Abstract:
A method for adjusting the temperature of a swimming pool having a filter system and a waterfall, comprising running the filter system at times of the day such that heat transfer with ambient air is optimized by the action of swimming pool water falling through the ambient air, and further comprising positioning and substantially fixing the position of a movable surface below the water fall to help maximize the heat transfer with the ambient air. For pools without waterfalls, it is further disclosed to utilize a conduit from a submerged water return opening to the movable surface which could be a raft.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Field of the Invention  
           [0002]    The present invention relates to a method and an apparatus which is helpful in the cost efficient cooling and heating of swimming pools using ambient air temperature.  
         CROSS REFERENCE TO RELATED APPLICATIONS  
         [0003]    Not applicable  
         BACKGROUND OF THE INVENTION  
         [0004]    For many years there has been the problem of heating swimming pools during cool weather and cooling down swimming pools in hot climates during hot weather. The problem of heating swimming pools during cool weather can be addressed by any of a number of different well know methods such as passing the pool water through a pool heater (i.e., gas, propane or electric heat exchanger). This passing of the pool water through the heat exchanger normally occurs during the filtration process. The problems with this well known method of heating pool water are the upfront expense of the pool heater, the space requirements for the heater and perhaps most significantly, the very high energy cost of running the pool heater. An additional method of heating pool water is to use solar heat in the heat exchanger rather than fossil fuels or electricity. Examples of patents using solar heat exchangers are set forth in U.S. Pat. No. 4,261,332 entitled “Solar Heating Systems” and U.S. Pat. No. 4,256,087 entitled “Swimming Pool Heater”. These solar heat exchange systems have, inter alia, the disadvantages of high upfront costs and space requirements.  
           [0005]    There have been fewer prior art inventions relating to cooling a swimming pool which is too warm. Nevertheless, this is a real problem in the summertime in hot climates. Often pools become so warm (above the 90+ degree Fahrenheit) that pool use is not as refreshing as in a cooler pool. U.S. Pat. No. 4,189,791 entitled “Swimming Pool Heating and Cooling System” describes a system using air pumps and temperature controllers to control the temperature of the pool using ambient air pumped into pipes located in the pool which act as a heat exchanger. Once again this invention has, inter alia, the problems high up front costs and space requirements. U.S. Pat. No. 3,941,154 entitled “Swimming Pool Water Circulation System” describes a water circulation system which contains fountains at the water level which can be pointed into the air in order to cool the water being recirculated into the pool. The disadvantages of such a system are the upfront capital costs and the need to retrofit old pools.  
           [0006]    What is needed is a simple method to cool or heat a pool. The method should be inexpensive to operate and require no retrofitting of the pool so that the upfront costs are minimized. All the prior art methods either are expensive to operate because of energy costs or expensive to install because of equipment needs or both.  
         SUMMARY OF THE INVENTION  
         [0007]    Accordingly, it is the object of this invention to provide a low cost method and apparatus to help in adjusting the temperature of swimming pools.  
           [0008]    In furtherance of the objects mentioned above, the present invention provides a method of cooling or heating a swimming pool using existing pool equipment and running the circulation system at times of the day which facilitate either heating or cooling of the pool. For example, running the circulation system at night to cool a pool during hot weather or alternatively running the circulation system during the hot part of the day to heat a pool which is too cool.  
           [0009]    This optimized timing of running a pool filter system is simple. To cool the pool, run the filter system during the coolest part of the day (usually late at night). To heat a pool, run the filter system during the hottest part of the day (normally during the afternoon and early evening). Since pool filters must be run some minimum period of time each day in any event, this optimized timing does not have any additional costs. This method works best in pools which have waterfalls (e.g., from the pool spa into the main pool) or in pools which have some other way to have the water fall or run throught the ambient air (e.g., a fountain). The exposure of the pool water to the ambient air rather than being recirculated to the pool under the surface of the water greatly increases the heat exchange between the ambient air and the pool.  
           [0010]    However, many pools do not have waterfalls, or if they do have a waterfall, the exposure of the pool water to the ambient air is not maximized because of the relatively limited time period the recirculated water is exposed to the ambient air during its fall into the pool. Accordingly, in a preferred embodiment of the invention an apparatus is provided which is a movable surface which is designed to let the recirculating pool water run over it while being exposed to the ambient air before running or dropping back into the pool. If the pool has only submerged water return openings, then a conduit can be used to channel the recirculated water onto the top of the movable surface and into the ambient air. By changing the size and shape of the movable surface (e.g., a raft) one can maximize the exposure of the recirculating pool water to the ambient air and accordingly maximize the heat transfer between the air and water. By having the movable surface irregularly shaped (e.g., tortuous paths caused by ripples, indentations, pebble shaped bumps, furrows, etc.) One can maximize the amount of time the recirculating water is on the movable surface and accordingly the heat transfer.  
         BRIEF DESCRIPTION OF THE DRAWINGS  
         [0011]    [0011]FIG. 1 is a top view of a movable surface situated under a spa waterfall.  
           [0012]    [0012]FIG. 2 is a side view of a movable surface and a conduit which forces recirculated water out of a submerged return opening onto the top of the movable surface. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    [0013]FIG. 1 shows movable surface  11  situated underneath of waterfall  14 . (A waterfall for the purpose of this disclosure is any recirculated water entering pool surface  13  from above pool surface  13 .) In this embodiment, movable surface  11  has a specific gravity less than that of water (i.e., less dense than water) and is accordingly floating on pool surface  13 . In other embodiments of the invention, just a section of movable surface  11  could be floating on pool surface  13  (e.g., a pontoon-like structure). There are many types of pool waterfalls but in the FIG. 1, waterfall  14  is caused by the recirculation of pool water into spa  20  which is at a higher elevation than pool surface  13  and accordingly during recirculation, water being recirculated into spa  20  falls back into pool surface  13  through waterfall  14  (caused by a low point in spa wall  23 ).  
         [0014]    In order to maximize the heat transfer of the pool water falling through waterfall  14 , movable surface  11  has been positioned and substantially fixed in position underneath waterfall  14  (movable surface  11  may move on the surface of the water, but should not float away). Therefore, instead of the recirculated pool water entering the pool immediately after dropping from the spa onto pool surface  13  it continues to be exposed to the ambient air because it falls upon movable surface  11  and is forced to run over its top surface which is exposed to ambient air. In a preferred embodiment of the invention, movable surface  11  has slightly raised side walls  17  which help channel the water from the end of moveable surface  11  situated underneath waterfall  14  to the opposite end of movable surface  11 . This channelling of the water along the entire length of movable surface  11  to the discharge end  18  of movable surface  11  maximizes the time the water is on the movable surface  11  which also maximizes the heat exchange between the water and the ambient air.  
         [0015]    This channelling of the recirculated pool water along the entire length of movable surface  11  could also be accomplished by having movable surface  11  slightly slanted downward away from the end of movable surface  11  under waterfall  14  and toward discharge end  18 . Another method of assuring that water runs over the entire length of movable surface  11  could be accomplished by having channels or indentations on the upper surface of movable surface  11 . Channels  15  near waterfall  14  could be designed to channel the water uniformity across the top of movable surface  11  by having channels  15  in a fan-like shape. The remainder of movable surface  11  could be formed to make a tortuous path (e.g., squiggly lines or a pebble-like contour) which maximizes the amount of time the recirculated pool water stays on movable surface  11 . Alternatively, the upper surface of movable surface  11  could be flat or slightly slanted toward discharge end  18 . Movable surface  11  in a preferred embodiment of the invention would double as a raft when not in use as a heat transfer surface. In cases where movable surface  11  has channels  15  or tortuous path  16  on the heat transfer side of the raft the opposing side could be smooth and usable as a raft by swimmers. This double-sided or dual purpose raft design would assure ultimate utility and ease of use. In this way, one would not even have to take raft out of the pool during use by swimmers since it doubles as a standard raft and can be used as either a normal flotation device for swimmers or as a heat exchanger.  
         [0016]    In order to hold movable surface  11  in place under waterfall  14  it is necessary to have some manner of an attachment means of device. There are hundreds or thousands of different types of attachment devices well known in the art available to assure that movable surface  11  remains under waterfall  14  (e.g., straps, Velcro®, buckles, magnets, hooks, etc.). In addition, numerous movable surfaces  11  could be attached together to maximize surface area for heat transfer. However, in order to use movable surface  11  interchangeably as a raft for swimmers and in order to mimimize retrofitting of the pool wall or pool deck  21 , one preferred embodiment would be to have strap or rope  27  detachably connected to movable surface  11  by means of detachable connection  25  and having the opposite end of rope or strap  27  connected to weight  22 . Detachable connection  25  could be any of a number of different detachable connections such as Velcro®, snaps, buckles and so forth. In light of the water environment, Velco® may be a preferred attachment device. Using weight  22  positioned on pool deck  21  such that strap  27  is taunt against movable surface  11  which allows positioning of movable surface  11  essentially anywhere around the perimeter of a pool without any retrofitting of pool deck  21  or the pool walls. Also weight  22  does not have to be very heavy or bulky since there should not be significant lateral forces on movable surface  11  to displace it from underneath waterfall  14 .  
         [0017]    This preferred attachment method and device has the following two advantages: (1) The attachment device is easily detachable from movable surface  11  so that it can be alternatively used as a raft when not in use as heat transfer surface, and (2) since it relies on weight  22  to hold the movable surface  1  in place, it requires no retrofitting of pool deck  21  or the walls of the pool.  
         [0018]    [0018]FIG. 2 sets forth an embodiment of the invention which is preferred when a swimming pool does not have a waterfall in which to place movable surface  11  underneath. Many pools do not have either waterfalls or spas. The water that is recirculated to the pool after filtering enters the pool through submerged water return openings below pool surface  13 . In pool configurations where water return opening  33  is submerged there is a need for a way to get the recirculated water up above pool surface  13  so that it will be able to run over movable surface  11 . A preferred method to get the recirculated water onto movable surface  11  is to use conduit  31  (as used herein, conduit  31  can be any kind of pipe or channel which changes the direction of the recirculated water exiting water return opening  33 ). One end of conduit  31  could abut against pool wall  21  and cover submerged return opening  33  at the end of return pipe  32 . The recirculated water in return pipe  32  normally exits into the pool below pool surface  13  through return opening  33 . However, because of the presence of conduit  31  and the pressure of the water in return pipe  32 , the return water instead travels up through conduit  31  to exit onto movable surface  11 . Once on movable surface  1  the water is subject to the heat exchange (either cooling or heating) caused by it&#39;s contact with the ambient air.  
         [0019]    In a preferred embodiment, conduit  31  can be attached or detached very simply in order to maximize ease of use. This mobility allows the pool to be used safely without a permanent conduit or pipe protruding into it. In an experiment, conduit  31  consisted of two separate rigid 2″ UL-90° Std. Bend PVC Sch. 40 (issue no. X-33658) conduit from Cantex fitted together with a standard 2″ PVC coupling. When fitted together the two conduits formed “S” shaped pipe approximately 40″ long. One end of this “S” shaped pipe (conduit  31 ) was abutted against return opening  33  and the other end protruded above pool surface  13  and rested against an end of movable surface  11 . The recirculating water pressure in the experiment was such that it exerted an outward pressure (away from pool wall  21 ) on conduit  31  which had to be counteracted. Counteracting such outward pressure was done by preventing movable surface  11  from moving away from pool wall  21 . In the experiment, this was done by manually holding the raft (movable surface  11 ) in place. Movable surface  11  was about 18-20 inches from pool wall  21  and return opening  33  was about 16-18 inches below pool surface  13 . Accordingly, the position of “S” pipe (conduit  31 ) was such that the water pressure from return opening  33  did not cause the “S” pipe to disengage from either pool wall  21  or movable surface  11 . In short, conduit  11  was stuck in between pool wall  21  and movable surface  11  without any need for permanently anchoring conduit  31  to either movable surface  11  or pool wall  21 .  
         [0020]    Identical with the attachment means set forth in FIG. 1, movable surface  11  could also be prevented from moving away from pool wall  21  by using detachable strap or rope  27  connected to weight  22 . (Unlike in FIG. 1, however, movable surface  11  would probably not abut against pool wall  21  because of the need to accomodate conduit  31 .) The position of return opening  33  (i.e., depth below pool surface  13 ) could necessitate different configurations and/or lengths for conduit  31 . One especially preferred method of addressing varying positions of return opening  33  and/or pressure of water exiting return opening  33  is to design conduit  31  so that its length may be easily varied. One method of easily varying the length of conduit  31  is to make conduit  31  “telescoping pipe” by means well known in the art. The varying length of conduit  31  also requires varying the length of rope or strap  27  so that the distance from movable surface  11  and pool wall  21  can be varied as well.  
         [0021]    The present invention has been described above with reference to a preferred embodiment. However, those skilled in the art will recognize that changes and modifications may be made in the described embodiments without departing from the nature and scope of the present invention. Various changes and modifications to the embodiment herein chosen for purposes of illustration will readily occur to those skilled in the art. To the extent that such modifications and variatins do not depart from the spirit of the invention, they are intended to be included within the scope thereof which is assessed only by a fair interpretation of the following claims, enable those skilled in the art to understand and practice the same, the invention claimed is: