US2213464A

US2213464A - Electric water heater unit

Info

Publication number: US2213464A
Application number: US237864A
Authority: US
Inventors: Harrison H Fogwell
Original assignee: THERMADOR ELECTRICAL Manufacturing CO
Current assignee: THERMADOR ELECTRICAL Manufacturing Co
Priority date: 1938-10-31
Filing date: 1938-10-31
Publication date: 1940-09-03
Anticipated expiration: 1957-09-03

Description

Sept. 3, 1940. H. H. FoGwELl. 2,213,464

ELECTRIC WATER HEATER UNIT Filed Oct. 5 1, 1938 HARR/ K/ECH, FOSTER HA ,QR/5 KJ FOR MEF/RM A7' ORA/frs.

Patented Sept. 3, 1940 UNITED STATES PATENT ELECTRC WATER HEATER UNIT Application October 31, 1938, Serial No. 237,864

9 Claims.

My invention relates to the water heater art and more particularly to a water heater having a novel type of cold water inlet. Although the invention may be used with any type of water heater, it is of particular utility when used in connection with an electric Water heater having an electric resistance adapted to accomplish the heating therein, and, accordingly, the invention will be described as embodied in such a water heater, although it is to be understood that I do not intend to be limited thereto.

Electric water heaters are generally old and well known in the art, and commonly include a tank having an electric heating element of the high resistance type extending into the tank adjacent 'the bottom thereof, and have a cold water inlet positioned above the heating element so as to introduce cold water from a source of supply into the tank as the hot water is withdrawn therefrom through suitable piping. Such heaters are normally provided with suitable thermostats for controlling the application of electric current to the heating element in accordance with the temperature of the water in the tank. 25 In the ordinary type of water heater described, especially Where water containing large amounts of calcium or other salts must be heated, the deposit of these salts on the directly heated surfaces of the heating element is very great. It has been stated that this deposit of undesirable salts is due to the fact that ebullition, or the formation of steam, takes place in the water in contact with these surfaces, and a typical boiler scale is formed which greatly reduces the heat transfer from the metal of the heater element to the water. The formation of such scale, which I define herein as meaning any type of deposit from the water, such as, for example, calcium salts, lime salts, or other salts, may be more accurately explained as resulting from the creation of a supersaturated solution thereof in contact with the surface of the heating element from which the scale is deposited, although this normally occurs only when ebullition takes place. Consequently, heaters of this type require frequent cleaning, which is expensive and troublesome to the users thereof.

In some of the prior art heaters of this general type, furthermore, the areas of the heating elements are maintained at a minimum, with resultant high temperatures per unit areas. In heaters of this type scale quickly forms on the surfaces of the heating element due to the high temperature per unit area thereof, which is undesirable.

(Cl. 21S-39) I have discovered that the formation of scale on a heating element, as described above, may be prevented or reduced to a minimum by directing the flow of cold inlet water over at least part of the surface of the heating element, and, therefore, this is primary object of my invention.

It is another object of my invention to provide a heating element for an electric Water heater of a novel form having a large surface area so as to permit maintaining a low temperature per unit area on the surface of the heating element.

Still another object of the invention is to provide an electric water heater having a heating element of tubular cage form and providing a nozzle means for directing a ow of cold inlet water through the interior of the cage before it is permitted to mix with the warm water in the heater surrounding the cage.

Another object of my invention is to provide a water heater having a surface providing a source of heat for water in the heater, there being means for directing a now of Coldwater over and in contact with at least a portion of the surface so as to prevent the formation of scale thereon and to remove any scale formed thereon.

Other objects and advantages of .my invention will appear from the following specification and the drawing, which are for the purpose of illustration only, and in which:

Fig. 1 is an elevational view partly in. section of a water heater embodying my invention.

Fig. 2 is an enlarged perspective view of the novel form of nozzle of my invention.

Fig. 3 is an enlarged view, partly in section, of the heating element of the invention.

Fig. 4 is an enlarged sectional view taken on the line 4-4 of Fig. 3.

Referring to the drawing, Fig. l shows an outer shell Il) having a base El therein spaced upwardly from the lower end of the shell and provided with an annular flange l2 for supporting a water tank i3 which serves as a storage reservoir for hot water and also provides a compartment within which the water may be heated as hereinafter described. The tank i3 is provided with an inlet pipe lll which passes upwardly through the base ll, between the tank and the outer shell l Q, and is suitably connected to an inlet means l5 to be described hereinafter. The inlet pipe I4 and the inlet means l5 are adapted to convey water from a source of supply (not shown) to the interior of the tank l 3 for the purposes of heating and storage. The water tank i3 is also provided with a discharge pipe l5 which likewise passes upwardly through the base l l, be-

tween the tank and the outer shell l0, and is connected to the top of the tank as is well known in the art. The discharge pipe l5 serves to convey hot water from the'water tank i3 to a suitable point of use (not shown).

As will be noted, the inlet pipe lil extends to a point above the top of the water tank i3 and is connected at this high point to the discharge pipe i6 by meansof a by-pass tubing il. The purpose of the by-pass tubing l? is to prevent water in the tank i3 from being accidentally siphoned therefrom through the inlet pipe ifi in the event of a failure of pressure in the source of supply and an opening of other valves or faucets communicating with the inlet pipe. If this occurs, some water may be siphoned out of the tank i3 to create a partial vacuum at the top thereof, but as soon as the partial vacuum is created it is communicated to the inlet pipe l@ through the by-pass tubing Il, and no further water is siphoned out of the tank i3, thus maintaining water at all times in the tank above the level .of the heating element therein, as described hereinafter.

Secured to the inner wall of the outer shell l is a heating element box i9 having a suitable opening 53S in the inner wall thereof aligned with an opening 2i formed by a fiange collar 22 on a wall of the water tank i3. Extending into the water tank i3 through the openings 2! and 2l is a heating element 23, shown in detail in Figs. 3 and 4. The heating element 23 has a base member 24 adapted to be secured to the wall of the heating element box IB by suitable bolts 25 or otherwise so as to form a fluid-tight cover for the opening 2d. Extending through suitable openings 2S in the base member 2li are a plurality of tubular blade members 27 positioned to form a circle as shown in Fig. 4. The outer ends 23 of the tubular blade members 2l' are sealed closed, as by brazing or otherwise, and an annular spacer ring 29 is provided adjacent thereto in order to hold the outer ends of the blade members rigid relative to each other. The blade members 2l may be soldered or otherwise secured to the base member 2li so as to provide a Huid-tight joint therewith. Each of the blade members il is provided with a high resistance wire 3&5 insulated from the inner surface of the blade members by a suitable thin insulating jacket 3l formed of mica or other heat resistant material, the ends of the wires 3i! being connected to an electric current line 32 which leads out of the shell l@ through the base l l to a suitable source of power. Connected in the electric current line 32 is a thermostatic switch mechanism 33, as is well known in the art, comprising a thermostat element 3d projecting into the interior of the water tank i3 and being housed in a housing 35 formed on the tank, and a switch mechanism 3E adapted to be actuated in response to changes in temperature recorded by the thermostat element. Accordingly, when the temperature inside the water tank i3 drops below a predetermined minimum, the thermostat element 3d operates the switch mechanism 3@ to complete the circuit in the electric current line 32 to supply electricity to the high resistance wires 30, which quickly serves to heat the interior of the tank i3 and any water contained therein. It is to be noted that the blade members 2i' of the heating element 23 arel formed so as to provide a relatively large surface area in contact with the water in the tank i3, so that the temperature per unit of area of the blade members is maintained relatively low. As

pointed out herein, the maintenance of low temperature per unit of area on the heating element decreases the tendency of the unit to form scale and facilitates the removal of such scale as may be formed. Preferably each blade presents in cross section a flat gure with one of its edges directed toward the axis of the cylindrical chamber enclosed by the blades and with its sides in juxtaposition with the sides of the next adjacent blades.

In the preferred embodiment shown, the inlet means i includes a pipe elbow ii@ having threads Lil adapted to receive the threaded end of the inlet pipe lli and having external threads l2 adapted to be threadedly received in a liange collar 43 carried in a suitable opening in the tank I3. Formed integrally with the pipe elbow ill or attached thereto by suitable means is a tubular nozzle il@ having formed in the end thereof slots t5 to form ngers ri, the fingers being crimped.l together at their outer ends to provide a substantially circular orice (il. As shown in Fig. 1, the inlet means i5 when in position has its tubular nozzle ill projecting into the interior of the tank i3 and into the open end of the heating element 23, in axial alignment therewith. Connected to the lower end of the tank i3 is an exhaust pipe 50 having an exhaust valve 5l connected thereto so as to permit drainage of the tank by manual means as desired.

In operation, cold water is introduced into the tank I3 through the inlet pipe ld and the inlet means l5, the cold water being ejected through the tubular nozzle bld under line pressure so as to create a yflow of cold water longitudinally through the cage or chamber formed by the tu, bular blade members 2l of the heating element 23. Some cold water is also discharged from the tubular nozzle Lili through the slots l5 in a radial direction, so that the flow therefrom is both longitudinal and radial. When electric current is introduced into the electric current line 32 by suitable switching means (not shown), the thermostatic switch mechanism 33 operates in response to the temperature of the cold water in the tank i3 to close the circuit in the electric current line, and current is then supplied to the high resistance wires Si) of the heating element 23, accompanied by a material rise in temperature thereof which is transferred through the insulating jacket 3i to the tubular blade members 2 from which it is transferred to the water in the tank I3, thus raising the temperature of the water in the tank. Action of the heating element 23 continues until the temperature of the water in the tank I3 rises to a predetermined value, at which time the thermostatic switch mechanism operates to open the circuit of the electric current line 32, thus shutting off the current supplied to the high resistance wires 3Q. Insulating material, such as finely ground cork, 52 is provided between the walls of the tank is and the inner walls of the shell il) so as to retain as much of the heat within the tank l 3 as possible. However, as soon as the heating element 23 is deenergized, the temperature of the water in the tank I3 will commence to decrease by heat radiation or by withdrawal of hot water and will continue to do so until the temperature reaches a predetermined minimum, at which time the thermostatic switch mechanism 33 will operate to again energize the heating element 23. This cycle of heating and allowing the water to cool in the tank i3 causes the formation of scale on the tubular blade members 2l of the heating element 23. This formation of scale is retarded or prevented entirely by providing the heating element with a large surface area and maintaining a low temperature per unit area thereon when the element is energized. When the line of the discharge pipe IS is open, as by opening a faucet or other valve in the line, the line pressure in the inlet pipe I4 causes a discharge of hot water from the interior of the tank I3 into and through the discharge pipe I6, and at the same time a ow of cold water enters the tank through the inlet means I5. As described hereinabove, cold Water is discharged into the tank I3 from the tubular nozzle i4 in a longitudinal stream which travels through the interior of the cage or chamber formed by the tubular blade members 21 of the heating element 23 and also in radial streams forced outwardly through the slots 45 of the nozzle. The cold water then leaves the cage or chamber formed by the tubular blade members 21 and passes into the other portions of the tank through the elongated, relatively narrow outlets dened between adjacent blades and having deep extended side walls. The inow of cold water to the heating element exerts a washing action on the tubular blade members thereof, tending to remove scale therefrom, and quickly reduces the temperature of the water in the area adjacent the thermostatic switch mechanism 33 so as to actuate the switch mechanism to energize the heating element 23. Energization of the heating element 23 causes the tubular blade members 2l thereof, which are ordinarily formed of a metal such as copper, to expand materially, whereas the action of the stream of cold water flowing into the tank I3 through the inlet means I5 tends to cause the scale formed on the tubular blade members to contract, thus creating an unequal expansion and contraction of the blade members and the scale, respectively, which is instrumental in causing the scale to crack and peel off the blade members, it being washed therefrom by the action of the cold water and settling to the bottom of the tank I3 in small particles or remaining in suspension in the water in the tank so that these particles may be carried out of the tank through the discharge pipe line I6. It will thus be recognized that every time water is drawn out of the tank through the discharge pipe I6 and cold water is injected into the tank through the inlet means I5, the unequal expansion and contraction conditions set up, described above, will remove scale from the tubular blade members 2l, thus preventing the accumulation of large deposits of scale during normal use of the unit. Furthermore, by utilizing a jet of cold water projected from the tubular nozzle 44, I accomplish a very desirable washing action on the blade members 2l, which tends to carry away any particles of scale removed by the relative expansion and contraction described. Also, as will be noted, since the jet of cold inlet water projected through the inlet means I5 is directly in contact with a material portion of the surface area of the blade members 2'! providing a rapid circulation of cool water therearound, the tendency to form scale is greatly reduced during the inflow of the cold water since the concentration of the solution of scaleforming salts near the surface of the tubular blade members is prevented by the inflow, as is also prevented ebullition of the water at this point.

It will thus be understood that I have shown and described a device which not only prevents or tends to prevent the formation of scale on the heating element thereof, but also eiectively removes any scale formed in small pieces prior to the accumulation of substantial amounts thereof. This is particularly advantageous in that the particles of scale removed from the heating element 23 are suiiiciently small to be carried out of the tank I3 with the water discharged therefrom through the discharge pipe I6, and no substantial accumulation of large particles occurs in the bottom of the tank. This obviates the disadvantages found in heaters of the prior art type in which if there is any removal of scale at all, it is removed in large akes which cannot be carried out of the heater tank through the discharge line thereof, but accumulate in the bottom, requiring periodic cleaning operations which are both expensive and inconvenient. In accomplishing my desired results, the particular form of inlet means l5 and its cooperating relation to the heating element 23 are an important feature of the invention, and although I have shown a preferred embodiment thereof, it will be understood that anyI other construction may be substituted therefor which will accomplish the ends desired, i. e., to.. introduce cold inlet water into a heater tank so as to impinge on at least a substantial area of the heating element thereof. Furthermore, although I have shown and described my invention in simple and practical form, it is to be recognized that certain parts or elements thereof are representative of other parts, elements, or mechanisms `which may be used in substantially the same manner to accomplish `substantially the same results, and, therefore, it is to be understood that the invention is not to be limited to the details disclosed herein but is to be accorded the full scope of the following claims.

I claim as my invention:

l. In a water heating device, the combination of: a tank for retaining water; a plurality of elongated heating elements in said tank providing a relatively large total exterior heating area and arranged to encompass a central chamber and to provide narrow outlets from said chamber to the other portions of said tank, said outlets having relatively extended side Walls; and means for directly introducing cold water from outside said tank into said chamber and discharging said water to all portions of said chamber and through said outlets.

2. In a water heating device, the combination of: a tank for retaining Water; a relatively large number of elongated heating elements arranged annularly in the interior of said tank with their sides in relatively close juxtaposition to enclose a cylindrical chamber circumferentially bounded by said elements, said chamber having elongated, relatively narrow, longitudinally arranged radial outlets formed between adjacent elements; and means for directly introducing cold water from outside said tank into one end of said chamber and directing it in a longitudinal stream through substantially the entire length of said chamber.

3. In a water heating device, the combination of: a tank for retaining water; a relatively large number of elongated heating elements arranged annularly in the interior of said tank with their sides in relatively close juxtaposition to enclose a cylindrical chamber circumferentially bounded by said elements, said chamber having elongated, relatively narrow, longitudinally arranged radial outlets formed between adjacent elements; means for directly introducing cold water from outside said tank into one end of said chamber and directing it in a longitudinal stream through substantially the entire length of said chamber;

and means for closing the end of said chamber remote from said one end of said chamber.

4. In a water heating device, the combination of: a tank for retaining Water; a plurality of relatively flat, elongated heating elements arranged annularly in the interior of said tank with their sides in relatively close juxtaposition to enclose a cylindrical chamber circumierentially bounded by the edges of said elements, said chamber having elongated, relatively narrow, longitudinally arranged radial outlets formed between the sides of adjacent elements; and means for directly introducing cold water from outside said tank into one end of said chamber and directing it in a longitudinal stream through substantially the entire length of said chamber.

5. Ina water heating device, the combination of: a tank for retaining water; a relatively large number of relatively dat, elongated heating elements arranged annularly in horizontal position in the interior of said tank with their sides in relatively close juxtaposition to enclose a cylindrical chamber circumferentially bounded by the edges of said elements, said chamber having elongated, relatively narrow, longitudinally arranged radial outlets formed between the sides of adjacent elements; and means for directly introducing-cold water from outside said tank into one end of said chamber and directing it in a longitudinal stream through said chamber.

c 6. In a water heating device, the combination of: a tank for retaining water; a relatively large numberof relatively flat, elongated heating elements arranged annularly in the interior of said tank with their sides in relatively close juxtaposition to enclose a cylindrical chamber circumferentially bounded by the edges of said elements, said chamber having elongated, relatively narrow, longitudinally arranged radial outlets formed between the sides oi adjacent elements; means for directly introducing cold Water from outside said tank into one end of said chamber and directing it in a longitudinal stream through substantially the entire length of said chamber; and means for closing the end of said chamber remote from said one end oi said chamber.

`r7. In a water heating device, the combination of: a tank for retaining water; a relatively large number of elongated heating elements arranged annularly in the interior of said tank with their sides in relatively close juxtaposition to enclose a cylindrical chamber circumferentially bounded by said elements, said chamber having elongated,

relatively narrow, longitudinally arranged radial outlets formed between adjacent elements; and means for directly introducing cold water from outside said tank into one end of said chamber and directing it both in a longitudinal stream through substantially the entire length of said chamber and in radial streams toward said outlets.

8. In a water heating device, the combination of: a tank for retaining water; a relatively large number of elongated heating elements arranged annularly in the interior of said tank with their sides in relatively close juxtaposition to enclose a cylindrical chamber circumferentially bounded by said elements, said chamber having elongated, relatively narrow, longitudinally arranged radial outlets formed between adjacent elements; means for directly introducing cold water from outside said tank into one end of said chamber and directing it both in a longitudinal stream through substantially the entire length of said chamber and in radial streams toward said outlets; and means for closing the end of said chamber remote from said one end oi said chamber.

9. In a water heating device, the combination of: a tank for retaining water; a relatively large number of relatively flat, elongated heating elements arranged annularly in horizontal position in the interior of said tank and adjacent the bottom thereof, with their sides in relatively close juxtaposition to enclose a cylindrical chamber circumferentially bounded by the edges of said elements, said chamber having elongated, relatively narrow, longitudinally arranged radial outlets formed between the sides of adjacent elements; means for directly introducing cold water from outside said tank into one end of said chamber and directing it both in a longitudinal stream through substantially the entire length of said chamber and in radial streams toward said outlets; and means for closing the end of said chamber remote from said one end of said chamber;

HARRISON I-I. FOGWELL.