Compare centrifugal forced draft fan directions for boiler combustion-air supply, burner pressure and higher-resistance air-side systems. QIYUE FAN organizes the product family by boiler scale, pressure demand and the complete air-supply route.
Select the Fan from the Complete Combustion-Air Route
A boiler forced draft fan should not be selected from motor power or boiler capacity alone. Confirm the required combustion-air volume, total air-side resistance, inlet temperature, burner demand and control range before choosing the fan series.
Boiler and Fuel
Confirm boiler capacity, fuel, firing rate, burner type and maximum operating load.
Combustion Airflow
Use the confirmed maximum combustion-air demand and required operating range.
Air-Side Pressure
Include intake, filter, silencer, damper, duct, air-preheater and burner losses.
Control and Layout
Confirm damper or VFD control, rotation, outlet angle, motor standard and foundation.
Boiler Forced Draft Fan Product Series
Compare four representative product directions, then confirm the final operating point from airflow, total pressure, air temperature, drive arrangement and motor requirements.
G4-73 Boiler Forced Draft Fan
Clean-air-side direction for medium and large steam boiler combustion-air supply.
Reference direction: 2–670 t/h boilers · inlet air normally up to 80°C.
GY5-51 Boiler Draft Fan
Forced-draft direction for steam boilers and higher-pressure fluidized-bed combustion-air systems.
Reference direction: 2–670 t/h boiler systems · D-type coupling structure.
G6-41 Boiler Blower
Compact combustion-air blower direction for small and medium industrial boiler rooms.
Reference direction: 0.5–10 t/h industrial boilers · A- or D-type drive.
9-19 High-Pressure Fan
Pressure-oriented direction for boiler forced draft, combustion support and other higher-resistance air systems.
Selection focus: fan curve, system resistance, A/D drive and motor capacity.
Where the Forced Draft Fan Works
The FD fan pushes ambient or preheated combustion air toward the burner and furnace. Pressure selection must include every air-side component before the combustion zone.
Air Intake
Ambient air, intake hood or preheated-air return route.
Filter / Silencer
Inlet restriction, filtration and sound-control resistance.
FD Fan
Supplies airflow and pressure to the combustion-air system.
Preheater / Damper
Heat-recovery resistance and airflow-control losses.
Burner / Furnace
Terminal pressure demand and combustion-air distribution.
Which FD Fan Direction Should Be Reviewed First?
This matrix is a product-navigation tool. It does not replace fan-curve checking or final technical selection.
| Product Direction | Preliminary Position | Typical Review Focus | Important Confirmation |
|---|---|---|---|
| G6-41 | Small and medium boiler blower | Compact boiler-room combustion air | Boiler capacity, airflow, pressure and drive type |
| G4-73 | Medium and large boiler air supply | Large airflow clean-air-side duty | Air temperature, boiler scale and D-type layout |
| GY5-51 | Wider boiler and fluidized-bed duty | Higher-pressure boiler ventilation systems | Fan role, operating point and coupling arrangement |
| 9-19 | Higher-resistance pressure-first direction | Burner, preheater, filter or long-duct resistance | Fan curve, speed, motor load and air condition |
Forced Draft Fan vs Induced Draft Fan
FD and ID fans work on different sides of the boiler. The model direction, medium condition and selection risks are therefore different.
| Selection Point | Forced Draft Fan | Induced Draft Fan |
|---|---|---|
| System Position | Before burner or furnace | After boiler or dust-removal equipment |
| Main Function | Supplies combustion air | Extracts flue gas and supports negative pressure |
| Typical Medium | Ambient or preheated clean air | Hot flue gas, ash, moisture or treated exhaust |
| Pressure Route | Intake, filter, damper, preheater and burner loss | Boiler, collector, scrubber, duct and chimney loss |
| Primary Risk | Insufficient air or excessive furnace pressure | Temperature, dust, corrosion and draft instability |
Design from the Maximum Combustion-Air Duty
For a new boiler system, define the maximum firing condition and calculate pressure loss through every air-side component before selecting the fan.
● Boiler capacity, fuel and burner type
● Maximum combustion-air volume
● Required static or total pressure
● Intake, filter and silencer resistance
● Air-preheater and burner-register loss
● Control method, altitude and power supply
Match the Interface and Correct the Air-Supply Problem
For replacement work, current operating performance and connection dimensions are as important as the original fan model.
● Existing fan and motor nameplates
● Current airflow, pressure, speed and power
● Inlet, outlet and foundation dimensions
● Rotation and discharge angle
● Problem: low air, overload, noise or unstable pressure
● Site photos, drawings and available space
Configuration Must Match the Boiler Air Side
Drive Arrangement
A-, D- or another supported drive arrangement is selected according to model size, speed, motor layout and maintenance access.
Inlet Air Temperature
State whether the fan handles ambient air or preheated combustion air. Temperature affects density, performance and motor load.
Damper or VFD Control
Control method should match the boiler load range. Review low-load operation, motor margin and required pressure stability.
Rotation and Outlet Angle
Left- or right-hand rotation and discharge angle must match the actual duct direction. Confirm the viewing side before production.
Motor and Electrical Standard
Provide voltage, frequency, phase, enclosure, insulation, starting method and any project-specific efficiency requirement.
Connection and Foundation
For replacements, send inlet, outlet, base and shaft-center dimensions. A measured drawing reduces installation risk.
Typical Boiler Forced Draft Applications
Industrial Steam Boilers
Combustion-air supply for factory boiler rooms and process-steam systems.
Biomass and Coal Boilers
Primary or combustion-air support subject to fuel, burner and furnace requirements.
Fluidized-Bed Boilers
Higher-pressure combustion-air systems requiring operating-point confirmation.
Furnaces and Burners
Forced combustion or process-air delivery for furnace and burner systems.
Boiler Forced Draft Fan Questions
What is the function of a boiler forced draft fan?
It supplies combustion air to the burner or furnace and provides enough pressure to overcome the resistance of the complete air-supply route.
Can the fan be selected only from boiler capacity?
No. Boiler capacity gives an initial direction, but final selection requires combustion airflow, total pressure, air temperature, burner demand, control method and installation data.
What pressure losses should be included?
Include intake, weather hood, filter, silencer, damper, duct friction, elbows, air preheater, burner register and terminal-entry resistance.
Can a high-pressure 9-19 fan be used for forced draft?
It may be reviewed when the required operating point needs higher pressure. Airflow, total pressure, fan curve, speed, motor power, temperature and control range must all be confirmed.
What should be sent for a replacement FD fan?
Send fan and motor nameplates, airflow, pressure, speed, motor power, inlet and outlet dimensions, foundation dimensions, rotation, outlet angle, site photos and the current operating problem.
Related Boiler Fan Pages
Continue from the forced-draft product family to the combustion-air system guide, induced-draft family, high-temperature family or detailed FD-versus-ID comparison.
Industrial Forced Draft Fan System
Review combustion-air demand, burner resistance, air-preheater loss, duct pressure and fan control.
View FD System →Boiler Induced Draft Fans
Compare flue-gas extraction, dust-removal resistance and negative-pressure boiler fan directions.
View ID Fans →High-Temperature Industrial Fans
Review furnace, kiln, boiler and thermal-process hot-gas fan directions and configurations.
View High-Temp Fans →Forced Draft Fan vs Induced Draft Fan
Confirm fan position, airflow direction, medium condition and the main boiler selection risks.
Compare FD and ID →Send Your Boiler FD Fan Operating Point
Provide boiler capacity, fuel, burner type, combustion airflow, total pressure, inlet-air temperature, air-preheater resistance, control method, power supply, quantity and destination. For replacement projects, attach the fan nameplate and interface drawing.
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