What is the recommended method to increase the blower motor speed on a furnace?

The recommended method to increase the blower motor speed in a furnace involves closing up the motor pulley. This adjustment effectively changes the ratio of the motor speed to the blower speed. By reducing the size of the pulley, the motor can more efficiently transfer its rotational speed to the blower, resulting in increased airflow and enhanced heating performance within the system.

This method is commonly adopted because it does not require any significant electrical alterations or mechanical changes to the existing system, making it both a practical and efficient solution. It allows the motor to operate within its designed parameters while achieving increased performance.

In contrast, increasing the voltage supply can lead to excessive heat and potential damage to the motor, while modifying the fan blade shape could introduce imbalances or inefficiencies. Adding a second motor might complicate the setup and require additional modifications to the existing system, which is often unnecessary for achieving increased airflow. Thus, modifying the motor pulley is the preferred and safest method to effectively boost blower speed.