What is the best method to increase the speed of a furnace blower?

The best method to increase the speed of a furnace blower involves closing up the motor pulley. This adjustment alters the pulley ratio, effectively increasing the rotational speed of the blower motor in relation to the motor itself.

When the motor pulley is adjusted to a smaller size, the blower operates at a higher speed, enhancing airflow through the system. This change is efficient for achieving the desired airflow without the need for replacing components like the motor or ductwork.

Using a smaller motor pulley maximizes the output of the existing motor while maintaining the design's integrity and functionality, ensuring that the system does not operate under undue strain or inefficiency from excessive airflow.

In contrast, opening up the motor pulley would decrease the blower speed, while installing a higher horsepower fan motor may not be necessary if the existing system simply requires a speed adjustment. Increasing the size of the return air duct may improve the overall airflow, but it does not directly increase the speed of the blower itself.