| 摘要 |
<p>An extractor fan system for extracting air from a room, the system comprising : an extractor fan, which comprises an impeller for extracting air from a room, a motor for driving the impeller, and a controller for controlling operation of the motor; wherein the controller has at least one control input which detects at least one trigger event, and the controller controls the motor normally to operate at a first, background speed, and causes the motor to be switched off or operate at a second, lower speed than the first speed on detecting a first trigger event, and operate at a third speed on detecting a second trigger event.</p> |
