1 AN EVAPORATIVE AIR CONDITIONER Field of the Invention [0001] The present invention relates to evaporative air conditioners. [0002] One aspect of the present invention relates to a system for draining water from evaporative air conditioners. [0003] Another aspect of the present invention relates to a winterising flap for evaporative air conditioners. [0004] Evaporative air conditioners comprise: a housing defined by side walls, a base, and a top wall, with one or more of the side walls comprising water absorbent panels which allow air to flow through the panels into the housing, and with the base comprising a trough for holding water; a water distribution system positioned in the housing to supply water from the water trough to the panels; a fan for drawing air into the housing via the panels so that the air is cooled via heat exchange with water in the panels; and an outlet for discharging cooled air from the housing. [0005] Domestic evaporative air conditioners are usually roof-mounted, with the housing being supported well above the roof-line by means of a hollow dropper tube which also defines part of the duct work for supplying cooled air to a house. [0006] In use, the water distribution system of an evaporative air conditioner supplies water from the water trough in the base of the housing to the upper edges of the panels. The water flows downwardly and wets the panels. The water in the panels cools hot air drawn through the panels into the housing. As a consequence, at least a part of the water supplied to the panels is lost by evaporation. The remainder of the water flows downwardly from the panels into the water trough. Water from a mains source is supplied to the water trough as a make-up feed to replace water lost by evaporation.
2 [0007] When the evaporative air conditioner is not in use, unless water is drained from the water trough, the water in the water trough may be stagnant for prolonged periods of time and, in the final analysis, may become contaminated. [0008] It is known to provide evaporative air conditioners with drain systems to drain water from the water troughs when the evaporative air conditioners are not in use. [0009] Generally, the known drainage systems depend on maintaining a water-tight seal between valve or other components of the drainage systems during normal operation of the evaporative air conditioners and are not altogether satisfactory for this reason. Specifically, the performance of seals is prone to deteriorate over time due to wear of seal components. In addition, seal performance is often affected by grit and other particulate contaminants in the water. Moreover, seals invariably require relatively substantial applied force to operate properly. [0010] An object of the present invention is to provide an evaporative air conditioner which alleviates the disadvantage of evaporative air conditioners described in the preceding paragraph. [0011] It is also known to provide evaporative air conditioners with winterising flaps in the cooled air outlet or ductwork immediately downstream of the outlet. [0012] The main purpose of winterising flaps is to close the outlet/ductwork when evaporative air conditioners are not in use. This is a particularly useful feature in cool climates to prevent loss of heat from houses via the ductwork. [0013] Conventional winterising flaps are responsive to air flow through the outlet/ductwork. Specifically, the flaps are normally biased into a closed position and open in response to air flow through the outlet/ductwork caused by operation of evaporative air conditioners. The conventional winterising flaps tend to be unreliable for a range of reasons and are not altogether satisfactory arrangements. [0014] An object of the present invention is to provide an evaporative air conditioner having an improved winterising flap assembly.
3 [0015] According to an aspect of the present invention there is provided an evaporative air conditioner which comprises: a housing defined by side walls, a base and a top wall, with one or more of the side walls comprising water absorbent panels which allow air to flow through the panels into the housing, and with the base comprising a water trough; a water distribution system positioned in the housing to supply water from the water trough to the panels; a fan for drawing air into the housing via the panels so that the air is cooled via heat exchange with water in the panels; an outlet for discharging cooled air from the housing; and a motorised winterising flap located in the outlet. [0016] There is also disclosed herein an evaporative air conditioner which comprises: a housing defined by side walls, a base and a top wall, with one or more of the side walls comprising water absorbent panels which allow air to flow through the panels into the housing, and with the base comprising a water trough; a water distribution system positioned in the housing for supplying water from the water trough to the panels, the water distribution system comprising a pump for pumping water from the trough to the panels; a fan for drawing air into the housing via the panels so that the air is cooled via heat exchange with water in the panels; an outlet for discharging cooled air from the housing; and a water drainage system for draining water from the water trough, the drainage system comprising an open drain inlet that is movable between an operating position at which the drain inlet is above a maximum level of water in the water trough under normal operating conditions and a drain position at which the drain inlet is below the maximum normal operating level so that water can drain from the water trough via the drain inlet. [0017] This aspect of the present invention is based on the realisation that by providing an open drain inlet that is movable between operating and drain positions it is possible to avoid the use of seals and high operating force.
4 [0018] It is preferred that the drainage system comprise a means for moving the drain inlet between the operating and drain positions. [0019] It is preferred that the drainage system comprise a flexible hose having one end forming the drain inlet and the other end connected to an opening in the water trough. [0020] It is preferred that the evaporative air conditioner comprises a motor mechanically linked to the drain inlet for moving the drain inlet between the operating and drain positions. [0021] It is preferred that the evaporative air conditioner comprises a winterising flap for closing the cooled air outlet in the housing. [0022] It is preferred that the evaporative air conditioner comprise a motor mechanically linked to the winterising flap for operating the winterising flap. [0023] The winterising flap and the motor form a winterising flap assembly. [0024] It is preferred particularly that the evaporative air conditioner comprises a single motor mechanically linked to the drain inlet and the winterising flap for operating the drain inlet and the winterising flap. [0025] It is preferred that the motor be adapted to move the drain inlet and the winterising flap simultaneously. [0026] The water drainage system may be responsive to any preselected parameters. [0027] For example, the water drainage system may be adapted to operate on a time basis, whereby the drain inlet moving means moves the drain inlet from the operating position to the drain position after the evaporative air conditioner has been operating for a pre-selected period of time and thereafter returns the drain inlet to the operating position to drain at least a part of the water from the water trough while the drain inlet is in the drain position. [0028] It is preferred particularly that the water drainage system be responsive to a start-up sequence and a stop sequence of the evaporative air conditioner, whereby the start-up sequence 5 actuates the motor to move the drain inlet to the operating position and to maintain the drain inlet in that position while operation of the evaporative air conditioner continues, and whereby the shut-down sequence actuates the motor to move the drain inlet to the drain position and to maintain the drain inlet in that position so that water can drain from the water trough. [0029] The start-up sequence may comprise any suitable combination of steps carried out successively or simultaneously. [0030] By way of example, one start-up sequence comprises successively opening the winterising flap, operating the water pump to pump water from the trough to the panels to wet the panels, and thereafter operating the fan to draw hot air into the housing via the panels to cool the air and to discharge the cooled air from the housing via the outlet. A typical shut-down sequence comprises successively turning off the water pump, turning off the fan, and thereafter closing the winterising flap. [0031] It is preferred more particularly that the water drainage system be responsive to a control signal generated during the start-up and the shut-down sequences. [0032] The present invention is described further by way of example with reference to the accompanying drawings of which: [0033] Figure 1 is a vertical section through a preferred embodiment of an evaporative air conditioner formed in accordance with the present invention; and [0034] Figure 2 is a section along the lines 2-2 of Figure 1. [0035] The preferred embodiment of the evaporative air conditioner shown in the figures is adapted to be positioned above a roof (not shown) of a house (not shown) and be operable to supply cooled air via duct work (not shown) to the rooms of the house. [0036] With reference to the figures, the evaporative air conditioner comprises a housing, generally identified by the numeral 3, having: a base 5; 6 four side walls comprising water absorbent porous panels 7 which, when wet, cool hot air flowing therethrough into the housing by heat exchange between the hot air and the water; and a top wall 9. [0037] The air conditioner further comprises an outlet 13 for discharging cooled air from the housing 3 into the duct work. The outlet 13 is formed centrally in the base 5 and is defined by a moulded upstanding wall 15. [0038] The air conditioner further comprises a fan assembly 17 positioned in the outlet 13 for drawing air into the housing 3 via the water absorbent porous panels 7 and for forcing cooled air from the housing 3 via the outlet 13. [0039] The base 5 is moulded from plastics material and comprises a water trough, generally identified by the numeral 11. [0040] The water trough 11 forms part of a water distribution system for supplying water to the water absorbent porous panels 7. The other components of the water distribution system are located in the housing and are not shown in order to simplify the description. Typically, the components include a water distribution tray positioned immediately below the top wall 9 for distributing water received via a central inlet to the upper edges of the water absorbent porous panels 7. The components also include a pump for pumping water from the trough 11 to the inlet. In use, the trough 11 receives water as run-off from the water absorbent porous panels 7 and as a make-up feed to replace water lost from the panels 7 by evaporation. [0041] The air conditioner further comprises a motorised winterising flap assembly 31 that comprises: a winterising flap formed from a plurality of slats 37 in the outlet 13 downstream of the fan 17 for closing the outlet 13 when the air conditioner is not operating (not shown); and a motor M mechanically linked to the slats 37 for operating the assembly to open and close the slats 37. [0042] The above-described motorised winterising flap assembly 31 ensures reliable operation of the slats 37.
7 [0043] A particular advantage of the motorised winterising flap is that there is a substantial flexibility with respect to the location of the slats 37 in the outlet 13. With the conventional air responsive winterising flaps the location of the slats is governed by the need to have air flow conditions that could open the flaps. This requirement limits the range of options for positioning the flaps, and in some instances means that it is necessary to make undesirable trade offs in locating the flaps in positions that generate relatively high noise levels or make the flaps susceptible to being opened by wind rather than air flow generated by the fan. [0044] The motorised winterising flap is not subject to this disadvantage, and therefore the location of the slats 37 can be governed by general design considerations for the evaporative air conditioner. [0045] In particular, the applicant has found that one option to minimise noise is to locate the motor M upstream of the slats 3 externally of the outlet 13. [0046] The air conditioner further comprises a water drainage system for draining water from the water trough 11. [0047] The water drainage system comprises a flexible hose 21 that is connected at a lower end to an outlet opening 23 in the floor of the water trough 11. The upper end of the hose 21 defines an open drain inlet 25 of the water drainage system. [0048] The hose 21 is selectively movable between an operating position in which the hose 21 extends above the maximum level of water in the water trough 11 under normal operating conditions and a drain position (shown in outline in Figure 2) in which the hose 21 extends generally parallel to the floor of the water trough 11 below the maximum water level in the water trough 11 and can thereby drain water from the water trough 11. In the preferred embodiment shown in the figures the hose 21 is positioned so that when the hose 21 is in the drain position the drain inlet 25 is located in the deepest section of the water trough 11. [0049] The hose 21 may be moved between the operating and drain positions by any suitable means (not shown). In the preferred embodiment the hose 21 is mechanically linked to and is driven by the winterising flap motor M.
8 [0050] Therefore, in the preferred embodiment shown in the figures the water drainage system is responsive to the start-up and shut-down sequences of the evaporative air conditioner. [0051] More specifically, the start-up sequence of the air conditioner causes the winterising flap motor M to move the hose 21 to the operating position as the motor M opens the slats 37. As discussed above, in the operating position, the drain inlet 25 of the hose 21 is above the normal operating level of the water trough 11 and, as a consequence, under normal operating conditions water is not able to drain from the water trough 11. [0052] At the end of operation of the air conditioner, the shut-down sequence of the air conditioner causes the winterising flap motor M to operate to move the hose 21 from the operative position to the drain position shown in outline in Figure 2 as the motor M closes the slats 37. In the drain position, with the drain inlet 25 closely adjacent the floor of the deepest section of the water trough 11 water drains from the water trough 11 via the hose 21. [0053] The above-described water drainage system does not require the use of seals and high operating force which have been found to be a disadvantage in known evaporative air conditioners. [0054] A further advantage of the water drainage system is that it also acts as an overflow outlet for the air conditioner. In this connection, it can readily be appreciated that, if the water level in the water trough 11 exceeds the maximum normal operating level, as may occur inadvertently, the water level will rise until it reaches the open drain inlet 25 and, thereafter, water will flow from the water trough 11 via the hose 21 to maintain the water level at the drain inlet level. The use of a combined rather than separate drain outlet and water overflow significantly simplifies plumbing requirements. [0055] Further to the preceding paragraph, a further advantage of the water drainage system is that it makes it possible to drain periodically a part of the water from the water trough 11 by selectively flooding the water trough 11 while the hose 21 (and in more general terms, the drain inlet 25) is in the operating position so that water can flow via the hose 21 from the water trough 11. It can readily be appreciated that such selective flooding of the water trough 11 is an advantage in terms of diluting the level of minerals in the water in the trough 11.
9 [0056] Many modifications may be made to the preferred embodiment described above without departing from the spirit and scope of the present invention.