Patent Publication Number: US-6705107-B2

Title: Compact ice making machine with cool vapor defrost

Description:
REFERENCE TO EARLIER FILED APPLICATIONS 
     The present application is a continuation-in-part of application Ser. No. 09/800,105 filed Mar. 5, 2001, now abandoned, which is a continuation of application Ser. No. 09/363,754, filed Jul. 29, 1999, now U.S. Pat. No. 6,196,007, which claims the benefit of the filing date under 35 U.S.C. §119(e) of Provisional U.S. Patent Application Ser. No. 60/103,437 filed Oct. 6, 1998. Each of the foregoing applications are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to automatic ice making machines, and more particularly to a compact automatic ice making machine where the ice making evaporator is defrosted in a harvest mode by cool refrigerant vapor. 
     Automatic ice making machines rely on refrigeration principles well-known in the art. During an ice making mode, the machines transfer refrigerant from the condensing unit to the evaporator to chill the evaporator and an ice-forming evaporator plate below freezing. Water is then run over or sprayed onto the ice-forming evaporator plate to form ice. Once the ice has fully formed, a sensor switches the machine from an ice production mode to an ice harvesting mode. During harvesting, the evaporator must be warmed slightly so that the frozen ice will slightly thaw and release from the evaporator plate into an ice collection bin. To accomplish this, most prior art ice making machines use a hot gas valve that directs hot refrigerant gas routed from the compressor straight to the evaporator, bypassing the condenser. 
     In a typical automatic ice making machine, the compressor and condenser unit generates a large amount of heat and noise. As a result, ice machines have typically been located in a back room of an establishment, where the heat and noise do not cause as much of a nuisance. This has required, however, the ice to be carried from the back room to where it is needed. Another problem with having the ice machine out where the ice is needed is that in many food establishments, space out by the food service area is at a premium, and the bulk size of a normal ice machine is poor use of this space. 
     Several ice making machines have been designed in an attempt to overcome these problems. In typical “remote” ice making machines, the condenser is located at a remote location from the evaporator and the compressor. This allows the condenser to be located outside or in an area where the large amount of heat it dissipates and the noise from the condenser fan would not be a problem. However, the compressor remains close to the evaporator unit so that it can provide the hot gas used to harvest the ice. While a typical remote ice making machine solves the problem of removing heat dissipated by the condenser, it does not solve the problem of the noise and bulk created by-the compressor. 
     Other ice machine designs place both the compressor and the condenser at a remote location. These machines have the advantage of removing both the heat and noise of the compressor and condenser to a location removed from the ice making evaporator unit. For example, U.S. Pat. No. 4,276,751 to Saltzman et al. describes a compressor unit connected to one or more remote evaporator units with the use of three refrigerant lines. The first line delivers refrigerant from the compressor unit to the evaporator units, the second delivers hot gas from the compressor straight to the evaporator during the harvest mode, and the third is a common return line to carry the refrigerant back from the evaporator to the compressor. The device disclosed in the Saltzman patent has a single pressure sensor that monitors the input pressure of the refrigerant entering the evaporator units. When the pressure drops below a certain point, which is supposed to indicate that the ice has fully formed, the machine switches from an ice making mode to a harvest mode. Hot gas is then piped from the compressor to the evaporator units. 
     U.S. Pat. No. 5,218,830 to Martineau also describes a remote ice making system. The Martineau device has a compressor unit connected to one or more remote evaporator units through two refrigerant lines: a supply line and a return line. During an ice making mode, refrigerant passes from the compressor to the condenser, then through the supply line to the evaporator. The refrigerant vaporizes in the evaporator and returns to the compressor through the return line. During the harvest mode, a series of valves redirect hot, high pressure gas from the compressor through the return line straight to the evaporator to warm it. The cold temperature of the evaporator converts the hot gas into a liquid. The liquid refrigerant exits the evaporator and passes through a solenoid valve and an expansion device to the condenser. As the refrigerant passes through the expansion device and the condenser it vaporizes into a gas. The gaseous refrigerant then exits the condenser and returns to the compressor. 
     One of the main drawbacks of these prior systems is that the long length of the refrigerant lines needed for remote operation causes inefficiency during the harvest mode. This is because the hot gas used to warm the evaporator must travel the length of the refrigeration lines from the compressor to the evaporator. As it travels, the hot gas loses much of its heat to the lines&#39; surrounding environment. This results in a longer and more inefficient harvest cycle. In addition, at long distances and low ambient temperatures, the loss may become so great that the hot gas defrost fails to function properly at all. 
     Some refrigeration systems that utilize multiple evaporators in parallel have been designed to use hot gas to defrost one of the evaporators while the others are in a cooling mode. For example, in a grocery store with multiple cold and frozen food storage and display cabinets, one or more compressors may feed a condenser and liquid refrigerant manifold which supplies separate expansion devices and evaporators to cool each cabinet. A hot gas defrost system, with a timer to direct the hot gas to one evaporator at a time, is disclosed in U.S. Pat. No. 5,323,621. Hot gas defrosting in such systems is effective even though the compressor is located remotely from the evaporators due to the large latent heat load produced by the refrigerated fixtures in excess of the heat required to defrost selected evaporator coils during the continued refrigeration of the remaining fixtures. While there are some inefficiencies and other problems associated with such systems, a number of patents disclose improvements thereto, such as U.S. Pat. Nos. 4,522,037 and 4,621,505. These patents describe refrigeration systems in which saturated refrigerant gas is used to defrost one of several evaporators in the system. The refrigeration systems include a surge receiver and a surge control valve which allows hot gas from the compressor to bypass the condenser and enter the receiver. However, these systems are designed for use with multiple evaporators in parallel, and would not function properly if only a single evaporator, or if multiple evaporators in series, were used. Perhaps more importantly, these systems are designed for installations in which the cost of running refrigerant lines between compressors in an equipment room, an outdoor condenser, and multiple evaporators in the main part of a store is not a significant factor in the design. These refrigeration systems would not be cost effective, and perhaps not even practicable, if they were applied to ice making machines. 
     A good example of such a situation is U.S. Pat. No. 5,381,665 to Tanaka, which describes a refrigeration system for a food showcase that has two evaporators in parallel. A receiver supplies vaporous refrigerant to the evaporators through the same feed line as is used to supply liquid refrigerant to the evaporators. The system has a condenser, compressor and evaporators all located separately from one another. Such a system would not be economical if applied to ice machines where different sets of refrigerant lines had to be installed between each of the locations of the various parts. Moreover, if the compressor and its associated components were moved outdoors to be in close proximity to a remote condenser, the system would not be able to harvest ice at low ambient temperature because the receiver would be too cold to flash off refrigerant when desired to defrost the evaporators. 
     U.S. Pat. No. 5,787,723 discloses a remote ice making machine which overcomes the drawbacks mentioned above. One or more remote evaporating units are supplied with refrigerant from a remote condenser and compressor. Moreover, if a plurality of evaporating units are used, they can be operated independently in a harvest or ice making mode. The heat to defrost the evaporators in a harvest mode is preferably supplied from a separate electrical resistance heater. While electrical heating elements have proved satisfactory for harvesting ice from the evaporator, they add to the expense of the product. Thus, a method of harvesting the ice in the remote ice machine of U.S. Pat. No. 5,787,723 without electrical heating elements would be a great advantage. An ice making machine that includes a defrost system that utilizes refrigerant gas and can be used where the system has only one evaporator, or an economically installed system with multiple evaporators that also operates at low ambient conditions, would also be an advantage. 
     Another drawback to conventional ice making machines is their large size. In order to produce sufficient quantities of ice, large components are needed. A large cabinet is needed to house all of these components. When an ice machine is placed on top of a large ice bin in the back room of an establishment, its size is not much of a problem. However, as noted above, space out in the food service area, where the ice is needed, is often at a premium. 
     In addition, many ice machines are selected so that they will produce ice at a rate which meets overall daily demand at their location. However, often the demand for ice hits a peak, such as lunch time at a drive-up window on a hot day. It is not practical to install an ice machine at the drive-up window that can meet peak demand. Rather, it is more practical to have a smaller capacity ice machine and a storage bin that can accumulate ice in advance of peak demand. The storage bin is frequently built into the top of an ice and beverage dispenser. It would be advantageous if the ice machine were to sit on top of the dispenser and discharge into the bin. That would eliminate the need to transport ice from where it is produced into the top of the ice and beverage dispenser. However, the distance from the counter top where the dispenser is located to the top of the ceiling then limits how tall the combined ice machine and dispenser can be. 
     It would be of further advantage if the ice machine and bin arrangement allowed for ice to be dumped into the bin from a bucket filled from a different location to meet peak demand. Thus it would be beneficial if the ice machine could be configured to have a smaller “footprint” than the standard size opening on top of an ice storage area of an ice and beverage dispenser. Even if it is not necessary to dump extra ice into a storage bin underneath an ice machine, it would be beneficial if an ice machine were small enough so that a person could have access to clean the dispenser. Standard dispensers are 22, 24, 30 and 42 inches wide, and often about 24-28 inches deep. The ice storage bin may have an internal depth of less than 27 inches. Therefore, it would be beneficial if the cabinet of an ice machine were less than 18 inches deep, and more preferably less than 16 inches deep. 
     Once an ice machine is installed on top of an ice and beverage dispenser, it is cumbersome to service the ice machine from its rear. Thus, it would also be beneficial if components that may require service or exchange were accessible from the front of the machine. Water pumps have conventionally been located in the front of ice machines so that they can be replaced easily if needed. However, it is desirable to keep the motor of a pump assembly outside of the compartment where the water is being frozen into ice, both to protect the motor from getting wet, and to remove the possible source of contamination associated with a motor. Locating the pump motor outside of the water compartment, but arranging it so that the pump assembly could be removed from the front of the machine, if needed, especially in a compact machine, would be very desirable. 
     SUMMARY OF THE INVENTION 
     An ice making machine has been invented which includes one or more of the foregoing advantageous features. In a preferred embodiment, all of the foregoing advantages are met in one ice machine. In the preferred embodiment, the compressor and condenser are remote from the evaporator but the apparatus does not require electrical heaters to heat the ice-forming mold, nor does it require hot gas to travel to the evaporator from the compressor. In addition, the refrigeration system will function in low ambient conditions, and is not expensive to install. A preferred machine has a footprint less than 18 inches deep, and has the water pump motor located outside of the water compartment, yet the pump assembly can still be removed from the front of the machine for service. 
     In one aspect, the invention is an ice making machine comprising: a) a water system including a pump, an ice-forming mold and interconnecting lines therefore; and b) a refrigeration system including a compressor, a condenser, an expansion device, an evaporator in thermal contact with the ice-forming mold, and a receiver, the receiver having an inlet connected to the condenser, a liquid outlet connected to the expansion device and a vapor outlet connected by a valved passageway to the evaporator. 
     In a second aspect, the invention is a method of making cubed ice in an ice making machine comprising the steps of: a) compressing vaporized refrigerant, cooling the compressed refrigerant to condense it into a liquid, feeding the condensed refrigerant through an expansion device and vaporizing the refrigerant in an evaporator to create freezing temperatures in an ice-forming mold to freeze water into ice in the shape of mold cavities during an ice making mode; and b) heating the ice making mold to release cubes of ice therefrom in a harvest mode by separating vaporous and liquid refrigerant within a receiver interconnected between the condenser and the expansion device and feeding the vapor from the receiver to the evaporator. 
     In a third aspect, the invention is an ice making apparatus in which an evaporator is located remotely from a compressor and a condenser comprising: a) a condensing unit comprising the condenser and the compressor; b) an ice making unit comprising i) a water system including a pump, an ice-forming mold and interconnecting lines therefor; and ii) a portion of a refrigeration system including the evaporator in thermal contact with the ice-forming mold, a receiver and a thermal expansion device; and c) two refrigerant lines running between the condensing unit and the ice making unit comprising a suction line and a feed line, the suction line returning refrigerant to the compressor and the feed line supplying refrigerant to the ice making unit; d) the receiver having an inlet, a liquid outlet and a vapor outlet, the inlet being connected to the feed line, the liquid outlet being connected to the expansion device, which in turn is connected to the evaporator, and the vapor outlet being connected by a valved passageway directly to the evaporator. 
     In a fourth aspect, the invention is an ice making machine comprising: a) a water system including a pump, an ice-forming mold and interconnecting lines therefore; and b) a refrigeration system including a compressor, a condenser, an expansion device, and evaporator in thermal contact with said ice-forming mold, and a plurality of receivers, the receivers each having an inlet connected to the condenser, a liquid outlet connected to the expansion device and a vapor outlet connected by a valved passageway to the evaporator, and a receiver equalizer line interconnecting the receivers, the pump, ice-forming mold, evaporation and receivers being contained within a cabinet having a depth, a width and a height and at least one of its depth, width or height being less than 18 inches. 
     In a fifth aspect, the invention is an ice making apparatus in which an evaporator is located remotely from a compressor and a condenser comprising: a) a condensing unit comprising said condenser and said compressor; b) an ice making unit comprising i) a water system including a pump, an ice-forming mold and interconnecting lines therefore; and ii) a portion of a refrigeration system including said evaporator in thermal contact with said ice-forming mold, a plurality of receivers and a thermal expansion device; and c) two refrigerant lines running between the condensing unit and the ice making unit comprising a suction line and a feed line, the suction line returning refrigerant to the compressor and the feed line supplying refrigerant to the ice making unit; wherein the receivers each have an inlet, a liquid outlet and a vapor outlet, the inlet being connected to the feed line, the liquid outlet being connected to the expansion device, which in turn is connected to the evaporator, and the vapor outlet being connected by a valved passageway directly to the evaporator, and wherein the ice making unit is contained in a cabinet having a depth of less than 18 inches. 
     In a sixth aspect, the invention is an ice making apparatus in which an evaporator is located remotely from a compressor and a condenser comprising: a) a condensing unit comprising said condenser and said compressor; b) an ice making unit comprising i) a cabinet having a depth of less than 18 inches; ii) a water system including a pump, an ice-forming mold and interconnecting lines therefore inside said cabinet; and iii) a portion of a refrigeration system including said evaporator in thermal contact with said ice-forming mold, at least one receiver and a thermal expansion device inside said cabinet; and c) two refrigerant lines running between the condensing unit and the ice making unit comprising a suction line and a feed line, the suction line returning refrigerant to the compressor and the feed line supplying refrigerant to the ice making unit; d) wherein the at least one receiver has an inlet, a liquid outlet and a vapor outlet, the inlet being connected to the feed line, the liquid outlet being connected to the expansion device, which in turn is connected to the evaporator, and the vapor outlet being connected by a valve passageway directly to the evaporator, and further wherein the ice making unit is able to produce at least 500 pounds of ice per day under ARI standard rating conditions of 90° F. ambient temperature and 70° F. ambient inlet water temperature. 
     In the seventh aspect, the invention is a combination of an ice making unit and an ice and beverage dispenser comprising: a) an ice and beverage dispenser having an ice storage bin in the top thereof with a internal bin depth, and b) an ice making unit housed in a cabinet placed on top of the ice storage bin, the cabinet having a depth, the depth of the ice making unit being at least 8 inches less than the internal depth of the ice storage bin. 
     In an eighth aspect, the invention is a compact ice making unit comprising: a cabinet, a water system inside the cabinet, including a water pump, an ice-forming mold and interconnecting lines therefore, and a portion of a refrigeration system including an evaporator in thermal contact with the ice-forming mold, at least one receiver and a thermal expansion device, wherein the cabinet occupies a volume and wherein the ice making unit produces cubed ice at a rated capacity of 2500 pounds per day or less under ARI standard test conditions of 90° F. ambient temperature and 70° F. ambient inlet water temperature, and wherein the ratio of ice production rate to cabinet volume is at least 125 pounds of ice/day/ft 3 . 
     In a ninth aspect, the invention is an ice making unit comprising: a) a cabinet having a front panel covering a front panel opening, a water compartment behind the front panel, a mechanical compartment and a divider between the mechanical compartment and the water compartment, b) a water system inside the cabinet including a pump assembly, an ice-forming mold, a water reservoir, and interconnecting lines therefore, c) a portion of a refrigeration system including an evaporator in thermal contact with said ice-forming mold, at least one receiver and a thermal expansion device inside the cabinet, and d) the pump assembly comprising a motor and a pump housing, the pump assembly extending through the divider such that the pump motor is in the mechanical compartment and the pump housing is in the water compartment, and wherein the pump assembly can be removed through the front panel opening and replaced without the use of tools. 
     The use of cool refrigerant vapor from a receiver to defrost an evaporator has several advantages. It eliminates the need for an electrical heating unit, or the problems associated with piping hot gas over a long distance in a remote compressor configuration. Since the cool vapor is located inside the evaporator coil, there is excellent heat transfer to those parts of the system that need to be warmed. The system can be used to defrost the evaporator where there is only one evaporator in the refrigeration system, or multiple evaporators in series, as well as evaporators in parallel. 
     Since hot gas is not needed for the defrost, the compressor can be located remotely from the ice-forming evaporator. As a result, the cabinet holding the evaporator can be smaller. Thus, the footprint of the ice making machine can be reduced. Using two receivers, as in a preferred embodiment of the invention, allows the receivers to have a smaller diameter, thus allowing for a narrower ice machine. This allows the ice machine to be placed on top of a dispenser, yet not cover the entire ice storage bin opening. The open space between the front of the bin and the front of the ice machine can be covered with a removable cover, allowing extra ice to be poured into the ice storage bin from a bucket to meet peak demand, and allowing access to the ice storage bin for cleaning and/or sanitizing operations. The preferred embodiment also has a unique water pump assembly with the water pump motor located outside of the water compartment of the ice making machine. The unique water pump assembly can be removed through the face of the machine without the use of any tool. 
     These and other advantages of the invention will be best understood in view of the attached drawings. 
    
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a perspective view of a remote ice machine including an ice making unit and a condensing unit, utilizing the present invention. 
     FIG. 2 is an exploded view of the condensing unit of FIG.  1 . 
     FIG. 3 is a perspective view of the electrical area of the condensing unit of FIG.  2 . 
     FIG. 4 is a perspective view of the back side of the ice making unit of FIG.  1 . 
     FIG. 5 is a front elevational view of the ice making unit of FIG.  4 . 
     FIG. 6 is an elevational view of the receiver used in the ice making machine of FIG.  1 . 
     FIG. 6A is a schematic diagram of an alternate receiver for use in the invention. 
     FIG. 7 is a schematic drawing of a first embodiment of a refrigeration system used in the present invention. 
     FIG. 8 is a schematic drawing of a second embodiment of a refrigeration system used in the present invention. 
     FIG. 9 is a schematic drawing of a third embodiment of a refrigeration system used in the present invention. 
     FIG. 10 is a schematic drawing of a refrigeration system used in a dual-evaporator embodiment of the present invention. 
     FIG. 11 is a schematic drawing showing the location of various components on the control board used in the ice making machine of FIG.  1 . 
     FIG. 12 is a wiring diagram for the ice making unit of FIG.  4 . 
     FIG. 13 is a wiring diagram for the condensing unit of FIG. 2 using single phase AC current. 
     FIG. 14 is a wiring diagram for the condensing unit of FIG. 2 using three phase AC current. 
     FIG. 15 is a perspective view of a second remote ice machine including a compact ice making unit and a condensing unit, utilizing the present invention. 
     FIG. 16 is a schematic drawing of a fifth refrigeration system used in the present invention, and particularly for the ice machine of FIG. 15 using two interconnected receivers. 
     FIG. 17 is an exploded partial view of the rear of the ice making unit of FIG.  15 . 
     FIG. 18 is a perspective view of the rear of the ice making unit of FIG. 15 with the back panel removed. 
     FIG. 19 is a schematic drawing of a sixth refrigeration system used in the present invention, using four evaporators and two interconnected receivers. 
     FIG. 20 is a perspective view of the water pump housing mounted in the water reservoir of the ice making unit of FIG.  15 . 
     FIG. 21 is a top perspective view of an adapter for fitting the water pump into the ice making unit of FIG.  15 . 
     FIG. 22 is a bottom perspective view of the adapter of FIG.  21 . 
     FIG. 23 is another top perspective view of the adapter of FIG.  21 . 
     FIG. 24 is a top plan view of the adapter of FIG.  21 . 
     FIG. 25 is a cross-sectional view taken along line  25 — 25  of FIG.  24 . 
     FIG. 26 is a cross-sectional view taken along line  26 — 26  of FIG.  24 . 
     FIG. 27 is a partial side view taken along line  27 — 27  of FIG.  24 . 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS AND PREFERRED EMBODIMENTS OF THE INVENTION 
     FIG. 1 shows the preferred embodiment of the present invention, an automatic ice making apparatus or machine  2  having a condensing unit  6  and an ice making unit  8 . The condensing unit  6  contains a compressor  12  and condenser with a fan and motor and is generally mounted on the roof  104  of a building, or could be located outside on the ground or in a back room. The ice making unit  8  contains an evaporator and ice-forming mold, and is usually located in the main portion of a building. As shown, the ice making unit  8  typically sits on top of an ice storage bin  9 . The present invention can also be used in ice making machines where the compressor and/or condenser are located in the same cabinetry as the evaporator/ice-forming mold. However, in such situations, hot gas defrost works well and thus the invention is more particularly suited to remote ice making equipment. Novel refrigeration systems used in ice machines of the present invention may also be useful in other equipment which include refrigeration systems. 
     The preferred automatic ice making machine  2  is very similar to a Manitowoc brand remote ice making machine, such as the Model QY 1094 N. Thus, many features of such a machine will not be discussed. Instead, those features by which the present invention differs will primarily be discussed. Some components, such as the compressor  12 , will be discussed although there is no difference between that specific component in the Model QY 1094 N remote ice making machine and in the preferred embodiment of the invention. However, reference to these parts common to the prior art and preferred embodiment of the invention is necessary to discuss the new features of the invention. 
     The present invention is most concerned with the refrigeration system of the ice machine. Several different embodiments of refrigeration systems that could be used to practice the present invention will be discussed first. Thereafter, the total ice making machine will be described. 
     FIG. 8 depicts a first preferred embodiment of a refrigeration system  100  that can be used in ice machines of the present invention. The double line across the figure represents the roof  104  of FIG.  1 . The system  100  includes a compressor  112  connected to a condenser  114  by refrigerant line  113 . While one loop of condenser tubing is shown, it should be understood that the condenser may be constructed with any number of loops of refrigerant tubing, using conventional condenser designs. The refrigerant line  115  from the condenser is connected to head pressure control valve  116 . A bypass line  117  from the compressor also feeds into the head pressure control valve, such as a Head Master brand valve. The head pressure control valve  116  is conventional, and is used to maintain sufficient head pressure in the high pressure side of the refrigeration system so that the expansion device and other components of the system operate properly. The head pressure control valve  116  and bypass line  117  are preferred for low ambient temperature operation. 
     The refrigerant from the head pressure control valve  116  flows into receiver  118  through refrigerant line  119  and inlet  120 . Line  119  is often referred to as a feed line or liquid line. However, especially when the head pressure control valve opens, vaporous refrigerant, or both vaporous and liquid refrigerant, will flow through line  119 . Liquid refrigerant is removed from the receiver  118  through a liquid outlet  122 , preferably in the form of a tube extending to near the bottom of the receiver  118 . Liquid refrigerant travels from the receiver  118  through outlet  122  and refrigerant line  121  through a drier  124  and an expansion device, preferably a thermal expansion valve  126 . Refrigerant from the thermal expansion valve  126  flows to evaporator  128  through line  123 . From the evaporator  128  the refrigerant flows through line  125  back to the compressor  112 , passing through an accumulator  132  on the way. The accumulator  132 , compressor  112  and evaporator  128  are also of conventional design. 
     A unique feature of the refrigeration system  100  is that the receiver  118  has a vapor outlet  134 . This outlet is preferably a tube which extends only to a point inside near the top of the receiver. In the system  100 , all of the refrigerant enters into the receiver  118 . Refrigerant coming into the receiver is separated, with the liquid phase on the bottom and a vapor phase on top. The relative amounts of liquid and vapor in the receiver  118  will be dependent on a number of factors. The receiver  118  should be designed so that the outlet tubes  122  and  134  are positioned respectively in the liquid and vapor sections under all expected operating conditions. During a freeze cycle of an ice machine, the vapor remains trapped in the receiver  118 . However, when the system is used during a harvest mode of an ice making machine valve  136  is opened. The passageway between the receiver  118 , through vapor outlet  134  and refrigerant lines  131  and  133 , to the evaporator  128 , is thus opened, and the vapor outlet is connected by the valved passageway directly to the evaporator. Cool vapor, taken off the top of the receiver  118 , is then passed through the evaporator, where some of it condenses. The heat given off as the refrigerant is converted to a liquid from a vapor is used to heat the evaporator  128 . This results in ice being released from the evaporator in an ice machine. 
     The amount of vapor in the receiver at the beginning of a harvest cycle may be insufficient to warm the evaporator to a point where the ice is released. However, as vapor is removed from the receiver, some of the refrigerant in the receiver vaporizes, until the receiver gets too cold to vaporize more refrigerant. This also results in a lower pressure on the outlet, or high side, of the compressor. 
     When the pressure on the high side of the compressor falls below a desired point, the head pressure control valve  116  opens and hot gas from the compressor is fed to the receiver  118  through the bypass line  117  and liquid line  119 . This hot vapor serves two functions. First, it helps heat the liquid in the receiver tank  118  to aid in its vaporization. Second, it serves as a source of vapor that mixes with the cold vapor to help defrost the evaporator. However, the vapor that is used to defrost the evaporator is much cooler than the hot gas directly from the compressor in a conventional hot gas defrost system. 
     In the past it was believed that the sensible heat from the superheated refrigerant in the “hot gas defrost” in an ice machine was needed to heat the evaporator to where it releases the ice. However, in view of the discovery of the present invention, it is appreciated that it is the latent heat from the vapor condensing in the evaporator, rather than the hot gas from the compressor, that is needed for the harvest. Thus, by using a receiver of a unique design, ample amounts of cool vapor refrigerant may be supplied to the evaporator in a harvest mode. 
     FIG. 7 shows a second embodiment of a refrigeration system  10 , which was developed prior to the embodiment of FIG.  8 . The refrigeration system is just like refrigeration system  100  of FIG. 8 except that solenoid valve  30  and capillary tubes  27  were used in the system  10 . The same parts have thus been numbered with the same reference numbers, with a difference of  100 . If solenoid valve  30  is closed, the returning refrigerant flows through capillary tubes  27  in heat transfer relationship with the coils of condenser  14 . The heat from the condenser helps to vaporize any refrigerant in liquid form returning from the evaporator. It was discovered that the solenoid valve  30  and capillary tubes  27  were unnecessary for proper operation of the refrigeration system in an automatic ice making machine, as the liquid refrigerant coming from the evaporator  128  during the harvest mode would collect in the accumulator  132 . 
     FIG. 9 shows a third preferred embodiment of a refrigeration system  200 . This refrigeration system is particularly designed for use in an ice making apparatus where a condenser and compressor in condensing unit  206  are located remotely from an evaporator housed in an ice making unit  208 . The refrigeration system  200  uses the same components as refrigeration system  100 , with a few additional components. The components in system  200  that are the same as the components in system  100  have the same reference numbers, with an addend of  100 . Thus, compressor  212  in system  200  may be the same as compressor  112  in system  100 . System  200  includes a few more control items. For example, a fan cycling control  252  and a high pressure cut out control  254  are connected to the high pressure side of the compressor  212 . A low pressure cutout control  256  is included on the suction side of the compressor  212 . These items are conventional, and serve the same functions as in prior art automatic ice making machine refrigeration systems. A check valve  258  is included in the refrigerant line  219  on the inlet side of receiver  218 . In addition to drier  224 , a hand shut off valve  260  and a liquid line solenoid valve  262  are included in the refrigerant line from the receiver  218  to the thermal expansion valve  226 . FIG. 9 also shows the capillary tube and bulb  229  connected to the outlet side of the evaporator  228  which controls thermal expansion valve  226 . Not shown in FIG. 9 is the fact that the refrigerant line  221  between the liquid solenoid valve  262  and the thermal expansion valve  226  is preferably coupled in a heat exchange relationship with the refrigerant line  225  coming from the evaporator  228 . This is shown in FIG. 4, however. This prechills the liquid refrigerant coming from the receiver  218 , as is conventional. 
     The cold vapor solenoid  236  is operated just like the solenoid valve  136  to allow cool vapor from the receiver  218  to flow into the evaporator  228  during a harvest mode. The head pressure control valve  216  operates just like head pressure control valve  116  to maintain pressure in the high side of the refrigeration system  200 . 
     The J-tube  235  in accumulator  232  preferably includes orifices near the bottom so that any oil in the refrigerant that collects in the bottom of the accumulator will be drawn into the compressor  212 , as is conventional. 
     Sometimes ice machines are built with multiple evaporators. Where a high capacity of ice production is desired, two or more evaporators can produce larger volumes of ice. One evaporator twice as large would conceivably also produce twice the ice, but manufacturing such a large evaporator may not be practicable. The present invention can be used with multiple evaporators. 
     FIG. 10 shows a fourth preferred embodiment of a refrigeration system  300  where the ice machine has two evaporators  328   a  and  328   b . The refrigeration system  300  is just like refrigeration system  200  except some parts are duplicated, as described below. Therefore, reference numbers in FIG. 10 have an addend of  100  compared to the reference numbers in FIG.  9 . 
     Two thermal expansion valves  326   a  and  326   b  are used, feeding liquid refrigerant through lines  323   a  and  323   b  to evaporators  328   a  and  328   b , respectively. Each is equipped with its own capillary tube and sensing bulb  329   a  and  329   b . Likewise, two solenoid valves  336   a  and  336   b  are used to control the flow of cool vapor to evaporators  328   a  and  328   b  through lines  333   a  and  333   b . This allows the two evaporators to each operate at maximum efficiency, and freeze ice at their own independent rate. Of course it is possible to use one thermal expansion valve, but then, because it would be very difficult to balance the demand for refrigerant in each evaporator, one evaporator (the lagging evaporator) would not be full when it was time to defrost the other evaporator. 
     Having two separate solenoid valves  336   a  and  336   b  allows one valve to be closed once ice has been harvested from the associated evaporator. When it is time to harvest, solenoid valves  336   a  and  336   b  will open, and cool vapor from receiver  318  will be permitted to flow into lines  333   a  and  333   b  and into evaporators  328   a  and  328   b . Both evaporators go into harvest at the same time. However, once ice falls from evaporator  328   a , the valve  336   a  will shut, and evaporator  328   a  will be idle while evaporator  328   b  finishes harvesting. With valve  336   a  shut, cool vapor is not wasted in further heating evaporator  328   a , but rather is all used to defrost evaporator  328   b . Of course, the reverse is also true if evaporator  328   b  harvests first. 
     The receiver of the present invention must be able to separate liquid and vaporous refrigerant, and have a separate outlet for each. The vapor drawn off of the receiver will not normally be at saturation conditions, especially when the head pressure control valve is opened, because heat and mass transfer between the liquid and vapor in the receiver is fairly limited. In the preferred embodiment, the receiver  18  (FIG. 6) is generally cylindrical in shape, and is positioned so that the wall of the cylinder is vertical when in use (FIG.  4 ). Preferably, all of the inlet and outlet connections pass through the top of the receiver. This allows the receiver to be constructed with only one part that need holes in it, and the holes can all be punched in one punching operation to minimize cost. The inlet tube  20  can terminate anywhere in the receiver, but preferably terminates near the top. The liquid outlet  22  terminates near the bottom, and the vapor outlet  34  terminates near the top. Thus it is most practical to have all three tubes pass through the top end panel of the cylinder. Of course other receiver designs can be used, as long as cool vapor can be drawn from the receiver to feed the evaporator during harvest or defrost modes. FIG. 6A shows another receiver  418  where inlet  420  is mounted in the sidewall of the receiver  418 . The liquid outlet  422  also exits through the side wall of the receiver, but has a dip tube at a 90° bend so that the end of the outlet tube  422  is near the bottom of the receiver  418 . Similarly, vapor outlet  434  is mounted in the side but has an upturned end so that cool vapor from near the top of the receiver  418  will be drawn off. 
     The head pressure control valve performs two functions in the preferred embodiment of the invention. During the freeze mode, especially at low ambient temperatures, it maintains minimum operating pressure. During the harvest mode, it provides a bypass. If no head pressure control valve were used, the harvest cycle would take longer, more refrigerant would be needed in the system, and the receiver would get cold and sweat. Instead of a head pressure control valve, line  217  could join directly into line  215  and a second solenoid valve could be used in line  217  (FIG. 9) to allow compressed refrigerant from the compressor to go directly to the receiver  218 . However, then the electrical controls would require wiring to run between the condensing unit  206  (comprising the compressor and condenser) and the ice making unit  208  (comprising the evaporator and the receiver). With the preferred design of FIG. 9, those two sections can be separated by a roof  204  or wall and a great distance, and only two refrigerant lines need to run between the sections. Thus the ice making unit  208  can be located inside of a building, even close to where customers may want to receive ice cubes, and the compressor and condenser can be located outdoors, where the heat and noise associated with them will not disturb occupants of the building. 
     The refrigeration system of FIG. 9 can be used with the other components of a typical remote ice making machine with little change. For example, the control board for an electronically controlled remote ice making machine can be used to operate an ice making machine using the refrigeration system of FIG.  9 . Instead of the control board signaling the opening of a hot gas defrost valve at the beginning of a harvest cycle, the same signal can be used to open solenoid valve  236 . However, compared to the typical remote ice making machine, the compressor can now be located outdoors with the condenser. 
     The other components of the ice making machine can be conventional. For example, the ice machine will normally include a water system (FIG. 5) comprising a water pump  42 , a water distributor  44 , an ice-forming mold  46  and interconnecting water lines  48 . The ice forming mold  46  is typically made from a pan with dividers in it defining separate ice cube compartments and the evaporation coil is secured to the back of the pan. The ice machine can also include a cleaning system and electronic controls as disclosed in U.S. Pat. No. 5,289,691, or other components of ice machines disclosed in U.S. Pat. Nos. 5,193,357; 5,140,831; 5,014,523; 4,898,002; 4,785,641; 4,767,286; 4,550,572; and 4,480,441, each of which is hereby incorporated by reference. For example, a soft plug is often included in a refrigeration system so that if the ice machine is in a fire, the plug will melt before any of the refrigeration system components explode. 
     Typical components in the condensing unit  6  are shown in FIG.  2 . Beside the compressor  12  and condenser  14 , which is made of serpentine tubing (only the bends of which can be seen), the condensing unit will also include a condenser fan  50  and motor, access valves  52 , the head pressure control valve  16  and the accumulator  32 . Electrical components, such as a compressor start capacitor  54 , run capacitor  56 , relays, the fan cycling control  252 , the high pressure cutout control  254 , and the low pressure cutout control  256  are typically contained in an electrical section in one corner of the condensing unit  6 . 
     The ice making unit  8  holds the portion of the refrigeration system shown in FIG. 4 as well as the water system shown in FIG.  5 . In this instance, the components from refrigeration system  200  are depicted as being in the ice making unit  8 . However, the refrigeration system  10  or the refrigeration system  100  could also be used. Besides the evaporator  228  and receiver  218 , the ice making unit  8  preferably also includes the drier  224 , liquid solenoid valve  262 , check valve  258 , solenoid valve  236  and thermal expansion valve  226 . Because the receiver  218  is preferably built into the same cabinet as the evaporator  228 , it will normally be in room temperature ambient conditions. As a result, the receiver is kept fairly warm, which helps provide sufficient vapor to harvest the ice. 
     FIG. 11 depicts a control board  70  for use with the ice machine  2 . The elements on the control board can preferably be the same as the elements on a control board for the Model QY 1094 N remote ice machine from Manitowoc Ice, Inc. Lights  71 ,  72 ,  73  and  74  indicate, respectively, whether the machine is in a cleaning mode, if the water level is low, whether the ice bin is full, and whether the machine is in a harvest mode. There is also a timing adjustment  75  for a water purge that occurs between each freezing cycle. The control system fuse  76  and automatic cleaning system accessory plug  77  are also found on the control board, as are the AC line voltage electrical plug  78  and DC low voltage electrical plug  79 . The control board also includes spade terminations  80 ,  81  and  82  respectively for an ice thickness probe, water level probe and an extra ground wire for a cleaning system. 
     FIG. 12 is a wiring diagram for the ice making unit  8 . In addition to the control board  70  and many of its components, FIG. 12 shows wiring for a bin switch  83  and an internal working view of the cleaning selector toggle switch  84  for which the top position is for normal ice making operation, the middle position is the off position and the bottom position is the cleaning mode. FIG. 12 also shows the wiring for a water valve  85 , cool vapor solenoid valve  236  (and in dotted lines, the second valve  336   b  when dual evaporators are used), a water dump solenoid  86 , the water pump  42 , and the liquid line solenoid valve  262 . 
     FIG. 13 is a wiring diagram, showing the circuits during the freeze cycle, for the condensing unit  6  using 230V single phase alternating current. The compressor  12  main motor is shown, along with a crank case heater  87 . The high pressure cut out  254 , low pressure cut out  256 , fan cycle control  252  and condenser fan motor  50  with a built in run capacitor are also shown, along with the compressor run capacitor  56  and start capacitor  54 . A relay  88 , a contactor coil  91  and contactor contacts  92  and  93  are also shown. 
     FIG. 14 is a wiring diagram, again showing connections during the freeze cycle, for the condensing unit  6  using 230V three phase alternating current. Components that are the same as those in FIG. 13 have the same reference numbers. 
     As noted above, there is no need to run electrical wire between the condensing unit  6  and the ice making unit  8 . The ice making unit  8  preferably operates off of a standard wall outlet circuit, whereas higher voltage will normally be supplied to the condensing unit  6 . 
     The present invention allows for the compressor and condenser to be located remotely, so that noise and heat are taken out of the environment where employees or customers use the ice. However, the evaporator harvests using refrigerant. Test results show that these improvements are obtained without loss of ice capacity, with comparable harvest time and comparable energy efficiency. Further, since hot gas defrost is eliminated, the compressor is stressed less during the harvest cycle, which is expected to improve compressor life. Only two refrigerant lines are needed, because any hot gas from the head pressure control valve can be pushed down the liquid line with liquid refrigerant from the condenser, and then separated later in the receiver. 
     Preferably the refrigeration system uses an extra large accumulator directly before the compressor that separates out any liquid refrigerant returned during the harvest cycle. Vapor refrigerant passes through the accumulator. Liquid refrigerant is trapped and metered back at a controlled rate through the beginning of the next freeze cycle. 
     The compressor preferably pumps down all the refrigerant into the “high side” of the system (condenser and receiver) so no liquid can get into the compressor crank case during an off cycle. A magnetic check valve is preferably used to prevent high side refrigerant migration during off cycles. The crank case heaters prevent refrigerant condensation in the compressor crank case during off periods at low ambient temperatures. 
     Commercial remote embodiments of the invention are designed to work in ambient conditions in the range of −20 to 130° F. Preferably the ice making unit is precharged with refrigerant and when the line sets are installed, a vacuum is pulled after the lines are brazed in, and then evacuation valves are opened and refrigerant in the receiver is released into the system. The size of the various refrigerant lines will preferably be in accordance with industry standards. Also, as is common, the accumulator will preferably include an orifice. 
     The preferred amount of refrigerant in the system will depend on a number of factors, but can be determined by routine experimentation, as is standard practice in the industry. The minimum head pressure should be chosen so as to optimize system performance, balancing the freeze and harvest cycles. The size of orifice in the accumulator should also be selected to maximize performance while taking into account critical temperatures and protection for the compressor. These and other aspects of the invention will be well understood by one of ordinary skill in the art. 
     It should be appreciated that the systems and methods of the present invention are capable of being incorporated in the form of a variety of embodiments, only a few of which have been illustrated and described above. The invention may be embodied in other forms without departing from its spirit or essential characteristics. For example, rather than using an ice-forming evaporator made from dividers mounted in a pan with evaporator coils on the back, other types of evaporators could be used. Also, instead of water flowing down over a vertical evaporator plate, ice could be formed by spraying water onto a horizontal ice-forming evaporator. 
     While the ice machine of the preferred embodiment has been described with single components, some ice machines may have multiple components, such as two water pumps, or two compressors. Further, two completely independent refrigeration systems can be housed in a single cabinet, such as where a single fan is used to cool two separate but intertwined condenser coils. While not preferred, a system could be built where one compressor supplied two independently operated evaporators, where extra check valves and other controls were used so that one evaporator could be in a defrost mode while the other evaporator was in a freeze mode. 
     FIG. 15 shows a second preferred embodiment of the present invention, an automatic ice making apparatus or machine  402  having a condensing unit  406  and an ice making unit  408 . The condensing unit  406  is just like the condensing unit  6  of FIG. 1, and need not be further discussed. The ice making unit  408  is more compact than the ice making unit  8  of FIG. 1, and is shown sitting on top of an ice and beverage dispenser  409 . The ice and beverage dispenser  409  has a ice storage bin  412  in the top portion thereof. 
     One reason that the ice making unit  408  is compact is that the compressor, normally contained in the cabinet of an ice making unit in a remote system, is housed in the condensing unit  406 , as explained previously. Another reason the ice making unit  408  is compact is because it uses a plurality of receivers interconnected with a receiver equalizer line, as shown in FIGS. 16-18. The receiver used in the ice making unit must be large enough to hold refrigerant used to defrost the evaporator during a harvest cycle. Because it is pressurized, the receiver is preferably cylindrical. One large receiver was found to interfere with efforts to reduce the depth of the ice making unit  408 . Hence, in the preferred embodiment, two receivers  518   a  and  518   b  are used, each having a smaller diameter than the receiver  218  shown in FIG. 4. A six-inch diameter receiver can be replaced with two four-inch diameter receivers having about the same total volume. A taller, skinner receiver could be used, but then the machine height would have to increase. The receivers  518   a  and  518   b  have the inlet  520  vapor outlet  534  and liquid outlet  522  all passing through the top wall; just like receiver  218 . However, a receiver equalization line  598  interconnects the two receivers  518   a  and  518   b , constituting a tube passing into the receivers near their bottom. In this way, liquid refrigerant can flow between the two receivers. In fact, as far as the refrigeration system works, the two receivers act as one receiver. The other components of the refrigeration system  500  for the ice making unit  408  may be identical to the refrigeration system  200  shown in FIG.  9 . Therefore, the components in system  500  that are the same as components in system  200  have the same reference numbers, with an addend of  300 . One additional component, a suction line filter  570 , has been added to the refrigeration system  500 . 
     The compact ice making unit  408  has an additional improvement in that the water pump assembly is mounted so that the pump motor  460  is not located in the water compartment, yet the entire pump assembly can be removed from the front part of the ice making unit without the need for tools. The water pump assembly includes a motor  460  (FIG.  17 ), an adapter  470  (FIGS.  17  and  20 - 27 ) and a pump housing  490  (FIG.  20 ). The motor  460  and pump housing  490  are conventional, with the exception that the housing  490  includes a sleeve  491  with a flange  492  used to connect with the adapter  470 . Water is discharged from the pump through a discharge port into a hose  493  (FIGS.  17  and  20 ). The pump assembly and hose  493  both pass through holes in the base  420  of the machine compartment that sits over the back portion of the water reservoir or sump. The base  420  thus serves as a divider between the machine compartment and the water compartment. FIG. 20 shows the pump housing extending downwardly into the reservoir area of the ice making unit, but the reservoir is not included for sake of clarity. A water level sensor  454  also hangs down into the sump area. The hose  493  includes a T-fitting with an outlet  494  (FIG. 17) to a drain line that is preferably fitted with a solenoid dump valve (not shown). The adapter  470  will be explained in more detail below. 
     FIGS. 17 and 18 show several other components of the ice making unit  408 , such as service shut-off valves,  436  and  438 , an injection port  457  for injection of cleaning/sanitizing solutions from an automatic cleaning system, an evaporator inlet fitting  456 , an evaporator outlet fitting  458 , a water inlet hose  452 , thermal expansion valve  526  with its associated capillary tube and bulb  429 , drier  524 , liquid solenoid valve  562 , cool vapor solenoid valve  536 , water inlet solenoid valve  427 , electrical box  423 , and the suction line  432  and liquid line  434  that go to the remote condensing unit  402 . The suction line  432  and liquid line  434  have service loops  435  and  437  provided so that the ice making unit  408  can be rotated on top of the ice and beverage dispenser  409  if a service technician needs to have access to the back of the ice making unit. The water level sensor can be a capacitance sensor as used on commercial Manitowoc ice machines, or some other type of sensor. 
     FIG. 19 shows a refrigeration system  600  that can be used with four evaporators  628   a ,  628   b ,  628   c  and  628   d.  The refrigeration system  600  has two receivers  618   a  and  618   b  like the two receivers in refrigeration system  500 , and a suction line filter  670 . Otherwise, the components are like those in the multi-evaporator refrigeration system  300  of FIG.  10 . Therefore, reference numbers in FIG. 19 have an addend of  300  compared to the reference numbers in FIG.  10 . Also, where parts were duplicated, such as two thermal expansion valves  326   a  and  326   b  in FIG. 10, there are four parts in FIG. 19, such as four thermal expansion valves  626   a ,  626   b ,  626   c  and  626   d  in refrigeration system  600 . Four sets of capillary tubes and sensing bulbs  629   a-d  allow the evaporators  628   a-d  to operate independently. Also, there are two fan cycling controls  652   a  and  652   b.    
     The pump assembly adapter  470 , best shown in FIGS. 21-27, is preferably made of injection molded plastic and is then constructed with the pump motor  460  and pump housing  490  into the pump assembly. Studs extending from the motor are fastened to the sleeve  491 , sandwiching the adapter  470  between the motor  460  and the pump housing  490 . Using the adapter  470 , the pump assembly can be removed and inserted so that the motor  460  extends into the machine compartment through base  420 . 
     The adapter  470  includes a motor deck  472  and a flange  474 . The motor  460  is centered on the deck  472  by four extensions  475 . In the center of the deck  472 , a series of reduced diameter shoulders  476 ,  477  and  478  are formed. These are used to center the shaft (not shown) from the motor to the pump housing and hold a felt washer that prevents water from coming up the shaft to the motor  460 . 
     The flange  474  includes two locking tabs  480 . The locking tabs have a slot  481  (FIG. 27) in them extending in from one side, as will be explained hereafter. The base  420  of the machine compartment has a hole in it the same diameter as the deck  472 . There are two locking tab clearance slots  421 , one of which can be seen in FIG. 17, extending out from this hole. When the assembly is raised, so that the motor  460  passes through the hole in the base  420 , the deck  472  is able to pass through as well, up until the flange  474  hits the bottom of the base  420 . The locking tabs  480  pass through the clearance slots  421 . As the pump assembly is rotated clockwise (looking from above), the slots  481  allow the sheet metal of the base  420  to pass through until it hits the stop  483  at the end of the locking tab  480 . In this position, a stud (not shown) can pass through a hole (not shown) in the base  420  that is aligned with a hole  471  in the flange  474 . The stud is part of a standard quarter-turn fastener  486  (FIG.  20 ), and has a receptacle (not shown) on the top of the base  420 . The stud prevents the adapter  470  from rotating. However, when the pump assembly needs to be removed, the quarter-turn fastener can be turned back, the stud removed from the receptacle and hole  471 , and the adaptor  470  can then be rotated. This rotation brings the locking tabs back over the clearance slots, and the entire pump assembly can be dropped into the reservoir area. Preferably, the pump motor has an electric cord and plug on it that plugs into a mating electrical connector extending from the electrical box  423 . This pump wire is preferably sufficiently long so that the plug and mating connector pass down through the hole in the base  420  and are visible to the service technician, who can then easily disconnect the electrical wiring to the pump. 
     As shown in FIG. 15, the compact size of the ice making unit  408  allows the ice making unit to be mounted on the top of the ice storage bin section of the ice and beverage dispenser  409  with a good deal of clearance between the front of the ice storage bin and the front of the ice making unit cabinet  414 . This clearance is preferably covered by a cover  411  during normal use. However, the cover  411  can be removed so that the ice storage bin  412  can be cleaned. Also, if peak demand exceeds the storage of ice, additional ice can be added to the top of the ice storage bin  412  while the cover  411  is removed. 
     It is preferable that the cabinet  414  have a depth D, a width W and a height H, at least one of which is less than 18 inches. It is most preferable that the depth D be of less than 18 inches, preferably less than 16 inches, and most preferably about 14 inches or less. The width W of the cabinet  414  will preferably be the same as the width of the ice and beverage dispenser, such as about 22 inches or less. However, the compact size of the ice machine may also, or alternatively, allow for a width W less than the width of the ice storage bin  412 . The height H of the cabinet  414  will preferably be less than 32 inches. In one preferred embodiment, the cabinet  414  has a height of 30 ½ inches, a width of 22 inches, and a depth of only 14 inches. Yet, the ice making unit has a capacity of 900 pounds of ice per day when tested under Air Conditioning and Refrigeration Institute (ARI) standard testing conditions of 90° F. ambient temperature and 70° F. ambient inlet water temperature. This unit has a capacity-to-volume ratio of 166 pounds of ice/day/ft 3  of cabinet volume. Two smaller capacity units have also been developed in smaller height cabinets, one that produces 680 pounds of ice per day under the standard ARI test conditions, and the other which produces 570 pounds of ice per day under the standard ARI test conditions. These ice making machines have capacity-to-volume ratios of 144 pounds of ice/day/ft 3  and 133 pounds of ice/day/ft 3  respectively. By comparison, a fairly efficient ice machine from another company has a cabinet measuring 48×26×24 inches and has a reported capacity of 1855 pounds of ice per day at ARI standard test conditions, resulting in a capacity-to-volume ratio of 107 pounds of ice/day/ft 3 . Another machine on the market has a cabinet measuring 48×22×28 inches and a capacity of 2024 pounds of ice per day. This is only a capacity-to-volume ratio of 118 pounds of ice/day/ft 3  Thus, these larger machines, which should have a better capacity-to-volume ratio, fall short of 125 pounds of ice/day/ft 3 , whereas all three of the compact machines utilizing the present invention meet the 125 ratio, and two of them meet the more preferable 140 pounds of ice/day/ft 3  ratio. Of course, very large industrial ice making equipment, which produces over 3,000 pounds of ice per day, may be able to produce ice at such a preferable capacity-to-volume ratio. However, for commercial ice making machines, which are rated at 2,500 pounds of ice per day or less, such a capacity-to-volume ratio is a great advantage. 
     It will be appreciated that the addition of some other process steps, materials or components not specifically included will have an adverse impact on the present invention. The best mode of the invention may therefore exclude process steps, materials or components other than those listed above for inclusion or use in the invention. However, the described embodiments are to be considered in all respects only as illustrative and not restrictive, and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.