US3734065A - Fluid heater - Google Patents

Abstract

A fluid heater, particularly adapted for use with a swimming pool, has a powered gas burner therein for supplying high intensity heat to pool water flowing in a tubular heat exchanger adjacent the burner plate. The heat exchanger is arranged in a heater housing to define therewith a flow path adjacent the tubes for the products of combustion from the burner whereby heat by convection is supplied to the tubes from the exhaust gases. The input end of the heat exchanger includes a valve member adapted to maintain a predetermined rate of flow of water through the tubes and to bypass excess water back to the pool.

Description

United States Patent 1191 Reid, Jr. et al. [451 May 22, 1973 [54] FLUID HEATER 3,118,430 1 1964 Russell et a] ..122 250 R Inventors: Edward A. Reid Robert G. 3,267,909 8/1966 McClanahan ..122/250 R v d l b th fc l b 3,292,598 12/1966 Miller et al. ..l22/406R 3,315,646 4/1967 Witten, Jr. ..122/367 VR [73] Assignee: Columbia Gas System Service Corpgygflon Wil i t D L Primary Examiner-Kenneth W. Sprague Filed Dec 27 1971 Att0rneyHar0ld L. Stults 21 Appl. N6; 212,517 [57] ABSTRACT Related US A li ti Data A fluid heater, lparticularly aldapteg for uze withf a Swimming poo as a powere gas urner t ere1n or [63] Contmuat1on-1n-part of Ser. No. 7,445, Feb. 2, 1970, Supplying high intensity heat to pool water flowing in a tubular heat exchanger adjacent the burner plate. The heat exchanger is arranged in a heater housing to 2% g "122/250 122,367 i define therewith a flow path adjacent the tubes for the d 0 R 367/R products of combustion from the burner whereby heat 1 0 122,367 406 by convection is supplied to the tubes from the exhaust gases. The input end of the heat exchanger in- [56] R f r e Cit cludes a valve member adapted to maintain a e e we 5 e predetermined rate of flow of water through the tubes UNITED STATES PATENTS and to bypassexcess water back to the pool.

2,987,259 6/1961 Lindquist ..122/250 R 17 Claims, 8 Drawing Figures PATENIEU MAY 2: i973 SHEET 3 OF 3 FLUID HEATER This application is a continuation-in-part of copending U.S. Pat. application Ser. No. 7,445, filed Feb. 2, 1970, now U.S. Pat. No. 3,630,175, the disclosure of which is incorporated herein by reference.

This invention relates to fluid heaters and more in particular to a swimming pool heater having a powered gas burner for supplying high intensity heat to pool water.

In swimming pool water treatment systems presently available, water is conducted from the pool through a filtering and circulation system and is generally heated in a heater unit which forms part of the system and flow path for the water. Typically, these units utilize directblue flame non-powered gas burners, and they are relatively inefficient in the production of necessary heat. As a result, the cost of operation of conventional swimming pool heaters in order to maintain desirable water temperatures, particularly in large pools, is inordinately high.

It is an object of this invention to provide a fluid heater unit for efficiently maintaining desired water temperatures in swimming pools. It is another object of this invention to supply increased amounts of heat to water in a swimming pool circulation system. It is a further object of the invention to provide a swimming pool heater wherein the volume of water flowing through the heater is controlled for maximum heat transfer efficiency. It is a still further object of this invention to provide compact, efficient and inexpensive swimming pool water heaters.

In accordance with an aspect of this invention, a generally gas-tight housing is provided in which an apertured base member or gas burner plate is mounted along with a blower to form a powered gas burner system. A heat exchanger comprising a plurality of finned tubes interconnected to permit liquid flow therebetween is positioned below the burner plate to receive the heat of combustion of gases on the burner plate. The heater is sealed so that all of the products of combustion flow between and around the tubes and provide additional heat by convection and conduction to the tubes prior to discharge from the heater. Deflector baffles are provided below the heat exchange tubes and beneath the spaces between conduits to force the products of combustion passing through the heat exchanger to contact the entire surface area of the tubes to provide substantially uniform convective heat thereto.

The burner plates used with the fluid heater of the present invention are formed of a ceramic material having venturi-like apertures or orifices, as disclosed in commonly assigned copending U.S. Pat. application Ser. No. 775,978, filed Oct. 2, 1968, now abandoned, the disclosure of which application is incorporated herein by reference. Flashback of flame through the orifices is prevented by the venturi-like configurations which afford a throat portion of small cross section leading to an expanding or diverging outlet portion so that at least the requisite flow velocity is maintained within the throat portion for avoiding flashback over a relatively wide range of gas flow rates. Combustion of gases within the expanding portion of the orifices prevents lift off of the flame front in all operating conditions and will heat portions of the ceramic plate to incandescence to form radiant heat. By supplying the combustible gas to burners of this type at relatively high mass flow rates, with a powered air supply or blower, as disclosed in commonly assigned copending U.S. Pat. application Ser. No. 116,192, filed Feb. 17, 1971, the disclosure of which application is also incorporated herein by reference, a blue flame operating mode is achieved wherein a stable blue flame flame front is formed on the entire surface of the burner plate which can be modulated to produce heat outputs of up to 2,000,000 BTUs per hour per square foot of surface. This output is substantially above that total available with the infrared mode of operation of the burner plate and thus a greater total heat output is achieved from the combustible gases and the same burner plate so that the capacity of the fluid heater can be increased without any substantial increase in size. Moreover, it is contemplated that the capacity can be varied by simply modulating combustion through the burner plate to increase its heat output and increasing the number of heat exchanger tubes utilized.

Typically, pool water is supplied to the heater of this invention through a control bypass valve which maintains the desired flow of water through the heat exchanger and bypasses any surplus water from the pool filtration system back to the pool.

The construction of the preferred embodiment of the present invention, as well as the advantages thereof will become further apparent from the following specification when considered in conjunction with the accompanying drawing wherein:

FIG. 1 is a perspective view of one embodiment of the swimming pool heater of the present invention showing the front and one side thereof;

FIG. 2 is a perspective view similar to FIG. 1 showing the rear and the other side of the heater;

FIG. 3 is a sectional view of the heater of FIG. 1, with parts broken away, taken on line 3-3 of FIG. 2;

FIG. 4 is a sectional view, with parts broken away, taken along line 4-4 of FIG. 3;

FIG. 5 is a sectional view, taken along line 55 of FIG. 4;

FIG. 6 is a sectional view, similar to FIG. 3, of another embodiment of the invention;

FIG. 7 is a sectional view of the heater of FIG. 6, with parts broken away, taken along line 77 of FIG. 6; and

FIG. 8 is a partial sectional view, taken along line 88 of FIG. 6.

Referring now to the drawings in detail, and particularly to FIGS. 1 and 2 thereof, there is illustrated a generally rectangular swimming pool heater 150, constructed in accordance with the present'invention and having an outer decorative housing 152 including front and rear wall panels 154 and 156 respectively. The rear wall 156 of housing includes three openings 20, 21 and 22 through which the various water and gas lines extend for connection with the heater components therein. Water from the pools filter system is supplied through opening 20 to inlet 24 of a manifold 160 and flows therefrom through a multiple tube heat exchanger 162 which extends between manifold 160 and manifold 164. The heat exchanger illustrated in FIG. 4 is a four pass type which utilizes two tubes 166 in each pass of the water flow from one manifold to the other;

however, it is noted that one, or more than two tubes,

may be used in each pass as desired. As illustrated, however, tubes 166 are arranged in pairs and there are four pairs 168, 169, 170 and 172 extending from rear manifold 160 to front manifold 1.64.

The ends of each of the tubes 166 are mounted in and suitably sealed to, their associated manifold. Manifold 164 includes a central wall 176 which divides the manifold into two separate chambers 178 and 180, whereby chamber 178 connects the downstream end of the first pair of tubes 168 to the upstream end of the second pair 169, and chamber 180 connects the downstream end of pair 170 with the upstream end of pair 172.

Referring now to manifold 160, it is seen that this manifold includes an interior wall 182 which separates the manifold into two sections 184 and 186. Manifold section 184 provides a bypass passage for excess water bypassed from heat exchanger 162 by a valve 40, positioned between manifold inlet 24 and manifold section 186 at the entrance to heat exchanger 162, so that it is returned directly to the pool through outlet passage 36. The center portion of valve 40 includes conduit member 42 which is connected to manifold 160 at one end adjacent the inlet 28 to manifold section 186, and has its free end 46 extending into inlet 24. An annular valve member 48 is slidably mounted on conduit 42 and includes an annular sealing surface 50 adapted to engage a mating valve seat 52 on manifold 160 at inlet 24. Valve member 48 is biased against seat 52 by a spring 54 in order to close the annular opening between conduit 42 and inlet 24.

In pool water heaters it is desirable to maintain a constant flow of water through the heat exchanger to prevent excessive lime build-ups therein, and valve 40 is provided to maintain this desired rate. Thus, the diameter of conduit 42 and the compression characteristics of spring 54 are chosen to permit only the maximum desired flow rate into the heat exchanger so that when the total water flow from the filtration system is equal to or below the desired flow rate through the heat exchanger, all water flow through conduit 42, and through tubes 168.

When the total water flow rate from the filtration system increases above the desired flow rate through the heater, the additional force exerted by the increased flow of water against the tapered face 50 of valve member 48 moves it against the action of spring 54 away from its seat 52. Thus, the additional water flowing into the unit bypasses valve 40 and tubes 168 and flows directly through manifold section 184 to outlet 36 where it is mixed with heated water from the heat exchanger 162 and returned to the swimming pool. Spring 54 is designed to maintain valve member 48 on its seat if the total water flow rate from the filtration system is equal to or less than the desired flow rate through the heater coil.

Manifold section 186 provides intercommunication between the various tubes 166 and is provided with a pair of integral partition walls 190 which divide the section into chambers 192, 194 and 196. Water entering inlet opening 24 of manifold 160 communicates with chamber 192 through valve 40 and at most only the maximum desired flow rate enters chamber 192 through conduit 42. The water in chamber 192 is in direct communication with the inlet ends of the pair of heat exchange tubes 1'68 and flows through these tubes in the first pass across the heater to chamber 178 in manifold 164. The water is returned from chamber 178 on its second pass through conduit 169 to chamber 194 where it is in communication with the inlet ends of the third pair of tubes 170. At the'end of the third pass, the water flows from chamber 180 through tubes 172 to chamber 196 where it is discharged through opening 198 into manifold section 184 and returned through outlet 36 to the pool.

Heat exchanger 162 is mounted in an intermediate portion of housing directly below planar heating unit 210. Heater unit 210 includes a generally rectangular plenum chamber 212 which corresponds substantially in size to the heat exchanger, 162. An apertured ceramic burner plate 214, more fully described hereinafter, is provided as the base of plenum 212. A combustible mixture of gas and air is supplied to plenum chamber 212 through duct 216 from powered blower 218 and a gas supply line (not shown). The air required for combustion is drawn by fan 218 through an opening 220 which is formed in front panel 154 and is provided with a deflector plate 222, thereby eliminating unsightly flues and ducts.

Burner plate 214 is provided with a plurality of venturi-like apertures 220 having a generally cylindrical inlet throat port 78 and an expanding outlet portion 82 on its outer face 224 opposite the upper surfaces of tubes 166. As disclosed in the above-mentioned US. Pat. application Ser. No. 116,192, in burner plates of this type, with relatively high mass flow rates as provided when combustion air is supplied from a powered blower with the combustible fuel, a laminar flow is established in throat portion 78 which is projected into diverging outlet portion 82 as a central jet which separates from the surface of outlet portion 82 so as to create a relatively high velocity turbulent recirculating flow around the central laminar flow or jet.

The diverging outlet portions of the orifices define edges along the surface of the burner plate and as the jet of gas passes out of the orifices adjacent the surface edges a second turbulent recirculating flow is produced at the surface of the plate as the jet separates at the downstream side of the plate and the velocities of the high velocity turbulent flow are decreased as the turbulent flow moves over the edges. The resulting turbulent flow at the surface of the plate provides a self-igniting or piloting action for igniting the air-gas mixture issuing from the diverging portion of the orifice to insure that combustion will occur along the surface of the plate rather than at a location within the diverging portion of the orifices at the high mass flow rate produced by the powered blower arrangement. As a result, a blue flame front, having a relatively short flame length, (less than 1 inch, and typically between one-eighth inch and onehalf inch) is produced on the surface of the plate. It has been found that the heat output of such a burner plate, operated in this manner will be from 200,000 to 2,000,000 BTUs per hour per square foot of surface area. This represents a substantial increase in the amount of heat output and range of heat modulation, as compared to previously proposed conventional gas burners and infrared gas burners. Thus, the heat produced by a given area of burner plate is greatly increased and, as a result, the heater unit of the present invention may be made substantially smaller than other known swimming pool heater units. It is noted that in order to initially ignite the flowing gases, a spark or glow coil ignition system (not shown) is provided in the preferred embodiments in lieu of conventional pilot lights since the latter may readily be blown out under high winds when the heater is used for outdoor pools.

The heat produced by burner plate 214 is directed downwardly toward tubes 166 to heat the tubes and the water flowing therein. These tubes, as seen in FIGS. 3 and 5, are spaced from each other and are provided with radiating fins which are adapted to absorb heat by convection from the products of combustion formed as a result of the combustion in burner 214, which products are discharged downwardly upon and through the spacing between the tubes. It is noted that tubes 166 may be provided with other known types of surface extensions in lieu of fins in order to enhance heat transfer. In addition, because of the relatively short flame lengths occurring with the operation of burner plate 214, the exchanger can be located extremely close (approximately one inch) to the burner plate so that the heat is applied directly to the heat exchanger tubes with little loss of heat by conduction through the walls of the heater between the burner plate and the heat exchanger. As a result, the present fluid heater can be made 60 percent smaller in size than conventionally proposed swimming pool heaters. Moreover, because the plate 214 is above heat exchanger 160, any condensation forming in the heater will form on the relatively cool tubes 166 as the hot gases pass through; this condensate falls from the tubes to the base 240 of housing 150 which is sloped to direct the moisture to a drain 242 for discharge. As a result, no condensate will drip upon the burner plate, as occurs with previously proposed fluid heaters, and thus the heater is still more efficient for that reason. Because condensation forming on the heat exchanger tubes does not affect the operation of the burner, the water flow rates through the heat exchanger can be increased, resulting in increased heater efficiency and preventing build-up of lime deposits in the heat exchanger tubes.

A plurality of generally inverted T-shaped deflectors 230 are mounted below tubes 166 downstream of the flow of products of combustion which deflects the hot gases around the bottom portion of the tubes to increase distribution of the gases and effect an increased and more uniform transfer of convective heat therefrom. While deflectors 230 have been illustrated as T- shaped members, it is noted that other deflector shapes may also be utilized, and in particular it is foreseen that flat or curved plate members will provide satisfactory deflection of gases.

After the products of combustion pass between deflectors 230 they flow downwardly into discharge chamber 232 immediately below heat exchanger 162. Chamber 232 is thermally insulated at its sides and front by plates 234 to conserve heat and effect maximum heat transfer by convection to tubes 162. However, the rear portion of chamber 232 is open to permit the escape of the relatively cooled exhaust gases through an opening 236 having a deflector 238 in rear wall 156.

In operation the heater is adapted to function automatically when the pool pump is in operation and is provided with a conventional thermostat or aquastat (not shown) which senses inlet water temperature. If the water temperature is below the desired minimum temperature, the fan or blower 218 is turned on by conventional control means and when it is up to speed, the electric gas valve and ignition system are actuated to start the burner and heat pool water flowing through valve 40 and tubes 168. A flame proving system (not shown) is provided to detect ignition and shut down the burner on failure of the burner to ignite. In addition, a high limit temperature switch in the outlet 36 of manifold 160 may be provided to prevent overheating of the unit in the event of insufficient water flow and a timer can be incorporated with blower 218 to cool the unit after the burner shuts off and thereby reduce the lime build-up in the heat exchanger.

An important feature of the present construction, particularly the use of the powered blue flame burner arrangement, is the fact that the heat output of the burner can be modulated over a wide range up to at least 2,000,000 BTU s per hour per square foot so that the capacity of the fluid heater can be readily varied. It has been found that the heat output of the heater can be increased by increments of 250,000 BTUs per hour simply by increasing the number of ports on the burner plate, using a larger blower and providing one additional row of heat exchanger tubes 162 for each 250,000 increment desired. Thus, for example by adding a single row of additional heat exchangers, as illustrated in FIGS. 6-8, the capacity of the heater is approximately doubled while the physical size of the heater is increased only approximately 15 percent. As a result, the present invention permits the construction of a family of swimming pool heaters which can be constructed in a modular manner utilizing the same basic heat exchanger tubing module (i.e. the layers of tubes 168-472 and manifold 164), controls, burner tile and burner plenum.

For example, the smallest heater in the family, a 250,000 BTU/hr. heater, would use a single heat exchanger module comprising tubes 168-172 and manifold 164, a small combustion air blower, and the ceramic burner plate (which is the same plate in all cases) would simply have a portion of the orifices therein blocked in order to reduce the total port area. For the next larger fluid heater, i.e. a 500,000 BTU/hr. heater, a second heat exchanger module, a larger combustion air blower, and the burner plate with its normal number of ports would be utilized. Further increased capacity heaters can be made by simply using an additional heat exchanger module and a larger blower for each 250,000 BTU increment desired. For each of such increments it has been found that a 15 percent increase in the physical size of the appliance is required to accommodate the larger blower and additional heat exchanger. However, it is to be noted that this increased size obtains a substantial increase in capacity. For example, a 1,000,000 BTU/hr. heater has a capacity 300 percent greater than the smallest or 250,000 BTU/hr. heater, with only a 50 to percent increase in size. It is also noted that the above heater outputs are exemplary only, since the specific output of the heaters will vary in accordance with the size of the burner plate selected for use in a given family of heaters. Accordingly, it is seenthat by the disclosed heater construction a very efficient and compact family of fluid heaters are provided which achieve substantial production economies for the manufacturer because of the high degree of component commonality between the various heaters in a given family of heaters.

Referring specifically now to FIGS. 6-8 of the drawing, there is illustrated a fluid heater from a family of heaters, in which an additional layer or row of heat ex changer tubes 166' are provided, along with a larger capacity blower to double the output capacity of the heater as compared to that of the embodiment shown in FIGS. l-5. The structure, function and operation of the heater of this embodiment is :similar to the previously described embodiment, and accordingly, numerals applied to the elements of the prior embodiment are utilized below to indicate like parts.

The additional heat exchanger 162 is identical to heat exchanger 162 and includes a plurality of heat exchanger tubes 166 arranged in pairs 168', 169, 170 and 172 extending from and being suitably sealed to a rear manifold 164' and a front manifold 160. Manifold 164 is identical to previously described manifold 164 but manifold 160 is modified somewhat from manifold 160 in order to accommodate the additional row of heat exchanger tubes. As seen in FIG. 7, chamber 192 is isolated from chamber 184 by a wall 197. Thus, the water from the swimming pool, (which enters manifold 160 and upper heat exchanger 162 in the same manner as in the previously described embodiment) flows through heat exchanger tube pairs 168, 169, 170 and 172 in the manner indicated by the arrows in FIG. 7, into chamber 196 and from there (FIG. 6) flows into the lower pair of tubes 172'. The water flows through tubes 172, 170' 169, 168' in a reverse direction from the flow of water in the heat exchangers and is discharged into chamber 184 of manifold 160 at the ends of the pairs 168 of heat exchanger tubes. From there the water is returned to the pool through outlet 36.

As in the prior embodiment, the upper layer 162 of heat exchanger tubes are located relatively close to the burner plate 214 so as to receive heat directly from the burner with less attendant heat loss through the walls of the heater between the burner and the heat exchanger. The second layer 162 of heat exchanger tubes are mounted in close relationship to the first layer. Typically, these tubes have a diameter of approximately l% inches and are mounted 2 inches on center.

As seen in FIG. 8, the tubes 166 and 166' are mounted in vertical alignment with cross-shaped deflectors 230' therebetween. These deflectors deflect the hot gases around the bottoms and sides of tubes 166 and along the tops and sides of tubes 166' to increase distribution of the hot gases and effect an increased and more uniform transfer of convective heat therefrom. Inverted T-shaped deflectors 230 are provided below tubes 166 for the same purpose. Alternatively, it is contemplated that the tubes 166' can be staggered with respect to tubes 166, i.e. located between and below tubes 166, so that deflectors 230' may be omitted.

The operation of this embodiment of the fluid heater is substantially the same as heater 150 previously described and thus need not be described in detail.

It is thus seen that the first described embodiment of the invention is readily modified to increase its capac ity. To further increase that capacity, all that is required is the provision of an additional layer or layers of heat exchanger tubes, a larger blower and a slight modification in the construction of manifold 160, as would be clear to one skilled in the art in view of the above description.

Although the illustrative embodiments of the invention have been described herein with reference to the accompanying drawings and for heating water for swimming pools, it is to be understood that the invention is not limited to that field of use or to the precise embodiments described herein, and that other fluids may be heated and that various changes and modifications may be effected therein by one skilled in the art without departing from the true scope or spirit of this invention.

What is claimed is:

1. A fluid heating device in the fluid flow path of a water circulation system comprising, a heat transfer conduit forming a portion of said fluid flow path, a powered gas burner located closely adjacent said conduit and adapted to supply heat directly to said conduit to heat the water flowing therein upon combustion of fuel in said burner, a generally airtight housing adapted to contain said conduit and said burner, said housing including an exhaust opening adapted to discharge products of combustion formed by said gas burner, whereby said housing and said conduit cooperate to define a flow path in said housing for said products of combustion whereby heat is provided to said conduit by convection from said products of combustion.

2. A device as defined in claim 1 wherein said powered gas burner includes a burner plate having a plurality of orifices extending therethrough, each of said orifices including a throat portion of relatively small cross section extending from an inlet at one surface of said plate and an expanding outlet portion extending from said throat portion to an opening at an opposite surface of the plate opposite said coil and having cross-sections increasing from said throat portion to said opening.

3. A device as defined in claim 2 including, means for supplying a combustible air-gas mixture to said one surface of said plates for passage through said orifices at a mass flow rate such that there is established a central jet of said mixture through each of said orifices from said throat portion towards said outlet portion, a relatively high velocity turbulent zone of air-gas mixture between said jet and the walls of said orifice, and flow separation of said jet and said high velocity turbulent zone of said air-gas mixture at the edge portion of the outlet openings of said orifice outlet portions, to provide a zone of turbulent, low velocity recirculating flow along the surface of said plate in which substantially unrestricted flame propagation occurs.

4. A device as defined in claim 3 wherein said housing is thermally insulated along the exterior thereof whereby a substantial portion of the heat from said products of combustion is transferred to heat transfer conduit by convection and heat loss through said housing is avoided.

5. A device as defined in claim 4 wherein said housing includes a second opening through which condensate forming on said heat transfer conduit is discharged.

6. A device as defined in claim 1 wherein said burner is positioned adjacent the upper portion of said housing and includes, a base member adapted to produce high intensity heat upon combustion of gases within the burner, said conduit including a plurality of heat transfer ducts operably interconnected for fluid communication therebetween, said ducts being located below said base member to receive heat therefrom.

7. A device as defined in claim 6 wherein said heat transfer ducts comprise spaced finned members whereby the products of combustion from said burner flow between and around said ducts prior to discharge through said exhaust opening.

8. A device as defined in claim 7 including, a plurality of deflection plates mounted in said housing below said heat transfer ducts to deflect combustion products flowing between said ducts to effect substantially uniform convective heating of said ducts by said products of combustion.

9. A device as defined in claim 7 wherein said base member comprises, a burner plate having a plurality of orifices extending therethrough, each of said orifices including a throat portion of relatively small crosssection extending from an inlet at one surface of said plate and an expanding outlet portion extending from said throat portion to an opening at an opposite surface of the plate opposite said heat transfer ducts and having cross-sections increasing from said throat portion to said opening.

10. A device as defined in claim 9 including, means for supplying a combustible air-gas mixture to said one surface of said plate for passage through said orifices at a mass flow rate such that there is established a central jet of said mixture through each of said orifices from said throat portion towards said outlet portion, a relatively high velocity turbulent zone of air-gas mixture between said jet and the walls of said orifice, and flow separation of said jet and said high velocity turbulent zone of said air-gas mixture at the edge portion of the outlet openings of said orifice outlet portions, to provide a zone of turbulent, low velocity recirculating flow along the surface of said plate in which substantially unrestricted flame propagation occurs.

11. A device as defined in claim 10 wherein said means is a powered blower.

12. A fluid heating device comprising, a substantially airtight housing, powered gas burner means in said housing for producing high intensity blue flame heat therein positioned adjacent the upper portion of said housing, said powered gas burner means including a powered blower for supplying a combustible air-gas mixture to the burner and a base member adapted to produce high intensity blue flame heat upon combustion of gases within the burner, means defining a flow path for said fluid through said device closely adjacent said bumer means whereby said fluid is heated by said high intensity heat, said means defining a fluid flow path including a plurality of heat transfer ducts operably interconnected for fluid communication therebetween, said ducts being located below said base member and closely adjacent thereto to receive said high intensity heat directly from said burner, said housing having an exhaust opening therein for the products of combustion formed in said burner and confining said products of combustion prior to discharge through said opening adjacent said flow path defining means to supply heat to said fluid by convection.

13. A fluid heating device comprising, an insulated housing defining a heating chamber therein, powered gas burner means mounted within said chamber adjacent the top of said housing and having an apertured substantially planar base portion adapted to produce high intensity blue flame heat in said chamber upon combustion of gases adjacent said apertures, a plurality of generally elongated tubular heat transfer ducts mounted within said housing below but closely adjacent said burner and receiving said high intensity heat therefrom, said heat transfer ducts being connected in liquid communication with each other to provide a flow path for said water and defining an exhaust chamber with the base of said housing, said exhaust chamber having an exhaust opening therein adapted to provide communication between said exhaust chamber and the atmosphere, whereby products of combustion from said burner flow downwardly through and around said coil members to said exhaust chamber and said exhaust opening to supply additional heat by convection to said coils and the water flowing therein.

14. A device as defined in claim 13 for heating water for a swimming pool including, valve means operatively connected to one of said heat transfer ducts for supplying a predetermined volume flow of water to said ducts and bypassing excess water back to the pool.

15. A device as defined in claim. 13 including, a plurality of deflection plates mounted in said housing below said heat transfer ducts to deflect said products of combustion about said ducts prior to discharge from said housing to effect substantially uniform convecting heating of said ducts by said-products of combustion.

16. The device as defined in claim 13 wherein said heat transfer ducts are mounted in a plurality of layers in said housing.

17. The device as defined in claim 16 wherein the ducts in each of said layers are in vertical alignment.

. UNITED STATES PATENT OFFICE 1 CERTIFICATE OF CORRECTION Patent NO. 3,73 +;o65 Dated May 22, 1973 Inventor s) Edward A Reid, Jr. and Roberfbj G Venendaal It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

- Claim 13; line 25, change "coil members to--heat transfer Signed and sealed this 27th day of November 1975.

SEAL I Attest: 1 I

EDWARD M.PLETCHER-,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents PSCOMM'DC 60376-P69 w p.s. GOVERNMENT rnlfrrlggs OFFICE: I!" o-up-sy, 1

FQRM PO-105O (10 63)

Claims (17)

1. A fluid heating device in the fluid flow path of a water circulation system comprising, a heat transfer conduit forming a portion of said fluid flow path, a powered gas burner located closely adjacent said conduit and adapted to supply heat directly to said conduit to heat the water flowing therein upon combustion of fuel in said burner, a generally airtight housing adapted to contain said conduit and said burner, said housing including an exhaust opening adapted to discharge products of combustion formed by said gas burner, whereby said housing and said conduit cooperate to define a flow path in said housing for said products of combustion whereby heat is provided to said conduit by convection from said products of combustion.

2. A device as defined in claim 1 wherein said powered gas burner includes a burner plate having a plurality of orifices extending therethrough, each of said orifices including a throat portion of relatively small cross section extending from an inlet at one surface of said plate and an expanding outlet portion extending from said throat portion to an opening at an opposite surface of the plate opposite said coil and having cross-sections increasing from said throat portion to said opening.

3. A device as defined in claim 2 including, means for supplying a combustible air-gas mixture to said one surface of said plates for passage through said orifices at a mass flow rate such that there is established a central jet of said mixture through each of said orifices from said throat portion towards said outlet portion, a relatively high velocity turbulent zone of air-gas mixture between said jet and the walls of said orifice, and flow separation of said jet and said high velocity turbulent zone of said air-gas mixture at the edge portion of the outlet openings of said orifice outlet portions, to provide a zone of turbulent, low velocity recirculating flow along the surface of said plate in which substantially unrestricted flamE propagation occurs.

4. A device as defined in claim 3 wherein said housing is thermally insulated along the exterior thereof whereby a substantial portion of the heat from said products of combustion is transferred to heat transfer conduit by convection and heat loss through said housing is avoided.

5. A device as defined in claim 4 wherein said housing includes a second opening through which condensate forming on said heat transfer conduit is discharged.

6. A device as defined in claim 1 wherein said burner is positioned adjacent the upper portion of said housing and includes, a base member adapted to produce high intensity heat upon combustion of gases within the burner, said conduit including a plurality of heat transfer ducts operably interconnected for fluid communication therebetween, said ducts being located below said base member to receive heat therefrom.

7. A device as defined in claim 6 wherein said heat transfer ducts comprise spaced finned members whereby the products of combustion from said burner flow between and around said ducts prior to discharge through said exhaust opening.

8. A device as defined in claim 7 including, a plurality of deflection plates mounted in said housing below said heat transfer ducts to deflect combustion products flowing between said ducts to effect substantially uniform convective heating of said ducts by said products of combustion.

9. A device as defined in claim 7 wherein said base member comprises, a burner plate having a plurality of orifices extending therethrough, each of said orifices including a throat portion of relatively small cross-section extending from an inlet at one surface of said plate and an expanding outlet portion extending from said throat portion to an opening at an opposite surface of the plate opposite said heat transfer ducts and having cross-sections increasing from said throat portion to said opening.

10. A device as defined in claim 9 including, means for supplying a combustible air-gas mixture to said one surface of said plate for passage through said orifices at a mass flow rate such that there is established a central jet of said mixture through each of said orifices from said throat portion towards said outlet portion, a relatively high velocity turbulent zone of air-gas mixture between said jet and the walls of said orifice, and flow separation of said jet and said high velocity turbulent zone of said air-gas mixture at the edge portion of the outlet openings of said orifice outlet portions, to provide a zone of turbulent, low velocity recirculating flow along the surface of said plate in which substantially unrestricted flame propagation occurs.

11. A device as defined in claim 10 wherein said means is a powered blower.

12. A fluid heating device comprising, a substantially airtight housing, powered gas burner means in said housing for producing high intensity ''''blue flame'''' heat therein positioned adjacent the upper portion of said housing, said powered gas burner means including a powered blower for supplying a combustible air-gas mixture to the burner and a base member adapted to produce high intensity ''''blue flame'''' heat upon combustion of gases within the burner, means defining a flow path for said fluid through said device closely adjacent said burner means whereby said fluid is heated by said high intensity heat, said means defining a fluid flow path including a plurality of heat transfer ducts operably interconnected for fluid communication therebetween, said ducts being located below said base member and closely adjacent thereto to receive said high intensity heat directly from said burner, said housing having an exhaust opening therein for the products of combustion formed in said burner and confining said products of combustion prior to discharge through said opening adjacent said flow path defining means to supply heat to said fluid by convection.

13. A fluid heating device comprising, an insulated housing defining a heating chamber therein, Powered gas burner means mounted within said chamber adjacent the top of said housing and having an apertured substantially planar base portion adapted to produce high intensity ''''blue flame'''' heat in said chamber upon combustion of gases adjacent said apertures, a plurality of generally elongated tubular heat transfer ducts mounted within said housing below but closely adjacent said burner and receiving said high intensity heat therefrom, said heat transfer ducts being connected in liquid communication with each other to provide a flow path for said water and defining an exhaust chamber with the base of said housing, said exhaust chamber having an exhaust opening therein adapted to provide communication between said exhaust chamber and the atmosphere, whereby products of combustion from said burner flow downwardly through and around said coil members to said exhaust chamber and said exhaust opening to supply additional heat by convection to said coils and the water flowing therein.

14. A device as defined in claim 13 for heating water for a swimming pool including, valve means operatively connected to one of said heat transfer ducts for supplying a predetermined volume flow of water to said ducts and bypassing excess water back to the pool.

15. A device as defined in claim 13 including, a plurality of deflection plates mounted in said housing below said heat transfer ducts to deflect said products of combustion about said ducts prior to discharge from said housing to effect substantially uniform convecting heating of said ducts by said products of combustion.

16. The device as defined in claim 13 wherein said heat transfer ducts are mounted in a plurality of layers in said housing.

17. The device as defined in claim 16 wherein the ducts in each of said layers are in vertical alignment.

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