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Publication numberUS3901308 A
Publication typeGrant
Publication dateAug 26, 1975
Filing dateJun 24, 1974
Priority dateJun 24, 1974
Publication numberUS 3901308 A, US 3901308A, US-A-3901308, US3901308 A, US3901308A
InventorsIsaac Berger
Original AssigneeCarrier Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electrical overload control for a combination apparatus
US 3901308 A
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Description  (OCR text may contain errors)

United States Patent 1191 Berger 1 1 ELECTRICAL OVERLOAD CONTROL FOR A COMBINATION APPARATUS [75] Inventor: Isaac Berger, Hacienda Heights Calif [73] Assignee: Carrier Corporation, Syracuse, N.Yi

[221 Filed: June 24, 1974 [211 App]. No.: 482,172

52 us. Cl. 1. 165/2; 62/230; 219/485; 307/39 511 im. Cl. "021 3/14 [58} Field of Search 1 Aug. 26, 1975 Primary ExaminerWilliam E. Wayner Attorney, Agent, or Firm-J. Raymond Curtin; Barry Er Dcutsch [57] ABSTRACT A control for a combination apparatus including an electric water heater and mechanical refrigeration unit employed in an air conditioning system. The control prevents the compressor of the refrigeration unit from operating when the electric water heater is energized even though the temperature demand of the space being conditioned requires cooled air from the air conditioning system. The fan of the system adapted to route air to be conditioned over the evaporator will be selectively energized in response to the temperature demand of the space being conditioned even though the compressor is inoperable due to the energization of the electric water heater.

6 Claims, 3 Drawing Figures -SOLISUF'.

PATENTEDAUBZBIQYS FIG. 2

ELECTRICAL OVERLOAD CONTROL FOR A COMBINATION APPARATUS BACKGROUND OF THE INVENTION This invention relates to improvements in a control for combination apparatus of the type having an air conditioning unit and another unit, such as an electric water heater requiring heavy power demands.

In many applications wherein it is desired to provide electric space heating, electric water heating, and electric air conditioning, it has been found that a single packaged unit including apparatus adapted to provide each of the aforementioned functions is highly desirable. The packaged unit or apparatus may be placed in a space such as a closet wherein a minimal of otherwise usable space is used for the unit. Such a unit has been found particularly suitable for use in gardentype apartments or light commercial installations.

In US Pat. No. 3,767,894, such a unit is disclosed, the unit including a control system operable to limit the total current demand when the unit is operating to provide both heated air for the space being served and hot water.

In many installations, such as apartment complexes, employing the combination apparatus, electrical usage for the total installation is monitored at a single meter. If the air conditioning unit and other heavy power demand device of the combination apparatus, should function simultaneously, the peak power demand for the particular installation would be at a relatively high level. Thus, the year-round demand rate charge by the utility delivering electrical energy to the installation will be at an increased level. To the owner of the installation, the increased operating costs resulting from the foregoing is highly unsatisfactory.

However, although it is highly desirable to prevent the simultaneous operation of both the air conditioning unit and other heavy power demand device, the inoperability of the air conditioning unit when temperature conditions normally would require same, may cause inconvenience and discomfort to the occupants of the space being served by such system. Not only would the foregoing be unsatisfactory from the occupants viewpoint, but same would be equally unsatisfactory from the owner's viewpoint, since in the ultimate, he might lose tenants as a result of such discomfort.

In order to limit the discomfort and inconvenience to the occupants, the fan of the air conditioning system adapted to route air to be conditioned in heat transfer relation with the refrigerant flowing through the evaporator will be selectively energized in response to the cooling demand of the space, even though the compressor ofthe system is maintained inoperable. The circulation of air will provide convective cooling during the period of time when the compressors remain inoperable due to the energization of the other heavy power demand device. As soon as the demand is satisfied, the compressor may once again be energized in response to a demand for conditioned air.

SUMMARY OF THE INVENTION It is an object ofthis invention to provide a combina tion apparatus having an air conditioning system and a second device having a relatively heavy power demand, wherein when the second device is energized, the compressor of the system will be inoperable, yet air may be circulated in the space being served by the air conditioning system.

This and other objects of the present invention are obtained in a combination apparatus including a refrigeration unit of an air conditioning system and a second device, for example an electric water heater, having a relatively heavy power demand. When the electric water heater element of the water heater is energized in response to a demand for water heating imposed on the water heater, the compressor of the refrigeration unit will be prevented from being energized even though the space being served by the air conditioning system requires cooled air. However, the fan of the system adapted to circulate air to be cooled in heat trans fer relation with refrigerant passing through the evaporator will be selectively energized in response to the requirements of the space for conditioned air even though the compressor cannot be energized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I illustrates a combination apparatus including an electric water heater and a refrigeration unit;

FIG. 2 illustrates schematically a control circuit for the combination apparatus; and

FIG. 3 illustrates a schematic of the refrigeration unit of the combination apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is shown a preferred embodiment of the present control for a combination apparatus. In referring to the various figures of the drawing, like numerals shall refer to like parts.

Referring in particular to FIG. 1, there is disclosed a combination apparatus 10 having an upper housing shell 11 and a lower housing shell 12 secured together by suitable means. Upper housing I] is provided with an opening covered by grill 14 to emit air into the interior of the housing. An arcuately shaped refrigerant evaporator coil 16 is disposed behind grill l4, and a filter element 17 is inserted between the evaporator coil and the grill as shown, or on the outside of the grill, if desired. Evaporator coil 16 forms a portion of a refrigeration unit to be more fully described hereinafter. Liquid refrigerant is supplied to the evaporator through fitting 36 and leaves therefrom as a vapor through fitting 37. A fan 15 is located in upper housing 11 within the arcuate section of evaporator coil [6 for drawing air to be conditioned through grill l4 and filter 17, to thereafter pass in heat transfer relation with the refrigerant flowing through evaporator coil 16. The refrigerant absorbs heat from the air and is vaporized thereby. The air is cooled to a desirable temperature level as a result ofits rejection of heat to the refrigerant. The air is then discharged from fan 15 through a suitable discharge duct which is connected to the joint element 19 formed on the top of the housing.

One or more electric space heater elements 20 are provided within the discharge passage 21 of fan 15 for reheating of air being cooled and dehumidified or for providing heating of the air when temperature conditions in a space being served by the apparatus 10 poses a demand on the apparatus for heating. A suitable condensate pan 22 extends from the lower portion of the upper housing I] to remove condensate formed during the passage of air over evaporator 16. The condensate is formed as a result of the cooling of the air below its dew point.

Lower housing shell contains a water heater tank which is insulated by a layer of fiberglass 26 or other suitable material from the exterior of the shell, One or more electric hot water heater elements 27 are provided within the interior of water heater tank 25 to provide the required water heating upon the demand therefor. An inlet connection 28 is provided for supplying water to the tank 25 and an outlet connection 29 is provided for discharging heated water from the tank. In addition, a drain connection 30 is provided with a suitable valve at the lower portion of tank 25 to allow the tank to be drained, and a pressure relief valve is provided adjacent the top of the tank. A removable access panel 31 is provided in lower housing shell 12 to enable servicing of water heater elements 27. Electric service is provided by connecting an electric power line 34 to a control compartment 32.

Referring now to FIG. 3, there is disclosed a schematic diagram of the refrigeration unit of apparatus 10. The refrigeration unit is employed in an air conditioning system to provide relatively cool air to the space being served by the apparatus.

In addition to evaporator coil 16 heretofore noted, the refrigeration unit includes compression means, shown as a reciprocating type refrigerant compressor 40. High pressure, vaporous refrigerant gas is discharged from reciprocating compressor to line 41. Line 41 communicates with condenser 42. The vaporous refrigerant passes through the condenser where a cooling medium, for example ambient air, is routed thereover by fan 43. The vaporous refrigerant rejects heat to the ambient air and is condensed thereby.

The liquid refrigerant leaves condenser 42 and passes through line 44, thermal expansion means 45, shown as a thermal expansion valve and then passes through fitting 36 into evaporator coil l6.

As noted before, air to be cooled is routed over the evaporator coil and thereby rejects heat to the refrigerant gas passing therethrough. The refrigerant gas is vaporized as a result of its absorbing heat from the air and passes via line 46 to the suction side of compressor 40. The refrigeration unit hereinabove described is of a conventional type well known to those skilled in the art.

Referring particularly to FIG. 2, there is schematically illustrated a preferred embodiment of a control in accordance with the present invention. Line current is provided to the control at terminals 51, 52. The control illustrated in this embodiment includes a two-stage space heater comprising electric space heater elements 53 and 54 and a single-stage electric water heater element 55.

A water heater thermostat 56 has a first normally closed switch 57 and a second normally open switch S8, responsive to a sensed demand for water heating imposed on the control. A transformer having a line voltage primary winding 48 and a low voltage secondary winding 59 supplies current for operation of the low voltage components of the control. The low voltage components include a manually selectible heat-cool switch 49 for selecting either heating or air conditioning, as desired. When switch 49 is in a position to pro vide heating, terminals 60 are connected to each other. When switch 49 is in a position to provide air conditioning, terminals 6] are connected to each other as illustrated in the drawing.

Room thermostat 62 is located in the space to be conditioned for sensing a heating or cooling demand imposed upon the control. When contact 63 ofthermostat 62 is connected to the common terminal as illustrated in the drawing, the space to be cooled is warmer than the set point temperature and a demand for cool ing is indicated. Conversely, when the cooling demand is satisfied or there is a heating demand imposed upon the control, contact 64 of the thermostat is connected to the common terminal. When switch 49 is in a heating position, closing of contact 64 of thermostat 62 energizes space heat control relay 66', and when switch 49 is in the cooling position, connecting thermostat contact 63 to the common terminal energizes air conditioning relay 67. Additionally, a second relay 68 con nected in parallel with air conditioning relay 67 will also be energized when contact 63 is connected to the common terminal. Connected in series with relay 68, for a reason to be more fully disclosed hereinafter, is a normally closed switch 69.

A two-speed electric fan motor 70, having a low speed terminal 71 and a high speed terminal 72, is provided to operate fan 15. As noted previously, fan 15 is provided to route air over evaporator coil 16. Fan [5 will also route air over the electric space heater elements. The low speed terminal 71 of fan motor is in series with normally closed air conditioning relay contact 75 and the high speed terminal 72 of motor 70 is in series with normally open air conditioning relay contact 76. Consequently, fan motor 70 normally runs on low speed during the heating mode of operation and is switched to high speed operation when air conditioning is required and relay 67 is energized. Space heat control relay 66 has a pair of contacts 77, 78 connected thereto. Energization of relay 66 in response to a demand for heating closes contacts 77 and 78 to energize the space heaters. As disclosed in U.S. Pat. No. 3,767,894, it may be desirable to delay the energization of the fan motor for a period of time after current is supplied to the space heaters. The delay period permits the space heater elements to warm up before air is routed thereover. This prevents a cold blast of air from being discharged into the space being conditioned.

Assume room thermostat 62 senses that the space temperature has increased beyond its set point. If switch 49 is in a position to provide cooling, the closure of the switch controlled by the room thermostat will en ergize the air conditioning relay 67 to cause fan motor 70 to operate at high speed. ln addition, relay 68 in parallel with the air conditioning relay will also be energized. Relay 68 is the main compressor relay, the energization thereof causing compressor 40 of the refrigera tion unit to become operable.

In the event water heater thermostat S6 senses a de mand for water heating, switch 58 closes thereby energizing water heater element 55. In addition, relay 80 in parallel with water heater element 55 will also be ener gized. The energization of relay 80 will open normally closed switch 69. As noted before, switch 69 is con nected in series with compressor relay 68. The opening of switch 69 will render the compressor inoperable even though the room thermostat senses a demand for cooling. However, although the compressor is inoperable when the water heater element is energized due to a demand for heated water, fan motor 70 will remain energized when the room thermostat senses a demand for relatively cool air to thereby partially satisfy the cooling requirement in the space being conditioned.

The circulation of air via the continued operation of the fan motor will provide convective cooling to reduce the discomfort to occupants of the space that might otherwise occur due to the inoperability of the com pressor of the refrigeration unit.

It should be understood that, although the combination apparatus has been particularly described as comprising a mechanical refrigeration unit of a type employed in an air conditioning system and an electric water heater, the electric water heater may be replaced by any other device that has a heavy electrical power demand when energized, for example an electrostatic air filter.

While a preferred embodiment of the invention has been described and illustrated, the invention should not be limited thereto, but may be otherwise embodied within the scope of the following claims.

I claim:

I. In a combination apparatus including a mechanical refrigeration unit employed in an air conditioning system and a second unit having a relatively heavy electric power demand when energized, the improvement of a control comprising:

means to energize said second unit in response to a demand imposed thereon;

means to sense the temperature of air in a space being served by said air conditioning system to selectively energize and deenergize the compressor of said refrigeration unit. said air conditioning system including fan means operable to route air to be conditioned in heat transfer relation with refrigerant passing through the refrigeration unit evaporator, the refrigerant absorbing heat and being vaporized thereby; and

means to deenergize said compressor regardless of the sensed air temperature when said second unit is energized, said fan means of said air conditioning system being selectively energized in response to the sensed air temperature even though said compressor is inoperable due to the energization of said heater element, whereby air is circulated in said space served by said air conditioning system.

2. A combination in accordance with claim 1 wherein said second unit is an electric water heater having an electric water heater element.

3. A combination in accordance with claim 2 wherein said apparatus further includes heating means to provide relatively warm air to said space.

4. The method of operating a combination apparatus having a mechanical refrigeration unit employed in an air conditioning system and a second unit having relatively heavy electric power demands when energized, comprising the steps of:

energizing the second unit in response to a demand imposed thereon;

energizing the compressor of the refrigeration unit in response to a demand for relatively cold air in the space being conditioned, the compressor circulating refrigerant through the refrigerant flow circuit;

circulating air to be cooled in heat transfer relation with the refrigerant passing through the evaporator of the refrigeration unit, the air losing heat to the refrigerant and the refrigerant being vaporized thereby; and

deenergizing the compressor of the refrigeration unit regardless of the requirements in the space for cold air when the second unit is energized, the fan of the refrigeration unit being selectively energized to circulate air in the space being conditioned even though the compressor remains deenergized due to the energization of the second unit.

5. A method as set forth in claim 4 further including the step of energizing an electric heater; and

passing air in heat transfer relation with the electric heater element to warm the air to meet requirements of the space being conditioned.

6. A control for a combination apparatus of a type including an electric water heater having an electric water heater element and a mechanical refrigeration unit employed in an air conditioning system to provide relatively cold air to a space being conditioned, said control comprising:

a water heater thermostat having switch means associated therewith adapted to respond to a demand for water heating imposed on said control, said water heating element being connected in an electrical circuit controlled by said water heater thermostat to selectively energize and deenergize said water heater element in response to the sensed demand for water heating;

space thermostat means having switch means associated therewith adapted to respond to a demand for space cooling imposed on said control, said refrigeration unit being connected in an electrical circuit controlled by said space thermostat means to energize and deenergize said compressor in response to the sensed demand for space cooling, said air conditioning system further including fan means operable to route air to be cooled in heat transfer relation with refrigerant passing through said evaporator, said fan means also being connected in said electrical circuit controlled by said space thermostat means; and

means to deenergize said compressor regardless of the sensed air temperature when said heater element is energized, said fans means of said air conditioning system continuing to be selectively energized in response to the sensed air temperature of said space even though said compressor is rendered inoperable due to the energization of said heater element, whereby air is circulated in said space.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2736844 *Jul 28, 1951Feb 28, 1956Wesley Hicks WElectric load regulator
US3515892 *Apr 26, 1968Jun 2, 1970Us ArmyLoad disabling circuit
US3767894 *Sep 18, 1972Oct 23, 1973Carrier CorpCombination electric water heater and electric space heater
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4110827 *Oct 29, 1976Aug 29, 1978Honeywell Inc.Load cycling with space temperature feedback
US4141407 *Mar 29, 1977Feb 27, 1979Briscoe Harry HPower demand limiting circuit
US4147296 *Dec 9, 1977Apr 3, 1979Honeywell Inc.Proportional demand limit controller
US4160153 *Jun 24, 1977Jul 3, 1979Pako CorporationDuty cycle shared proportional temperature control
US4242554 *May 31, 1978Dec 30, 1980General Electric CompanyEffective time ratio browning in a microwave oven employing high thermal mass browning unit
US4263962 *Jun 13, 1977Apr 28, 1981General Electric CompanyHeat pump control system
US4310770 *Dec 3, 1980Jan 12, 1982Ohio Agricultural Research And Development CenterDemand load control
US4915162 *Aug 3, 1989Apr 10, 1990Sanden CorporationMethod and apparatus for heater current control for automatic vending machine
US5036676 *Sep 21, 1990Aug 6, 1991Carrier CorporationMethod of compressor current control for variable speed heat pumps
Classifications
U.S. Classification62/230, 307/39, 219/485
International ClassificationF25B49/02, F24F11/02, H02J3/14, F25D29/00
Cooperative ClassificationY02B70/3275, H02J3/14, Y02B30/765, Y02B70/3266, F25B49/02, Y02B70/3225, Y04S20/244, Y04S20/222, Y04S20/242, F25D29/00
European ClassificationF25B49/02, H02J3/14, F25D29/00