What Are ID Fans and FD Fans?
Induced Draft (ID) Fans
ID fans pull air or gases from a system. Typically, they are installed near the outlet, where they extract flue gases from industrial processes. Commonly, ID fans are used in boilers and furnaces. Consequently, they create a negative pressure, which helps remove byproducts of combustion.
Forced Draft (FD) Fans
FD fans push air into the system. Generally, they are placed at the inlet, supplying fresh air necessary for combustion. By creating positive pressure, FD fans ensure that enough air is available for efficient burning.
Key Differences Between ID Fan and FD Fan
| Feature | ID Fans | FD Fans |
|---|---|---|
| Position | At the outlet of the system | At the inlet of the system |
| Function | Extracts flue gases | Supplies fresh air for combustion |
| Pressure | Creates negative pressure | Creates positive pressure |
| Primary Use | Emission control and removal of exhaust gases | Ensures sufficient air supply for combustion |
| Common Applications | Boilers, furnaces, pollution control | Boilers, combustion chambers, drying equipment |
Frequently Asked Questions About ID and FD Fans
What is the difference between an ID fan and an FD fan?
An ID (induced draft) fan draws flue gases and air out of a boiler, furnace, or industrial system, while an FD (forced draft) fan supplies fresh air into the combustion system.
Which is better, an ID fan or FD fan?
Neither is universally better. The right fan depends on the system design, airflow requirements, temperature, pressure, and operating conditions.
What is an ID fan used for?
ID fans are used to remove combustion gases, hot air, and process fumes while maintaining negative pressure within industrial equipment such as boilers and furnaces.
Can an ID fan and FD fan be used together?
Yes. Many boiler and combustion systems use both FD and ID fans to control air supply, flue gas removal, and furnace pressure.
How do I choose the right ID fan for my application?
Consider airflow, pressure requirements, gas temperature, dust or particulate levels, material compatibility, and operating conditions. A qualified fan supplier can help determine the appropriate specification.
Next read: How Regular ID Fan Servicing Improves Workplace Safety and Compliance
CONTACT US FOR FREE CONSULTATION!
Have A Question?
Get in touch with us now!







