US3612004A

US3612004A - Water heater

Info

Publication number: US3612004A
Application number: US879153A
Authority: US
Inventors: Edward Cancilla; Bernard E Mcclanahan
Original assignee: ACE TANK AND HEATER CO
Current assignee: ACE TANK AND HEATER CO
Priority date: 1969-11-24
Filing date: 1969-11-24
Publication date: 1971-10-12
Anticipated expiration: 1988-10-12

Abstract

A water heater in which water is circulated through a coil wound in the form of a truncated cone with a base turn thereof of maximum diameter disposed adjacent the inner wall of the heater housing and the remaining turns thereof having diminishing diameters proceeding from the base turn to the top of the coil. By supporting the base turn of the coil, the remaining turns of the coil are substantially self-supporting and can undergo considerable expansion and contraction in response to temperature changes within the heater. The coil generally conforms to the shape of the flame generated by a burner located below the coil and provides for a relatively high rate of heat transfer to the circulating water when equipped with a baffle. The coil baffle may comprise a striplike element wound about and mounted on the outside of the coil so as to extend between adjacent coil turns.

Description

United States Patent Inventors Edward C'ancilla Los Angeles; Bernard E. McClanahan, La Habra, both of Calif. Appl. No. 879,153 Filed Nov. 24, 1969 Patented Oct. 12, 1971 Assignee Ace Tank and Heater Company WATER HEATER 9 Claims, 4 Drawing Figs.

U.S. Cl 122/250 R, 122/367 C Int. Cl F221; 21/26 Field of Search 122/249, 250, 367 C; 165/163 References Cited UNITED STATES PATENTS 1,979,008 10/1934 Morrow 122/250 l/1964 Russell et a1 122/250 FOREIGN PATENTS 455,351 1/1928 Germany 122/249 501,884 7/1930 Germany 122/249 Primary Examinerl(enneth W. Sprague Attorney-Fraser and Bogucki ABSTRACT: A water heater in which water is circulated through a coil wound in the form of a truncated cone with a base turn thereof of maximum diameter disposed adjacent the inner wall of the heater housing and the remaining turns thereof having diminishing diameters proceeding from the base turn to the top of the coil. By supporting the base turn of the coil, the remaining turns of the coil are substantially selfsupporting and can undergo considerable expansion and contraction in response to temperature changes within the heater. The coil generally conforms to the shape of the flame generated by a burner located below the coil and provides for a relatively high rate of heat transfer to the circulating water when equipped with a bafi'le. The coil baffle may comprise a striplike element wound about and mounted on the outside of the coil so as to extend between adjacent coil turns.

PATENTEDUBHZISYI 3,612,004

INVENTORS EDWARD CANOILLA By BERNARD E. MCOLANAHAN FIG.- 4 z ATT NEYS WATER HEATER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to liquid-heating systems and more particularly to a new and improved heater for use in liquidheating systems.

2. Description of the Prior Art Where a large volume of a heated fluid is required, as for example in commercial lauridries and swimming pools, it is well known to recirculate a volume of fluid between a reservoir, pool or tank and a heating apparatus within which the temperature of the fluid is raised by the transfer of heat energy from the burning of a combustible material such as gas. In general, previously known coiland tube-type heaters-have suffered from numerous disadvantages. Such heaters frequently experience heat exchanger distortion due to the expansion and contraction undergone when operating under ambient temperature conditions of, for example, 40 F. to 140 F. during the nonfiring period and firebox combustion temperatureconditions of, for example, 1,500" F. to 1,700 F. during the heating cycle. Such distortion opens the flue gas passages thereby reducing the heat exchanger efficiency and the heat exchanger capacity. Substantial floorspace is often required due to the elongated arrangement of straight tube heater boilers. The result has been a high cost of operation due to loss of heat exchanger efficiency and heat exchanger capacity and a relatively short heater boiler life due to eventual loss of capacity.

One arrangement of a water heater which overcomes the above-noted disadvantages is illustrated in U.S. Pat. No. 3,118,430 of James A. Russell and Bernard E. McClanahan, issued Jan. 21, 1964. Such arrangement utilizes a uniquely shaped coil in combination with a baffle plate to provide greatly improved efficiency through the achievement of relatively high heat transfer rates per surface area of the coil tubing. The coil is shaped so as to form two truncated cones, the top and bottom turns thereof of maximum diameter being disposed adjacent the inner wall of the heater housing and the coil diameter diminishing in directionsproceeding inwardly from the opposite top and bottom turns to a minimum substantially at the midpoint therebetween. With the baffle plate mounted within the coil and adjacent the midpoint, hot combustion gases generated within the heater housing and below. the coil rise to the inside of the lower portion of the coil where they are directed through the coil to the outside thereof, then back through the coil to the inside at the upper portion thereof.

A different type of water heater which provides for relatively high rates of heat transfer circulates water through a plurality of horizontal, generally parallel tubes having baffle elements which may be of generally T-shaped cross section.

mounted in conjunction therewith. Such arrangements however require a rather elaborate burner array to properly heat the tubes. Moreover, the parallel tube and baffle structure typically undergoes rapid deterioration, even where substantial bracing and support is provided, resulting in a substantial reduction in the heat transfer rate.

Accordingly, a heat exchanger with a coil arrangement of the tubing is generally preferred. Such arrangements are generally self-supporting, highly efficient and capable of withstanding expansion and contraction over long periods of time without deterioration. Factors such as the variable coil angle allow design optimization of heat exchanger efficiency versus free flow of combustion flue gas required for clean, safe and efl'icient combustion in a heater boiler fired by gas or other fuels. Coiled arrangements of the tubing generally conform to the natural shape of the combustion flame pattern in a round heater boiler allowing the design of a smaller, more compact boiler. Such arrangements offer additional design advantages by insulating the top portion of the combustion chamber thereby reducing insulating costs and the heat loss of the heater boiler. However, while the particular coil arrangement-shown in U.S. Pat. No. 3,1 18,430 functions in a highly efficient and effective manner, it may be desirable for some heater applications to provide a somewhat different type of arrangement. This may result from manufacturing or production considerations. It may also result from design considerations such as the degree to which the coil may be self-supporting and thereby not require extensive internal bracing, the extent to which the coil may expand and contract to accommodate relatively high temperatures and temperature changes, and the degree to which the total coil length may be shortened to lower its cost or the overall size of the heater without accompanying reduction in the heating capacity.

BRIEF SUMMARY OF THE INVENTION The present invention provides a liquid heater in which the liquid is circulated through a heating coil made of tubing fitted with fins concentric to the tubing and spaced over a substantial portion of its length. The coil is wound into a truncated cone having a maximum diameter at the bottom winding or turn thereof, the diameter diminishing in an upward direction from the bottom turn to the top turn. I-Iot combustion gases generated within the heater housing and below the heating coil rise to the coil where they pass between adjacent turns of the coil from the inside to the outside of the coil to heat the liquid. Generation of the gases is controlled according to the temperature of the liquid at the heater output to maintain the liquid at a constant selected temperature level. The liquid is continuously circulated through the' heater, to make the heated liquid available upon demand for delivery to the point of use.

In accordance with particular features of the invention, the heating coil is provided with a flue baffle at the top thereof and a coil baffle onthe outside thereof. The platelike flue baffle is disposed within the top coil turn to force hot combustion gases at the inside of the coil through the adjacent turns to the outside. The coil baffle extends between adjacent turns of the coil delaying the passage of combustion gases therethrough and at the same time increasing the turbulence of the gases. The coil baffle may comprise a striplike element wound into a coil so as to extend between each adjacent pair of turns when mounted on the outside of the coil. The striplike element is preferably generally L-shaped in cross section so as to present two generally planar portions thereof for mounting on different onesof each adjacent pair of turns of the coil. Alternatively the coil baffle may comprise an integral or unitary element generally shaped in the form of a truncated cone for mounting on the outside of the coil.

In accordance with particular aspects of the invention, the reduced speed and greater turbulence of the hot combustion gases as provided by the coil baffle greatly increase the rate of heat transfer from the hot gases to the liquid in the tubing, providing a greater amount of heat transfer to the liquid per unit area of tubing surface. The shape of the coil itself generally conforms to that of the flame from a gas-generating burner located below the coil to further enhance the rate of heat transfer. Less tubing is accordingly required to effect a given amount of heat transfer, enabling the construction of heaters of lower cost and smaller size for a given heating capacity. With the lowest or base turn of the coil supported within the heater housing, the remaining turns lend considerable physical support to one another without the need for cumbersome bracing and support members within the heater. The coil is thereby free to expand and contract over a much greater range enabling the use of higher temperatures and greater temperature ranges of operation. This allows a considerably greater latitude in the variation and control of design parameters such as flue gas products, flue gas temperature, stack or exhaust gas temperature, and thermal efficiency to obtain higher heat transfer loading.

In accordance with further aspects of the invention, the circulating liquid travels a circuitous path through the heater, and the heat applied to the circulating liquid is diverted within the heater so as to contact as much of the circulating liquid as possible. All obstructions are removed from the liquid flow path within the heater, providing for the flow of a relatively large volume of the liquid through the heater for use upon demand.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more par ticular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings, in which:

FIG. 1 is an elevated view of a heater in accordance with the present invention;

FIG. 2 is a sectional view of the heater of the present invention taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged sectional view of several turns of a coil and accompanying baffle shown in FIG. 2; and

FIG. 4 is a perspective view of the coil and accompanying baffle shown in FIG. 2.

DETAILED DESCRIPTION The following description of the present invention and its operation will be given, utilizing water as an example of the liquid which is to be heated and maintained at a predetermined temperature. It is to be understood, however, that any liquid may be utilized which is to be maintained at a predetermined temperature and supplied in volume upon demand.

Referring now to the drawings, and particularly to FIG. 1 thereof, there is illustrated an elevational view of a heater in accordance with the present invention. As is therein shown, the heater includes an outer jacket 11 having an outer top 12 and a base 13. Protruding from the outer top 12 is an exhaust stack 14 having an apron 15 at the upper end thereof. The exhaust stack 14 and the apron 15 provide a conduit for exhaust gases from the heater housing through the stack to a chimney or vent (not shown) in normal operation, and also provide an escape path for the exhaust gases in the event that the chimney or vent attached to the stack 14 becomes obstructed.

Located beneath the base 13 of the housing 11 is an upper floor pan 16 and a fire shield 17. Beneath the fire shield there is disposed a lower floor pan 18. Protruding from the side of the outer jacket 11 of the heater is a water outlet 19 and a water inlet 21. Disposed adjacent the water inlet 21 is a drain cock 22. In the normal course of operation, water to be heated enters through the water inlet 21, passes through the heater, and is removed from the heater by way of water outlet 19. In case the water distribution system is shut down for main tenance repairs, or the like, the water may be drained from the heater by use of the drain cock 22.

Located adjacent the water outlet 19 is a heat control unit or thermostat 23. The thermostat is adapted to sense the temperature of the water which leaves the heater and serves as a high-temperature limiting element to prevent overheating of the water. The thermostat 23 is interconnected by means of conduit 31 and junction box 32 to a solenoid valve 25 which is utilized to control the flow of gas to the burner. The solenoid 25 is disposed within a gas inlet conduit 24.

Also disposed within the gas inlet conduit 24 is a gas pressure regulator 26. The regulator is utilized to maintain the pressure of the gas entering the gas burner relatively constant, irrespective of pressure variations in the gas source connected to the conduit 24. A main gas valve 27 is also connected within the gas inlet conduit 24. A pilot light gas inlet tube 28 extends from the main gas valve 27 through and into the gas burner disposed within the fire shield 17 located beneath the base 13 of the heater. A pilot safety control valve 29 is disposed between the pressure regulator 26 and the solenoid gas valve 25. The function of the pilot safety control is to remove the supply of gas from the main burner if the pilot light should become extinguished in a manner well known to the prior art. For this purpose, a thermocouple (not shown) may be positioned adjacent the pilot light flame and connected to the valve 29 via a conduit 29A.

Referring now more particularly to FIG. 2, a heater in accordance with the present invention is illustrated in a sectional view taken along line 2-2 of FIG. I. As is illustrated in FIG. 2, the heater includes an innerjacket 41. A layer of insulation may be provided between inner jacket 41 and outer jacket 11. Supported within the inner jacket 41 is a heater coil 42 in the shape of a truncated cone. The coil 42 comprises tubing 43 of appropriate heat transfer material such as copper having a plurality of fins 44 of copper or other appropriate material concentrically mounted on the outside of the tubing 43 over substantially the entire length thereof, The coil 42 has a base or bottom winding or turn 45 of maximum diameter supported by the inner jacket 41. Although the turn 45 may be mounted against the inner jacket 41 using a bracket or other appropriate device, the turn 45 is preferably supported by at least one strap 46. The strap 46 has the opposite ends thereof affixed to the top of the inner jacket 41 so as to extend downwardly and encircle the bottom turn 45, as shown in detail in FIG. 3. The diameters of the remaining turns of the coil 42 diminish in an upward direction to a minimum at an upper or top winding or turn 47. The upper end of the coil 42 is connected to a water outlet coupling 48 of the water outlet 19, and the lower end of the coil 42 is connected to a water inlet coupling 49 of the water inlet 21. A platelike flue baffle 50 is positioned against the upper or top turn 47 of the coil to close off the upper end of the coil. The flue baffle 50 is affixed to a bracket 51 extending between the opposite walls of the inner jacket 41. The bracket 51 forces the flue baffle 50 against the top turn 47 of the coil 42 lending support to the upper portion of the coil and at the same time cooperating with the strap 46 to allow considerable expansion and contraction of the coil 42 due to temperature changes, A coil baffle 52 is mounted on the outside of the coil 42 so as to extend between adjacent turns of the coil.

Disposed within the upper floor pan 16 is a burner ring 53 and a burner head 54 which are adapted to cooperate in the manner of a Bunsen burner. The burner ring 53 is supported by a bracket 55.

In operation, when gas is supplied to the burner ring 53 and is ignited by the pilot light, the flame therefrom extends through the burner head 54 and up into the interior of the heater unit. The flames as they extend upward are drawn toward the exhaust stack 14 so that the flames and hot exhaust gases contact the heater coil 42. The flames assume a configuration similar to the inside of the coil 42 to provide maximum heating of the coil 42. As the flames and gases contact the heater coil, heat is transmitted through the heater coil and to the water which is flowing therethrough. The hot combustion gases rise to the inside of the coil 42 where they are caused by the flue baffle 50 to pass between the adjacent turns of the coil to the outside of the coil, then to the exhaust stack 14. The flue baffle 50 may be fabricated of any appropriate material such as stainless steel or cast iron which will not distort due to temperature changes.

In accordance with the invention, the coil baffle 52 causes the hot combustion gases to pass between the turns of the coil 42 with less speed and greater turbulence, providing a greater rate of heat transfer to the water circulating through the coil. The coil baffle 52 resides on the outside of the coil 42 as defined by the outer edges of the fins 44 and restricts the flow of the gases to relatively narrow paths as defined by the space between adjacent lengths of the tubing 43 provided by the spaced fins 44 and openings 56 provided between adjacent lengths of the baffle 52.

The particular coil baffle 52 of FIG. 2 is illustrated in greater detail in FIGS. 3 and 4 in conjunction with the heater coil 42, the coil 42 being illustrated primarily in dotted outline in FIG. 4 for clarity. In the particular arrangement of the coil baffle 52 so illustrated, the baffle 52 comprises a striplike element 57 wound in the form of a truncated cone so as to have a maximum diameter at the bottom or base turn thereof and a regularly diminishing diameter in a direction proceeding toward the top thereof. The element 57 is mounted on the outside of the coil 42 so as to extend between adjacent turns of the coil. The striplike element 57 is bent along an axis generally parallel to the longitudinal axis thereof so as to assume a generally L-shaped cross section, the two resulting generally flat or

planar portions

58 and 59 thereof on the opposite sides of the bend being mounted on different ones of each adjacent pair of turns of the coil 42. The striplike element 57 may be made of any appropriate material, such as gauge steel, which is easily formed, will maintain its shape, and will not distort when subjected to substantial temperature changes. The element 57 is mounted on the outside of the coil 42 as defined by the edges of the fins 44 using an appropriate technique such as brazing.

The particular coil baffle 52 illustrated in FIGS. 2-4 is shown and described for purposes of example only, and it should be understood that other appropriate arrangements may be used according to the invention. In one alternative arrangement, for example, the baffle 52 comprises a single or unitary element of appropriate material configured in the form of a truncated cone. The unitary element includes an appropriate array of apertures or perforations therein to provide a suitable combustion environment. The coil 42, moreover, need not be circular in cross section but instead can have a cross section which is oval or rectangular in shape where design considerations so dictate.

It will be appreciated by those skilled in the art that the higher rate of heat transfer provided by the coil and baffle combination of the present invention provides higher water temperatures or larger volumes of water having a given temperature. Moreover, for a given quantity of water to be supplied at a given temperature, the resulting heater may be reduced in size and cost. For example, heaters constructed according to the invention have been found to provide a heat loading on the order of 8,000 B.t.u. per square foot of heating surface as opposed to a heat loading on the order of 5,000 B.t.u. per square foot of heating surface in the case of heaters of the type shown in the previously referred to US. Pat. No. 3,1 18,430. With the bottom turn 45 of the coil 42 supported by the strap 46 against the heater housing, the remainder of the coil 42 is substantially self-supporting and requires little in the way of internal bracing or support members. The coil 42 is accordingly free to expand and contract over a considerable range, permitting the use of relatively high temperatures and substantial temperature ranges. in water heaters constructed and tested according to the invention, combustion gases having temperatures within a range of l,400 to 2,000 F. were easily accommodated in conjunction with nonoperating or ambient temperatures on the order of 32 to 70 F. The high heat transfer rate and coil flexibility provided by the invention give the designer considerable latitude in varying and controlling design parameters of the heater such as the flue gas products, the flue gas temperature, and the thermal efficiency to obtain high heat transfer loading.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in fonn and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. For use in a heater in which hot gases are directed onto a tubular member to heat liquid circulating through the tubular member, the tubular member having at least two different lengths thereof disposed adjacent one another, a baffie for mounting on the tubular member to slow and create a turbulence among hot gases flowing between the adjacent lengths of the tubular member, the baffie including a striplike element bent along a longitudinal axis thereof to form two different portions thereof on opposite sides of the bend, the two different portions of the striplike element being adapted for mounting on different ones of the adjacent lengths of the tubular member so that the element extends between the adjacent lengths.

a gas burner at the base of the combustion chamber for generating hot gases;

a heating coil in the form of a helically wound tubing member having a plurality of fins encircling the member along substantially its entire length, the tubing member being wound with a regularly diminishing diameter of each turn beginning at the base of the coil and proceeding toward the top thereof to form a truncated cone, the fins of adjacent turns of the coil being in contact in order to define the spacing therebetween;

means for positioning the lower end of the coil adjacent to the cylindrical walls in order to prevent the hot gases from flowing along the walls to the outside of the coil;

baffle means associated with the heating coil for restricting the flow of the hot gases through the spacing between the adjacent turns of the coil; and

means for coupling opposite ends of the tubing member of the heating coil to corresponding portions of the waterheating system.

4. The invention defined in claim 3 above, further including second baffle means associated with the heating coil at the top thereof for preventing the hot gases from flowing through the top of the heating coil.

5. The invention defined in claim 4 above, wherein the firstmentioned baffle means comprises a strip of material wound around the mounted on the outside of the heating coil so as to extend between adjacent turns of the heating coil, and the second baffle means comprises a platelike element mounted on the top turn of the heating coil.

6. in a liquid heating system in which hot gases are generated within a housing, the combination comprising:

a heating coil through which liquid to be heated is circulated, the coil being wound with a regularly diminishing diameter of each turn beginning at one end of the coil an proceeding toward the other end thereof, the coil being disposed within the housing to permit the hot gases to flow between the turns thereof; and

baffie means associated with the coil for restricting the flow of the hot gases between the turns of the coil, the baffie means comprising a striplike element wound into a coil having a regularly diminishing diameter of each turn beginning at one end thereof and proceeding toward the other end thereof, the striplike element being mounted on the outside of the heating coil so as to extend between adjacent turns of the heating coil.

7. The invention defined in claim 6 above, wherein the striplike element is bent along an axis thereof so as to be generally L-shaped in cross section, the element as so bent presenting two generally planar portions thereof for mounting on different ones of each adjacent pair of turns of the heating coil.

8. In a liquid heating system in which hot gases are generated within a housing, the combination comprising:

a heating coil through which liquid to be heated is circulated, the coil having a plurality of encircling fins along substantially its entire length and being disposed within the housing to permit the hot gases to fiow between turns thereof; and

a baffie element mounted on the fins so as to extend between adjacent turns of the coil.

9. The invention defined in claim 8 above, wherein the baffle element is an elongated striplike element which is wound into a configuration similar to that of the coil and which includes at least one relatively gradually curved surface common to substantially all of the fins on the coil.

19 UNITED STATES PATENT OFFlCE d] m 1 n CERTlFICAiE OF CORRPJCTION Patent No. 3,612,004 Dated October 12, 1971 Inventor(s) Edward Cancilla et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

in Column 6, line 35, "the" (first occurrence) should read "and"; line 43, "an" should read --and--.

Signed and sealed this 1 1 th day of July 1972.

(SEAL) Attest:

EDWARD M.FLETCHER',JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

Claims

1. For use in a heater in which hot gases are directed onto a tubular member to heat liquid circulating through the tubular member, the tubular member having at least two different lengths thereof disposed adjacent one another, a baffle for mounting on the tubular member to slow and create a turbulence among hot gases flowing between the adjacent lengths of the tubular member, the baffle including a striplike element bent along a longitudinal axis thereof to form two different portions thereof on opposite sides of the bend, the two different portions of the striplike element being adapted for mounting on different ones of the adjacent lengths of the tubular member so that the element extends between the adjacent lengths.

2. The invention defined in claim 1 above, wherein the striplike element is wound into a coil having a regularly diminishing diameter in a direction from one end of the coil to the other end of the coil.

3. A gas burning water heater for use in a water-heating system in which water is continuously circulated through the heater comprising: a combustion chamber having upright cylindrical walls; a gas burner at the base of the combustion chamber for generating hot gases; a heating coil in the form of a helically wound tubing member having a plurality of fins encircling the member along substantially its entire length, the tubing member being wound with a regularly diminishing diameter of each turn beginning at the base of the coil and proceeding toward the top thereof to form a truncated cone, the fins of adjacent turns of the coil being in contact in order to define the spacing therebetween; means for positioning the lower end of the coil adjacent to the cylindrical walls in order to prevent the hot gases from flowing along the walls to the outside of the coil; baffle means associated with the heating coil for restricting the flow of the hot gases through the spacing between the adjacent turns of the coil; and means for coupling opposite ends of the tubing member of the heating coil to corresponding portions of the water-heating system.

5. The invention dEfined in claim 4 above, wherein the first-mentioned baffle means comprises a strip of material wound around the mounted on the outside of the heating coil so as to extend between adjacent turns of the heating coil, and the second baffle means comprises a platelike element mounted on the top turn of the heating coil.

6. In a liquid heating system in which hot gases are generated within a housing, the combination comprising: a heating coil through which liquid to be heated is circulated, the coil being wound with a regularly diminishing diameter of each turn beginning at one end of the coil an proceeding toward the other end thereof, the coil being disposed within the housing to permit the hot gases to flow between the turns thereof; and baffle means associated with the coil for restricting the flow of the hot gases between the turns of the coil, the baffle means comprising a striplike element wound into a coil having a regularly diminishing diameter of each turn beginning at one end thereof and proceeding toward the other end thereof, the striplike element being mounted on the outside of the heating coil so as to extend between adjacent turns of the heating coil.

8. In a liquid heating system in which hot gases are generated within a housing, the combination comprising: a heating coil through which liquid to be heated is circulated, the coil having a plurality of encircling fins along substantially its entire length and being disposed within the housing to permit the hot gases to flow between turns thereof; and a baffle element mounted on the fins so as to extend between adjacent turns of the coil.