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Boiler Induced Draft Fan Surge: A Serious Warning, Not Just a Vibration

Boiler Induced Draft Fan Surge: A Serious Warning, Not Just a Vibration

Once a boiler induced draft (ID) fan enters surge, the flue duct can shake violently like thunder, while the motor current and pressure gauges fluctuate dramatically. This is not just the fan “struggling to breathe”—it can lead to catastrophic failures such as impeller breakage and flue duct rupture.

What Causes Fan Surge?
Surge occurs when the system resistance becomes too high or the actual airflow drops below the fan’s minimum stable flow rate. Common causes include:

  • Ash accumulation blocking the flue duct
  • Inlet guide vanes or dampers accidentally closed
  • Parallel fans competing for airflow
  • Fan speed or inlet guide vane opening set too low

Emergency Response

  • Immediately open the inlet guide vanes or outlet dampers wider, or increase the fan speed to restore airflow.
  • If multiple fans are operating in parallel, balance their output first.
  • If the surge cannot be eliminated quickly, shut down the surging fan immediately to prevent severe damage.

How to Prevent Surge

  • Clean the flue duct regularly to prevent ash buildup.
  • Set a minimum airflow limit in the control system.
  • Install surge detection and protection devices for early warning and automatic protection.

Customer Testimonials

Trusted by industrial partners across 30+ countries — real feedback from our global clients.

“We’ve been using Dajing’s 9-19 high-pressure centrifugal blowers for our dust removal system. The airflow performance is excellent, and the noise level is much lower than our previous models. Truly reliable quality.”

Ali Rahman Maintenance Engineer, Power Plant – UAE

“The 4-72 series blowers from Dajing have been running non-stop in our cement production line for two years with zero breakdowns. Their team provided fast delivery and technical guidance during installation.”

Sergey Ivanov Production Manager, Cement Factory – Kazakhstan

“Our HVAC contractor switched to Dajing’s products for a recent government building project. The energy efficiency and build quality exceeded expectations. Definitely a long-term partner.”

Mohamed Al-Farid HVAC Project Supervisor, Government Contractor – Saudi Arabia

“We ordered customized GY4-73 induced draft blowers for our boiler system. Dajing’s engineers adjusted the impeller size precisely to our parameters — performance and after-sales support were outstanding.”

Nguyen Thanh Binh Technical Director, Thermal Equipment Co. – Vietnam

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