US1738086A

US1738086A - Water heater

Info

Publication number: US1738086A
Application number: US610471A
Authority: US
Inventors: Frank L O Wadsworth
Original assignee: Individual
Current assignee: Individual
Priority date: 1923-01-03
Filing date: 1923-01-03
Publication date: 1929-12-03
Anticipated expiration: 1946-12-03

Description

1929. F. o. WADSWORTH 1,738,086

WATER HEATER Filed Jan- 5, 1923 3 Sheets-Sheet 2 4 m 4/ I 1 M Dec. 3, 1929. F. o. WADSWORTH 1,738,086

WATER HEATER Filed Jan. 3, 1923 3 Sheets-Sheet 5 Inventor.

Patented Dec. 3, 1929 UNITED STATES PATENT OFFICE WATER HEATER Application filed January 8, 1923. Serial No. 610,471.

My invention relates generically to apparatus for heating liquids, and particularly to that type of structure that is generally designated an instantaneous hot water heater. The generic object of the present improvements is to produce a simple, easily fabricated, reliable and eflicient species of apparatus, which will be less expensive to construct, and also more economical in operation, than the various forms of heaters now used for the same purpose.

A more specific object of this invention is to substantially increase the efficiency of fuel consumption, and the percentage of ab- 13 sorption of the heat so generated, without increasing the complexity or first cost of the heat generating and the heat absorbing elements.

Another particular purpose of my present invention is to provide a very simple and fool proof mechanism, for automatically turning on, or cutting off, the supply of fuel to the heating burners, which is actuated by the kinetic or physical flow of fluid through 95 the heating elements, and which is also controlled by the temperature of the flowing liquid, so that fuel is consumed only when that temperature is below a preadjusted and predetermined point. Or stated more explicitly this particular object of the invention is the provision of a velocity controlled device (as contra-distinguished from a pressure regulated device) which will act instantaneously in opening or closing a fuel supply valve whenever liquid begins or ceases to flow through the apparatusindependently of any variations of hydrostatic or hydraulic pressure conditions thereinand which will also act with equal promptness in intermittently closing and reopening the said valve during the continuation of the flow, whenever the temperature of the liquid rises above or falls below a predetermlned point. I

A further object of these im rovements is to eliminate any substantial resistance to the movements of the velocity-actuated-temperature-governed valve-mechanism, and thereby increase the sensitiveness and reliability of the fuel controlling devices; and as one means for accomplishin this object I provide a combination of exible metallic bellows or sylphon elements which are arranged to act directly on the fuel supply valve without the intervention or use of any pistons, guides, packing boxes or similar frictionally retarded members ;thereby avoiding the difficulties that result from the corrosion, or seizing and sticking of difiicultly accessible or unlubricated parts of the working mechanism.

Still another purpose of the present improvements is the provision of a very simple, compact, and sensitive form of thermostat, which has a large direct range of action for very small changes of temperature in the flowing water-and is thus capable of effecting the necessary movements of the thermostatic control devices without the use of multiplying levers or other similar instrumentalitiesand which serves only to direct the application of. the velocity produced forces without itself exerting a great amount of motive energy.

In order that these, and other features and advantages of this invention may be fully understood by those skilled in this art, I have shown, and hereinafter describe, several alternative forms of my improved water heater construction; but these are to be regarded as illustrative only, and not as limiting the scope of application of these improvements.

In the accompanying drawings:

Fig. 1 is a. composite view of one exemplification of my invention, which shows a portion of this construction in front elevation, and the remaining portion thereof in vertical section on a central plane; Fig. 2 is a sectional plan view on the plane 22 of Fig. 1; Fig. 3 is a vertical section on a larger scale, through the control mechanism of this oranization; Fig. 4 is another vertical section t irough one of the heating burners; Figs. 5 and 6 are fragmentary detail views showing certain alternative heating coil constructions;

Fig. 7 is a side elevation of a second form of and 12 are vertical sections through two other forms of control devices that may be used in place of those shown in Figs. 3 and 9; Fig. 13 is asimilar section of still another form of valve actuating mechanism that embodies certain features of my present improvements and which may also be used in conjunction with the general constructions depicted in Figs. 1, 2, 7 and 8; and Figs. 14 and 15 are diagrams illustrating one of the specific features of advantage of my'preferred forms of heating coils as shown in Figs. 1 and 5 or 8 and 9. i

The organization shown on the first sheet of my drawingsFigs. 1 to 4 inclusive-comprises a cylindrical shell 1, which is closed at the bottom by a plate, 3, and is provided with a concentric sheet metal jacket 4, that forms therewith a narrow annular air space 5. A short closed drum 6 is fitted closely in the lower slightly contracted end of the shell 1, and is held at a short distance above the bottom plate 3 by the central foot or lug 7. The upper end of the annular space 5 is in communication with the external air through I a row of openings 10 in the jacket 4; and the lower portion of this space communicates with the chamber between the drum 6 and the plate 3 through the series of transverse ports 11 in the wall of the shell 3. The drum 6 carries an inner and outer row of gas burners 1212 etc., the detail construction of which is illustrated in Fig. 4. As there shown each of these burners consists of a hollow stem support 13, which is screwed into the lower head of the drum 6 and projects up through a larger opening in the upper end thereof; a mixing tube 14 which is threaded over the upper enlarged head of the stem 13 and is screwed down thereon until its lower flanged end is in sealedcontact with the drum head; and a perforated hood or cap 15 which is screwed onto the upper end of the mixing tube 14. The head of the stem 13 is perforated with one or more restricted ducts 16 for the passage of gas from the interior of the drum 6 to the mixing tube 14; and the top of the latter is preferably covered with supply of gas to the burners 12; and a smaller independent connection 20 leads from the pilot light 21-which is located at a convenient point in the combustion chamber containing theburners 12to the main fuel supply conduit 22.

The operation of that portion of the organization which has thus far been described is as follows: When gas is admitted to the conduit 18 (in the manner to be explained later) it fills the interior of the drum 6 and issues through the ducts 16 in a series of high velocity jets which are thoroughly mixed with the streams of air that are coincidently drawn upward through the stems 13, from the chamber between the drum 6 and the plate 3. The mixed gas and air flows upwardly, through the tubes 14, and the screens 17, and outwardly through the perforated or slotted sides of the caps 15, and is ignited by the constantly burning pilot light 21. The upward movement of the air from the lower chamber results in a corresponding inflow of airthrough the row of openings 10, downwardly through the annular space 5, and inwardly through the series of radial ports 11- to the said chamber; and this inflowing current of air is preheated to a considerable degree, in its passage over the hot walls of the shell 1 surrounding the combustion space, before it is drawn into the burners 12. This recuperative or regenerative action of the parts very considerably diminishes the loss of heat by radiation from the heater jacket, raises the temperature of the gases of combustion, and thus substantially increases both the rapidity and the efliciency of the heating operations. This last result is of particular value and advantage in the use of the instantaneous type of hot water heater which is herein illustrated and described.

The upper end of the combustion chamber, containing the

burners

12 and 21, is partially closed by an annular Lshaped bracket 23 whose upper surface is provided with two helico-spiral grooved-

edge ribs

24 and 26 and with an intermediate row of forked supports 25 that are respectively adapted to receive and rigidly support the lower turns of three concentrically disposed volute coils of pipe which constitute the heat absorbing elements of the organization. Each of these heating coils is made up of two tubes 2728, 2930 and 3132, which are wound in parall'el to form a tightly closed volute, or frusto-conical, wall; and the contiguous or adjacent ends of successive coils are cross connected by the semi-spiral loops or turns, 33, and 34 (as indicated by dotted lines in Fig. 1) so as to form a continuous twin tube conduit that is coupled, at its upper ,and outer end, to a water inlet fitting 35by means of the semispiral turn 36 and the manifold 37'and is connected, at its lower and inner end, to the hot water discharge union 46 by means of the three-quarter spiral loop 38 and the manifold 39. The outer coil 31-32 is surrounded by an annular water jacket 40, whose lower flanged edge rests on the bracket 23 and projects down over the adjacent edge of the lower shell 1; and the upper ends of all three loo coils (27-28, 29-30 and 31-32) are covered by a double dome cap 41-42 that is supported and held in place by the upper flanged edge of this water jacket. The inner dome 42 of the heater cap is provided with a helicospiral grooved edge that engages closely with the upper turn of the intermediate coil 30; and the inner surface of this dome is preferably lined with a sheet or layer of insulating or heat resisting material 43, whose lower edge projects down inside of the said turn and forms therewith a seal, which will prevent the direct passage of the gases of combustion from the upper ends of the coils 27-28 and 29-30 into the space between the two domes 41-42. The assembled coil, bracket and cap members (27-28, 29-30,

'31-32, 23-24-26 and 41-42-43) constitute, in effect, a return flue boiler which conducts the gases of combustion from the burner chamber in the shell 1 up through the center of the inner coil 27-28; thence downwardly through the annular space between the inner coil and the intermediate coil 29-30; and then outwardly and upwardly, around the supports 25 and through the annular chamber between the intermediate and outer coils, 29-30 and 31-32; and discharges them into the hollow cap 41 from which they passto the chimney flue 44.

The lower end of the water jacket 40 is connected to the cold water supply pipe and the upper end of this jacket is connected to the adjacent extremity of the outer coil 31-32-36-37 by the elbow fitting The water entering the heater therefore flows upwardly through the jacket 40, then downwardly through the outer coil, then upwardly through the intermediate coil and then downwardly again through the inner coil, from which it passes-through the sp ral turns 38 y and the manifold connection 39' -to the hot water outlet union 46.

The water discharge fittings-which contain the fuel control mechanism-are shown in elevation at the right of Fig. 1, and are illustrated in sectional detail in Fig. 3. They comprise a flanged T box 47 which is rigidly bolted to the overlapped edges of the shell and jacket members 14-40, and which is joined to the hot water outlet union 46 by the short nip 1e 48; and a reducing sleeve coupling 49 w iich connects the upper outlet of the T with the house service pipe 50. The lower boss of the fitting 47 is threaded to receive the valve box 19; andthe latter is provided at its lower end with a flanged sleeve coupling 51 which connects the said box with the gas conduit 18. The flow of gas from the fuel supply pipe 22, through the said box 19 and the connection 51 to the conduit 18, is

controlled by a downwardly opening valve 52 which is mounted on the upper end of a metal bellows or sylphon member 53 that is attachedto the flanged end of the coupling 51. The interior of the sylphon, 53, is in communication with the hot water outlet through a lateral passageway 54 in the head of the coupling 51, and a pipe union connection 55 between this head and the box 47; and it contains a spring element 56 that cooperates with the water pressure on the head of the sylphon 53 in holding the valve 52 against its seat. The box 19 also contains a second syl phon 57, which is of the same cross sectional area as the sylphon 53, and which bears, at its lower end, on the central stem of the valve 52. This sylphon 57 is attached to a head 58 which is fitted closely in the recessed opening on the lower side of the T box 47, and which has a central hub or boss that projects up into the interior of the said box. This boss is centrally bored to receive a doubleball valve 59-60, .which is confined therein by the lower beveled end of the vertical Pitot tube element 61; and it is also provided with two side passageways 62 and 63, the first of which leads from the opening below the valve 59-60 to the end of a horizontal Pitot tube 64 that is positioned in the center of the water discharge passage of thebox 47, and the other of which leads from the opening between the valve heads 59-60 to the interior of the sylphon 57. The double ball valve element is attached to the lower end of a rod 65 that asses up through the opening of the Pitot tu and through a central stulfing box in a U- shaped head, 66, which is interposed and clamped between the

parts

47 and 49; and the valve is normally held in its upper positionshown in Fig. 3-by means of a spring 67 that bears on the lower end of the rod 65. The upper extremity of this rod is engaged by the top plate of a third sylphon member 68' which is attached to the upper face of the head 66, and which is enclosed in a thin metal cap 69 that is also hermetically secured to the said head; and the space between the sylphon 68 and the cap 69 is partially fillede. g., to the level L-with a volatileliquid having a boilin point which isin the neighborhood of the esired temperature of the hot water supply. The head 66 is laterally perforated with passageways 70-70 etc., which allow the Water to flow freely from the up er end of the casing 47 to theannular'space etween the sleeve 49 and the sylphon cap 69; and it is also provided with a vent or duct 71 which leads from the interior of the sylphon 68 to a drain port 72 in the flanged end of the box 47.

The 0 eration of the valve and valve control mec anism last described is as follows: When no liquid is flowingthrough the beaten the pressure of the water'inthe two

sylphon bellows

53 and 57 is the same and the valve 52 is then held in its closed position by the spring thermostat 68-69 is then insufiicient to overcome the tension of the spring 67 and the valve 59-60 closes the opening at the base of the vertical Pitot tube 61 but allows the water to pass freely from the tube 64 through the passages 62-63 to the interior of the sylphon 53. If now a house service tap, or other outlet in the line 50, is opened the resulting flow of water past the Pitot tube 64 produces a velocity pressure at the open orifice of the said tube. which is transmitted to the sylphon 57 and which is suflicient to overbalance both the normal hydrostatic pressure in the connections 55-5-53 and the tension of the spring 56. The superior force thus exerted on the head of the upper sylphon opens the valve 52 and permits the gas to flow into the lower part of the valve box 19 and thence, through the openings 73 in the head 51, to the burner conduit 18. When the flow of water is stopped the hydrostatic pressure in the two sylphons is again balanced and the "alve 52 is closed by the spring 56. If, during the continuation of the flow, the temperature rises above a certain predetermined point the vapor pressure in the thermostatic chamber 68-69 will become suflicient to overcome the tension of the spring 67 and the valve 59-60 will be forced down thereby shutting off communication between the passageways 62 and 63 and opening communication between the reversed Pitot tube 61 and the interior of the sylphon 57. The negative velocity or suction pressure at the opening of this tube will then be transmitted to the upper bellows and the pressure therein will be immediately reduced below that in the lower sylphon; and the valve 62 will be instantaneously closed by the combined effect of this difference in pressure and of the spring 56. When the temperature is again reduced below the point of thermostatic control the condensation of vapor in the chamber 68-69 permits the spring 67 to again raise the valve 59-60; the velocity pressure in the Pitot tube 64 is again transmitted to the sylphon 57; and the force thus exerted on the upperside of the valve 52 overcomes the tension of the spring 56 and once more opens communication between the fuel supply pipe 22 and the burner conduit 18. I

The point at which the thermostatic valve members, 59-60-65, will be shifted-by a change in the temperature of the flowing water-can be varied within wide limits, either by changing the character of the liquid in the thermostat chamber, or by changing the tension of the spring 67, or both; but in order to provide for varying this point while the heater is in continued operation I preferably provide means for alteringthe relative position of the assembled parts 58-67 with respect to the thermostat elements 65- 68-69. In the present exemplification of my invention this relative adjustment of the parts is provided for by beveling the upper surface of the head 58 and interposing between it and the casing 47 a reversely beveled and transversely movable plate 74 that can be shifted laterally by means of the differential screws 75-76. \Vhen adjusted to the desired positions the relatively movable parts are clamped tightly against the casing 47 by means of screws 77-77 etc. which are threaded into ribs on the interior of the box 19; which pass down through the head of the sleeve 51; and are locked in place by nuts 78 on the lower side thereof.

Figs. 5 and 6 illustrate modifications of the twin tube conduit construction shown in Fig. 1. In the arrangement depicted in Fig. 5 the two parallel tubes 3132, which constitute the outer coil (or the tubes 27-28 and 29-30 which make up the inner and intermediate coils) are wound in offset or staggered relation to each other-instead of in the vertically superimposed relation shown in Fig. l-and the completed unit takes the form of a double walled helix whose successive turns overlap and interlock in such manner as to both increase the structural rigidity of the coil, and also more effectually retard any transverse leakage of the gases of combustion through its interstices. The annular spaces, a. between the contacting sides of the staggered turns may also be filled with asbestos, or some fibrous cement; and the superimposed edges thereof may be advantageously brazed or soldered together at intervalsas indicated at w, w-while the coil is being made up. In the modification shown in Fig. 6 the parallel tubes 27-28 (or 2930 and 31-32) are of oval or elliptical cross section and are wound in slightly offset and overlapped relationship; the contiguous sides of these tubes being spot welded or brazed together (at w, w, etc.) to prevent any accidental displacement of the superimposed turns during the winding, or the subsequent assembling operations. The use of oval or elliptical pipe, in place of circular pipe of the same cross-section, increases the ratio between the heat absorbing surface of the coil and the volume of the liquid contained therein, and thereby increases the rapidit and effectiveness of the instantaneous (sicg heating action when the liquid first begins to flow through the coils and the gas 1s first turned on.

'The extended absorbing surface which is presented by all of the previousl described coil constructions will quickly a stract the larger part of the heat from the gases of combustion-as they pass up and down between the concentric coil walls-and will lower the temperature of those gases to below that of boiling water. The steam constltuent of the gases-which results from the combustion of the hydrogen constituents in the fuel-will therefore be condensed and the water of con- 1,vss,ose

densation will drain back, through suitable orifices in the bracket 23, into the lower part of the heater shell. In order to revent this liquid from escaping onto the cor of the room or chamber in which the heater is placed, the drum 6 is provided with an upwardly extending flange or lip 80 to form a pan or basin 81, which may be emptied at suitable intervals throu h a drain cock 82. The improved form of urner construction which I employ prevents any of this water of condensation from entering the mixing tubes 14 even when it collects to the full depth of the an 81; and the retention of this water in the ower part of the heater shell is advantageous not only on the score of cleanliness, but also because it prevents any injurious overheating of the burner parts and the as connections thereto. The importance of t is last mentioned feature of operation may be realized when it is understood that, inlon continued' periods of o ration, the cap and gauge elements 15-1 may, without such coolmg, become almost, or quite, redhot.

The construction shown in Figs. 7 8 and 9 com rises a flanged shell 1", which is open at 'the ottom, and which is provided at the top with a rabbeted edge that receives a sheet metal extension 85; and a as supply drum 6 which fits closely in the lower part of the shell 1, and is sup rted on the inturned lower flange thereo by the annular rib 7. A late 3 is interposed between the rib 7" an its flanged support,and forms, in conjunction with the contiguous end of the drum 6, an air supply reservoir at the base of the heater. The shell 1 and the cylindrical extension 85 are surrounded by a concentric sheet metal jacket 4 which forms therewith an annular air space 5 that is incommunication with the lower air reservoir through a row of portopenings 11" in the shell 1 and a corresponding series of holes 11 in the annular rib 7. The upper ends of the concentric walls 4-85 are covered by a tri 1e walled cap 41-8642'* which is provi ed with a series of vertical flues, 87, '87, that afford free communication between the inner chamber of the heater shell and the chimney opening 44", in the top wall 41 of the cap; and a second row of

inclined flues

10, 10 which are located between the upper ends of the flues 87-87, and pass through this chimney openin to an enclosed chamber 88 between the intermediate and bottom .walls 8 of the said cap. The chamber 88 is in co munication with the upper end of the annular space 5, through the series of peripheral ports 10", 10" etc.; and the con nected passageways and chambers 10--88- 10**-5-11*-11"; allow a continuous flow of air from around the hot cap and down the side walls of the heater to the air reservoir below the gas supply drum 6. This drum is provided with a cluster of heating burners" connected to the main fuel supply 12" that are identical in construction with the one shown in detail in Fig. 4; and it is ipe 22" by means of the conduit 18 and t e valve casing 19". When gas is admitted to the drum by the action of the automatic control mechanism, it passes to the burners 12 and is there mixed with air that is drawn upward from the lower air reservoir (through the burner stems 13, 13); and the mixed as and air is ignited by the flame of a suita le pilot light which is constantly supplied with gas through the by-pass connection 20.

The heating coil members which are used in this second illustrative embodiment of my invention comprise seven flat spirals, 90- 91-92-93-94-95 and 96, each one of which is made up of three tubes that are coiled in vertically superimposed parallel relationship. The six upper spirals are arranged in three pairs 96-95, 94-93, and 92-91, each of which is preferabl structed as an integral unit, by ben 'n or offsetting three parallel tube elements at t eir centers-as indicated at 97 etc-and then successively coiling the offset halves of these elements in opposite directions on a collapsible flanged, or grooved, mandril with removable spacing strips interposed between successive turns of the spirals. During the operation of winding-or subsequently, after the removal of the collapsible mandril frame and the spacing strips from the completed unit-the contacting sides of the parallel tube elements may be advantageousl soldered or brazed or spot welded toget er at intervals-as indicated at win Fig. 10-so as to maintain the said elements in the desired relationship and also increase the rigidity of the spiral coils. The completed units are suspended in position in the upper part of the heater shell by means of the central rod 98 and the cross bars 99 that are secured thereto at suitable intervals; and chordally disposed strips 100 may, if desired, be interposed between the spirals 96-95, 94-93, and 92-91, in order to more firml support the upper portions of these paire or double units.

The ends of the upper and outer turn of the top spiral 96 are slightly offset from the plane of the coil and connected to a cold water inlet pipe 45 by means of the flared manifold coupling 37; and the inner turn of the bot tom spiral 90 is likewise bent out to one side of the coil and coupled to the hot water disa charge fitting 46" by means of the manifold 39". The outer adjacent ends of the successive spirals, 95 and 94,93 and 92, 91 and 90, are

. cross connected in series by suitable manifold and sleeve couplings, 101-102-103 etc. that are preferably brazed or welded together; and the coupled members thus form a continuous conduit through which water flows from the inlet 45 to the center of the upper spiral 96, then outwardly through the turns of the spiral 95, then successively inwardly and outwardly through the coils of the units 9493, and 92-91, and then inwardly again through the turns of the lower spiral 90 to the outlet fitting 39 46.

The automatic mechanism for controlling the flow of fuel to the gas drum 6 is shown in enlarged sectional detail in Fig. 9. It comprises an upwardly opening valve element 52" which is normally held on its seat in the casing 19 by the joint action of gravity and of the gas pressure in the supply pipe 22. This valve is positioned between the adjacent heads of the two

sylphon members

53 and 57" which are of the same cross sectional area and which are of substantially the same length. The lower sylphon 53 is mounted on a centrally perforated plate which is clamped in position between the lower end of the casing 19 and a manifold plug-coupling 51 that is also connected with the cold water pipe 45 (see Fig. 7) and the interior of this sylphon is in constant communication with the said pipe through the passage ways vi -55 in the connection 51. The upper sylphon 57 is mounted on a plate 58 which is threaded onto the lower end of a flanged sleeve 58, and which is also clamped in position between the upper end of the box 19 and the elbow fitting 47; and the latter is coupled to the hot water outlet union 46 by the nipple and union connection 48 The top of the elbow 47 is connected to the house service pipe 50 by an offset cap-coupling 49; and the upper portion of this coupling contains a vapor thermostat, that consists of a thin metal shell 69* containing a sylphon element 68*, the space between these parts being partially filled with a volatile 1i uid L. The lower head 66, of the shell 69, is t readed onto the upper end of the sleeve 58"; and the upper head of the said shell is provided with a central extension 7 that passes up throu h the cap 49* and is locked and sealed in ace thereon by the nut and washer 77. T e sleeve 58 is fitted tightl into a central cross rib in the elbow box 4 and is centrally bored to receive a hollow balanced plunger valve 59, which is attached to the lower end of a rod that passes up through a stufling box in this sleeve, and bears on the upper plate of the sylphon element 68'. The sleeve is also provided with an internal annular port 62, that communicates at one side with the openingin a horizontal Pitot tube 64-which faces inwardly, or

toward the incoming stream of water flowing of fuel to the heater burners.

104, and is normally held in its upper position (Fig. 9)in which the ports 104 are just above the annular port 62, and the lower edge of the valve is just above the row of ports 63*by the spring 67 The functional action of this last described control mechanism is the same as that of the one shown in Fig. 3. When the water is at restin the system the hydrostatic pressure in the two sylphons, 53 and 57 is the same; and the valve 52 is closed. When a house service tap, in the line 50*, is opened and cold water begins to flow through the heater pipes, and outlet connections 4648 47 49 the pressure in the sylphon 57 is reduced by the velocity suction, or ejector, action of the reversed Pitot tube nozzle 61 which is at that time in communication with the interior of the said sylphon through the ports 63 63 -and the valve 52 is opened by the superior pressure in the passage way 54 and the lower sylphon 53 The opening of this valve permits the fuel to flow from the supply pipe 22, through the conduit 18 and fuel drum 6*, to the burners 12*, where it is mixed with air drawn from the air reservoir below the drum 6, and ignited by. the pilot light. The water which flows through the multiple tube coils 9690, is quickly raised in temperature by the heat of the burning fuel and when the temperature reaches a predetermined point the vapor pressure in the thermostat cells 6869 overcomes the tension of the spring 67 and the valve 59 is moved downwardly thereby closing the ports 63 and simultaneously establishing communication between the ports 62, 104 and 63. The pressure in the upper sylphon 57 then becomes equal to the impact or velocity pressure at the orifice of the Pitot tube 64; and as this pressure exceeds the static pressure in the opening 54' and the lower sylphon 53, the valve 52* is immediately closed and the supplyof gas is cut off from the main heating burners. The resultant drop in temperature in the flowing water reduces the pressure in the thermostat 68"69 and the spring 67 lifts the valve 59 to its initial position thereby cutting off communication between the Pitot tube 64 and the sylphon 57 a and reestablishing connection between that sylphon and the reversed Pitot tube 61. The resulting drop in pressure in the upper sylphon chamber allows the valve 52* to be again opened to admit a fresh supply When the flow of water is stopped the pressure is immediately equalized throughout the systemregardless of the final position of the valve 59" and the main fuel valve 52 is then closed by the joint action of gravity and of the gas pressure on its upper face.

The predetermined joint of thermostatic cut oil', may be readily varied within wide limits by changing the liquid in the vapor pressure cell 6869' or by altering the initial tension in the spring 67. This result may also be effected by loosening the lock nut 7 7 a ,and revolving the cell 69-thus lowering or tained. Any leakage of liquid through the screw joint between the head 66 and the sleeve 58or through the sliding joint between the stufiing box in the sleeve and the rod 65is drained away through the constantly open ports 71"72 that lead from the space around the thermostat rod 65 to the exterior of the casing 47.

Fig. 10 illustrates a slightly modified form of the triple tube conduit construction shown in Fig. 8. In this modification the parallel elements of the coils 93---94 (or of the other coils 909192-9596) are wound in slightly offset relation-instead of the vertically superimposed relationship illustrated in Fig. 8-for the purpose of laterally deflecting and breaking up the rising streams of hot gases, as theypass between successive turns of the coils, and thus more continuously and completely equalizing the temperature conditions in different parts of the heating chamber. The construction shown in Fig. 10 also differs from that of Fig. 8 in the vertical spacing relationship between the upper and lower members of the paired coils ;the members 93'94 being relatively much closer to each other than the members 9192, 93-94, and

9596; and it will be apparent that the oppositely wound, or right and left hand, spirals of these coils may, if desired, be allowed to rest directly on each other and thus avoid all necessity for using any intermediate supporting or spacing strips, such as are indicated at 100, 100 etc.

Figs. 11 and 12 illustrate other forms of automatic control mechanisms which operate in the same generic manner as those shown in Figs. 3 and 9; and which can be used in conjunction with the general organizations depicted in Figs. 1 and 2, or Figs. 7 and 8; or in combination with various other forms of he iter coil construction-such, for example, as are outlined in Figs. 1 of my earlier Patents Nos. 1,131,021, 1,146,826, 1,156,949, 1,- 243,017, 1,248,579, etc.-or, for that matter, in any analogous construction of the instantaneous heater type in which the supply of fuel is controlled and governed jointly by the flow and the temperature of the water in the heater coils. In the first of these mechanisms (Fig. 11) the fuel valve 52 is arranged in a vertical position, and is attached directly to the free end of a horizontal sylphon 53 and is normally held in its closed position against the pressure of the gas in the supply conduit.- 22"by the spring 56". The supporting head, 105, of the sylphon 53", is screwed into the bottom of a recessed pocket, which is formed in the side of the casing 47",

and which is in direct communication with the threaded outlet that receives the burner conduit 18'. A valve box 19 is bolted to the outer face of the casing N -in line with the axis of the valve and sylphon elements 52", 53 -and this box contains a second sylphon 57 which is attached to a projecting boss 58 on the side of the box. The central portion of the casing 47 is bored to receive a double acting poppet valve, 59"60", which is confined between the head 105 and'an opposing head 106 which is screwed to the inner face of the casing. The head 105 is provided with a central opening 54 which leads from the end of the poppet valve chamber to the interior of the sylphon 53; and the space between the valve heads 59"60 is in constant communication with the interior of the sylphon 57 through the angled duct 63"-which leads from the body of the casing 17 through the central rib that crosses the opening to the conduit 18 and the cooperating passage way 107 that passes down one side of the box 19', through theboss 58", and terminates in registry with a port in the adjacent head of the said sylphon. The central opening in the head.106which forms a continuation of the cavity containing the valve heads 59', 60

is provided with a lateral port that opens into a chamber 108, between the head and the casing 47"; and this chamber is in constant communication with the interior of the sylphon 53" through the passage way 109 (dotted) and the port 110. The inner end ofthe valve chamberadjacent the head 60 is provided with a lateral duct 62 which leads to a vertical Pitot tube 64 that is faced inwardly, or toward the stream of water entering through the nipple connection 48; and the outer end of this same chamber-adjacent the head 59"is provided with a similar duct that communicates with asecond vertically positioned Pitot tube 61 that faces upwardly and outwardly, or toward the discharge opening from the casing 47. This discharge opening contains a vapor thermostat member, which consists of a sylphon element 68", an enclosing metal cap 69", and a head 66' that is screwed into the upper end of the casing-the closed chamber between the hermetically sealed parts, 66 68 69", being partially filled with a volatile liquid L. The movable head of the sylphon 68? is connected to the stem 65" of the valve 59"60", by means of the rod 65 and the bell crank lever 74"; and the relative position of the connected parts may be adjusted by means of the set screw 76".

When the water is cold, or below the point at which the thermostat is designed to act, the

the spring 67 that is interposed between the head of the valve stem 65 and the stufiing box, through which the stem passes, in-the head 106., When there is no discharge of liquid through the casing connections 48"47"50 the hydrostatic pressure in the two sylphons, 53 57, is balanced; and the main fuel valve is then held closed by the spring 56. But whenever an outward flow of water is started (as by opening a tap in the service pipe 50) the velocity pressure at the opening of the Pitot tube 64 is transmitted 'to the outer sylphon 57 through the passage ways 6263107--while the pressure in the passage 54 and the inner sylphon 53 is simultaneously diminished by the suction or ejector action at the opening of the reversed Pitot tube 61". The opposing pressures on the "alve 52 are thus altered to such an extent as to overcome the tension of the spring 56", and to completely open the valve, thus admitting the full supply of fuel to the burner conduit 18". If the temperature of the flowing liquid reaches a predetermined point, the increased vapor pressure in the thermostat member 68"-69 overcomes the tension of the spring 67 and the double action valve 59"60 is moved outwardly. When this movement occurs the valve head 59 will cut off communication between the Pitot tube 61' and the interior of the sylphon 53 and simultaneously open communication between this tube and the interior of the outer sylphon 57 through the passage ways 63107;while the valve head 60 will coincidently close the opening between the other Pitot tube 64 and the passage 63 and open communication between that tube and the sylphon 53-through the passage ways 62", 108, 109, 110. The velocity pressure conditions in the two

sylphon chambers

53 and 57 are thus reverse; and the valve 52 is instantly and firmly closed by the now preponderantpressure in the inner sylphon and the cooperating tension of the spring 56". If the temperature of the flowing water drops again the condensation of vapor in the thermostat chamber permits the valve 59"60" to be restored to its initial position by the spring 67"; and a preponderant kinetic or velocity pressure, suflicient to overcome the spring 67 and once more open the valve 52",

is again established in the outer sylphon 57 When the flow of water is stopped, all velocity pressures are immediately eliminated and a uniform hydrostatic pressure is established in the system regardless of the position of the valve 59 60 thus permitting the valve 52 to be closed by the action of the spring 56 alone.

In the construction illustrated in Fig. 12 the water discharge opening through the casing 47 is made in the form of a Venturi orifice whose oppositely beveled sides 6461 are respectively in communication with the hot water outlet nozzle 48 and with the lower end of a sleeve coupling 49 that connects the said casing with the house service pipe 50.

The coupling 49 contains a vapor thermostat which is similar in construction to the ones shown in Figs. 3 and 9 (previously described) and which is supported on an I- shaped base 66 that is clamped in position between the

parts

47 and 49. The lower flange of the base 66 is perforated to' permit the water to flow freely into the lower end of the sleeve 49; and the latter is provided with a helically disposed rib 112 which compels the flowing liquid to pass several times around the thermostat shell 69, before it escapes into the service pipe 50. The body of the casing 47 is provided with a vertical chamber, which is laterally apertured to receive the main fuel supply pipe 22; and which is bored and threaded, at its lower end, to carry the valve sleeve 19 that is, in turn,

connected with the fuel delivery conduit 18.

The casing chamber and its valve sleeve liner contain two vertically superimposed

sylphons

53 and 57, the first of which is mounted on a head 105 that is bolted against the upper closed end of the chamber, and the second of which is supported on a rib 58 that projects from one side of the valve sleeve 19. The main fuel valve 52 is interposed between the adjacent ends of the two sylphons 53 and 57 and is preferably integral with the lower head of the first mentioned element. The casing 47 is further provided with a second vertical chamber which is between the sylphon containing recess and the Venturi tube 6461, and which contains a double ball poppet valve 5960, that is confined in place therein between the heads 106 and 114. This poppet valve is attached to a stem 65 which passes up through the head 106 and through a stufiing box in the base 66 and engages with the upper head of the thermostat sylphon 68; and it is normally held in its upper positionas shown in Fig. 12by the adjustable spring elements 657 6 that are mounted in the lower head 114. The cavity which contains the upper head 59 of the valve is in communication with the throat opening of the Venturi tube through a duct 115; and the cavity containing the lower head 60 communicates with the upstream end 64 of the tube through a port 116. The interior of the upper sylphon 53 is in communication with the space between the valve heads 5960, through the duct 54 and a port 110 in the head 105; and the interior of the lower sylphon 57 communicates with the space below the valve head 60through the passage way 63 the annular channel 117 and the passage 107and also with the space above the upper head 59, through the passages 107117-109 (dotted) and 108.

The operation of this last described control mechanism is as follows: When a flow of water is established through the Venturi tube 64-61, the velocity pressure at the throat of the tube is less than at its upstream or inlet end 64; and when the poppet valve IS in the position shown in Fig. 12in which the pressure in the lower sylphon. This

condilivery pipes

22 and 18. The sy tion will remain unchanged until the temperature of the flowing water is raised to such a point that the resultant vapor pressure in the thermostat chamber 6869 overcomes the preadjusted tension of the spring 65, and moves the poppet valve downward to its lower position. This movement shuts off communication between the port 116 and the interior of the lower sylphon 57, and simultaneously establishes a connection between this port and the

passage ways

54 and 110 which lead to the sylphon 53; and'the same movement coincidently shuts off communication between the throat duct 115 and the upper sylphon, and opens communication be tween this duct and the ports and passages,

108109117 and 107, which lead to the lower sylphon. Under such circumstances the upper side of the main valve 52 is subjected to the preponderant velocity pressure at the inflow or upstream side of the Venturi tube 6461; and this pressure cooperates with the action of gravity, and of the gas pressure in the supply pipe.22, in quickly and positively closing the said main valve. When the temperature of the flowing water falls below the point of thermostatic cut off. the condensation of vapor in the chamber 6869 permits the spring 65 to restore the poppet valve 5960 to its upper position, and to thus reestablish the first described pressure conditions ;in consequence of which the valve 52 is again opened. When the flow of water through the casing 47 is stopped the hydrostatic pressures are at once equalized in all of the passages and chambers of the casing 47; and the main valve 52 will then be closed by the action of gravity (supplemented by the gas pressure on its upper side) regardless of the position of the poppet valve 5960.

Fig. 13 illustrates another simple and eflicientconstruction, in which the variation of the velocity pressure at different points in a Venturi discharge tube is utilized to control the opening and closing-of a main supply val In this exemplification of my present improvements the last named valve (here indicated at 52) is located in a valve chamber 19, which is separate and distinct from the one containing the actuating sylphon 57, and which is provided with end and side apertures to receive the fuel sup ly and del phon 57 is mounted on a head 58 that is screwed into the side of the main casing 47; and the latter is connected to the water outlet from the heater, or other device with which it is used, by the nipple 48. The Venturi tube opening 6461 leads from this connection to a lateral aperture in the upper wall of the casing 47, which is threaded to receive the sleeve coupling 49 that carries the lower end of the service discharge pipe 50. The sleeve 49 is provided on its inner surface with a helical rib or vane 112 that closely embraces the outer shell of a vapor thermostat element 6869; and the latter is provided with a head 66 which is mounted on a short annular support 120, that projects up from the floor of the water passage on the down stream side of the Venturi tube. The body of the casing is also provided with a central chamber which contains a short poppet valve element 59, that is confined therein by the elongated head 106; and this valve is operatively connected to the thermostat element 68 by means of the valve stem 65. the bell crank lever 74 and the vertical rod 65. The valve is normally held in its left hand position (shown in Fig. 13)

by the spring 65; spring, as well as the operative relation of the connecting elements, 657465, can be adjusted by the nuts 76.

The actuating sylphon member 57 is in this case mounted in a closed chamber and is exposed to water pressure on both its interior and exterior. The interior of the sylphon is in constant communication with the opening 116, at the upstream or inlet side of the Venturi tube, 6461, through the duct 63, the \annular channel 117 and the passage 107;

and the chamber surrounding the sylphon is normally connected to the throat opening 115, of the Venturi tube, through the port 54 and the cavity containing the poppet valve 59. The free end of this sylphon is operatively connected to the main fuel valve 52 by means of the rod 121 which passes through a stuffing box in the closed end of the sylphon chamber, and through an unpacked aperture in the adjacent wall of the valve box 19, and is provided with an adjustable washer 122; and the said valve is normally held closed by a spring 56 that is interposed between it and a removable cross bar 123. But when a stream of water flows through the Venturi tube 6461 (with the valve 59 in its indicated position) the hydrostatically 'equal water pressure on the two sides of the sylphon 57 are unbalanced; and the preponderant velocity pressure at the upstream port 116 ted to flow from the pipe 22 into the front end of the box 19 and thence to the conduit and the tension of this,

18. This movement brings the washer 122 into pressure engagement with the'adjacent outer face of the valve box 19 and prevents any leakage of gas from the opening through which the rod 121 passes. When the temperature of the flowing water exceeds a pre-' both sides,-viz, the velocity pressure at the upstream orifice 116 and the main valve 52 will be closed by the joint action of the spring 56 and the gas pressure in the pipe 22. A subsequent drop in temperature results in a restoration of the poppet valve to its initial position, and a reestablishment of an excess or preponderant velocity pressure on the interior of the sylphon 57' which will overcome the initial tension of the valve spring 56 and again open the main valve 52. When the flow of water stopsthe hydrostatic pressures are at once equalized in all of the passage ways and chambers of the casing 47 and the main valve 52 will then be closed, regardless of the position of the temperature controlled poppet valve 59.

All of the illustrative control mechanisms which have been described-i. e., those shown separately in Figs. 3, 9, 11, 12 and l3are characterized by the same generic mode of operation, although they differ quite widely from one another in structural form. In all cases the actuating forces that control, or effeet, the opening and closing of the main fuel control valve of the system, are what are termed velocity pressures, which are produced or set up by the flow of a stream of liquid over or past restricted orifices that lead to volumetrically variable chambers located outside of the main stream flow. These velocity pressures are primarily functions of the speed of movement of the flowing water with respect to the axes of the orifices at which they are established; and they are not dependent upon the actual passage of liquid into or through the said orifices; although some slight movement of this nature necessarily accompanies any change in volume in the chambers to which they lead. The functional mode of action of my improved velocity controlled mechanism is thus difl'erentiated and distinguished from previously used devices in which a control member is actuated by the pressure of a water stream against a piston or check valve elementas in the well known Ruud-Pittsburgh type of instan aneous water heater constructionor in which such a member is actuated by hydraulic differences in head at separated points in the water stream-as exemplified in the Braith- Waite-Wadsworth type of control apparatus. One of the marked advantages of the present invention is that substantially different velocity pressures may be produced at points where the difference in hydraulic head are negligible-by the herein described use of Pitot or Venturi tubes or equivalent deviceswithout interposing any physical obstruction, or any substantial functional resistance, to the free flow of water through the system. I am thus enabled to produce a very compact, self contained, and powerful control mechanism which will act very quickly in both opening and closing the supply valve member, without in any way throttling the continuous passage of liquid through the heater coils; and one which will not be sensibly affected in its action by any changes in either the hydrostatic or hydraulic pressures in the water supply or the water discharge conduits.

It will further be observed that all of the heater coil constructions which I have herein illustrated and described are characterized by the use of multiple tube conduits; viz, by the use of liquid conductors .which are made up of two or more pipes that are wound and connected in parallel. Some of the advantages of this feature of my improvements are diagrammatically indicated in Figs. 14 and 15. The wall thickness, T, of a circular pipe which is capable of withstanding a given internal pressure is proportional to the mean diameter, D, of the pipe. The weight of such a pipe-when the wall is thinis proportional to the thickness and the diameter; and, for a given bursting strength, this weight is therefore proportional to the square of the diameter. But. the cross sectional area of the pipe is also proportional to the square of the diameter; and for a given carrying capacity (i. e., a given volume of discharge at a given pressure) the weight of the conduit per unit length is therefore constant regardless of whether it may be made from one tube or from a number of tubes joined in parallel. But the heat absorbing and conducting surfaces of N tubes joined in parallel is greater than that of one larger tube of the same cross sectional area in the proportion of 1: /N. A twin conduit such as is shown in Figs. 1, 5 or 14, has therefore more than 40% greater surface area than a single tube of the same carrying capacity and length; and a triple tube conductor-like that shown in Figs. 8, 10 or 15has nearly 75% greater exposed area than such a single tube. The rate of conduction of heat from a gaseous medium to a liquid is proportional not only to the surface area of contact, but also to the thickness of the wall between the two media;

and since the wall. thickness of the multiple one tube conduit in the proportion of 1 z /N, the heat absorbing capacity of the twin tube and triple tube constructions may be, respectively, more than 60%, and more than 100%, 5 greater than that of the usual form of single- 7 tube heating coils of the same length, weight,

and cross-sectional area.

In the case of elliptical or flattened tubes (like those shown in Fig. 6) the ratio between 10 the surface area of the single circular pipe conduit and the multiple oval-tube conduit of the same aggregate cross section and length is even greater than 1: /Ne. g., it may be as large as 1 N but the thickness and weight of an oval or elliptical conductor must be greater than that of a circular conductor of the same carrying capacity and length (unless the material is different), and this fact somewhat increases the thermal resistance of the oval tube walls to heat transmission. The heat absorbing capacity of a twin oval-tube construction is therefore intermediate that of the twin-tube and. triple-tube coils shown in Figs. 1-14 and 815 (or alternatively in Figs. 5 and 10).

The great increase in heat absorbing power of all the multiple tube constructions considered above cooperates With the increased temperature of the gases of combustion resulting from the use of a preheating air jacket and of the improved burner construction heretofore describedin accelerating the so-called instantaneous action of the organization, and in increasing its thermal efficiency; But regarded from another view point the augmented heat absorption of my improved multiple tube construction makes it possible to very substantially reduce the length and the corresponding weight of the heating coils without reducing the present standard of thermal efficiency; and when copper is used as a material for these coils (as is the usual practice) the saving in the first cost of this item alone is a very material and important one. It is further possibleby the use of multiple tube coil unitsto substitute cold drawn steel tubing for the now commonly used copper tubing; and thereby efl'ect r0 further. economies in manufacture and operationsince the bursting strength of such steel tubing is in excess of that required in normal practice and the advantages of using tubes of flattened, or elliptical cross section like those shown in Fig. 6) can be obtained without the disadvantage of any increased weight per unit length. a

It will also be apparent 'tothose skilled in this art that the greatly increased heating etliciency of my improved constructionswhich results from the combination of means for preheating the air supplied to the burners with the means for. more rapidly and completely utilizing the greater heat thus generated in raising the temperature of the liquid in the heater coilsalso augments the effectiveness of the thermostatic control means for governing the supply of fuel to the apparatus in accordance with the variations in the temperature of the flowing liquid and thereby maintaining that temperature at the desired point. The air preheating means, the heat absorbing means, and the temperature control means all coact and mutually cooperate to effect the desired result; viz, the raising of the water in the heater to the desired temperature in the shortest possible time and the reduction in the time fluctuations in that temperature to, the greatest attainable degree. r

Othercharacteristic and novel features, and other specific advantages, of the various illustrative organizations herein described, will now be apparent to those skilled in the art to which the present invention appertains; and

with the preceding disclosure as a guide the parts and elements of my improved combinations may be readily modified and rearranged, to best meet special conditions of service, by any mechanic or engineer who is familiar with the construction and operation of the types of. apparatus in which these improvements-or any part of them-may be advantageously utilized. The accompanying drawings and descriptions are therefore to be considered as only illustrative of the many organizations which may embody my present invention; and they are not to be regarded as imposing per se any limitations on the scope of application thereof. t

\Vhat I claim, in this connection, is:

1. In a water heater the combination of a heating coil comprising a plurality of hollow conductors disposed in substantial contact with each other throughout their length and connected in parallel at their ends to form a multiple tube conduit, a fuel burner positioned below said coil, means for enclosing the a said coil and the said burner and for preventing any direct access of theexternal air thereto,and means jointly controlled by the flow and by the temperature of the liquid as it emerges from the multiple tube conduit, for varying the supply of fuel to the said burner and the resultant application of heat to the said conduit.

2. In a water heater the combination of a heating coil, open connections of substantially unchanged area between the ends of said coil and the inlet and outlet passages therefor and affording an unimpeded passage for the flow of fluid therethrough, a heating burner for the said coil, a valve for controlling the supply of fuel to the said burner, and means responsive to differences in velocity pressure *at-*ad acent points in the stream of liquid flowing through the said coil connections and acting to open or close the said valve when the temperature of'said liquid is respectively below or above a predetermined point.

3. In a water heater the combination of a heating coil, a fuel burner positioned below the said coil, a, valve placed in the fuel supply line to the said burner, a pair of volumetrlcally .variable vessels positioned on opposite sides of the said valve, and means responsive to changes in velocity at adjacent points in the stream of liquid flowing through said coil and acting to vary the pressure in one of the said vessels and thereby open the said valve when the temperature of the flowing liquid is below a predetermined point.

4. In a water heater the combination of a heating coil, a fuel burneradjacent thereto, a valve controlling the supply of fuel to the said burner, a pair of sylphon bellows positioned on opposite sides of the said valve, passage ways leading from the said bellows to two adjacent points in the outlet passage from the said coil, a thermostat positioned in the said outlet passage, and means controlled by said thermostat for opening and closing one-of said passage ways in response to variations in temperature.

5. In a water heater thecombination of a multiple tube heatingcoil, continuously open connections between both ends of the said coil and a water supply circuit and providing for an unimpeded flow of liquid therethrough, a plurality of heating burners therefor, a valve controlling the flow of fuel to the said burners, means for normally holding said valve closed when the liquid in the heater coils is at rest or is above a predetermined temperature, and means responsive to a velocity pressure produced by the flow of liquid over two adjacent orifices and acting to open said valve when the flowing liquid is below said predetermined temperature. I

6. In a water heater the combination of a heating'coil, a burner therefor, a valve controlling the supply of fuel to the said burner, means for creating differences in velocity pressure at closely adjacent points in the outlet passage from said coil, pressure ducts leading from said points to pres ure chambers on opposite sides of said fuel :valve, a thermo stat in said outlet passage, and means actu ated by said thermostat for controlling the flow of liquid through one or more of the said ducts for the purpose specified.

7. In a water heater the combination of a heating coil,.a fuel burner adjacent thereto, a valve for varying the supply of fuel tothe said burner, and a temperature controlledmechariis'm for'governing the movements of the said valve and comprising means for creating differences in velocity pressure at adjacent points in the water passage, an auxiliary valve chamber, ducts leading therefrom to the said points, a volumet'rically variable vessel in communication with the said chamber, a thermostat positioned in said water passage, and an auxiliary valve actuated by said thermostat for controlling communication between the said ducts and the said vessel.

8. In a water heater the combination of a heating coil, a heating burner therefor, and means for varying the supply of fuel to the said burner which comprises a Venturi tube in the water passage, a water chamber, ducts leading therefrom to the throat and up stream orifices of the said tube, a volumetrically variable vessel connected with said chamber, ,a valve therein, and means actuated by the change in temperature in the water passage for moving said valve and thereby controlling communication between said vessel and the said ducts.

9. In a water heater the combination of a hollow shell closed at its lower end, a heating coil mounted therein, a fuel burner positioned between the said coil and the closed lower end of the said shell and forming therewith an air reservoir, an air jacket surrounding the said shell and in communication with the said reservoir, and a multiple walled cap conjoining the upper ends of the said shell and the said jacket wall.

In testimony whereof I have hereunto set my hand.

FRANK L. O. WADSWORTH.