US1977303A - Steam heating system - Google Patents

Description

Oct. 16, 934- D. QR'OSTHWQAIT, JR 1,977,303

' STEAM HEATING SYSTEM File d Feb. 3, 1930 3 Sheets-Sheet l Y 2 @WM Q LITTLE g5.

Oct. 16, 1934. D. N. cRosTHwAl'T, JR

STEAM HEATING SYSTEM Filed Feb. 3, 1930 s Sheets-Sheet 5 muuimm Illllllll I I'll! Patented Got. 16, 1934 PATENT OFFICE STEAM HEATING SYSTEM David N. Crosthwait, Jr., Marshalltown, Iowa, assignor to C. A. Dunham Company, Marshalltow'n, Iowa, a corporation of Iowa Application February 3,1930, Serial No. 425,681 7 Claims. (01. 237-12) This invention relates to a new and improved steam heating system, and more particularly to an improved method for automatically feeding steam to the radiators at substantially the rate at which it is condensed.

More specifically the invention contemplates the use of an improved valve in the steam supply pipe which is automatically controlled by variations in the pressure differential existing between the supply and discharge sides of the radiator or radiators so that steam will be suppliedat substantially the rate at which it is consumed.

This invention is particularly applicable and 15 designed for use with a system of heating by sub-atmospheric steam, such as is disclosed in the patent to Dunham No; 1,644,114 granted October 4, 1927, although it will be apparent, as the disclosure progresses. that the principles of this invention are also applicable to a system utilizing steam at atmospheric or super-atmospheric pressures. In this Dunham type of heating system, the steam is circulated to and through the radiators 'or condensing spaces at sub-atmospheric pressures, which pressures are varied according to the amount of heat required for maintaining the space to be heated at the desired temperature. Steam traps are provided at the discharge side of the radiators, and a substantially constant pressure difierential suilicient to insure the circulation of steam through the system is maintained between the supply and discharge mains regardless of what the absolute pressure of the steam within the radiators may be. Orifice plates are positioned in the several supply conduits in advance of the respective radiator units for apportioning the flow of steam to each radiator in accordance with the condensing capacity of the particular unit.

It will be apparent that in a system such as has just been described, with the steam trap closed and a certain sub-atmospheric pressure established. in the return main, if the flow of steam to the radiator is in excess of the condensing requirements thereof, the pressure in the radiator will be raised and consequently the pressure differential between the supply and re-' turn sides of the radiator will be somewhat in creased. On the other hand, if the steam condenses within the radiator more rapidly than it is suppliedxthe pressure in the radiator will limp and consequently the pressure differential will decrease. According to the present inven- 'tion thesevariations from a normalpressure differential are utilized to automatically operate a 'normal pressure difierential.

control valve in the supply conduit whereby the flow of steam to the radiator, or radiators, will be varied to compensate for this change from a Under ordinary circumstances the valve will assume a position of substantial equilibrium whereby the rate of steam flow to the radiator is just sufficient to satisfy the condensing requirements, the pressure diiferential remaining substantially constant.

The principal object of this invention is to provide a new method for heating by steam, such as briefly described hereinabove and disclosed more in detail in the specifications which follow.

Another object is to provide an improved method of controlling the flow of steam to a radiating unit in accordance with the variations in the pressure difierential between the inlet and discharge sides of the radiator.

Another object is to provide an improved method for governing the rate of steam supply to a condensing system, which utilizes changes in pressure caused by varying differences between the rate of steam supply and the rate of condensation to actuate the controlling means.

Another object is to provide in a system such as described hereinabove, means to cut off the steam supply when a predetermined maximum temperature has been reached in. the space to be heated, and for again permitting the steam supply to be turned on when the temperature falls below this maximum.

Other objects and advantages of this invention will be more apparent from the following detailed description of one approved form of apparatus capable of carrying out the principles of this invention.

In the accompanying drawings:

Fig. 1 is an elevation showing the principal elements of a preferred form of sub-atmosphericsteam heating system, in which the improvements of this invention are incorporated.

Fig. 2 is a vertical central section through the improved flow-control valve.

Fig. 3 is an end elevation of this valve, looking from the right at Fig. 2.

sub-atmospheric steam heating system, the control system is also applicable for use with other types of heating systems, as will be hereinafter apparent. This heating system comprises a boiler or generator A, from which the steam flows through supply main B and the improved flow control valve C. The rate of steam supply is. controlled in the portion the space to be heated.

The controlled steam flow in main B passes through risers 1 and inlet valves 2 into the re. spective radiators D. Suitable orifice plates (such as disclosed in the Dunham patent hereinabove referred to) are interposed in the respective risers 1, preferably between the inlet valves 2 and the radiators for proportioning the steam flow to the respective radiators in accordance with the size or condensing capacity thereof. The steam traps E are adapted to close when the radiators are filled with steam and prevent 'the escape of steam therefrom. When condensate and non-condensible gases accumulate in the radiators, the traps E will open and permit the condensate and non-condensible gases to flow out orbe drawn out by the lower pressure maintained in the return side of the heating system. These gases and condensates flow out through pipes 3 into return main F and thence through the strainer 4 into the accumulator tank G. In a similar manner, the condensate and gases accumulating in the portion Bof the supply main pass out through float and thermostatic trap 5 into return main F and thence into the accumulator tank G. The exhausting mechanism H comprises a eparator tank 6 and a pump 7, driven by motor 8, to withdraw water from the lower portin of tank 6 and force it through ejector 9 and thence back into the upper portion of tank 6 together with the gases and condensate which are withdrawn from accumulator tank G through pipe 10 and check valve 11 into the exhauster casing. The gases are vented from separating tank 6 through pipe 12 provided with outwardly opening check valve 13. When a certain amount of liquid has accumulated in tank 6, a float controlled mechanism, indicated generally at 14, operates to open a normally closed valve so that the pump '7 can force a part of the liquid out through pipe 16 provided with check valve 1'7, and thence through pipes 18, 19 and 20 back into the boiler.

The exhausting mechanism H is operated whenever it is necessaryto build up the pressure difierential between the supply and discharge sides of the heating system, or whenever it is necessary to transfer accumulated condensate from the accumulator tank G to the separating tank 6. The control mechanism J comprises a differential pressure controller 21 which automatically opens and closes a switch 22 which operates through starter 23 to control the motor 8. The differential pressure controller 21 comprises a diaphragm subjected on its oppo-. site sides to the pressures existing in the supply and return sides of the heating system. For this purpose control pipes, 24 and 25 extend to surge tanks 26 and 2'7 positioned in the horizontal section 28 of an equalizing pipe 29 extending between the supply and return sides of the heating system, the relatively high pressure end of pipe 29 being in communication with the supply main B and the relatively low pressure end extending down to and communicating with the accumulator tank G. A check valve 30 is positioned in the equalizing pipe between the relatively, high pressure surge chamber 26 am the relatively low pressure surge chamber 27. This valve opens toward the high pressure side of the system and will normally remain closed unless for some reason a lower pressure temporarily exists in the supply main than the pressure in the return main, whereupon valve 30 will open so as to equalizethe pressures. The control mechanism J will operate, in a well known manner as described more at length in the Dunham patent hereinabove referred to, to cause the exhausting mechanism H to operate whenever the pressure differential between the supply and discharge sides of the heating system falls below a predetermined minimum and to throw the exhausting mechanism out of operation whenever the desired pressure differential has againbeen established. Also, a float controlled mechanism in the accumulator tank G (as disclosed in the Dunham patent) acts through switch mechanism 31 to start the operation of exhausting mechanism H whenever a predetermined amount of condensate has accumulated in the tank G.

A second equalizing pipe connection 32 extends between the foot of return main F and the boiler return pipe 18, and includes a normally closed check valve 33 opening toward the boiler. At such times as it may be desirable to operate the system at super-atmospheric pressures, or at sub-atmospheric pressures with the exhauster H out of operation, the stop-valve 33 in front of strainer 4 is closed, and the pipe connection 32 serves to permit condensate to gravitate to the boiler.

In a shunt pipe connection 13" extending around the control valve C between the portions 3 and B of the supply main, is positioned a reducing valve M, of substantially the form disclosed in the Dunham patent hereinabove referred to. This reducing valve embodies balanced cut-off valves whose movements to closed or opened positions are governed by the enclosed pressure diaphragm 34 and the adjust able weights 35 and 36. The diaphragm 34 is subject on one side to the steam pressure in supply main B through a pipe 37 connected at one end to the housing of the diaphragm and at the other to the supply main at a point sufficiently remote from the valve M to be uninfiuenced by pressure fluctuations in the vicinity of the valve. This reducing valve M is distinguished by the fact that the balancing weights 35 and 36 are so proportioned and positioned that a desired sub-atmospheric pressure may be maintained in the portion B of the supply main, while a somewhat higher pressure may exist in the supply main B leading from the boiler. By properly adjusting the weights 35 and 36 any desired degree of vacuum may be maintained in the portion B of the supply main. Preferably a pressure gauge 38 is provided to indicate this vacuum or sub-at-' I mospheric pressure.

It will be noted that gate valves 39 are positioned in the shunt pipe line B"' at either side of reducing valve M, and similarly gate valves are positioned at either side of the control valve C. Assuming for the moment that the valves 40 are closed and the valves 39 are open, the improved control valve 0 (hereinafter described) will be out of service and the steam pressure will be controlled entirely by the reducing valve M, in which case this system will operate substantially as set forth in the Dunham Patent No. 1,644,114, hereinabove referred to. The sub-atmospheric pressure of the steam supplied to the radiators D will be determined by a proper s ettingof the reducing valve M, and the exhausting mechanism H will be automatically operated whenever necessary so as to maintain the pressure in the return main F and exhaust side of the system lower, by a predetermined difierential, than the pressure established in the supply side of the system by the reducing valve M. The radiators D will thus be maintained full of steam at the proper low pressure for giving the desired heat output.

The improved control valve 0 will now be described, referring to Figs. 2 and 3 in addition to Fig. 1. This valve comprises a casing 41 having an internal web 42 separating the high pressure chamber 43 from the relatively low pressure chamber 44. Inlet port 45 connects the relatively high pressure chamber 43 with the supply main B, and outlet port 46 connects low pressure chamber 44 with the controlled portion B of the supply main. The web 42 is formed with the aligned valve seats 4'7 and 48, with which cooperate respectively the connected and substantially balanced valves 49 and 50. A removable closure plate 51 permits access to the upper portion of the casing 41. The lower portion of casing 41 is closed by a closure plate 52. having an outwardly projecting flange 53 secured to the casing by bolts 54, and an upwardly projecting flange 55 to center the plate 52 properly within the opening in the lower portion of the casing. The closure plate 52 is formed integrally with an upward extension 56 of the diaphragm casing member 57. This upper dished diaphragm casing member 57 is formed at its lower edge with an outwardly extending flange 58, and a similar lower diaphragm casing member 59 is formed on its upper edge with an outwardly extending flange 60. The two diaphragm casing members 57 and 59 are clamped together at opposite sides of an enclosed flexible diaphragm 62 by means of a plurality, of bolts 61 passing through the flanges .58 and and securing these flanges against the opposite faces of the peripheral portion of diaphragm 62. The chamber 63 within lower casing member 59 is open to the atmosphere through central passage 64. A pipe 65 leads from chamber 66 in the upper diaphragm casingto a surge chamber 67, which communicates through pipe 68 with the supply main B. The chamber 66 is separated from the main diaphragm chamber 69 above diaphragm 62 by a 'webor baflie .70 designed to prevent the formation of convection currents in the liquid that accumulates above the diaphragm and thus prevent undue heating of the diaphragm 62 from the steam passing through casing 41. The upper portion '71 of a lower diaphragm casing is supported from the lower portion- 59 of the upper diaphragm casing by means of a plurality of supporting struts 72. The lower member 73 of this lower diaphragm casing is clamped to the casing member 71 by a plurality of bolts 74 so as to enclose a second flexible diaphragm 75, similar to the first described diaphragm 62. The chamber 76 above diaphragm is open to the atmosphere through central passage 77. The lower diaphragm chamber 78 is connected through pipe 79 with a surge chamber 80 connected through Pipe 81 with return main F. The surge chambers 67 and 80 may be conveniently positioned adjacent one another and connected by the supporting member 82, although there is no fluid connection between these two chambers.

Referring again to Fig. 2, the valve structure comprising the two movable valves 49 and 50 is provided at its upper end with an adjustable screw 84 having a lock nut 85 thereon, this screw 84 engaging the cover plate 51 to limit the opening movement of the valves and thus prevent undue stresses on the diaphragms 62 and 75. The upper end of a valve stem 86 is threaded in valve structure 83 at 87, and provided with a lock nut 88. The valve stem 86 is slidable through a guide 89 in the closure plate 52 and also passes vertically downward through the central passage 90 in web 70. The lower threaded portion 91 of stem 86 passes through diaphragm 62 and is sealed thereto by means of the diaphragm plates 92 and 93 held in place by nuts 94 and lock nut 95. The outer edges of the diaphragm plates are preferably curved, as shown at 93', to prevent any cutting action on the diaphragm as it is flexed. The lower end of the threaded portion 91 of valve stem 86 is screwed into the yoke 96 and locked in place by nut 97. A lower valve stem 98 is similarly threaded into the lower side of yoke 96 and locked in place by nut 99. This valve stem 98 is sealed in the lower diaphragm 75 by means of diaphragm plates 100 and 101, and nuts 102 and 103, in the same manner as the upper valve stem is attached to the upper diaphragm. A lever 104 is intermediately pivoted at 105 to the lower end of a fulcrum link 106 suspended from lug 107 on diaphragm casing member 59. (me end of lever 104 is pivoted at 108 in the yoke 96. The other arm of lever 104 slidably carries a weight 109 which may be adjusted to difierent positions lengthwise of the lever arm by fixing a pin 110 in any one of a series of holes 111 in the lever. It will be apparent that by adjusting the weight 109 outwardly on the lever arm 104, the upward pressure exerted on the movable valve assembly will be increased. 7

It will be noted that opposed sides of the two connected diaphragms 62 and 75 are exposed to atmospheric pressure, whereas the upper side of the upper diaphragm 62 is subject to the pressure in the supply side of the heating system, whereas the lower side of lower diaphragm 75 is subject to the pressure in the return side of the heating system. Therefore, the net force tending to move the valve assembly downwardly to close the valves is always equal to the pressure differential between the supply and return sides of the system. It will now be apparent that when this downward force exerted by the pressure diflerential just equals the upward force exerted by the adjustable weight 109, the valves will be in a state of rest or equilibrium. If the pressure differential increases above this fixed normal, there will be a tendency to overcome the effect of weight 109 and close the valves. On the other hand, if the pressure differential decreases, the Weight l09'will overcome the fluid pressure and further open the valves.

- the tube 131 will a spring In case the valves 49 and Y50 areabsolutely balanced, that is of equal area, the device will operate as above described. I In case a semibalanced valve assembly used, the varying pressure eflect maybe compensated for by employing larger diaphragm plates 100 and-101 on one of the diaphragm's, than the diaphragm plates 92 and 93 Jon the other diaphragm. This will change the effective area of the flexible diaphragms and compensate for the unbalanced areas of the two valves 49 and, 50. balanced pressure due to the difference in elevation between diaphragms 62 and 75 may be compensated for by-aproper variation in the relative sizes of diaphragm'plates 92, 93 and lotl, 101.

A small bracket 113 from the lowergdi'aphragm casing 73. This motor operates, through gearing en-, arm 115, theclosed in the casing 114, a crank motor being so controlled, ,ashereinafter de-' scribed, as to movethe crank jarm 115 through successive arcs of 180 in the. same direction. The lower end of a stem or connecting rod 116 is pivoted at 116' on crank arm 115. Theblock 117 is slidable on the upper portion of stem 116, and a compression spring 118 surrounding this stem is confined between block 117 and an adjusting nut 119 and lock nut 120. Oppositely projecting studs 121 the arms of yoke 122 ,formed on one end of lever 123, which is intermediately pivoted at 124 in the lugs 125 projecting downwardly from diaphragm casing 59. ,The other end 126 of lever 123 engages the yoke 96-so that when the outer end 122 of the lever is elevated and theinner end 126 depressed, the valves 49 and 50 will be positively closed. When the outer am 122 of the lever is loweredand the inner arm 126 is elevated, the yoke 96 will be released so that the valves will be returned entirely-to the control of the differential pressure mechanism first described.

The motor. 112 is controlled automatically from thermostat L through the control panel K, so that the control valve C will be closed to entirely out off the steam supplied to the radia tors when a certain maximum temperature has been reached in the space where thermostat L is positioned, and the valve C will again be automatically returned to the control of the differential pressure mechanism when the temperature in this space to be heated has fallen below the predetermined maximum. The operation of this portion of the mechanism will be best understood by reference-to the wiring diagram shown in Fig. 4. The thermostat L, in the examplehere shown, comprises a member 127 which expands when heated so as to move arm 128 and through link 129 tip the pivoted yoke 130 carrying the tube 131, in which is enclosed a globule of mercury 132. In the position shown in Fig. 4, the member 127 is heated and has expanded so as to tip the tube 131 in such a direction that "the globule 132 closes a circuit between the contacts 133 and 134 in one end of the tube. At a lower temperature the member 127 will-contract so that be tipped in the opposite direction and globule 132 will close a circuit through the contacts 135 and 136 in the opposite end of the tube. A wire 137 extends from the two central contacts 134 and 135, and wires 138 and 139 respectively extend from theend contacts 133 and 136. The three wires 137, 138

' The un-' electric motor l12 'supported by} on block 117 are pivoted in automatic control switch 140 will be closed.

Red signal light 146 and green signal light 147 are adapted to be illuminated respectively when the thermostat is calling for heat, or when no heat is required. The-red and green signal lights 148 and l49qoperate in a similar manner, when the respective-manual control switches-;144 and 145 are operated to turn the heat 'ouor cut theheat off.

-At15 is indicated the automatic circuit controller jorthe valve operating motor 112. 7 This comprises-a fixed disc carrying a' 'continuous contactiring'151, a pair of similar arcuate contactrings 152 and 153, and a smaller pair of arcuate contacts 154 and 155, the latter arcuate contacts being positioned to overlap the spaces between the ends of contacts 152 and 153. A movable contact arm 156 centrally. pivoted at 157 is adapted to rotate in unison with the valve operating crank arm 115, in other words, this movable contact member will travel from the position shown in solid lines (Fig. 4) to the position shown in dotted lines, while crank arm 115 is moving through a corresponding arc of 180. The arm 156 carries connected contacts 158, 159 and 160 adapted to engage respectively with the ring 151, the pair of arcuate contacts.

152 and 153, and the inner pair of arcuate contacts 154 and 155. The inner pair of arcuate contacts 154 and 155 are connected by a wire 161, and wire 162 leads from contact 145 to the series field 163 of the motor whose armature is indicated at 112. With the parts in the position shown in Fig.4, the valve is opened, but the thermostat L has just operated in response to a maximum temperature to tilt to the left as shownand close a circuit through contacts 133 and 134. A motor operating circuitwill now be completed as follows: From positive lead 142 through switch 141, wire 164, armature 112, field 163, wire 162, contact 155, wire 161, contact- 154, wire 165, switch 140, wire 137, contact 134, mercury globule 132, contact 133, wire 138, switch 140, wire 166, arcuate contact 152, contact arm 156, circular contact 151, and wire 167 through switch 141 to the negative.main 143.

The motor will now commence to operate and will move the crank arm 115 and rotate the movable contact arm 156 in a clockwise direction. Before the contact 159 has passed off the end of arcuate contact 152, the contact 160 on the movable arm 156 will have contacted with the arcuatecontact 155. A shorter circuit will now be completed from wire 162 through contact 155, movable contact 160, contact arm 156, circular contact 151, and wire 167 to the negative main. When the movable contact arm 156 has reached the position shown in dotted lines, the contact.160 will pass off otthe end of shortarcuate contact 155, thus finally breaking the motor circuit and the parts will come to rest. The parts will now have been moved so as to positively close the valves 49 and 50 and shut ofi the supply of steam to the radiators.

When the temperature in the space to be heated has fallen sufficiently, the thermostat 127 will contract so that the mercury tube will be tilted in the opposite direction and a circuit completed between contacts 135 and 136. A motor operating circuit similar to that first described will now be completed from contact 136 of the thermostat throughwire 139, switch 140, wire 168, arcuate contact 153, contact arm 156, circular contact 151 and thence as before to the negative main. This operating circuit will be broken when the arm 156 has returned (in a clockwise direction) to the position shown in solid lines, Fig. 4.

With the valve in the open position, as shown in Fig. 4, a circuitthrough red signal lamp 146 is completed as follows: From positive lead 142, through switch 141, wire 169, lamp 146, wire 170, switch 140, wire 166, arcuate contact 152, switch arm 156, circular contact 151, and lead 167 back to negative main 143. When the valve is closed and contact arm 156 is in the dotted line position, a similar circuit will extend from wire 169 through wire 171, lamp 147, wire 172, switch 140, wire 168, arcuate contact 153, con tact arm 156 to the circular contact 151 and thence back to the negative main. Thus whenever the valve is open, the red lamp 146 will be I illuminated, and whenever the valve is closed and the system does not require heat the green lamp 147 will be illuminated.

In case the automatic control switch is opened, and it is desired to close the valve manually, the manually operated control switch 144 is closed, thus completing the first described motor operating circuit from wire 165 through wire 173, switch 144, and wire 174, to the wire 166 leading back to arcuate contact 152. In a similar manner the valves may be opened by closing the manually operated control switch 145, which completes a motor operating circuit fromwire 165 through wire 175, switch 145 and wire 176 to the wire 168 and thence to the arcuate contact 153. When switch 144 is closed to cause the open valve to be moved to closed position, a circuit through red signal lamp 148 will be completed from positive-main 142 through switch 141, wire 169, lamp 148, wire 177, switch 144,

wire 174, wire 166, arcuate contact 152, movable arm 156, circular contact 151, and wire 167 to the negative main. This circuit will be broken and the red light will be extinguished when the arm 156 reaches the dotted line position and the valve has been closed. In a similar manner when switch 145 is closed to open the valve, the green light 149 will be illuminated by an energizing circuit passing from positive main 142 through switch 141, wire 169, wire 178, lamp 149, wire 179, switch 145, wire 176, wire 168, arcuate contact 153, contact arm 156, circular contact 151, and thence through wire 167 to thenegative main. A control and signal system similar to that just described by way of example, is dis closed more in detail and claimed in the copending application of Dunham, Serial No. 396,209, filed Sept. 30, 1929.

'In describing the general operation of this heating system when using the improved control valve 0, we will first assume that the gate .valves 39 are closed and the gate valves 40 are opened so that the steam supply must pass through the supply main B and valve C to the portion B of the supply main from which the steam passes through risers l to the respective radiators D. The desired steam pressure in the boiler is obtained by proper control of the fires beneath the boiler A, or the danpers or other heat controlling mechanism with which the generator is supplied. The weight 109 is set to respond to a predetermined pressure difierential between the supply and return sides of the system, and the difierential controller J should be regulated to maintain substantially the same or a somewhat smaller pressure differential. As-

suming that the temperature in the building is below that at which thermostat L operates to close the valve C, and that the system is not yet filled with steam, the weight 109 will operate by gravityv to open the valves 49 and 50 to permit a free flow of steam through the valve C. The exhausting mechanism H will now be in operation to lower the pressure in the return main, but this exhausting action will extend throughout the system, since the traps E are now open. The traps 'will remain open until the radiators D are filled with steam, andduring this time the exhausting mechanism will be unable to establish any material pressure differential between the supply and return mains. When the steam fills the radiators D and reaches the traps E, the traps will automatically close, after which the exhausting mechanism H will be able to establish a lower pressure in the return main F than exists in the supply main B. As this pressure differential reaches the predetermined value, it will act on the diaphragms 62 and 75 to overcome the efiect of weight 109 and tend to close the valves 49 and 50, thus throttling the flow of steam to the radiators. As the operation of the valve is gradual, the valve in closing will reach a position where the rate of steam supply to the radiators is approximately equal to the rate of steam consumption or condensation in the radiators, so that the differential will remain substantiallyconstant and the valve will tend to remain in a state of rest or equilibrium in that position for feeding steam to the system at the rate at which it is required. If, for any reason, the rate of steam supply should exceed the desired rate of heat emission from the radiators, or that rate at which the radiators will condense steam to compensate for the heat loss from the building, the pressure differential will increase and the valve 0 will tend to close. The condensing rate of the radiators will then exceed the rate at which steam is being supplied and the supply pressure will drop so that the differential will diminish and the valve C will tend to open again under the influence of weight 109. It will be apparent that any increase in the pressure differential will tend. to cause the valve to close and any decrease in the difierential will tend to cause it to open, and that the gradual action of the valve in opening and closing between its extreme limits of travel will permit it to reach a position of substantial equilibrium that maintains the steam supply substantially equal to the condensingrate. It will thus be seen that the steam supply will seldom, if ever, be entirely cut ofi and a more building will be maintained.

When this heating system is in properly balanced working adjustment, the heat emitted from the radiators should substantially equal the heat loss from the building, which will, of course, vary in accordance with variations in the outside temperature, being greater when the outside temperature is lower and vice versa. Steam should be condensed in the radiators at a constant rate and at a temperature just sulficient to provide this desired constant heat from the radiators, and the rate of steam supconstant temperature in the emission plied through valve 0 should be just sulficient to compensate for the rate at which the steam is condensed so as to maintain the radiators filled with steam at the requis'te pressure and temperature. 4

Let us assume, for example, that the system is adjusted so as to maintain a pressure p in the radiate and the exhausting apparatus H is automaticallyegulated by controller J to maintain a fixed ,p ssuredifferential of, for example, one pound between the supply and return sides of the system, that is a pressure pl is maintained in the return main F. lit is to be understood that the principal function of the exhausting apparatus H is to the return main lower, by a substantially constant differential, than the pressure in the radiators, no matter what the absolute pressure in the radiators may; be, so that the exhausting apparatus, in cooperation with the steam-traps E 'will keep the radiators purged of condensate maintain this pressure through valve C, and

a -5. within the radiators, 5

' radiators and non-condensible gases. Obviously it is necessary to maintain a lower pressure in the return main than in the radiators so that the noncondensible gases will be drawn out when the steam traps open, and. in order that this pressure difierential may be maintained when the pressure within the radiators is atmospheric or sub-atmospheric, the exhausting mechanism is required to maintain a partial vacuum in the return main. Aside from this function, the exhausting mechanism has no direct control of the steam pressure within the radiators, but it does differential substantially constant, and variations in this pressure differential, as thus established, are utilized to automatically .control the valve C which in turn controls the absolute pressure and temperature of the steam within the radiators.

We have assumed that a pressure p has been established within the radiators, steam at this.

pressure and corresponding temperature condensing at a rate just sufficient to maintain the desired heat output from the heating system. Now let us assume that the outside temperature increases, there being a resultant decrease in the heat loss from the building, so that less heat will be required from the radiators, consequently the condensing rate will be lowered. Since steam is being supplied at a constant rate the steam cannot escape from the radiators except through condensation, the steam pressure willbe temporarily built up for example, to 9+1. At this time the pressure in the return main is still 10-1, and this increase in the-pressure differential between' the supply andreturn sides of the system will cause the valve C to partially close and cut down the rate of steam supply to the so that the pressure in the radiators will fall, for'example, to p1. The exhausting apparatus will now go into operation to lower the pressure in the return main still further in order to re-establish the pressure-differential necessary to withdraw non-condensible gases from the radiators. This will tend to cause valve 0- to open again and increase the steam supply to the radiators, but this valve will again .be automatically closed as soon as the steam maintain the-pressure in output from the radiators is just sufficient to maintain a fixed condensing rate.

on the other hand, assuming an initial pressure of p in the radiators and p-l in the return main, let us assume that the outside temperature falls so as to increase the heat loss from the building and consequently increase the rate of condensationin the radiators. Since steam is being supplied at a constant rate, but is being condensed at an increased rate, the pressure in the radiators will drop, for example, to p-l. The valve C will be automatically opened to increase the steam supply so that the pressure may be built up, for example, to p+2, assuming that at this pressure and consequent temperature the condensing rate will be constant to supply the desired heat emission. The exhausting apparatus will now permit the pressure in the return to build up to 10-1-1, but will hold the return pressure at this desired difierential below the supply pressure so that the radiators may be kept evacuated of condensate and non-condensible gases.

All of these pressures may be, and preferably are, subatmospheric, but it will be noted that the automatic operation of the system is dependent entirely upon pressure differences, absolute pressures (and consequent temperatures) .being immaterial to this operation, but these absolute pressures being automatically selected to establish the desired rate of heat out-.

put from the radiators.

the

If for any reason the temperature inside ,the

open and setting the weights on valve M so that it will only open when a substantially maximum vacuum has been reached in the heating system. Under all normal operations this valve M will remain closed and the steam supply to the radiators will be controlled by valve C. However, suppose that thermostat I? has caused motor 112 toclose the valve C then no steam 'wi11 be supplied to the system. If this condition persists, no steam being supplied to the system, the traps E will cool off and open, and the'exhauster H will build up a maximum vacuum in the system at which time the valve M will automatically open to admit enough steam to the system to keep the piping warm and prevent the radiators from chilling off. At the same time the heat emitted will be reduced to a minimum.

While this improved heating system has been here described and illustrated as utilizing only sub-atmospheric pressures, and this form of heating system will give most satisfactory results, it will be apparent that the valve C may be operated in the manner described in systems utilizing steam at atmospheric or super-atmospheric pressures. It is only essentialthat the necessary pressure differential be maintained between the supply and return sides of the system. If no pump or exhausting mechanism is used, it will be necessary to maintain a super-atmospheric pressure in the supply side of the system in order to provide the necessary pressure differential.

It is to be noted that in the construction of the improved control valve C, no stufling boxes are required. One side of each of the movable diaphragms 62 and is exposed to the atmosphere, whereas the pressure chambers at the other sides of the respective diaphragms will become filled with liquid so as to prevent the direct contact of steam with the diaphragms, thus effectively sealing the system against the loss of fiuid pressure and prolonging the life. of the diaphragms by protecting them from the direct action of the gases in the system.

The improved apparatus hereinabove disclosed has been made the subject matter of a divisional application filed Februar 4, 1931, Serial No. 513,242.

I claim:

1. The method of heating by steam which consists in introducing steam into a confined condensing space having separate supply and discharge ducts, efiecting the withdrawal from said space of non-condensable gases and condensate While retaining the steam therein, maintaining a pressure in the discharge duct lower than the pressure in the supply duct by a substantially constant diiTerence suflicient to keep up circulation and utilizing an increase or decrease in this pressure differential caused by variations in the rate of condensation within the condensing space to automatically and proportionately decrease or increase respectively the rate of steam supply through the supply duct to the condensing space.

2. The method of heating by steam which consists in introducing steam into a confined condensing space having separate supply and discharge ducts, effecting the withdrawal from said space of non-condensable gases and condensate while retaining the steam therein, maintaining a pressure in the discharge duct lower than the pressure in the supply duct by a substantially constant diiference sufiicient to keep up circulation, automatically increasing the rate of steam supply through the supply duct to the condensing space when this difierential falls below a predetermined standard, and decreasing this rate of steam supply when the difierential rises above the standard. 7

3. The method ofheating a space by steam which consists in introducing steam into a confined condensing space having separate supply and discharge ducts, eifecting the withdrawal from said space of non-condensable gases and condensate while retaining the steam therein, maintaining a pressure in the discharge duct lower than the pressure in the supply duct by a substantially constant difierence sufiicient to keep up circulation, automatically increasing the rate of steam supply through the supply duct to the condensing space when this differential falls below a predetermined standard, decreasing this rate of steam supply when the difierential rises above the standard and cutting off the flow of steam to the condensing space when a predetermined temperature is attained in the space to be heated.

4. The method of heating by steam which consists in introducing the steam from a common supply duct into a plurality of confined condensing spaces having a common discharge duct, through restricting orifices which limit the amount of steam introduced into each space to the capacity of such space to condense it, ma taining a pressure in the discharge duct lower by a predetermined substantially constant difference than that in the supply duct to eflect movement of fluids through said condensing spaces and withdrawal of non-condensable gases and condensate, automatically. increasing the rate of steam supply through the supply duct to the condensing spaces when this pressure differential falls below the predetermined standard, and decreasing this rate of steam supply when the differential rises above this standard.

5. The method of heating by steam which consists in introducing the steam from a common supply duct into a plurality of confined condensing spaces having a common discharge duct, through 1 restricting orifices which limit the amount of steam introduced into each space to the capacity of such space to condense it, maintaining a pressure in the discharge duct lower by a predetermined substantially constant difference than that in the supply duct to eflect movement of fluids through said condensing spaces and. withdrawal of non-condensable gases and condensate, varying the pressure of steam in the supply duct to vary the temperature of the steam in said spaces, automatically increasing the rate of steam supply through the supply duct to the condensing spaces when this pressure differential falls below the predetermined standard, and decreasing this rate of steam supply when the difierential rises above this standard.

6. The method of heating a space by steam which consists in introducing the steam from a common supply duct into a plurality of confined condensing spaces having a common discharge duct, through restricting orifices which limit the amount of steam introduced into each space to the capacity of such space to condense it, maintaining a pressure in the discharge duct lower by a predetemiined substantially constant difference than that in the supply. duct to effect movement of fluids through said condensing spaces and withdrawal of non-condensable gases and condensate, varying the pressure of steam in the supply duct to vary the temperature of the steam in said spaces, automatically increasing the rate of steam supply through the supply duct to the condensing spaces when this pressure differential falls below the predetermined standard, and decreasing this rate of steam supply when the diflerential rises above this standard and cutting oif the flow of ing space when a. predetermined temperature is attained in the space to be heated.

7. The method of heating by steam which consists in introducing steam under subatmospheric pressure into a confined condensing space having separate supply and discharge ducts, effecting the withdrawal from said space of noncondensable gases and condensate while retaining the steam therein, maintaining a pressure in the discharge duct lower than the pressure in the supply duct by a substantially constant difierence suflicient to keep up circulation, and automatically increasing or decreasingin response to a decrease or increase respectively in the pressure diiferential the sub-atmospheric 145 pressure maintained within the condensing space.

DAVID N. CROSTH'WAIT, JR.

steam to the condens- 130.

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