The present invention relates to an extractor fan and a control system therefor.

Extractor fans, such as in bathrooms or wetrooms, are conventionally actuated, either from an inoperative state or running at a background or trickle state, to have an increased fan speed by switching on of the light switch of the room in which the extractor fan is located, with the extractor fan being actuated for so long as the light switch remains switched on and/or for a predetermined period thereafter.

The present inventors have recognized that this mode of operation disadvantageously provides for increased noise, associated with operation of the extractor fan, during the very period in which a person is in the room which is fitted with the extractor fan. Indeed, with improvement in sound insulation in the fabric of buildings, the noise associated with extractor fans will become more noticeable.

The present inventors are thus proposing a mode of operation, in which, contrary to the existing control methodology, the extractor fan is actuated either to be inoperative or to have a decreased fan speed following a trigger event, such as switching on of the light switch to the room in which the extractor fan is located, and actuated to an increased fan speed at a predetermined interval thereafter, as either based on a time lapse or on another trigger event, such as switching off of the light switch.

In this way, noise associated with the extractor fan is at least reduced while a person is in the room which has the extractor fan .

The present inventors have also recognized that the extractor fan could include a sound detector, typically a microphone, for detecting an ambient noise level, and controlling the fan speed in dependence upon this detected noise level, whereby the extractor fan can be operated at higher speeds when the noise of the extractor fan would be masked by the ambient noise.

In one aspect the present invention provides 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.

In one embodiment the controller causes the motor to be switched off on detecting the first trigger event.

In another embodiment the controller causes the motor to operate at a second, lower speed than the first speed on detecting the first trigger event.

In one embodiment the first and third speeds are substantially the same.

In one embodiment the third speed is higher than the first speed.

In one embodiment the controller causes the motor to operate at the third speed for a predetermined time period.

In one embodiment a volume of air extracted while the motor operates at the third speed is at least as great as a difference in a volume of air extracted while the motor operates at the second speed as compared to operating at the first speed.

In one embodiment the at least one control input is a light switch which actuates a light in the room, and the first trigger event comprises actuation of the light switch, and the second trigger event comprises (i) de-actuation of the light switch, or (ii) a predetermined time interval following the first trigger event, optionally the first trigger event is reset where the light switch is further actuated during a predetermined time interval following the first trigger event.

In one embodiment the at least one control input is a motion sensor for detecting motion in the room, and the first trigger event comprises detection of motion by the motion sensor, optionally for a predetermined time period, and the second trigger event comprises (i) detection of no motion by the motion sensor, optionally for a predetermined time period, or (ii) a predetermined time interval following the first trigger event, optionally the first trigger event is reset where the motion sensor further detects motion during a predetermined time interval following the first trigger event.

In one embodiment the at least one control input is a temperature sensor for sensing temperature in the room, and the first trigger event comprises detection of temperature by the temperature sensor above a first, predetermined value or increasing above a first, predetermined rate, optionally for a predetermined time period, and the second trigger event comprises (i) detection of temperature by the temperature sensor below a second, predetermined value or decreasing below a second, predetermined rate, optionally for a predetermined time period, or (ii) a predetermined time interval following the first trigger event, optionally the first trigger event is reset where the temperature sensor further detects temperature above the first value or rate during a predetermined time interval following the first trigger event.

In one embodiment the at least one control input is a humidity sensor for sensing humidity in the room, and the first trigger event comprises detection of humidity by the humidity sensor above a first, predetermined value or increasing above a first, predetermined rate, optionally for a - 4 . P T/EP2014/078090 predetermined time period, and the second trigger event comprises (i) detection of humidity by the humidity sensor below a second, predetermined value or decreasing below a second, predetermined rate, optionally for a predetermined time period, or (ii) a predetermined time interval following the first trigger event, optionally the first trigger event is reset where the humidity sensor further detects humidity above the first value or rate during a predetermined time interval following the first trigger event.

In one embodiment the at least one control input is a gas sensor for sensing one or more gases in the room, and the first trigger event comprises detection of one or more gases by the gas sensor above a first, predetermined value or increasing above a first, predetermined rate, optionally for a predetermined time period, and the second trigger event comprises (i) detection of one or more gases by the gas sensor below a second, predetermined value or decreasing below a second, predetermined rate, optionally for a predetermined time period, or (ii) a predetermined time interval following the first trigger event, optionally the first trigger event is reset where the gas sensor further detects one or more gases above the first value or rate during a predetermined time interval following the first trigger event.

In one embodiment the at least one control input is a noise sensor for sensing noise in the room, and the first trigger event comprises detection of noise by the noise sensor above a first, predetermined value, optionally for a predetermined time period, and the second trigger event comprises (i) detection of noise by the noise sensor below a second, predetermined value, optionally for a predetermined time period, or (ii) a predetermined time interval following the first trigger event, optionally the first trigger event is reset where the noise sensor further detects noise above the first value during a predetermined time interval following the first trigger event. In one embodiment the at least one control input is a light sensor for sensing light intensity in the room, and the first trigger event comprises detection of light by the light sensor above a first, predetermined value, optionally for a predetermined time period, and the second trigger event comprises (i) detection of light by the light sensor below a second, predetermined value, optionally for a predetermined time period, or (ii) a predetermined time interval following the first trigger event, optionally the first trigger event is reset where the light sensor further detects light above the first value during a predetermined time interval following the first trigger event.

In one embodiment the at least one control input is a flow sensor for detecting flow at at least one water outlet in the room, and the first trigger event comprises detection of flow by the flow sensor, either onset or cessation of flow, and the second trigger event comprises a predetermined time interval following the first trigger event, optionally the first trigger event is reset where the flow sensor further detects flow during a predetermined time interval following the first trigger event.

In one embodiment the controller comprises a plurality of control inputs.

In one embodiment the first trigger event is a first to occur of the first trigger events of the plurality of control inputs.

In one embodiment the second trigger event is a last to occur of the second trigger events of the plurality of control inputs.

In another aspect the present invention provides 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 a noise sensor for detecting noise in the room, and the controller controls the motor normally to operate at a first, background speed, and causes the motor to operate at a second, higher speed than the first speed on detecting, optionally for a predetermined time period, noise by the noise sensor above a first, predetermined value.

In one embodiment the controller causes the second speed to be increasingly higher in correspondence to an increasing noise level as detected by the noise sensor.

In one embodiment the controller causes the motor to operate at the second higher speed until detecting noise by the noise sensor below a second, predetermined value, optionally for a predetermined time period.

In one embodiment the controller causes the motor to operate at the second higher speed for a predetermined time interval following detection of noise by the noise sensor above the first value, optionally, where the noise sensor further detects noise above the first value during a predetermined time interval following detection of noise by the noise sensor above the first value, the controller causes the motor to operate at the second higher speed for a further predetermined time interval following the further detection of noise by the noise sensor above the first value.

In one embodiment the controller causes the motor to be switched off or operate at a third speed following operation at the second speed, and operate at a fourth speed following being switched off or operating at the third speed.

In one embodiment the third speed is lower than the first speed.

In one embodiment a volume of air extracted while the motor operates at the second speed is at least as great as a difference in a volume of air extracted while the motor operates at the third speed as compared to operating at the first speed. 2014/078090

- 7 -

In one embodiment the first and fourth speeds are substantially the same.

In a further aspect the present invention provides 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 a flow sensor for detecting, optionally for a predetermined time period, flow at at least one water outlet in the room, and the controller controls the motor normally to operate at a first, background speed, and causes the motor to operate at a second, higher speed than the first speed on detecting flow by the flow sensor.

In one embodiment the controller causes the motor to operate at the second higher speed until detecting, optionally for a predetermined time period, no flow by the flow sensor.

In one embodiment the controller causes the motor to be switched off or operate at a third speed following operation at the second speed, and operate at a fourth speed following being switched off or operating at the third speed.

In one embodiment the third speed is lower than the first speed.

In one embodiment a volume of air extracted while the motor operates at the second speed is at least as great as a difference in a volume of air extracted while the motor operates at the third speed as compared to operating at the first speed.

In one embodiment the first and fourth speeds are substantially the same. In one embodiment the room is a bathroom or wetroom. The present invention also extends to a bathroom or wetroom fitted with the above-described fan system.

Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which :

Figure 1 illustrates an extractor fan system in accordance with a first embodiment of the present invention;

Figure 2 illustrates a first exemplary control mode of the extractor fan system of Figure 1;

Figure 3 illustrates a second exemplary control mode of the extractor fan system of Figure 1;

Figure 4 illustrates a third exemplary control mode of the extractor fan system of Figure 1;

Figure 5 illustrates a fourth exemplary control mode of the extractor fan system of Figure 1;

Figure 6 illustrates a fifth exemplary control mode of the extractor fan system of Figure 1;

Figure 7 illustrates an extractor fan system in accordance with a second embodiment of the present invention;

Figure 8 illustrates a first exemplary control mode of the extractor fan system of Figure 7;

Figure 9 illustrates a second exemplary control mode of the extractor fan system of Figure 7; 2014/078090

- 9 -

Figure 10 illustrates an extractor fan system in accordance with a third embodiment of the present invention;

Figure 11 illustrates one exemplary control mode of the extractor fan system of Figure 10.

Figures 1 to 6 illustrate an extractor fan system in accordance with a first embodiment of the present invention.

The extractor fan system comprises an extractor fan 3, which comprises an impeller 5 for drawing an air flow from a room RM, here a bathroom or wetroom, to atmosphere, a motor 7 for driving the impeller 5, and a controller 9 for controlling operation of the motor 7, both in switching the motor 7 on and off and controlling the speed of the motor 7 and hence the speed of the impeller 5.

The controller 9 has a control input 11 which detects at least one trigger event TE, in this embodiment first and second trigger events TE1, TE2.

In this embodiment the control input 11 is a switch, here a light switch for the room RM, and the first trigger event TE1 is actuation of the light switch and the second trigger event TE2 is either de-actuation of the light switch or a predetermined time interval following the first trigger event TE1.

In another embodiment the control input 11 could be a motion sensor, and the first trigger event TE1 is actuation of the motion sensor and the second trigger event TE2 is a predetermined time interval following the first trigger event TE1. In one embodiment the first trigger event TE1 is reset where further actuation of the motion sensor occurs during the predetermined time interval. In one embodiment the motion sensor is a proximity sensor. In another embodiment the motion sensor is a camera with image processing software implemented to detect motion in the captured image. In a further embodiment the control input 11 could be a temperature sensor, and the first trigger event TEl is detection of a temperature above a first, predetermined threshold and the second trigger event TE2 is either detection of a temperature below a second, predetermined threshold, which in one embodiment corresponds to the first threshold, or a predetermined time interval following the first trigger event TEl.

In a further embodiment the control input 11 could be a humidity sensor, and the first trigger event TEl is detection of a humidity above a first, predetermined threshold and the second trigger event TE2 is either detection of a humidity below a second, predetermined threshold, which in one embodiment corresponds to the first threshold, or a predetermined time interval following the first trigger event TEl.

In a further embodiment the control input 11 could be a noise sensor, and the first trigger event TEl is detection of a noise above a first, predetermined threshold and the second trigger event TE2 is either detection of a noise below a second, predetermined threshold, here for a predetermined time period, which in one embodiment corresponds to the first threshold, or a predetermined time interval following the first trigger event TEl. In one embodiment the first trigger event TEl is reset where further actuation of the noise sensor occurs during the predetermined time interval. In one embodiment the noise sensor is a microphone.

In a further embodiment the control input 11 could be a light sensor, and the first trigger event TEl is detection of light above a first, predetermined threshold and the second trigger event TE2 is either detection of light below a second, predetermined threshold, here for a predetermined time period, which in one embodiment corresponds to the first threshold, or a predetermined time interval following the first trigger event TEl. In one embodiment the first trigger event TEl is reset where further actuation of EP2014/078090

- 11 - the light sensor occurs during the predetermined time interval. In one embodiment the light sensor is a photodetector.

In a still further embodiment the control input 11 could be a flow sensor which detects flow from at least one water outlet in the room RM, and the first trigger event TEl is detection of flow, either the onset or cessation of flow, and the second trigger event TE2 is a predetermined time interval following the first trigger event TEl. In one embodiment the first trigger event TEl is reset where further actuation of the flow sensor occurs during the predetermined time interval.

In a yet further embodiment the control input 11 could be a gas sensor, and the first trigger event TEl is detection of a gas above a first, predetermined threshold and the second trigger event TE2 is either detection of a gas below a second, predetermined threshold, which in one embodiment corresponds to the first threshold, or a predetermined time interval following the first trigger event TEl. In one embodiment the gas sensor could be configured to detect a gas component, such as carbon dioxide, or an odor, such as arising from methane.

Exemplary modes of operation of the extractor fan system will now be described hereinbelow. It will be understood that the reference to the control input 11 being a light switch or motion sensor is merely done for exemplification, and the control input 11 could be any of those as described above.

Mode #1A

In a first mode of operation, as illustrated in Figure 2, the controller 9, which controls the motor 7 normally to operate at a first, background speed SI, causes the motor 7 to be switched off on detecting a first trigger event TEl, here corresponding to switching on of the light switch, and causes the motor 7 to be switched on and operate at the first speed SI on detecting a second trigger event TE2, here corresponding to switching off of the light switch.

In an alternative embodiment the second trigger event TE2 could be a predetermined time interval following the first trigger event TEl.

With this arrangement, there is no noise associated with operation of the extractor fan while a person is in the room RM.

Mode #2A

In a second mode of operation, as illustrated in Figure 3, the controller 9, which controls the motor 7 normally to operate at a first, background speed SI, causes the motor 7 to be switched off on detecting a first trigger event TEl, here corresponding to switching on of the light switch, and causes the motor 7 to be switched on and operate at a second speed S2, here a higher speed than the first speed SI, for a predetermined time interval, on detecting a second trigger event TE2, here corresponding to switching off of the light switch.

In an alternative embodiment the second trigger event TE2 could be a predetermined time interval following the first trigger event TEl.

With this arrangement, there is no noise associated with operation of the extractor fan while a person is in the room RM, and, by virtue of providing for an increased fan speed S2 following the second trigger event TE2, accumulated humid air is extracted rapidly when a person should have left the room RM. In a preferred embodiment the volume of air extracted while the extractor fan is operating at the increased fan speed S2 is at least as great as the volume of air not extracted while the extractor fan is inoperative.

Mode #3A In a third mode of operation, as illustrated in Figure 4, the controller 9, which controls the motor 7 normally to operate at a first, background speed SI, causes the motor 7 to operate at a second, reduced speed S2 on detecting a first trigger event TEl, here corresponding to switching on of the light switch, and causes the motor 7 to operate at the first speed SI on detecting a second trigger event TE2, here corresponding to switching off of the light switch.

In an alternative embodiment the second trigger event TE2 could be a predetermined time interval following the first trigger event TEl.

With this arrangement, there is reduced noise associated with operation of the extractor fan while a person is in the room RM.

Mode #4A

In a fourth mode of operation, as illustrated in Figure 5, the controller 9, which controls the motor 7 normally to operate at a first, background speed SI, causes the motor 7 to operate at a second, reduced speed S2 on detecting a first trigger event TEl, here corresponding to switching on of the light switch, and causes the motor 7 to operate at a third speed S3, here a higher speed than the first speed SI, for a predetermined time interval, on detecting a second trigger event TE2, here corresponding to switching off of the light switch.

In an alternative embodiment the second trigger event TE2 could be a predetermined time interval following the first trigger event TEl.

With this arrangement, there is no significant noise associated with operation of the extractor fan while a person is in the room RM, and, by virtue of providing for an increased fan speed S3 following the second trigger event TE2, accumulated humid air is extracted rapidly when a P T/EP2014/078090

- 14 - person should have left the room RM. In a preferred embodiment the volume of air extracted while the extractor fan is operating at the increased fan speed S3 is at least as great as the reduction in the volume of air extracted while the extractor fan is operating at the reduced fan speed S2.

Mode #5A

In a fifth mode of operation, as illustrated in Figure 6, the controller 9, which controls the motor 7 normally to operate at a first, background speed SI, causes the motor 7 to operate at a second, reduced speed S2 on detecting a first trigger event TE1, here corresponding to actuation of a motion sensor, with the first trigger event ΤΕ being reset through further actuation of the motion sensor, and causes the motor 7 to operate at a third speed S3, here a higher speed than the first speed SI, on detecting a second trigger event TE2', here corresponding to a predetermined time interval following the reset first trigger event ΤΕΓ. In this mode of operation, the first trigger event TE could be repeatedly reset with further actuation of the motion sensor, as would be expected by occupancy of the room RM.

With this arrangement, there is no significant noise associated with the fan while a person is in the room RM, and, by virtue of providing for an increased fan speed S3 following the second trigger event TE2', accumulated humid air is extracted rapidly when a person should have left the room RM. In a preferred embodiment the volume of air extracted while the extractor fan is operating at the increased fan speed S3 is at least as great as the reduction in the volume of air extracted while the extractor fan is operating at the reduced fan speed S2.

Figures 7 to 9 illustrate an extractor fan system in accordance with a second embodiment of the present invention. The extractor fan system comprises an extractor fan 103, which comprises an impeller 105 for drawing an air flow from a room RM, here a bathroom or wetroom, to atmosphere, a motor 107 for driving the impeller 105, and a controller 109 for controlling operation of the motor 107, both in switching the motor 107 on and off and controlling the speed of the motor 107 and hence the speed of the impeller 105.

The controller 109 has first and second control inputs 111a, b, each being different and detecting at least one trigger event TE, in this embodiment each detecting first and second trigger events TEl, TE2.

In this embodiment the first of the first trigger events TEl is taken as the first trigger event for the controller 109, and the second of the second trigger events TE2 is taken as the second trigger event for the controller 109.

In this embodiment the first control input 111a is a switch, here a light switch for the room RM, and the first trigger event TEl for the first control input 111a is actuation of the light switch and the second trigger event TE2 for the first control input 111a is either de-actuation of the light switch or a predetermined time interval following the first trigger event TEl for the first control input 111a.

In this embodiment the second control input 111b is a motion sensor, and the first trigger event TEl for the second control input 111b is actuation of the motion sensor and the second trigger event TE2 for the second control input 111b is a predetermined time interval following the first trigger event TEl for the second control input 111b. In one embodiment the first trigger event TEl for the second control input 111b is reset where further actuation of the motion sensor occurs during the predetermined time interval, thereby resetting the second trigger event TE2 for the second control input 111b. In one embodiment the motion sensor is a proximity sensor. In another 8090

- 16 - embodiment the motion sensor is a camera with image processing software implemented to detect motion in the captured image.

With this arrangement, the first of the actuation of the light switch and the motion sensor is taken as the first trigger event TEl, and the second trigger event TE2 is taken as the last of de-actuation of the light switch, the elapse of the predetermined time period following actuation of the light switch and the elapse of the predetermined time period following actuation of the motion sensor or the last actuation thereof, if actuated more than once.

In a further exemplary embodiment the second control input 111b could be a temperature sensor, and the first trigger event TEl for the second control input 111b is detection of a temperature above a first, predetermined threshold and the second trigger event TE2 for the second control input 111b is either detection of a temperature below a second, predetermined threshold, which in one embodiment corresponds to the first threshold, or a predetermined time interval following the first trigger event TEl for the second control input 111b.

In a yet further embodiment the second control input 111b could be a humidity sensor, and the first trigger event TEl for the second control input 111b is detection of a humidity above a first, predetermined threshold and the second trigger event TE2 for the second control input 111b is either detection of a humidity below a second, predetermined threshold, which in one embodiment corresponds to the first threshold, or a predetermined time interval following the first trigger event TEl for the second control input 111b.

In a still further embodiment the second control input 111b could be a noise sensor, and the first trigger event TEl for the second control input 111b is detection of a noise above a first, predetermined threshold and the second trigger event TE2 for the second control input 111b is either detection of a noise below a second, predetermined threshold, here for a predetermined time period, which in one embodiment corresponds to the first threshold, or a predetermined time interval following the first trigger event TEl for the second control input 111b. In one embodiment the first trigger event TEl for the second control input 111b is reset where further actuation of the noise sensor occurs during the predetermined time interval. In one embodiment the noise sensor is a microphone.

In a yet further embodiment the second control input 111b could be a light sensor, and the first trigger event TEl for the second control input 111b is detection of light above a first, predetermined threshold and the second trigger event TE2 for the second control input 111b is either detection of light below a second, predetermined threshold, here for a predetermined time period, which in one embodiment corresponds to the first threshold, or a predetermined time interval following the first trigger event TEl for the second control input 111b. In one embodiment the first trigger event TEl for the second control input 111b is reset where further actuation of the light sensor occurs during the predetermined time interval . In one embodiment the light sensor is a photodetector.

In a still further embodiment the second control input 111b could be a flow sensor which detects flow from at least one water outlet in the room RM, and the first trigger event TEl for the second control input 111b is detection of flow, either the onset or cessation of flow, and the second trigger event TE2 for the second control input 111b is a predetermined time interval following the first trigger event TEl for the second control input 111b. In one embodiment the first trigger event TEl for the second control input 111b is reset where further actuation of the flow sensor occurs during the predetermined time interval .

In a yet further embodiment the second control input 111b could be a gas sensor, and the first trigger event TEl for the second control input 111b is detection of a gas above a first, predetermined threshold and the second trigger event TE2 for the second control input 111b is either detection of a gas below a second, predetermined threshold, which in one embodiment corresponds to the first threshold, or a predetermined time interval following the first trigger event TE1 for the second control input 111b. In one embodiment the gas sensor could be configured to detect a gas component, such as carbon dioxide, or an odor, such as arising from methane.

In alternative embodiments the first control input 111a could be any of the devices mentioned in association with the second control input 111b, and the second control input 111b could be a light switch as mentioned in relation to the first control input 111a.

Exemplary modes of operation of the extractor fan system will now be described hereinbelow.

Mode #1B

A first mode of operation is illustrated in relation to Figure 8. In this mode of operation, the controller 109 controls the motor 107 normally to operate at a first, background speed SI.

The controller 109 causes the motor 107 to be switched off on detecting a first trigger event TEli of one of the first and second control inputs 111a, b, here corresponding to switching on of the light switch of the first control input 111a.

Following detection of this first trigger event TEli of the first control input 111a, the second trigger event TE2i for the first control input 111a is set as switching off of the light switch of the first control input 111a.

The controller 109 then detects a first trigger event TE1 ₂ of the other of the first and second control inputs 111a, b, here corresponding to actuation of the motion sensor of the second control input 111b. In the event that the controller 109 detects a further first trigger event TE1 ₂ of the second control input 111b, the first trigger event TEI2' of the second control input 111b is reset.

Following detection of this first trigger event TE1 ₂ , TE1 ₂ ' of the second control input 111b, the second trigger event TE2 ₂ for the second control input 111b is set as a predetermined interval following the first trigger event TE1 ₂ of the second control input 111b, or the further first trigger event TE1 ₂ ' of the second control input 111b, if reset, here as determined by actuation of the motion sensor of the second control input 111b.

The controller 109 causes the motor 107 to remain switched off until the later of the second trigger events TE2i, TE2 ₂ , TE2 ₂ ' of the first and second control inputs 111a, b is reached.

Following detection of the later of the second trigger events TE1 ₂ , TE22, TE2 ₂ ' of the first and second control inputs 111a, b, the controller 109 causes the motor 107 to be switched on and operate at the first speed SI .

In an alternative embodiment the second trigger event TE1 ₂ of the first control input 111a could be a predetermined time interval following the first trigger event TEli of the first control input 111a .

With this arrangement, there is no noise associated with operation of the extractor fan while a person is in the room RM.

Mode #2B

A second mode of operation is illustrated in relation to Figure 9. In this mode of operation, the controller 109 controls the motor 107 normally to operate at a first, background speed SI . EP2014/078090

- 20 -

The controller 109 causes the motor 107 to operate at a second, reduced speed S2 on detecting a first trigger event TEli of one of the first and second control inputs 111a, b, here corresponding to switching on of the light switch of the first control input 111a.

Following detection of this first trigger event TEli of the first control input 111a, the second trigger event TE2i for the first control input 111a is set as switching off of the light switch of the first control input 111a.

The controller 109 then detects a first trigger event TE1 ₂ of the other of the first and second control inputs 111a, b, here corresponding to actuation of the motion sensor of the second control input 111b. In the event that the controller 109 detects a further first trigger event TE1 ₂ of the second control input 111b, the first trigger event TE1 ₂ ' of the second control input 111b is reset.

Following detection of this first trigger event TE1 ₂ , TE1 ₂ ' of the second control input 111b, the second trigger event TE2 ₂ for the second control input 111b is set as a predetermined interval following the first trigger event TE1 ₂ of the second control input 111b, or the further first trigger event TE1 ₂ ' of the second control input 111b, if reset, here as determined by actuation of the motion sensor of the second control input 111b.

The controller 109 causes the motor 107 to remain at the second, reduced speed S2 until the later of the second trigger events TE2i, TE2 ₂ , TE2 ₂ ' of the first and second control inputs 111a, b is reached.

Following detection of the later of the second trigger events TE1 ₂ , TE2 ₂ , TE2 ₂ ' of the first and second control inputs 111a, b, the controller 109 causes the motor 107 to operate at a third speed S3, here a higher speed than the first speed SI. In an alternative embodiment the second trigger event TEI2 of the first control input 111a could be a predetermined time interval following the first trigger event TEli of the first control input 111a.

With this arrangement, there is no significant noise associated with the extractor fan while a person is in the room RM, and, by virtue of providing for an increased fan speed S3 following the later of the second trigger events TE1 ₂ , TE2 ₂ , TE2 ₂ ' of the first and second control inputs 111a, b, accumulated humid air is extracted rapidly when a person should have left the room RM. In a preferred embodiment the volume of air extracted while the extractor fan is operating at the increased fan speed S3 is at least as great as the reduction in the volume of air extracted while the extractor fan is operating at the reduced fan speed S2.

Figures 10 and 11 illustrate an extractor fan system in accordance with a third embodiment of the present invention.

The extractor fan system comprises an extractor fan 203, which comprises an impeller 205 for drawing an air flow from a room RM, here a bathroom or wetroom, to atmosphere, a motor 207 for driving the impeller 205, and a controller 209 for controlling operation of the motor 207, both in switching the motor 207 on and off and controlling the speed of the motor 207 and hence the speed of the impeller 205.

The controller 209 has a control input 211 which detects at least one trigger event TE, in this embodiment first to fourth trigger events TE1, TE2, TE3, TE4.

In this embodiment the control input 211 is a noise sensor, and the first trigger event TE1 is detection of a noise above a first, predetermined threshold and the second trigger event TE2 is either detection of a noise below a second, predetermined threshold, here for a predetermined time period, which in one embodiment corresponds to the first threshold, or a predetermined time interval following the first trigger event TEl. In one embodiment the first trigger event TEl is reset where further actuation of the noise sensor occurs during the predetermined time interval. In one embodiment the noise sensor is a microphone.

In an alternative embodiment the control input 211 could be a flow sensor which detects flow from at least one water outlet in the room RM, and the first trigger event TEl is detection of flow, either the onset or cessation of flow, and the second trigger event TE2 is a predetermined time interval following the first trigger event TEl. In one embodiment the first trigger event TEl is reset where further actuation of the flow sensor occurs during the predetermined time interval.

An exemplary mode of operation of the extractor fan system will now be described hereinbelow.

Mode #1C

A mode of operation is illustrated in relation to Figure 11. In this mode of operation, the controller 209 controls the motor 207 normally to operate at a first, background speed SI.

The controller 209 causes the motor 207 to be operated at a second speed S2, higher than the first speed SI, when a first trigger event TEl is detected, here corresponding to the noise sensor of the control input 211 detecting a noise above a first predetermined threshold, typically caused by running a bath or a shower, here sampled over a predetermined period.

The controller 209, following detection of a second trigger event TE2, here corresponding to the noise senor of the control input 211 detecting a noise level below a second predetermined threshold, in this embodiment the same as the first predetermined threshold, typically when a bath or shower is no 8090

- 23 - longer being run, and here sampled over a predetermined period, causes the motor 207 to be switched off for a predetermined time interval.

The controller 209 then, following detection of a third trigger event TE3, here corresponding to the elapse of a predetermined time interval from the second trigger event TE2, causes the motor 207 to be operated at a third speed S3, here a higher speed than the first speed SI .

The controller 209 then, following detection of a fourth trigger event TE4, here corresponding to the elapse of a predetermined time interval from the third trigger event TE3, causes the motor 207 to be operated at a fourth speed S4, in this embodiment the same as the first speed SI .

With this arrangement, the extractor fan is operated at a higher throughput while a person is in the room RM, but this is when the ambient noise in the room RM is greater than that of the extractor fan, such as in running a bath or shower, and there is no significant noise associated with the extractor fan while a person is in the room RM, such as either subsequent to use of the shower or while in the bath, and, by virtue of providing for an increased fan speed S3 following the third trigger event TE3, accumulated humid air is extracted rapidly when a person should have left the room RM.

In a preferred embodiment the volume of air extracted while the extractor fan is operating at the increased fan speed S3 is at least as great as the reduction in the volume of air extracted while the extractor fan is inoperative.

Finally, it will be understood that the present invention has been described in its preferred embodiment and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.