US3162752A - Water heater and control therefor - Google Patents

Description

1964 H. R. KINSELLA, JR 3,162,752

WATER HEATER AND CONTROL THEREFOR Filed Sept. 24. 1962 United States Patent 3,162,752 WATER HEATER AND CONTROL 'llHEREFtBR Howard E. Kinsella, in, Atiton, Mo, assiguor to Whitelliodgers Company, St. Louis, Mo., a corporation of Missouri Filed Sept. 2d, 1962, Ser. No. 225,6% 1 Claim. (Cl. 219-420) This invention relates to domestic water heaters having electrical resistance heating elements and particularly to an arrangement wherein automatic control means operates the heating elements at a predetermined normal electrical load but permits operation at a somewhat higher electrical load to partially restore the preselected water temperature under conditions wherein an unusually large drawoti of hot water results in a drop in water temperature below a predetermined point.

Being confronted with wide variations in electrical load, with outstanding peakperiods, many suppliers of electrical power have imposed limitations on power use in connection with domestic water heaters. While such limitations may cause no appreciable inconvenience under conditions of normal water usage, an objectionable delay in replenishing the hot water supply may result when the occasionally large drawofl of hot water occurs. Based on the proposition that the occasional large drawoil is a relatively infrequent random occurence not likely to appreciably increase the usual periodic load peaks, I have provided an electric water heater including autoiatic means whereby the electrical load is temporarily increased above the usual power supply limitation for a period sufiicient to partially restore the preselected water temperature under conditions wherein the water temperature drops to a point considerably lower than that which would result from the usual drawoff.

in the drawing;

The sole figure of the drawing schematically illustrates a domestic water heater with associated electrical heating elements and controls therefor constructed in accordance with the present invention.

Referring to the single figure of the drawing, numeral Ml indicates a vertically arranged water tank having a lower fitting 12 to which a cold water line 14 is connected and an upper fitting id to which a hot water line 18 is connected. The tank is provided with an upper electrical resistance heater illustrated at 20, an intermediate electrical resistance heater 2i and a lower resistance heater 2?... The heaters 2d, 211, and 22 may be of any suitable type and construction and preferably encircle the tank in heat conductive relationship therewith. Resistance heater 21 may be placed at any desired position, preferably near the upper end of the tank in which position operation time will be considerably less than when placed in the lower portion of the tank. Arranged near the upper end of the tank are thermostats 24 and 26 and arranged near the lower end of the tank is a thermostat 28. Each of the thermostats consists of a bimetal disc 39 in good heat transfer relationship with the tank. The discs 36 have a hot position, as shown, in which they are outwardly convex and a cold position in which they are outwardly concave, which latter position they assume in response to predetermined decreases in temperature. The action from one position to the other is a snap action. Each of the thermostats is further provided with rod 32 operatively connected at one end to the center of disc 3t and carrying at its other end a switch blade 34. In thermostat 24, the switch blade 34 cooperates with two opposed pairs of stationary contacts 36-38 and 40-42. in thermostats 2d and 28, the blade 34 cooperates with single pairs of stationary contacts 44-46 and 48-50), respectively. Thermostat 24 is therefore a double pole,

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double throw thermostatic switching device and thermostats 26 and 28 are double pole, single throw devices.

Circuit connections connecting heating elements 29, 2-1, and 22 with power source terminals 52 and 54 will now be described. Upper resistance heater 2%) is connected across the power source terminals 52 and 54 through a lead 56, contacts 40-42 and switch blade 34 of thermostat 24, a lead 58, a lead 60, and a lead 62. Lower heating element 22 is connected across terminals 52 and 54 through the lead 56, a lead 64, contacts 36-38 and switch blade 34 of thermostat 24, a lead 66, a lead 68, contacts 43-50 and blade 34 of thermostat 28, and lead 62. Intermediate heating element 21 is connected across the power source terminals 52 and 54 through the lead 56, lead 64, lead 74, contacts 44-46 and switch blade 34 of thermostat 26, the leads 76 and '78, and the lead 62.

Operation Thermostats 2d, 26, and 28 are all shown in a hot or open position, which they assume when the temperature of the water in tank 1d attains the desired temperature. The calibration or temperature settings of upper thermo stat 24 and lower thermostat 28 may be substantially the same, or lower thermostat 28 may be set to operate at a slightly lower temperature than upper thermostat 24, while the temperature setting of thermostat 26 is considerably lower than either. When heated water is drawn from the upper part of the tank, cold water is admitted to the lower portion of the tank so that thermostat 28 senses the temperature drop first and closes first, thereby energizing lower heating element 22. If the withdrawal of heated water is light or moderate only thermostat 28 will close, and reheating will be accomplished by heating element 22 alone. If the withdrawal is continued, the inflow of cold water will subsequently lower the water temperature at the upper part of the tank and upper thermostat 24 will close. Closing of thermostat 24 effects energization of upper heating element 2@, but due to sep aration of blade 34 from contacts 36-38, lower element 22 will be simultaneously de-energized so that now only upper element 20 is energized. If withdrawal of heated water is stopped at this point energization of upper heating element 24) will continue until the desired water temperature in the upper part of the tank is restored, whereupon thermostat 24 will open and contacts 36-33 will he reclosed. Reclosing of contacts 36-38 again completes the energizing circuit for lower element 22, which now continues to operate until the water temperature in the lower portion of the tank is restored and thermostat 28 opens.

If withdrawal of heated water is continued considerably beyond the point which effects the closing of thermostat 24 with its contacts did-42, the thermostat 26 will close. Closing ofthermostat 26 now completes an energizing circuit for the intermediate heater 21 which then operates concurrent with the upper heating element 20 to eltect a rapid partial recovery of the desired water temperature. As the water temperature of the tank rises under these conditions, thermostat 26 opens first thereby de-energizing heater 2i, and upper element 2% will now continue to operate alone until thermostat 24 opens with respect to its contacts til-42. When thermostat 24 moves to its other position closing its contacts 36-38, the lower heating element 22 will then operate alone until thermostat 28 opens.

I claim:

in a water heating tank having a first upper electrical resistance heater positioned to heat water in the upper portion of the tank and circuit connections for the energization thereof completed through one side of an upper double throw thermostatic switching device when it moves to one throw position in response to a decrease in water temperature in the upper portion of the tank, and a second lower electrical resistance heater positioned to heat water in the lower portion of the tank and circuit connections for the energization thereof completed through a lower single throw thermostatic switching device when it closes in response to a decrease in temperature in the lower portion of the tank and through the other side of said double-throw device when it moves to its other throw position in response to a temperature rise, whereby either may operate to restore the water temperature in its respective portion of the tank but concurrent operation of the heaters is prevented; the improvement which consists in the provision of a third electrical resistance heater positioned to heat water in the upper portion of the tank and circuit connections for the energization thereof independently of said upper double throw thermostatic switching device and said lower single throw thermostatic switching device, and said circuit connections for said third heater including a second single throw thermostatic switching device responsive to the water tempertaure in the upper portion of the tank and calibrated to close at a temperature substantially below that which efl ects the movement of said upper double throw thermostatic switching device to its said one position and to reopen upon temperature rise at a point below that which results in the movement of said double throw switching device to its said other position, and said first, second, and third heaters being electrically connected in parallel with each other across an electrical power source.

References (Iited in the file of this patent UNITED STATES PATENTS 2,157,910 McCormick May 9, 1939 2,377,440 Ostherheld June 5, 1945 2,380,545 Pankow July 31, 1945

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