US3796193A

US3796193A - Boiler construction

Info

Publication number: US3796193A
Application number: US00350220A
Authority: US
Inventors: A Martin; E Shirley
Original assignee: American Standard Inc
Current assignee: Trane US Inc
Priority date: 1973-04-11
Filing date: 1973-04-11
Publication date: 1974-03-12
Anticipated expiration: 1991-03-12
Also published as: CA977636A; JPS50201A

Abstract

This application covers a wet base boiler of the multi-section type, that is, a boiler in which the firebox is ''''surrounded'''' by water, but one of the legs of each section, i.e., the left leg, is finned to increase the rate of heat transfer to that leg, while the other leg, i.e., the right leg, may remain unfinned. This one-sided finned construction results in an improved quality of steam for boilers operated to generate steam. A tankless water coil may be added to the boiler, either positioned in the water chamber above the firebox or in the nipple port area. In either case, there will be a clockwise water movement throughout the sections of the boiler due to the difference in the heat transfer properties of the right and left legs, causing the water to move downwardly in all of the right legs where the temperature will be somewhat lower and to move upwardly in all of the left legs. This circuital travel of the water through the legs of the various sections also improves the heat transfer to the water flowing through the tankless coil.

Description

Martin et al.

[ Mar. 12, 1974 BOILER CONSTRUCTION [75] Inventors: Allan E. Martin, Hacketstown, N.J.;

Edmund C. Shirley, Albany, Ind.

[73] Assignee: American Standard lnc., New York,

[22] Filed: Apr. 11, 1973 [21] Appl. No; 350,220

[52] U.S. Cl 122/225 R, 122/225 B [51] Int. (:1. F22b 23/00 [58] Field of Search 122/223, 225 R, 226, 227,

Primary Examiner-Kenneth W. Sprague Attorney, Agent,'0r Firm-Jefferson Ehrlich; Robert G. Crooks [57] ABSTRACT This application covers a wet base boiler of the multisection type, that is, a boiler in which the firebox is surrounded by water, but one of the legs of each section, i.e., the left leg, is finned to increase the rate of heat transfer to that leg, while the other leg, ie., the right leg, may remain unfinned. This one-sided finned construction results in an improved quality of steam for boilers operated to generate steam. A tankless water coil may be added to the boiler, either positioned in the water chamber above the firebox or in the nipple port area. In either case, there will be a clockwise water movement throughout the sections of the boiler due to the difference in the heat transfer properties of the right and left legs, causing the water to'move downwardly in all of the right legs where the temperature will be somewhat lower and to move upwardly in all of the left legs. This circuital travel of the waterthrough the legs of the various sections also improves the heat transfer to the water flowing through the tankless coil.

21 Claims, 5 Drawing Figures PATENTEDHAR 12 m4 SHEETZ nr 2 FEG.3

FEG.5

BOILER CONSTRUCTION This application relates generally to boilers and, more particularly, to multi-section boilers of the wet base type, that is, boilers embodying a firebox which feeds heat to water contained in the several sections each of which include interconnected conduits or other passages surrounding the firebox, the conduits usually including a basal leg located beneath the firebox, right and left side legs in the corresponding sides of the firebox, and a compartment segment above the firebox.

One of the principal objects of this invention is to improve the operation of a wet base type of boiler and to increase its efficiency.

Another of the principal objects of this invention is to simplify the construction and improve the operating efficiency ofa wet base boiler and improve its heat generating capacity per unit of fuel used while reducing the cost of production of such a boiler construction.

In a US. Pat. No. 3,554,167, issued Jan. 12,1971, to A. E. Martin et al., assigned to the same assignee as the present application, there is described a form of wet baseboiler having a plurality of sections each including right and left water legs on the corresponding sides of the firebox, a basal water leg positioned beneath the firebox and a water chamber segment or leg joining the upper ends of the right and left legs and positioned above the firebox. The right and left legs are unfinned conduits of the same cross-sectional dimensions and of the same length, but a refractory plate or plates are inserted within the firebox against one of the side walls of the firebox, i.e., the right wall, which serve to delay the transfer of heat from the firebox to the water within the right legs without affecting the transfer of heat to the water of the left legs or the basal legs. By this construction, the delay in the transfer of heat to the right legs renders the water in the right legs at a temperature which is somewhat lower than that within the left legs. Hence, the water in the left legs rises due to its higher temperature, while the water in the right legs descends. This may be regarded as a thermal pump effect, driving the water in the boiler into a circuitous path. The water thus rises in each left leg, then travels to the right in each water chamber segment, then travels downwardly in each right leg and then moves to the left in each basal leg. This clockwise circulation is repeated again and again, thereby improving the operating efficiency of the boiler.

However, the insertion of the refractory plate or plates against one of the side walls of the firebox substantially changes heat transfer from the burning fuel in the firebox. Furthermore, the refractory plates are removable and sometimes become chipped 'or broken during removal or after installation and use, thereby increasing the breakage hazards and reducing the life of the construction. In addition, refractory plates are costly and, aside from the inherent reduction in heat transfer introduced by such plates, they are also subject to breakage in shipment and during storage. They also reduce the effective heating space within the firebox. The invention of the present application overcomes these problems by eliminating the costly and somewhat fragile refractory plates.

According to the present invention, one of the two equal legs of each section of the wet base boiler is supplied with fins or other metallic projections to improve the rate at which heat is supplied to the water flowing therethrough while the other leg remains unfinned. The unfinned legs of all of the sections are preferably positioned beneath the steam discharge port or nipple port, as it is sometimes called, which interconnects the water chamber segments of the several sections so that the two legs of each section are fluidically coupled to the nipple port via the water chamber segments. The addition of fins or other metallic projections to the left legs of the sections to increase the rate of heat transfer from the firebox to the left legs introduces a significant improvement in the quality of the steam generated in a boiler used for supplying steam.

If a wet base boiler having finned left legs is also equipped with a so-called tankless heating coil which may be positioned in the nipple port or in the so-called steam chest adjacent to and perpendicular to the nipple port near the top of the boiler, an improvement in the heat transfer property of the boiler will be achieved. The heat extracted by the tankless coil to raise the temperature of the water flowing through the tankless coil will aid in moving the-water in the right leg of each section in a downward direction because of its lower temperature and the water the left leg of each section in an upward direction. This will create a circulatory or clockwise motion in each section which will be repeated again and again, and it significantly improves the overall efficiency of the boiler operation.

This same improved water circulation just outlined is obtained from a hot water boiler as well as from a steam boiler when, in either case, the boiler is equipped with a tankless coil and has finned legs on one side, i.e., the left side, of each boiler section.

This invention, together with its further objects and features, will be better and more clearly understood from the more detailed description and explanation hereinafter following when read in connection with the accompanying drawing in which:

FIG. 1 shows a cross-sectional view of a wet base steam boiler when cut along a line mid-way between the right and left side walls of the boiler;

FIG. 2 illustrates a front elevational view, in crosssection, of a wet base water boiler of this invention equipped with a tankless coil and viewed from the front face of the boiler",

FIG. 3 shows a schematicrepresentation, shown'in cross-section, of the wet base boiler illustrating the path of water traveling through the water sections and compartments of the sections of the boiler where the left legs are finned and the boiler is equipped with a tankless coil;

FIG. 4 shows a cross-sectional view of one of the sections of the boiler taken along the line 44 of FIG. 3; and

FIG. 5 illustrates a portion of a boiler employed for steam production, but excluding a coil for separately heating domestic water.

The same or similar reference characters will be employed throughout the drawing to represent the same or similar parts wherever they may occur throughouttermediate sections and two end sections, all of which are coupled to each other. The firebox is designated FE and, as seen in FIGS. 1, 2 and 3 of the drawing, the firebox F8 is positioned within the four fluidically interconnected segments of each section of the boiler, namely sections RL, BL, LL and WC. A nipple port NP fluidically interconnects all of the sections, the nipple port NPbeing directly connected to the water chamber WC segments of all of the sections. The nipple port, designated NP, may be in the upper right-hand corner of the boiler, as shown, extending from about the front of the boiler to about the rear of the boiler. The nipple port NP, being in communication with the upper chambers WC of all sections, receives the heated water or the generated steam, as the case may be for a water or steam boiler. A tankless water heater TH may, if desired, be mounted within the water compartments WC of the boiler, as shown in FIG. 2, for separately heating water in the conventional manner. If desired, the tankless water heater TH may be mounted within the nipple port NP, as shown in FIG. 3. A fuel burner is shown in FIG. 1 and is designated EU. The construction of the fuel burner need not be explained because it is well known.

It will be noted that the right leg RL and the left leg LL of each section are substantially equal in length and have substantially the same cross-sectional dimensions, butthe left legs LL are finned while the right legs RL are unfinned. For example, both legs RL and LL of each section may be substantially rectangular in crosssection. The basal leg BL of each section of the boiler fluidically interconnects the right leg RL and the left leg LL of each section to allow water to flow freely between the two interconnected legs. The upper water compartments WC, as already noted, interconnect all of the right legs RL with all of the corresponding left legs LL of the several sections. The firebox FB may be regarded as located at the axis of the water passages or paths of all of the sections for feeding heat to all sections. As will become apparent from the disclosure of this invention, the firebox FB may also be regarded as the axis of the circulation or flow path of the water within the sections as the water is heated. The water may be considered as in active rotary motion about the firebox FB while being heated by the flaming gases within the firebox F8.

The employment of a basal water leg BL beneath the firebox FB, because it is exposed to the heat of the firebox FB, improves the heat absorbing property of the circulating water. The basal legs BL also serve to insulate the firebox F8 from the ground and maintain the ground surface at a safe temperature. The boiler may be employed for hot water production or for steam production, as may be desired, and the hot water or steam, whichever it may be, will be delivered to, and discharged through, the nipple port NP which is common to all of the sections and is connected to all sections through the passages of the water chamber segments WC.

By reason of the provision of fins FN on the left legs LL, and assuming a uniform fire temperature in the firebox FB, heat will be transferred to the fluid in the left legs at a rate which Will be significantly different from the rate of heat transfer to the right legs. Indeed the rate at which heat is transferred to the left legs will be higher than the heat transfer rate to the right legs, and this difference is due to the addition of the fins FN to the left legs. It is this unequal rate of heat transfer per unit of the weight or per unit of the volume of the fuel that produces the desired effects of this invention. The more fins or other metallic extensions superimposed on the left legs LL, the greater will be the difference in the heat transfer rates between the right legs RL and the left legs LL. Thus, the heat transfer differential may be controlled as desired.

In a steam boiler, such as that shown in FIG. 5, steam collects above the water level WL, i.e., in the steam chest SC, as the temperature near the top of the water compartment segments WC reaches the boiling temperature. The generated steam travels over the surface of the water WL through the steam chest region SC to and through the nipples of the several sections forming the nipple port NP at a velocity which depends upon the height of the water line WL as well as on the rate at which steam is generated. Thus, as the water line WL rises, the steam velocity will increase due to the reduction in the space through which the generated steam must flow, and vice versa, and, as the steaming rate increases, the velocity will likewise increase, and vice versa. If the steaming rate increases, there will also be an increased steam bubble formation, and the increased bubble formation will act to raise the water line WL. The water line WL will rise as additional bubbles develop because the water volume and the bubble volume combine additively. This combination cuts down the open space above the combination through which the steam is required to travel in leaving the boiler through the nipple port NP. The steam bubble formation may be greater in one area than in other areas.

The steam bubble concentration will be less in the right legs RL of each section than in the left legs LL because of the slower reaction to the flame temperature of the firebox FB by the right legs which are unfinned. Consequently, because the composite nipple port NP of the several sections is positioned above all of the right legs RL, the water level at and near the nipple port region NP will be less disturbed due to the presence of fewer steam bubbles than the water above the left legs LL. This, therefore, reduces the percentage of water picked up by the traveling steam as it exits to and through the nipple port NP. Thus, the steam quality will be improved. This is an important improvement.

Thus, by embodying fins or other metallic projections on the left legs LL, improved steam quality is effected.

It will also be observed that, in FIG. 2, a tankless heater coil TH is embodied in the water chamber segments WC extending from the left side of the steam boiler to the right side of the boiler. In this steam boiler, the heat of the firebox F8 is used to develop steam to be supplied, for example, to heat the interior space of a building, but the coil TH transports water to be heated separately and to be supplied by the boiler for other purposes. As cold water reaches coil TH, it absorbs heat from the hot water in the water chamber WC. The cold water, in traveling from left to right in coil TH and absorbing heat from the water within chamber segments WC, cools the water within chamber segments WC. The water within the chamber segments WC that is relatively cooled becomes more dense and drops. The dense water, therefore, flows into the right legs RL of the various boiler sections.

The increased density of the water flowing into the right legs RL from the water chamber segments WC is accompanied by the relatively higher temperature of the water in the left legs LL. This creates what may be regarded as a form of heat pump which acts so as to drive the water within each section into a circulatory or clockwise path around the firebox P8 of the boiler. That is, the more rapidly heated water in the left legs LL will move upwardly, while the more slowly rising temperature or lower temperature of the water in the right legs RL will cause the water in the right legs RL to change direction and move downwardly. The path of the water may then be traced as traveling in a downward direction in all of the right legs RL, then to the left in all of the basal legs BL, then upwardly through all of the left legs LL, and then to the right through the water chamber segments WC. This clockwise circulation will be continued and repeated. As heat is absorbed by the water raised in temperature as it flows through and out of the heater coil TH, the temperature of the fluid in the water chamber segments WC will drop. The drop in temperature soon interrupts the production of steam within the boiler and this interruption of steam production will continue until the transfer of heat to the water within coil TH ceases or drops to a substantially lower rate.

In the arrangement shown in FIG. 3 in which the tankless heater coil TH is positioned within the nipple port NP, there will be a similar cooling effect on the water within the water chamber segments WC adjacent to the tankless heater TH as cold water flows into and through the heater TH and is heated by the hot water within chamber segments WC. Thus, as in the case of the FIG. 2 arrangement, which embodies a differently located tankless heater TH, the cooling effect developed in heating the water within the heater TH results in an increased density of the water within the chamber segments WC at the right side of the boiler. Hence, the cold water will move downwardly through the various right legs RL of the several sections, while the water in the finned left legs LL will move upwardly. A similar circulatory or clockwise movement of water within the boiler ofFIG. 3 will be developed in that arrangement.

The boilers of the type shown in FIGS. 2 and 3 may be used to produce hot waterfor so-called space heating or for producing steam for space heating or for other purposes. In any case, the water of elevated temperature, or the steam, as the case may be, will be driven through the composite nipple port NP to supply the building or other structure where the heated fluid medium is to be utilized, for example, for heating the building. All four legs RL, BL, LL and WC of the several sections will be active in moving the water to be heated in a continuous circuitous path in, for example, the clockwise direction and, at the same time, heat will be transferred from the flaming gases of the firebox F8 to the water in all four surrounding legs. Because of the addition of the tankless heater coils TH to the boilers of FIGS. 2 and 3, hot water will be also made available for separate use, as may be desired.

Thus, by applying fins or other metallic projections .to one of the legs of each section, for instance, the left legs LL, two effects will be coordinated to improve the efficiency of a boiler, firstly, the effect of decreasing the relative temperature of the right legs RL thereby to diminish the bubble formation in the region of the nipple port NP above the right legs RL during steam boiler operation and, secondly, a relative cooling of the temperature of the water reaching the right legs RL due to the heating of water traversing the coil TH, thereby to introduce the circulatory or clockwise movement or rotation of the water around the firebox F B in all of the sectionsv during tankless operation in steam or hot water boilers. Steam quality (namely, dryness), noise reduction, fuel consumption and general overall efficiency of the boiler are concomitantly developed.

In a steam or hot water boiler equipped with a tankless hot water coil TH as exemplified by FIGS. 2 and 3, the boiler will operate to generate steam or hot water, as the case may be, for space heating or for other purposes, and the operation will be fully effective as long as no water, or substantially very little water, passes through and is heated in the tankless water coil TH. As already indicated, when the steam boiler generates steam, the quality of the steam (i.e., its dryness) will be improved due to the increased heat flow to one of the legs, i.e., the left'legs, as described above in accordance with this invention. However, whenever the hot water -coil TH delivers a substantial quantity of hot water, the

density of the water within the water chamber segments WC of a steam or hot water boiler will increase as already noted supra. The transfer of heat to the water within the hot water coil TH will cause the temperature of the water within chamber segments WC to drop. If the boiler is a steam producer, the production of steam will cease. If the boiler is a hot water boiler, the drop in temperature above noted' will cause the controls (not shown) to shut off the flow of hot water to the spaces to be heated. For both steam and water boilers, the drop in boiler water temperature in the chamber segments WC causes the controls to turn on the fuel burner to maintain or raise the temperature of the boiler water. If, and only if, the temperature of the water within the steam or water boiler rises sufficiently, the controls will then allow energy to flow to the spaces to be heated during the time that water is being drawn from the tankless heater water coil TH.

The cross-sectional shapes of the two legs RL and LL of each section, although shown in FIG. 4 and described as preferably somewhat rectangular, may be of any other shape, such as circular, elliptical, etc., to achieve'the same or equivalent results.

By way of example, the left legs LL of the sections were shown as finned so as to increase the heat absorbing property of the water within the left legs LL (above that for the water within right legs RL). It will be understood that, if desired, the right legs RL may also be similarly finned, but the number of fins may be smaller or they may be smaller in their heat absorbing property vis-a-vis those of the left legs LL so as to maintain a significant or desired differential between the two sets of legs.

It will be further understood that the right legs RL of the sections may be finned while the left legs LL are unfinned or contain a reduced number of fins, the nipple port NP being positioned above the left legs LL. This reversed arrangement will similarly improve the quality of the system developed by a steam boiler and, if a tankless water heater is added to the structure and positioned either adjacent the water chamber segments WC or within the nipple port NP, the temperature differentials developed within the side legs will reverse the travel path into a counter-clockwise movement about the firebox FB.

It will be observed that the firebox FB has substantially no refractory plate or other obstruction therein. All of the heat generated by the burning fuel within the firebox is directly applied to the four segments of each section. This is an important structural improvement. It is a distinct improvement over the arrangement of the type shown in the aforementioned US. Pat. No. 3,554,167.

If desired, the several sections of the boiler may be sealed gas-tight so as to be usable under forced draft. The seal may be achieved by grooving one or both of the mating end-walls of each pair of adjacent sections and inserting a sealant therein, as shown and described in U. S. Pat. No. 3,533,379 to E. A. -Martin et al., issued Oct. 13, 1970 and assigned to the same assignee as the present application.

While this invention has been shown and described in certain arrangements and proportions merely for illustration and explanation, it will be readily apparent that the arrangements may be embodied in various forms and proportions, all within the scope of this invention.

What is claimed is:

l. A boiler consisting of a plurality of coupled sections to be filled with water, each section including two substantially equal side legs, a basal leg fluidically interconnecting the bottoms of the side legs and a compartment segment fluidically connected to the tops of the side legs, a firebox bounded by said side legs, said basal legs and said compartment segments, the heat emanating from the firebox being directly applied to said side legs, said basal legs and said compartment segments, and heat-conductive fins affixed to those side legs positioned on one side of said firebox to increase the heat transfer rate only with respect to the legs to which the fins are affixed.

2. A boiler according to claim 1 having a nipple port located above the compartments and positioned on that side of the boiler which is adjacent to the legs which do not embody fins.

3. A boiler according to claim 2 having a water heater coil mounted within the boiler for heating water separately transmitted through said coil.

4. A wet base boiler having a plurality of closely adjacent sections each having oppositely positioned side legs, .a basal leg interconnecting the bottoms of the side legs and a compartment segment interconnecting the tops of said side legs, a common firing space mounted between said side legs and also between the basal legs and said compartment segments and supplying heat to all of said legs and said compartment segments, a plu rality of metallic projections extending from one of the said legs of each section to vary the relative heat transfer rate to said opposing legs, whereby water supplied to the boiler and heated by the firebox will circulate continuously through all of the legs and the compartment segments in a path in which the water in the side legs bearing metallic projections flows upwardly while the water in the opposite side legs moves downwardly.

5. A wet base boiler according to claim 4 in which av nipple port is provided near the top of the compartment segments to receive the heated water of the compartment segments and any accompanying steam derived from the heated water.

6. A wet base boiler according to claim 5 including a water heater coil within the boiler for transmitting water which is supplied separately from the water traveling through the side legs of the sections.

7. A wet base boiler according to claim 6 in which the side legs are of substantially rectangular cross-section.

8. A wet base boiler having a plurality of coupled sections each of which includes two spaced substantially parallel side legs of substantially equal cross-sectional dimensions and a basal leg interconnecting the lower ends of the side legs, a firebox seated on the basal legs of said sections and between the side legs, a compartment segment for each section positioned above the firebox and connected to the upper ends of the side legs so that water may flow between the said side legs and the compartment segments, means for determining the directivity of the water flow through the sections, said means comprising finned extensions applied to the legs located on one side of said firebox to increase the rate of heat transfer to said legs, the direction of water flow being in one direction in'the side legs on one side of the firebox and in the opposite direction in the side legs on the other side of the firebox.

9. A wet base boiler according to claim 8 including a coil through which watermay be independently transmitted, said coil being mounted within the boiler so as to be heated by the water in the compartment segments.

10. A wet base boiler according to claim 9 in which the side legs have substantially rectangular crosssections.

1l.-A Wet base boiler according to claim 10 in which a nipple port is composited in the compartment segments above the side legs which do not have the finned extensions.

12. A wet base boiler having a plurality of adjacent coupled sections having opposed side legs which are heated from a common source of heat, and means for controlling the directivity of water flow through said sections, the legs on one side of each of the sections being finned while those on the other side of each section are unfinned, whereby water to be heated will flow in one direction through the finned legs and in the op posite direction through the unfinned legs.

13. A wet base boiler according to claim 12 in which the means for controlling the directivity of water flow includes a tankless water heating coil mounted in the boiler and heated by water traversing said sections.

14. A wet base boiler according to claim 13 having a nipple port positioned substantially vertically above the unfinned legs of the sections.

15. A wet base boiler according to claim 14 in which the cross-section of the legs are substantially rectangular.

16. A wet base boiler having a plurality of adjacent coupled sections each having two parallel spaced legs, a basal leg connecting the bottoms of said legs and a water compartment segment near the top of the section connected to the tops of the legs and so arranged that water in said sections may be heated from a common source of heat, a water heating coil to be heated by the water in said compartment, and means for controlling the directivity of water flow through said sections, the legs on one side of each of the sections being finned while those on the other side of each section are unfinned, whereby water to be heated will flow in one direction through the unfinned legs and in the opposite direction through the finned legs.

17. A wet base boiler according to claim 16 having a nipple port positioned substantially vertically above the unfinned legs of the sections.

18. A wet base boiler according to claim 17 in which the cross-section of the legs are substantially rectangular.

19. A boiler comprising a plurality of coupled sections to be filled with water, each section including two spaced parallel substantially equal side legs and a basal leg fluidically interconnecting the bottoms of the side legs, one of the side legs of each section being substantially finned while the opposite side leg is unfinned, a firebox seated between said parallel side legs and on said basal legs, a compartment segment for each section positioned above the firebox and fluidically interconnecting the upper ends of the side legs of said section, a water heater coil heated by water in said compartment segments, a nipple port mounted in said boiler above the unfinned side legs, the heat emanating from the firebox to be directly applied to all said side legs and said basal legs and to said compartment segheater coil is mounted in the nipple port.

Claims

1. A boiler consisting of a plurality of coupled sections to be filled with water, each section including two substantially equal side legs, a basal leg fluidically interconnecting the bottoms of the side legs and a compartment segment fluidically connected to the tops of the side legs, a firebox bounded by said side legs, said basal legs and said compartment segments, the heat emanating from the firebox being directly applied to said side legs, said basal legs and said compartment segments, and heat-conductive fins affixed to those side legs positioned on one side of said firebox to increase the heat transfer rate only with respect to the legs to which the fins are affixed.

4. A wet base boiler having a plurality of closely adjacent sections each having oppositely positioned side legs, a basal leg interconnecting the bottoms of the side legs and a compartment segment interconnecting the tops of said side legs, a common firing space mounted between said side legs and also between the basal legs and said compartment segments and supplying heat to all of said legs and said compartment segments, a plurality of metallic projections extending from one of the said legs of each section to vary the relative heat transfer rate to said opposing legs, whereby water supplied to the boiler and heated by the firebox will circulate continuously through all of the legs and the compartment segments in a path in which the water in the side legs bearing metallic projections flows upwardly while the water in the opposite side legs moves downwardly.

5. A wet base boiler according to claim 4 in which a nipple port is provided near the top of the compartment segments to receive the heated water of the compartment segments and any accompanying steam derived from the heated water.

8. A wet base boiler having a plurality of coupled sections each of which includes two spaced substantially parallel side legs of substantially equal cross-sectional dimensions and a basal leg interconnecting the lower ends of the side legs, a firebox seated on the basal legs of said sections and between the side legs, a compartment segment for each section positioned above the firebox and connected to the upper ends of the side legs so that water may flow between the said side legs and the compartment segments, means for determining the directivity of the water flow through the sections, said means comprising finned extensions applied to the legs located on one side of said firebox to increase the rate of heat transfer to said legs, the direction of water flow being in one direction in the side legs on one side of the firebox and in the opposite direction in the side legs on the other side of the firebox.

9. A wet base boiler according to claim 8 including a coil through which water may be independently transmitted, said coil being mounted within the boiler so as to be heated by the water in the compartment segments.

10. A wet base boiler according to claim 9 in which the side legs have substantially rectangular cross-sections.

11. A wet base boiler according to claim 10 in which a nipple port is composited in the compartment segments above the side legs which do not have the finned extensions.

12. A wet base boiler having a plurality of adjacent coupled sections having opposed sidE legs which are heated from a common source of heat, and means for controlling the directivity of water flow through said sections, the legs on one side of each of the sections being finned while those on the other side of each section are unfinned, whereby water to be heated will flow in one direction through the finned legs and in the opposite direction through the unfinned legs.

19. A boiler comprising a plurality of coupled sections to be filled with water, each section including two spaced parallel substantially equal side legs and a basal leg fluidically interconnecting the bottoms of the side legs, one of the side legs of each section being substantially finned while the opposite side leg is unfinned, a firebox seated between said parallel side legs and on said basal legs, a compartment segment for each section positioned above the firebox and fluidically interconnecting the upper ends of the side legs of said section, a water heater coil heated by water in said compartment segments, a nipple port mounted in said boiler above the unfinned side legs, the heat emanating from the firebox to be directly applied to all said side legs and said basal legs and to said compartment segments and causing the water in the unfinned legs to move in one direction while the water in the opposite legs moves in the opposite direction.

20. A boiler according to claim 19 in which the water heater coil is mounted in said compartment segments.

21. A boiler according to claim 19 in which the water heater coil is mounted in the nipple port.