Gas Fitter Practice Test

To increase the furnace blower speed, which procedure is recommended?

1. Close up the motor pulley

2. Open up the motor pulley

3. Increase the size of the return air duct

4. Install a higher horsepower fan motor

The correct answer is: Close up the motor pulley

To increase the speed of the furnace blower, a common and effective method is to adjust the motor pulley. Specifically, this procedure involves opening up the motor pulley, allowing the blower to reach higher speeds by increasing the diameter of the pulley. A larger pulley enables the motor to turn the blower faster, thus increasing airflow. While closing up the motor pulley might initially seem like a viable option, it actually reduces the speed of the blower. If the goal is to enhance airflow by speeding up the blower, the pulley size must be appropriately chosen to achieve the desired velocity without compromising efficiency. Increasing the size of the return air duct could improve air circulation, but it wouldn’t necessarily increase the speed of the blower itself. Similarly, installing a higher horsepower fan motor might provide a more powerful airflow, but it also would entail additional modifications and could lead to compatibility issues with existing equipment. Therefore, adjusting the motor pulley size is the most direct and effective method to achieve an increase in blower speed.