GB2310253A - Ventilation fan - Google Patents

Description

VENTILATION FAN This invention relates to ventilation fans, and especially to ventilation fans for attachment to ventilation ducts.

Such fans are used to ventilate rooms such as bathrooms, toilets, kitchens, utility rooms having no external walls, because ventilation is much less of a problem when there are external walls, since a fan can be mounted in an aperture in that wall. Commonly, ventilation ducts are located in ceiling spaces between the ceiling and the floor surface above, the ducts extending to for example air bricks at the side of the building.

A problem which arises is that current construction techniques are moving over to concrete flooring and a comparatively narrow void between the lower surface of the flooring and the plasterboard suspended underneath. In fact the current depth is around only two inches.

Ventilation fans have been proposed for use with such a narrow clearance, by using rectangular ducts communicating with air bricks, but in each case the fan is located wholly below the plasterboard or extends through the plasterboard to a substantial extent.

The invention provides a ventilation fan for attachment to a rectangular ventilation duct, comprising a housing for a centrifugal fan, the housing being arranged to be mounted on a surface with the axis of the fan normal to the surface, the housing having an air inlet which is in an axial direction with respect to the fan and an air outlet which is in a radial direction with respect to the fan, and wherein the outlet is adapted to connect directly to the rectangular ventilation duct.

By making the outlet from the housing of such a shape to connect directly to the rectangular ventilation duct, a thinner fan arrangement is possible, and it becomes possible to mount the fan even in a restricted void.

The fan housing may be in two parts split about a plane perpendicular to the axis of the fan and, in the case of a ceiling mounted fan, the lower part of the housing may contain the motor. It then becornes possible to fit the fan after the ceiling has been installed (in the case of a new building) subject only to the cutting of a circular aperture in the ceiling, because the lower part of the housing can be offered up through the aperture to the upper part secured to the lower part of the floor above. This would also make it possible to service the motor readily.

Although reference has been made to securing the fan on a ceiling, the fan is equally suitable for being secured to a vertical stud wall or cavity wall, in which case the duct would usually extend upwards to a suitable opening.

A ventilation fan suitable for attachment to a rectangular ventilation duct and constructed in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of the fan and duct; and Figure 2 is a sectional view of the fan, partly simplified, when secured in position.

Referring to the drawings, the fan is mounted in the void between the lower surface of a concrete floor 1 and the upper surface of a plasterboard ceiling 2. Before the plasterboard ceiling 2 is hung, a rectangular ventilation duct 3 extending to an air brick at an outside wall is secured to the lower surface of the concrete floor 1.

The fan housing is in two parts, namely, a lower part 4 and an upper part 5. The lower part contains the fan motor (not shown) and a centrifugal fan 6 having backward curved blades. The motor drives the blades (as shown in an anti-clockwise direction), the rotor defining a hollow cylinder with a vertical axis and the blades extending vertically over the height of the cylinder with the inner edge of the blades on the inner diameter of the cylinder and the outer edge of the blades on the outer diameter of the cylinder, with the blade being arranged so that the inner diameter leads the outer diameter.

Air is drawn into the eye of the fan vertically upwards into the inlet opening7 and it is thrown outwards radially by the fan blades, whereupon it enters the duct 3 from the outlet 8 of the housing. This is defined by an inverted U-shaped section of the member 5 and a flat extension of the member 4. When the two parts 4 and 5 are clamped together, the opening 8 is formed.

Typically, the fan is assembled and disassembled as follows. Part 5 would be secured to the lower face of the concrete floor 1 by means of screws Sa, Sb, 5c, typically when the duct 3 is installed. The lower part of the housing 4 carrying the fan motor which is connected to a suitable supply and the centrifugal fan is offered up to the upper part 5 through an aperture 2a in the plasterboard ceiling and the two parts are secured together by bolts 4a, 4b, 4c thereby clamping the housing over the duct 3. A gasket 3a may be provided at the end of the duct 3 for sealing purposes. A fascia grille 9 is then lifted to the aperture 2a, a filter. 10 carried by the fascia grille 9 covering the inlet 7 of the housing. The fascia grille is secured by means of bolts 11 and extensions 12. The extensions 12 are held by means which is not shown in a tangential position when the fascia grille 9 is being fitted and are mounted in such a way that they project outwards when the screws 11 are turned, for the purpose of screwing the bolts 11 against the ceiling 2 using the projections 12 as nuts which can be regarded as extending outwardly beyond the periphery of the hole 2a. Trim pieces 13 can then be inserted if desired.

The construction is very thin in the vertical direction, permitting the ventilation fan to be housed almost wholly within the roof void, by virtue of the rectangular air outlet mating with the rectangular duct 3. In addition, servicing of the fan and motor is simple since it is merely necessary to undo the fascia grill and then take the two parts of the housing apart and lower the lower part through the aperture, having disconnected the electrical lead, for inspection.

Of course variations may be made without departing from the scope of the invention.

Thus, for example, there is no need for the upper part of the housing 5 to be fitted before the ceiling is hung. Instead, this part could be inserted through the aperture 2a as well if desired. Equally, the invention is not restricted to fans for positioning in a ceiling, but would also apply to a fan mounted to connect to a duct 3 sunk into a vertical wall. The duct would extend vertically in such a case to a suitable opening. Or the ventilation fan could be secured in a floor if desired.

Claims (5)

1. A ventilation fan for attachment to a rectangular ventilation duct, comprising a housing for a centrifugal fan, the housing being arranged to be mounted on a surface with the axis of the fan normal to the surface, the housing having an air inlet which is in an axial direction with respect to the fan and an air outlet which is in a radial direction with respect to the fan, and wherein the outlet is adapted to connect directly to the rectangular ventilation duct.

2. A ventilation fan as claimed in claim 1, in which the housing is in two parts split in a direction perpendicular to the axis of the fan.

3. A ventilation fan as claimed in claim 2, in which the lower part of the housing may be passed through an aperture into a void above the aperture in order to be connected to the other part.

4. A ventilation fan as claimed in claim 3, in which the part of the fan to be inserted through the aperture carries the fan and motor.

5. A ventilation fan substantially as herein described with reference to the accompanying drawings.