhaust, which allows it to produce higher pressure. This type of fan is well-suited for long-distance air movement and systems with obstacles. The initial cleaning procedure is the same as disconnecting the system first. Then, follow the steps below in sequence:
Blade Cleaning
Use a vacuum cleaner or soft brush to clean the fan blades. Be careful not to damage or bend the blades. Taking incorrect steps could affect performance.
Motor Inspection
Next, check for dust buildup on the motor. Use compressed air or a brush to clean the motor and other electrical components. Always avoid spraying water or moisture.
Fan Housing Inspection
Check the fan housing for dust and dirt buildup. Clean it with a damp cloth, ensuring that you avoid moisture near electrical components. If the fan uses bearings, lubricate them according to the manufacturer’s recommendations. Perform regular inspections and cleaning every 6 to 12 months.
Simple ASCII Style Centrifugal Fan
Simple ASCII Style Centrifugal Fan
Centrifugal Subtypes
Additionally there are three common subtypes of centrifugal fans. They use the same general maintenance steps described above. However, each design has unique features and additional considerations.
Sub-type: Backward Curved Fans
This fan design features blades curved backward in the direction of the airflow, as the name implies. These fans are typically in commercial and industrial HVAC systems, where efficient air movement and high-pressure handling are required, all while consuming less power.
Sub-type: Forward Curved Fans
This is one of the HVAC fan types with blades that curve forward in the direction of the airflow. These fans can be in smaller air handling units and residential systems, where they operate quite quietly while relying on moderate air pressure.
Compared to backward curved fans, forward curved fans are more suitable for low-pressure systems, but they are less efficient.
Sub-type: Plug Fan
This is one of the HVAC fan types with a centrifugal design, where the motor is integrated with the fan wheel. This design reduces space and noise, making it no wonder that this fan is often in rooftop units, air handling units, and various other HVAC systems to increase efficiency with a compact design.