The owners of a condominium apartment block in a temperate west coast
climate are looking for ways to adjust the incoming air volume of a
rooftop blower continuously supplying outdoor-temperature
pressurization air to the hallways (ie. low volume in winter, medium
volume in spring and fall, high volume in summer).

I'd appreciate your feedback on whether it will be practical and safe
to use a rheostat to vary the speed of the blower powered by an
electric motor, and whether there might be a better way to adjust the
volume of unheated/uncooled air which must be delivered non-stop.

1/4hp, 1725rpm, 6-pole 120vAC motor
Belt-driven Delhi G9 standard squirrel cage air blower

Thanks in advance for your replies.
Darro