The Direct Drive Roof Exhaust Fan is a roof-mounted ventilation fan for continuous exhaust in commercial and industrial buildings. The direct-drive motor connects directly to the fan wheel, eliminating belts and pulleys for a compact roof-mounted exhaust arrangement.
Key Specifications
|
Parameter |
Specification |
|
Airflow |
500–25,000 CFM / 850–42,500 m³/h |
|
Static Pressure |
Up to 1.5 in. wg / 373 Pa |
|
Fan Wheel Diameter |
12–48 in. / 305–1,219 mm |
|
Motor |
Single-phase / Three-phase |
|
Motor Voltage |
115 V, 208–230 V, 460 V, 575 V |
|
Frequency |
50 / 60 Hz |
|
Operating Temperature |
-29°C to 60°C |
|
High-Temperature Option |
Up to 149°C |
|
Housing |
Aluminum / Galvanized Steel / SS304 / SS316 |
|
Discharge |
Up-blast / Down-blast |
|
Drive |
Direct Drive |
Roof Installation
Curb Connection: Confirm fan base dimensions and curb dimensions against the approved installation drawing.
Roof Opening: Match the curb opening to the existing or planned roof opening before installation.
Discharge Direction: Up-blast discharges air vertically above the roof; down-blast discharges air downward around the curb.
Replacement Projects: Provide the existing fan model, base dimensions, curb dimensions and roof opening for dimensional matching.
Roof Curb: Galvanized steel roof curbs can be supplied for new installations.
Fan Construction
Fan Wheel: Backward-inclined or airfoil centrifugal wheel, statically and dynamically balanced.
Housing: Heavy-gauge spun aluminum or galvanized steel; SS304 and SS316 are available.
Drive Assembly: Direct-drive motor connects directly to the fan wheel without belts or pulleys.
Curb Cap: One-piece spun cap provides the connection between the fan and roof curb.
Screens: Galvanized or stainless steel bird/insect screens can be fitted at the discharge.
Airflow & Operating Performance
The fan delivers airflow from 500 to 25,000 CFM (850–42,500 m³/h) against system static pressure up to 1.5 in. wg (373 Pa). Its operating performance is determined by the relationship between airflow and static pressure at the actual system operating point.
Performance data can be provided to verify airflow and static pressure requirements under the specified operating conditions.
Outdoor Construction
Housing Materials: Aluminum, galvanized steel, SS304 or SS316 can be specified according to the installation environment.
Discharge Screen: Galvanized or stainless steel screens can be used at the discharge opening.
Backdraft Control: Gravity or motorized backdraft dampers can be specified where reverse airflow must be controlled when the fan is stopped.
Temperature: Standard operating temperature is -29°C to 60°C; high-temperature configurations are available up to 149°C.
Applications
Manufacturing Facilities
General building exhaust and removal of process heat.
Warehouses & Logistics Centers
Roof-level exhaust for heat and stagnant air.
Commercial Buildings
General building ventilation and exhaust.
Industrial Facilities
Exhaust of heated or contaminated building air where the fan specification is suitable.
Inspection & Documentation
Each completed fan is inspected against the confirmed order and technical drawing before shipment.
Fan Wheel & Rotation: Inspect blade installation, wheel clearance and fastener tightness, then run the fan to confirm correct rotation without blade interference or abnormal contact.
Motor Data: Check motor model, power, voltage, phase and frequency against the confirmed order and nameplate.
Dimensions & Curb Connection: Measure the fan base, outlet, mounting dimensions and curb connection against the approved drawing.
Electrical Operation: Check motor starting, wiring and running current during operation and record the measured current.
Balance & Vibration: Run the assembled fan at operating speed and check for abnormal vibration or rotating imbalance.
Final Assembly: Check fasteners, guards, screens, dampers and other specified components before packing.
Documentation: GA drawing, performance data, motor datasheet, wiring diagram, installation instructions, O&M manual and applicable inspection records can be supplied with the confirmed order.
Supply Information
MOQ: 1 set for standard orders; OEM orders from 10 sets.
Lead Time: 15–25 working days for standard orders; 25–40 working days for OEM orders.
Packaging: Export plywood case or reinforced carton with protective film.
Spare Parts: Motors, screens, dampers and other specified replacement parts can be supplied.
OEM: Nameplates, labels and packaging marks can be prepared for private-label orders.
RFQ Information
For quotation and technical confirmation, provide:
Required airflow: CFM or m³/h
Required static pressure: In. wg or Pa
Motor power supply: Voltage / phase / frequency
Discharge: Up-blast or down-blast
Roof opening and curb dimensions
Existing fan model, nameplate and installation dimensions for replacement
Operating air temperature and any requirement above 60°C
Required accessories: Backdraft damper, bird/insect screen, roof curb or disconnect switch
Quantity and installation location
FAQ
Q: What is a direct drive roof exhaust fan?
A: A direct drive roof exhaust fan uses a motor connected directly to the fan wheel, without a belt-and-pulley transmission system.
Q: What is the difference between a direct drive and belt drive exhaust fan?
A: Direct drive removes belts, pulleys and related belt-tensioning components, while belt drive uses a separate belt transmission between the motor and fan wheel.
Q: How do I calculate the required roof exhaust fan airflow?
A: Calculate the required building air changes or exhaust volume in CFM or m³/h, then verify the required airflow against the system static pressure.
Q: What static pressure should I use when choosing a roof exhaust fan?
A: Use the total resistance of the connected ductwork, dampers, filters, louvers and other system components at the required operating airflow.
Q: Can a roof exhaust fan replace an existing fan?
A: Yes. Replacement orders should use the existing fan's model, nameplate and installation dimensions to match the replacement fan and roof connection.
Q: What information should be checked before replacing a roof exhaust fan?
A: Check the existing fan's airflow duty, motor power supply, discharge direction, base and curb dimensions, roof opening and connected duct arrangement.
Q: Does a roof exhaust fan require a roof curb?
A: A roof curb provides the mounting and transition interface between the roof opening and fan. The curb dimensions should match the fan base and roof opening.
Q: What maintenance does a direct drive roof exhaust fan require?
A: Maintenance mainly includes checking the motor, fan wheel, fasteners, screens, dampers and electrical connections, together with periodic inspection for abnormal noise or vibration.
Q: What causes abnormal vibration in a roof exhaust fan?
A: Common causes include fan-wheel imbalance, loose fasteners, installation misalignment, damaged rotating components or motor-related problems
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