A rheostat is a device that allows you to regulate the current in a circuit. You can use a rheostat to control speed in any variable speed drive (VSD) motor. Some motors are designed to be run only at one speed, but most can be adjusted. A large-bladed fan running slowly will make less noise and vibration than a small-bladed fan going full tilt but put out the same CFM. it also gives you some control as the seasons change. Your temps might be fine now but in July it could be a different story. You might find yourself using more of the fan's capacity during the hottest months of the year. The cheapest, most easily obtainable rheostat I've seen is at pet stores, which sell them for regulating lights on lizards and snakes.
Note - a dimmer switch and a rheostat are not the same thing. Rheostats use resistors to regulate the voltage in the line. Dimmers actually turn the light on and off very quickly (actually, every time the AC current alternates - tiny fractions of a second). The dimmer just extends the length of the "off" cycle so the lights appear to dim but does nothing to the voltage). If you put a fan on a dimmer you will likely toast the motor.
~cb
(who will be running for President of the Science Club this fall...) |