GB2310764A

GB2310764A - A control circuit unit for a fan

Info

Publication number: GB2310764A
Application number: GB9704183A
Authority: GB
Inventors: Alan Charles Hudson; Gary Richard Hudson
Original assignee: HI TEC MANAGEMENT SERVICES LIM
Current assignee: HI TEC MANAGEMENT SERVICES LIM
Priority date: 1996-02-27
Filing date: 1997-02-27
Publication date: 1997-09-03
Also published as: GB9704183D0; GB9604053D0

Abstract

A control circuit unit for a bathroom fan comprises a front plate 30 having mounted on its rear face a double-pole switch 20 accessible through the front plate, a fuse holder 21 also accessible through the front plate, and a transformer 22, all connected together. Preferably the fuse holder is a captive fuse holder, and preferably also the switch is key-operated. Preferably the front plate also includes an indicator light 23 energized from the low-voltage output side of the transformer. The unit may also include a printed circuit board (PCB) located behind the switch, the fuse holder, and the transformer, lying parallel to the front plate. This PCB can carry connector pins to the switch and fuse holder. Further, this PCB can carry a timing circuit for controlling the fan.

Description

Fan Control Circuitry The present invention relates to circuitry for energizing and controlling fans and the likc. particularly for controlling humidity.

The use of a bathroom for running and taking a shower or a bath often generates e large quantity of humid air. In modern dwelling houses. particularly smell ones. it is undesirable to allow this air to escape into the rest of the house when the use of the bathroom is terminated and its door is opened. It is therefore becoming common to provide a fan for extracting humid air from the bathroom and venting it to the outside of the house.

The high humidity of bathrooms can easily result in conductive paths being formed on or over electrical equipment, and also facilitates the production of relatively low resistance earthing paths. Further. users of bathrooms are liable to have damp or wet hands and bere feet which are also damp or wet. The danger of electrical shocks from bathroom equipment is therefore high.

In view of this danger. fairly stringent regulations exist governing the provision and use of electrical equipment in bathrooms. Mains-powered lights are still permissible. but their switches must either be outside the bathroom or mounted on the ceiling and cord-operated. and the use of low voltage lights is being encouraged. In fact, most items of electrical equipment should have their switches outside the bathroom rather than inside. the wiring to such items should include isolating switches. and they should operate on low voltage rather than mains voltage.

These requirements apply to fans in particular. Thus e fan installation which complies with the current regulations requires a 2-pole isolating switch. a fuse, end a transformer. all located outside the bathroom itself. (The fan itself is of course inside the bathroom, generally located on an outside wall.) While there is no difficulty in principle in installing such a system, it requires the installation of 3 separate units (the switch, the fuse, and the transformer) all outside the bathroom. This results in an unattractive array of units. all normally let into the wall outside the bathroom. To minimiz;- damage to the wall resulting from connections between the units, the units are normally placed close together. Since the units also have, in general, slightly different appearances, this results in an ugly cluster. Also, installing the items involves a substantial amount of time and effort and hence cost, and there is always the danger of an error being made in the installation and connection of the units.

The general object of the present invention is to alleviate or overcome these problems.

Accordingly the invention provides e control circuit unit for a fan, comprising a front plate having mounted on its rear face e double-pole switch accessible through the front plate, a fuse holder also accessible through the front plate, end a transformer, all connected together. Preferably the fuse holder is a captive fuse holder, and preferably also the switch is key-operated.

Preferably the front plate also includes an indicator light energized from the low-voltage output side of the transformer.

The unit may also include a printed circuit board (PCB) located behind the switch, the fuse ,holder, and the transformer, lying parallel to the front plate.

This PCB can car'wry connector pins to the switch and fuse holder. Further, this PCB can carry a timing circuit for controlling the fan.

Fan control circuitry embodying the invention will now be described, by way of example, with reference to the drawings, in which: Fig. 1 is 8 general diagram of a bathroom including a fan; Fig. 2 is a circuit diagram of the fan and associated circuitry; and Fig. 3 is a simplified diagram of the control circuit unit.

Fig. 1 shows a house with a bathroom 10 having a fan 11 mounted over a vent 12 in an outside wall. The fan is energized from e control circuit unit 13 which is mounted on the hall side 14 of the inner wall 15 of the bathroom, ie outside the bathroom itself. The bathroom 10 also contains a humidity sensor 16 which controls the fan.

Fig. 2 is a block circuit diagram of the fan ii, control circuit unit 13, humidity sensor l, and associated circuitry. The fan consists of a motor 1 IA which is mechanically coupled to a set of propeller blades I IB. The motor ii A is energized from a 220 V meins supply (shown as L-N-E) vie the control circuit unit 13. The humidity sensor 16 consists of a sensing element 16A which is coupled to a switch 16B which is connected in series between the fan 11 and the control circuit unit 13.

The control circuit unit 13 comprises a fuse element 21, a switch 20, a transformer 22, and an indicator light 23. The switch 20 is a double pole switch, which is connected to the 240 V side of the transformer 22, via the fuse element 2 1 in series in the L line. The indicator light 23 is connected across the 12 V output side of the transformer 22, in parallel with the lines to the fan 11. The locations of the switch and fuse holder can of course be interchanged.

The control circuit unit 13 is intended for flush mounting on the wall 14.

For this purpose, a suitable recess must be cut in the wall and a box fixed in the recess. The control circuit unit can then be fitted into the box. The rear face of the front plate of the control circuit unit (which will normally be of white plastics material) will be flat against the front edge of the box, and the front plate will then be fixed to the box by a pair of bolts. The front plate is preferably of 8 standard size, corresponding to a double 13 A socket, end the box is preferably, elso of the corresponding standard size.

t Fig. 3 shows the front plate 30 of the control circuit unit. At one end of this unit, the fuse element 21 is mounted, projecting through 8 vertical cut-out in the front plate as shown. The fuse element 21 comprises a fuse holder which is captive in a housing lying behind the front plate 30; the holder cen be pulled forward to make the fuse accessible for checking and replacement if necessary.

The switch 20 is mounted adjacent to the fuse element 21, and also projects through a respective vertical cut-out in the front plate, to enable it to be operated.

At the other end of the control circuit unit, the transformer 22 is mounted behind the front plate 30. The L (live) and N (neutral) mains supply lines are connected to one side of the switch 20, with the L end N outputs from the switch being connected to the high voltage side of the transformer 22; the L connection passes through the fuse element 21 while the N connection is direct. The low voltage output lines LV from the transformer 22 are fed to the fan 11, es described above with reference to Fig. 2. In addition, the front plate 30 has a circular cut-out through which the indicator light 23 projects; this indicator light is connected across the LV output of the transformer 22, as described above.

The four components 20, 21, 22, and 23 can of course be arranged in any convenient layout behind the front plate 30. The arrangement shown has the advantage that the two terminals for the incoming meins cable are adjacent to each other, and the wiring between the fuse holder and switch and the switch and transformer is short. The space behind the front plate 30 is restricted, so the transformer 22 preferably has flying leads rather then terminal pegs, to minimize the volume which it occupies.

The system shown in Fig. 1 is normally intended to be permenently switched on, with the fan being turned on and off by the humidity sensor. (Other devices for cotrolling the fan cbn also be used, eg a switch controlled by the opening and closing of the door to the bathroom, the turning on and off of the bathroom light, etc.) The switch 20 is therefore preferably of a key-operated type rather than having an operating lever, so that the householder cannot readily turn the system off. (The key may conveniently consist of a handle with a fork on the enbd, resembling a small spanner, which can grip the operating bar in the switch.) The system may also include a switch 17 (Fig. 1) which is opereted by the opening and/or closing of the bathroom door. The control unit 13 (Fig. 2) will then include a power supply 24 which energized a timer 25 which is connected across, ie in parallel with, the sensor switch 16. When the door switch 17 is operated, the timer 25 closes the parallel path around the sensor 16 and so operates the fan 11 for a suitable preset time period, typically between 3 and 20 minutes. Other switches, eg a light switch, may be used to control the timer, either instead of or together with the door switch 17 shown.

The power supply 24 and timer 25 are preferably mounted on a PCB (not shown), which is located in the control unit 13. The PCB can conveniently be located behind the switch 20, fuse holder 21, and transformer 22, lying parallel to the front plate 30 of the control unit. This PCB can also carry projecting pins which can be connected directly to the switch 20 and fuse holder 21, together with flying leads to the transformer 22, leads to the sensor 16 and switch 17, etc. Alternatively, two separate PCBs can be used, one located behind the switch 20 and fuse hlder 2 1 to provide the connections to and between those units end the other located eg beside the transformer 22 and carrying the power supply 24 and timer 25.

The timer 25 may include an adjustment control for setting its time period, eg in the form of a set of DIL (dual in-line) switches. This control is preferably accessible only from inside the control circuit unit 13, although if desired, e hole may be provided in the front plate 30 through which the adjustment control can be reached by eg a screwdriver.

Claims

1 A control circuit unit for a fan, comprising a front plate having mounted on its rear face a double-pole switch accessible through the front plate, a fuse holder also accessible through the front plate, and a transformer, all connected together.

2 A control circuit unit according to claim 1 wherein the fuse holder is a captive fuse holder.

3 A control circuit unit according to either previous claim wherein the switch is key-opersted.

4 A control circuit unit according to any previous claim wherein the front plate also includes an indicator light energized from the low-voltage output side of the transformer.

5 A control circuit unit according to any previous claim including a printed circuit board (PCB) located behind the switch, the fuse holder, end the transformer, lying parallel to the front plate.

6 A control circuit unit according to claim 5 wherein the PCB carries connector pins to the switch and fuse holder.

7 A control circuit unit according to either of claims 5 and 6 wherein PCB carries a timing circuit for controlling the fan.

8 A control circuit unit substantially as herein described.

9 Any novel and inventive feature or combination of features specifically disclosed herein within the meaning of Article 4H of the International Convention (Paris Convention).