Collection 5 models

INDUCTOR® AXIAL IN-LINE BOOSTER DUCT FANS

Rooms at the end of a long duct run can receive less conditioned air than rooms closer to the central HVAC system. Suncourt Inductor® in-line duct booster fans are engineered and designed to increase airflow through existing forced-air ductwork, helping address rooms that stay too hot or too cold without major duct system changes.

  • Increases register airflow to fix rooms that remain consistently too hot or cold.
  • Mounts at any angle inside flexible or rigid metal air duct runs.
  • Energy-efficient 120v Class B thermally protected motor.
  • Engineered for maximum airflow boost and quiet operation. 
  • Available for 4-, 5-, 6-, 8-, and 10-inch round ductwork.
Jump to the buying guide
INDUCTOR® AXIAL IN-LINE BOOSTER DUCT FANS
UL 1995 Certified
MET Listed
12-Month Limited Warranty
Class B Thermally Protected Motor
Engineered and Assembled in the USA
Buying guide

How to choose INDUCTOR® AXIAL IN-LINE BOOSTER DUCT FANS

Balance Temperature Issues Across Long Duct Runs

Long duct runs, undersized ductwork, room location, and other system conditions can reduce the amount of conditioned air reaching a room. This can leave some spaces uncomfortable even when the central HVAC system is operating normally.

The Inductor in-line duct booster fans are installed within existing ductwork to increase airflow toward an underperforming register. The fans are designed for forced-air heating and cooling systems and can provide a practical alternative to major HVAC system changes.

The available models range from 4 to 10 inches in diameter, with boosted airflow ratings from 65 to 650 CFM, depending on the model. The fans can be installed at different angles and are suitable for metal or flexible duct. Installation should leave the fan accessible for service, cleaning, or repair.

INDUCTOR® fans are intended for conditioned-air duct systems with airflow temperatures between 40°F and 140°F. They must not be used for dryer venting or exposed to rain or excessive moisture. Electrical installation must comply with applicable codes and standards.

Key Benefits:

  • Designed to increase airflow through duct runs serving rooms with inadequate heating or cooling delivery.
  • Class B motors include thermal protection with automatic reset to help protect the motor from excessive temperature.
  • Certified to UL 1995 heating and cooling equipment standards for safe duct integration.
  • Low power draw keeps operational electricity costs minimal throughout the year.
  • Available for 4-, 5-, 6-, 8-, and 10-inch round ducts. 
  • Single-speed corded design provides straightforward installation and control options. 
  • Compatible with Suncourt® VS100 and VS200 solid-state speed controls.

Warranty and Product Support

INDUCTOR® Axial In-Line Booster Duct Fans are backed by a 1-year limited warranty.

Technical Specifications

Specification DB204C DB205C DB206C DB208C DB210C
Duct Diameter 4 in 5 in 6 in 8 in 10 in
Blade Material Polycarbonate Polycarbonate Polycarbonate Polycarbonate Aluminum
Max Boosted CFM 80 130 250 500 650
Free-Air CFM 65 75 160 210 300
Power 30 W 30 W 30 W 55 W 120 W
Current 0.30 A 0.35 A 0.35 A 0.70 A 1.50 A
Voltage 120 V 120 V 120 V 120 V 120 V
Motor Class B, thermally protected Class B, thermally protected Class B, thermally protected Class B, thermally protected Class B, thermally protected

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Category FAQ
01 What is a duct booster fan?
A duct booster fan is an in-line fan installed within HVAC ductwork to increase airflow through a duct run. Suncourt Inductor fans are designed to help deliver more conditioned air to rooms that receive insufficient airflow.
02 Why do certain rooms stay chronically cold or hot?
Rooms far from the central HVAC unit experience airflow loss due to friction along long duct runs. In addition, second-story rooms face rising heat, while spaces over unheated areas lose thermal energy quickly.
03 What is the difference between free air and boosted air CFM?
Free air CFM measures fan output in open space without duct resistance. Boosted air CFM reflects the maximum airflow volume passed through the duct booster fan before the unit creates resistance inside an active HVAC duct run.
04 Can I use a rheostat to control fan speed?
No. Never use a standard rheostat because lowering voltage will overheat the motor winding and trip the thermal protector. Speed control requires a solid-state controller such as the Suncourt VS100 or VS200.
05 How much airflow can an Inductor fan provide?
The available models are rated for up to 80, 130, 250, 500, or 650 boosted CFM, depending on the model and duct diameter. Free-air CFM ratings are lower because they represent airflow without the fan connected to ductwork.
06 Can an in-line duct fan be used as an inline duct heater with a fan?
No. An in-line Inductor duct fan is an airflow booster, not a heater. It moves existing heated or cooled air through the ductwork and does not add heat to the air.
Resources & Downloads

Also available as PDF

Product brochurePDF Frequently Asked QuestionsPDF Video Resource
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