Abstract:
Apparatus for automatically draining the water from an evaporative cooler when operation thereof is terminated and for periodically draining, flushing and replacing the water during operation of the cooler. The apparatus includes a comparatively small reservoir tank, which depends from the bottom of the cooler, for containing the cooler&#39;s water supply and a pump, a siphon drain valve and at least the float of a float controlled water supply shutoff valve. The water is recirculatingly supplied from the tank to the cooler and returns to the tank and that water will increase in mineral concentration and other cooler damaging contaminants during such recirculation. When both the pump and water supply are shutoff, such as upon termination of cooler usage, the apparatus will automatically commence its drainage operational mode wherein the returning water will raise the water level in the tank to prime the siphon drain valve which drains the water from the tank. By periodically interrupting operation of the pump only, the apparatus will automatically commence its draining, flushing and refilling operational mode wherein the returning water will prime the siphon drain valve which drains the tank at a faster rate than makeup water is supplied thereto which causes flushing of the tank, and when drainage is complete, the siphon drain valve will lose its prime and the incoming fresh water will refill the tank. The tank is provided with an especially configured floor so that the pump will positively interrupt the siphoning action at the appropriate time during the draining, flushing and refilling operational mode of the apparatus and a special timing device is employed to initiate and control pump operation during that operational mode.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of a copending U.S. Patent Application Ser. No. 115,041, filed on Jan. 24, 1980, now U.S. Pat. No. 4,255,361, which is a continuation-in-part of a copending U.S. Patent Application Ser. No. 007,027, filed on Jan. 29, 1979 which issued as U.S. Pat. No. 4,192,832, on Mar. 11, 1980, all by the same inventor. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to evaporative coolers and more particularly to an improved automatic flushing and draining reservoir apparatus for use with evaporative coolers. 
     2. Description of the Prior Art 
     Evaporative coolers of the type having an air handler mounted in a cabinet for drawing air into the cooler through wettable cooler pads and delivering the evaporatively cooled air to a point of use, having the necessary water supply contained within a floor pan or sump. The water level within the sump is maintained at a predetermined level by a float controlled inlet valve that is suitably connected to a source of water under pressure such as a domestic water line. A pump is mounted in the sump and operates to supply water to the cooler&#39;s water distribution system which in turn distributes the water to the cooler pads. The wet cooler pads will cool the air being drawn therethrough by the air handler in accordance with the well known evaporative principle, and the unevaporated water will drain under the influence of gravity from the pads and return to the sump. 
     During such operation, the water, which inherently contains minerals such as calcium chloride and other impurities, will increase as to its concentration of those minerals due to the evaporation process. As the mineral concentration increases, the rate of precipitation will also increase which results in mineral deposition, or scaling, of the various cooler components. Such mineral deposition causes calcification of the cooler pads, clogging of the water passages, corrosion of the metal and the like, but the most serious problem is with the electric motors and wiring. When the calcium chloride salts are deposited on the wiring, terminals, and the various parts of the electric motors themselves, moisture in the cooler is attracted to the salts and will form a moist pasty salt substance which shorts out those electric components. To keep such mineral deposition to a minimum, the cooler should be periodically drained, flushed and refilled with fresh water. However, since such draining, flushing and refilling is something which should be accomplished on a regular and a rather frequency schedule, as determined by the characteristics of the water, it is something that is almost always forgotten or simply ignored. 
     The above described problem of mineral deposition is compounded by the fact that the water is stored within the sump which serves as a reservoir. Thus, the various cooler components are continuously subjected to a moist environment by being directly exposed to a relatively large body of water in the bottom of its cabinet. Unless the sump is drained at the end of a cooling season, or prior to other periods of nonuse, such direct exposure of the components to the water body is something that can, and often is, continuous whether the cooler is operating or not. Draining of the sump preparatory to a period of nonuse is no guarantee that the sump will remain dry for the period of nonuse in that leakage from the inlet supply line and/or rain entering the cooler cabinet through the pads will collect in the sump. 
     The above described problems and shortcomings of prior art evaporative coolers is something that has long been recognized and various attempts have been made to solve, or at least, minimize some of those problems. For example, devices which dispense chemicals into the water to reduce mineral concentration and deposition problems have been suggested, however, such devices have not received commercial acceptance due to the minimal benefits derived, cost, and the maintenance requirements. 
     One particular prior art device has been suggested in U.S. Pat. No. 2,828,761, for automatically draining, flushing, and replacing the water in the cooler&#39;s sump and for draining a large portion of the water therefrom when the inlet water supply to the sump is shutoff. Briefly, this prior art device includes a sheet metal dam which is located within the sump of the cooler. A oneway check valve is located in the wall of the dam so that water is free to flow from the main reservoir portion of the sump into the relatively smaller dam portion but is prevented from flowing in a reverse direction. A pump and siphon valve are located inside the dam and a float controlled water inlet valve is located in the main reservoir portion of the sump to maintain the water level in the sump and in the dam, due to the free flow through the checking valve, at a predetermined level. During operation of the cooler, the pump delivers water from the dam portion to the cooler&#39;s water distribution system which in turn supplies water to the cooler pads, and the unevaporated water will return from the pads, by gravity, to the main reservoir portion of the sump. When the pump is turned off, water in the cooler&#39;s water distribution system will drain back into the dam area only, due to the reverse flow checking provided by the check valve, thus raising the water level therein to a point where it primes the siphon valve. When the siphon valve is thus primed, water in the dam will be drained therefrom and the water in the main reservoir portion of the dam will flow through the check valve into the dam and will exit the dam through the siphon valve. When the water supply is left on during such an operation, the result is that a draining, flushing and water replacement action takes place, and due to the outlet and siphon valve being sized to drain the sump at a faster rate than the water inlet line can replace the water, the water level will drop until the siphon valve loses its prime, whereupon refilling of the sump with fresh water takes place under control of the float operated inlet valve. This same operation occurring when the water supply to the cooler is shutoff results in draining of most of the water from the sump. 
     This particular prior art flushing and draining device has not received commercial acceptance for several reasons. In the first place, the amount of water contained in the water distribution system of an evaporative cooler is quite small and will, in most cases, be insufficient to achieve priming of the siphon valve. Secondly, the check valve of this prior art structure is a constant source of problems, in that the water pressure differential on the opposite sides thereof is all that can be relied upon for opening and closing of the valve, and that pressure differential is exceedingly small. The small pressure differential relied on to open and close the check valve precludes the use of a spring or other device to bias the valve toward its closed position. Therefore, the check valve is a passive rather than a positively acting device, and achieving a fully closed position when such a state is critical is oftentimes not achieved. To illustrate this point, there can be no leakage through the check valve when the draining cycle is initiated in that such leakage would prevent the water level in the dam from reaching the point where the siphon valve is primed. In addition to the passive action of the check valve, it by necessity, is operated under water and this subjects the valve to corrosion, scaling and the like, and the valve often is jammed by foreign matter such as dirt, wood shavings from the excelsior pads and the like. Thirdly, this prior art device is incapable of completely draining all of the water from the dam and the main reservoir portion of the sump in that both the check valve and the inlet to the siphon valve are spaced upwardly from the bottom of the sump. Therefore, the desirability of draining the sump when the cooler is inoperative cannot be completely achieved and a relatively large surface area of water will remain. Further, when the pump is shutoff to accomplish a draining, flushing and water replacement cycle, water will not be supplied to the cooler pads for a considerable length of time due to the amount of water that must be drained and replaced to fill the entire relatively large sump before normal operation can be resumed. Since warm air will continue to be drawn through the pads by the air handler during such a cycle, the pads will dry out rather rapidly, and upon drying, dust, dirt and the like will be extracted from the pads by the air moving therethrough. 
     In addition to the inherent problems of this particular prior art structure, it does nothing to remove the cooler components from direct exposure to the water in the sump either during operation or during nonuse of the evaporative cooler, and is incapable of automatically draining rain water or the like which enters the cooler during nonuse periods. 
     Therefore, a need exists for a new and improved automatic flushing and draining reservoir apparatus for evaporative coolers which overcomes some of the problems and shortcomings of the prior art. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention a new and improved automatic flushing and draining reservoir apparatus for evaporative coolers is disclosed. The reservoir apparatus includes a tank, which may be integrally formed, or may be suitably attached to the floor pan of the evaporative cooler so as to be located immediately below an opening formed through the floor pan. A pump, siphon valve, and at least the float portion of a float controlled water inlet valve are located in the tank with the pump being used to supply water to the cooler&#39;s water distribution system, the siphon valve being used during the flushing and draining operations, and the float controlled water inlet valve being operable to maintain the water level in the reservoir tank at a predetermined operating level. 
     In operation, the reservoir apparatus of the present invention will deliver water from the tank to the cooler&#39;s water distribution system which directs the water to the cooler&#39;s pads. Unevaporated water from the cooler pads returns by gravity into the floor pan of the cooler and will pass through the opening thereof into the tank. To place the apparatus of the present invention in a flushing operational mode, the pump is turned off and the water inlet supply is left on. Water returning from the cooler pads will add to the water that drains from the water distribution system to raise the water level in the tank to a flooded level which primes the siphon valve. Such priming of the siphon valve will drain the tank. The flow capacity of the siphon valve is considerably larger than the flow capacity of the inlet water supply line, thus, during draining of the tank fresh water will continuously enter and dilute the water that is being drained. Such diluting will dissolve some of the minerals which were previously precipitated and they will exit the tank during the draining. When the draining is complete, the siphon valve will lose its prime, with this action being positive due to the special configuration of the tank, and the float controlled water inlet valve will refill the tank with fresh water. In the draining mode, both the pump and the water inlet supply line are shutoff, the siphon valve will be primed in the above described manner and the tank will be completely drained and will remain that way due to the inlet water supply being shutoff. 
     Considering that the tank must be large enough to contain the siphon valve, at least the float portion of the water inlet valve, and at least the inlet or suction portion of the pump, the tank should be as small as possible with regard to its surface area so that when the evaporative cooler is shutoff the amount of water returning therefrom to the tank will be sufficient to raise the water level from its normal operating level to a level which will prime the siphon valve. The amount of returning water needed to effect priming of the siphon valve is minimal due to the relatively small surface area of the tank, and since both the water returning from the cooler pads and that draining from the cooler&#39;s water distribution system are employed to achieve the desired priming of the siphon valve, a sufficient quantity of water is always available to accomplish that task even in the smallest size evaporative coolers. 
     By placement of the tank below the floor pan of the cooler, water will never stand in the floor pan which reduces scaling and corrosion of the pan itself and the other cooler components, and will also reduce the cooler&#39;s direct exposure to a water body having a relatively large surface area. Even further reduction of such direct exposure of the cooler is achieved by providing the tank with a cover that is spaced above the opening formed through the cooler&#39;s floor pan. This same positioning of the reservoir tank below the floor pan eliminates the need for a flow checking valve as in the hereinbefore described prior art structure thus eliminating, or substantially reducing, the possibility of scaling, corrosion, or contamination causing the reservoir apparatus to become inoperative. 
     In the reservoir of the present invention, the inlet to the siphoning valve is located in a downwardly upset dimple, or depression, formed in the bottom of the tank so that the inlet is below the bottom of the tank. This, in conjunction with the lack of a check valve, allows complete and automatic drainage of the water from the cooler and from the reservoir in a draining mode when both the pump and the water supply line are shutoff. 
     The inlet portion of the pump is also located in a downwardly upset dimple, or depression, formed in the bottom of the tank and this dimple is connected by means of a narrow depressed channel to the dimple in which the inlet end of the siphon valve is positioned. This special tank bottom configuration provides a positive acting drainage stop in that the pump will draw all the water away from the inlet of the siphon valve when tank drainage is completed during the flushing operational mode. In conjunction with this positive drainage stop feature, the apparatus of the present invention is preferably provided with a special timing means which operates to shutoff the pump at the commencement of the flushing operation, turn it back on momentarily when the tank drainage is completed to positively stop the drainage action of the siphon valve, and then turn the pump off again during the refilling of the reservoir to expedite refilling and prevent the pump from drawing air, and then returning the pump to its normal on state when the flushing operation is completed. 
     Other advantages, both from manufacturing and aesthetic standpoints, results from the reservoir apparatus of the present invention. Since the water supply is no longer contained within the cooler cabinet itself, the overall height of the cabinet can be reduced which results in a more aesthetically appealing low profile structure, and a substantial savings of material is achieved. Further, the depth of the floor pan can be reduced in that it no longer serves as a reservoir, thus, the floor pan can be the same as the roof pan which results in savings from the standpoints of tooling, material, handling and the like. 
     Accordingly, it is an object of the present invention to provide a new and improved automatic flushing and draining reservoir apparatus for use with evaporative coolers. 
     Another object of the present invention is to provide a new and useful reservoir apparatus of the above described character which includes a flushing operational mode that reduces the scaling, calcification, and corrosion of the cooler by automatically draining, flushing and replacing the cooler&#39;s water supply each time the cooler&#39;s pump is shutoff. 
     Another object of the present invention is to provide a new and improved reservoir apparatus of the above described character which includes a draining operational mode that will completely drain all of the water from the cooler and the reservoir tank when the pump and the inlet water supply are shutoff. 
     Another object of the present invention is to provide a new and improved reservoir apparatus of the above described type which removes the water supply from the sump, or floor pan, of the evaporative cooler and locates it in a more remote location which reduces scaling, calcification, corrosion and direct exposure of the cooler to a water body having a relatively large surface area. 
     Another object of the present invention is to provide a new and improved reservoir apparatus of the above described character which will not add any mechanisms having moving parts that could contribute to failure of the apparatus. 
     Another object of the present invention is to provide a new and improved reservoir apparatus of the above described character which includes a tank that is positioned below an opening in the cooler&#39;s floor pan for containing the cooler&#39;s water supply, and receiving the unevaporated water returning from the cooler. 
     Another object of the present invention is to provide a new and improved reservoir apparatus of the above described type in which the water level in the tank is maintained at a predetermined level by a float controlled water inlet valve having at least the float portion thereof located within the tank. 
     Another object of the present invention is to provide a new and improved reservoir apparatus of the above described character in which water returning from the cooler&#39;s pads and water draining from the cooler&#39;s water distribution system upon shutting off of the pump, will raise the water level in the tank to prime a siphon valve mounted therein to cause complete drainage of the tank. 
     Still another object of the present invention is to provide a new and improved reservoir apparatus of the above described character which is provided with a special tank bottom configuration which allows positive stopping of the drainage operation of the siphon valve during the automatic flushing operational mode. 
     Yet another object of the present invention is to provide a new and improved reservoir apparatus of the above described type which includes a special timing means for controlling pump operation during the automatic flushing operational mode. 
     The foregoing and other objects of the present invention, as well as the invention itself, may be more fully understood from the following description when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary sectional view of the typical evaporative cooler which includes the automatic flushing and draining reservoir apparatus of the present invention. 
     FIG. 2 is a fragmentary sectional view taken on the line 2--2 of FIG. 1. 
     FIG. 3 is a sectional view similar to FIG. 2 and showing a modification of the automatic flushing and draining reservoir apparatus of the present invention. 
     FIG. 4 is an enlarged fragmentary sectional view taken along the line 4--4 of FIG. 2. 
     FIG. 5 is an enlarged sectional view taken along the line 5--5 of FIG. 4. 
     FIG. 6 is a fragmentary sectional view of the reservoir apparatus of the present invention which schematically shows a special timing means for automatically and periodically switching the apparatus of the present invention into the flushing operational mode, and controlling pump operation during that mode. 
     FIG. 7 is a timing diagram illustrating the operational sequence of the special timing means for controlling pump operation during the flushing operational mode of the apparatus of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring more particularly to the drawings, FIG. 1 shows a fragmentary portion of a typical evaporative cooler, which is indicated generally by the reference numeral 10, with that evaporative cooler including the automatic flushing and draining reservoir apparatus of the present invention, with the apparatus being indicated in its entirety by the reference numeral 12. 
     The evaporative cooler 10 includes, among other things, an air moving blower assembly 13, a floor pan 14, wettable cooler pads 15, and a water distribution plumbing system or network 16. Since evaporative coolers are well known in the art, it is not deemed necessary to completely illustrate such a structure and only a brief description of operation will be given to facilitate understanding of the reservoir apparatus of the present invention. 
     Typically, water under pressure is supplied to the plumbing system 16 which carries the water to the upper portion of the cooler&#39;s cabinet and distributes it to the top of each of the cooler pads 15. The cooler pads are thus wetted so that air being drawn into the cabinet through the pads by means of the air moving blower assembly 13, will be cooled by evaporation. Some of the water trickling down through the cooler pads 15 will, of course, evaporate and the remaining unevaporated water will drain into the cooler&#39;s floor pan 14. 
     In accordance with the present invention, the floor pan 14 of the evaporative cooler 10 is provided with an opening 18 so that the unevaporated water draining from the cooler pads 15 will pass through the opening 18 into the automatic draining and flushing reservoir apparatus 12 of the present invention. 
     As will hereinafter be described in detail, the automatic flushing and draining reservoir apparatus 12 of the present invention, includes the major components of a tank 20 for containing water 22 that is used in operation of the cooler 10, a pump 24 having an inlet, or suction end 25, for supplying the water 22 to the cooler, a float controlled shutoff valve 26 for initially supplying the water 22 to the tank and periodically supplying makeup water thereto, and a siphon drain valve 28 which is employed for draining purposes. 
     As seen in FIGS. 1 and 2, the tank 20 is an upwardly opening structure having a bottom floor or wall 30, of special configuration as will hereinafter be described, with integral upstanding sidewalls 32. The tank may be of any convenient configuration, such as the rectangular shape shown, and may be formed integral with the floor pan 14 such as by a well known metal drawing operation, or the tank may be mounted to the bottom of the floor pan 14 in any suitable manner so as to be located below the opening 18 formed therethrough. With regard to physical size, the tank 20 is formed so as to present as small a water surface area as is possible for reasons which will be hereinafter described. 
     The float controlled shutoff valve 26 includes the usual valve assembly 36 having a water inlet boss 37, a water outlet boss 38, and is operated in the well known manner by a float 39 which is carried on the extending end of a rod 40 that is connected to the operating parts (not shown) of the valve assembly. A water supply line 42 has one of its ends suitably connected to the water inlet boss 37 of the valve assembly 36 which is mounted in one of the sidewalls 32 of the tank 20, and its opposite end (not shown) is for connection to a suitable source of water under pressure such as a domestic water line. In this manner, the water 22 will be initially supplied to the tank 20 and thereafter will be periodically reopened under control of the float 39 to supply makeup water thereto and thus maintain the water level in the tank at a predetermined normal operating level 44. 
     The pump 24 may be of any suitable type which will pump the water 22 from the tank 20 into the water distribution plumbing network 16 of the evaporative cooler 10. 
     The siphon drain valve 28 as seen best in FIGS. 4 and 5, includes a standpipe 50 that is mounted in a downwardly upset dimple, or depression 52 formed in the floor 30 of the tank 20. The bottom end of the standpipe 50 passes through the bottom of the depression 52 and is provided with threads 53 by which a hose (not shown) or other suitable disposal means may be connected thereto. A cylindrical cap 54 is demountably mounted in the bottom of the tank 20 on suitable support legs 55 so as to be coaxial with the standpipe 50. As shown, the support legs 55 rest on the floor of the tank 20 at equally spaced increments about the depression 52 which positions the closed top portion of the cap 54 above the upper end of the standpipe 50 to provide an open water passage zone 56 therebetween, with the zone 56 being located above the normal operating water level 44 in the tank 20. The cap 54 is provided with an elongated skirt portion which has an endless bottom edge 57 that is located within the depression 52 and is spaced above the bottom of the depression. The cap 54 is fabricated with a larger than usual radius at the internal juncture of its top and skirt portions which cooperates with the rounded top edge of the standpipe 50 to provide a freeflowing path for water and to insure that no obstructions are present which could snag or otherwise trap foreign matter in the flow path. The purpose for locating the open edge 57 of the cap 54 within the depression 52 and locating the open water passage zone 56 immediately above the normal operating water level 44 will hereinafter be described in detail. 
     In normal operation of the evaporative cooler 10, water under pressure is initially supplied to the tank 20 through the float control valve 26 to achieve the normal operating water level 44, and the float control valve will periodically open to supply makeup water to replace that lost by evaporation. The pump 24 will deliver the water 22 to the distribution plumbing networks 16 of the cooler 10, which wets the cooler pads 15 as hereinbefore described. The unevaporated water draining from the pads 15 will return to the tank 20 through the opening 18 in the floor pan 14 of the cooler, and recirculation of the water will continue as long as no externally applied interrupting force is applied. 
     The water 22 in the tank 20 will become increasingly contaminated with dirt and the concentration of minerals will increase during the above described normal operation of the cooler 10, and periodic flushing and replacement of the water is desirable to prolong the life of the cooler. Periodic flushing may be accomplished by shutting off the power to the pump 24 which allows the water in the cooler&#39;s plumbing network 16 to drain back into the tank 20, which, in conjunction with the unevaporated water draining back from the cooler pads 15, will raise the water level in the tank 20 from its normal operating water level 44 to a flooded level 60 which is shown in dotted lines in FIGS. 1 and 4. When the water raises to the flooded level 60, the zone 56 will be under water which results in priming of the siphon valve 28. With the siphon valve 28 primed, the water 22 will be drained from the tank 20. It will be noted that the size of the standpipe 50 is considerably larger in diameter than the water supply line 42, therefore, the rate at which the tank 20 is drained is considerably faster than the incoming rate of fresh water supplied through the float controlled shutoff valve 26. In this manner, a flushing action will take place and when the drainage is complete, the siphon valve 28 will lose its prime and fresh water will fill the tank 20 to the normal operating level 44 and normal operation of the evaporative cooler 10 will be resumed. 
     As mentioned above, the siphon draining of the tank 20 takes place simultaneously with the supplying of fresh water thereto during the flushing operational mode of the apparatus 12. In some instances, such as installations having higher than normal water line pressure, the incoming fresh water, along with bubbling and the like, will interfere with the siphon drain valve losing its prime when tank drainage is completed prior to the refilling operation. Although this interference with the siphon drain valve losing its prime at the desired time is a relatively infrequent occurance, the tank 20 of the apparatus 12 of the present invention is provided with an especially configured floor 30 which positively prevents the occurance of this problem. 
     The floor 30 is provided with a second downwardly upset dimple or depression 62 in which the inlet, or suction end 25 of the pump 24 is located, and this second depression 62 is connected to the first depression 52 by means of a narrow downwardly upset channel 64 formed in the floor 30 of the tank 30. In this manner, when tank drainage is completed during the flushing operational mode, switching the pump 24 on will cause it to draw all the water away from the inlet end 57 of the siphon drain valve 28 and will thus positively act to stop the siphoning action of the siphon drain valve 28. 
     The above described flushing operational mode, wherein the tank 20 is drained, flushed and refilled with fresh water, should be accomplished at periodic intervals during operation of the cooler 10 as mentioned above, and a second, or draining operational mode is employed when cooler operation is to be terminated. The draining operational mode, which is used at the end of a cooling season, or at other times of anticipated prolonged nonuse, is accomplished by simply shutting off the power to the pump 24 and shutting off the water supplied to the tank 20. Such action will prime the siphon drain valve 28 in the above described manner and tank drainage will result. Complete drainage is desirable so that the cooler 10 will not contain a standing body of water during periods of nonuse. It will be noted that positioning of the bottom edge 27 of the cap 54 within the depression 52 formed in the bottom of the tank 20 will cause complete drainage of the tank&#39;s bottom and only a relatively small amount of water will remain within the siphoning valve depression 52. 
     The water surface area within the tank 20 should be kept as small as possible. The reason for this may be apparent from the above operational description wherein it will be noted that when the pump 24 is shutoff the water returning from the cooler to the tank 20 will cause the siphon valve 28 to be primed. If the water surface area of the tank 20 is excessively large, the amount of returning water may be insufficient to raise the level of the water to the flooded level 60, and if the water level is raised slowly, due to an excessively large surface area, the water may simply spill over the upper edge of the siphon valve standpipe 50. In either case, the water passage zone 56 would not become completely flooded and this is necessary to cause priming of the siphon drain valve 28. 
     In addition to the above, the automatic flushing and draining reservoir apparatus 12 of the present invention is preferrably provided with a screen 66 and a cover 68. The screen is seen to be an endless upstanding structure which is supportingly carried on the floor 30 of the tank 20 and is configured to circumscribe the siphon drain valve 28 and the inlet end 25 of the pump 24. The screen 66 is used to prevent relatively large foreign objects, such as dislodged wood shavings from the excelsior pads 15 of the cooler 10, from passing into the siphon drain valve 28 and/or the pump 24 and clogging or otherwise interfering with the operation thereof. The cover 68 shields the interior of the evaporative cooler 10, and its components, from direct exposure to the water 22 within the tank 20, and will thus reduce the moisture content and mineral deposition within the cooler. 
     The cover 66 is a substantially planar structure of rectangular configuration similar to that of the tank 20, and is somewhat larger than the opening 18 so that the peripheral edge of the cover extends beyond the opening. A plurality of spacers 70 are suitably affixed to the downwardly facing surface of the cover 68 and are adjacent the peripheral edge thereof, and the spacers 70 are in resting engagement with the upwardly facing surface of the floor pan 14 of the cooler 10. Thus, the cover 68 is parallel with the bottom of the floor pan 14 and is in spaced overlaying relationship with respect to the opening 18 to provide a gap 72 through which the water returning from the pads 15 is free to enter tank 20. The cover 68 is demountably supported as described above and is provided with a plurality of cover stabilizing tabs 74 which depend from the cover into bearing engagement with the interior surfaces of the sidewall 32 of the tank 20. The cover 68 is provided with a suitable opening 76 through which the pump 24 extends upwardly so that the drive motor 78 of the pump will be located in the relatively drier environment of the cooler cabinet. Also, the cover 68 is provided with another opening 80 through which a suitable pipe 82 passes with the pipe being used for connecting the pump 24 to the cooler&#39;s plumbing system 16. 
     As hereinbefore mentioned, it is desirable to keep the tank 20 as small as possible. Therefore, the automatic flushing and draining reservoir apparatus of the present invention may be modified as shown in FIG. 3. In this embodiment, the valve assembly 36 of the float controlled shutoff valve 26 is supported above an opening 84 formed in the cover 68a by means of a suitable bracket 86. The bracket 86 has one of its ends attached, for example, the air moving blower assembly 13 and the valve assembly 36 is suitably carried on the opposite end of the bracket. With the valve assembly 36 mounted above the tank 20, the rod 40 extends angularly downwardly from the valve through the opening 84 in the cover 68a so that the float 39 is disposed for floating engagement with the water 22 in the tank 20. The water outlet boss 38 of the valve assembly 36 is disposed so that the water delivered by the valve will fall through the cover opening 84 into the tank. 
     The above described automatic flushing and draining reservoir apparatus of the present invention is automatic only to the extend that it will automatically drain flush and refill the tank in response to the pump 24 being shutoff and in some instances this may be accomplished manually. However, due to the desirability of periodically switching the apparatus to its flushing operational mode, it is preferred that the apparatus be implemented as a fully automatic system. 
     A preferred form of automatic equipment for use in conjunction with the automatic flushing and draining apparatus of the present invention is shown in FIG. 6 wherein a clock timing device 90, of the type well known in the art, is mounted in the power supply line 92 leading to the pump 24. The timer 90 may be operated in a conventional manner in that it may be operated to interrupt the power supply to the pump 24 at predetermined intervals, such as once every 24 hours, with such interruption being of a suitable duration to allow completion of the flushing operational mode. 
     However, with the floor 30 of the tank 20 being especially configured, as hereinbefore described, to allow positive stopping of the siphoning action of the siphon drain valve 28, it is preferred that the timer 90 be equipped and operated in the following manner. 
     The clock face 94 of the timer 90 is provided with a first power interrupt lug 96 and a second power interrupt lug 98 with those lugs being suitably positioned on the periphery of the clock face 94 to achieve a particular timing sequence which is described best in conjunction with the timing diagram of FIG. 7. 
     When the timer 90 operates in its conventional manner to bring the first power interrupt lug 96 into play, the pump 24 will be turned off for the duration indicated at T 1 . When the time T 1  commences, the siphon drain valve 28 will be primed and the tank 20 will drain and incoming fresh water will flush the tank. The duration of time T 1  is set so that its end coincides with the completion of tank drainage, and time T 2  starts at the end of time T 1 . When time T 2  starts, the pump 24 will be switched on to draw all the water away from the inlet 57 of the siphon drain valve 28 to positively stop the siphoning action thereof. The duration of time T 2 , which can be relatively short, is terminated when power interrupt lug 98 comes into play and starts the time period indicated as T 3 . The time period T 3  shuts off the pump 24 for a predetermined time to prevent it from drawing air during the time when the tank 20 is being refilled with fresh water. 
     It will be appreciated that the actual durations of the time periods T 1 , T 2  and T 3  will vary in accordance with several variables such as tank size, the flow rate of incoming fresh water, the drainage flow rate of the siphon drain valve 28 and the like. Therefore, due to the variables involved, actual times will have to be determined in accordance with particular equipment and installation parameters. 
     While the principles of the invention have now been made clear in illustrated embodiments, there will be immediately obvious to those skilled in the art, many modifications of structure, arrangements, proportions, the elements, materials, and components used in the practice of the invention, and otherwise, which are particularly adapted for specific environments and operation requirements without departing from those principles. 
     For example, the hereinbefore disclosed siphon drain valve 28 is the preferred embodiment due to its compact configuration. However, other structurally different siphoning devices could be used without affecting the operation of the apparatus 12, such as the well known inverted U-shaped siphon tube. 
     The appended claims are therefore intended to cover and embrace any such modifications within the limits only of the true spirit and scope of the invention.