This much I understand: If a blower doesn’t get enough supply air to feed it, the fanwheel will overspeed & cause the motor to overload. This is caused by the fanwheel not getting enough air to “bite into” & provide adequate resistance against the motor; the motor then runs freely & overloads. But what about the other way around? What will happen if the return air path is too restrictive for a particular blower?
Example, if a blower’s rating chart shows the highest SP (lowest CFM) that it is normally operated at, what will happen if there is too much restriction on the outlet/pressure side? In other words, if a blower is rated at 1000CFM at it's highest normal SP rating, what will happen if it is only allowed to deliver 700CFM? Will that cause the motor to overload as well? Or would the motor NOT overload, but the fanwheel would just sort of push up against a resistant wall of air?
Note: I recognize it wouldn’t be efficient, but my question is strictly about motor loading – nothing about efficiency, proper coil airflow, heat rise, etc., etc..)
I just love learning about all this stuff - Thanks again to everyone…