Comparing Forced Draft Versus Induced Draft
When comparing forced draft versus induced draft industrial fans, the primary difference is boiled down to push versus pull. Forced-draft fans focus the pressure and volume at the outlet of the fan to push air through a system, creating positive air pressure. Industrial induced draft fans operate by focusing the pressure and volume at the inlet of the fan to pull air through a system.
It’s not always either-or. Forced draft and induced draft fans often work in concert to maintain efficient and steady air pressure and control the flow using VFDs, dampers, & other accessories.
Application Considerations for Forced Draft Versus Industrial Draft Fans
Your application will determine the ultimate performance of your industrial fan whether its job is to push or pull the air through the system.
The Push: Forced draft fans accommodate higher process inlet temperatures, often working to push ambient air through burners to preheat air for boiler system efficiency. They can require less structural support and may offer a longer mechanical life than many induced draft fans because the cleaner ambient air is not as hard on the fan as the air often pulled through using induced draft.
The Pull: Induced draft fans often operate in harsh conditions handling process air that may include high temperatures, acidic airstreams, and other extreme exhaust gases. They can operate at higher efficiencies relative to forced draft fans, but the extreme conditions can require special attention to imbalance, excessive vibration, temperature, maintenance, and operating costs.
Industrial Fan Designs Support Push or Pull
While materials and accessories may differ, the same basic fan designs support both forced draft and induced draft fans. Those designs include:
- Backward Curved
- Backward Inclined
- High-Pressure Radial Open
- High-Pressure Radial Shrouded
- Industrial Exhauster Air Handling
- Industrial Exhauster Paddle Wheel
- Industrial Exhauster Radial Shrouded
- Radial Tipped
More Information on Forced Draft Versus Induced Draft Industrial Fans
Contact an AirPro application engineer to discuss your industrial application.