Normally used in bathroom or WC locations. Designed to be permanently connected and run at a very low trickle speed continuously. Incorporates a condensation (humidity) sensor which automatically switches the fan on to boost speed when the condensation level builds up. Once the condensation clears the fan reverts to trickle speed. It can also be connected to work with the room light switch, when the light is turned on the fan switches to boost speed, when the light is switched off the fan continues to run for the pre-set time then reverts back to trickle speed. Requires at least a permanent unswitched live and neutral connection. If the timer functionality is required then an additional switched live connection is required. Additionally there is a pull cord which can switch the adjust the boost speed from high to low settings. This fan can be installed surface mounted or semi-flush.