US2344555A - Heating and cooling system - Google Patents

Description

March 21, 1944.

W. L. MCGRATH HEATING AND COOLING SYSTEM Filed Dec. 51, 1941 INVENTOR.

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Afforner Patented Mar. 21, 1944 UNlTED STATES PATENT OFFICE,

HEATING AND COOLING SYSTEM William L. McGrath, Philadelphia, Pa., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application December 31, 1941, Serial No. 425,049

7 Claims.

This invention relates to air conditioning systems and controls therefor, particularly systems wherein a heated or cooled medium is circulated to a space for controlling the temperature therein.

' system is measured in terms of the amount of water being circulated to maintain a given ternperature and the heat content of the water is adjusted accordingly. The volume of water being circulated may depend upon the demands of individual zones or individual radiators or heat exchange devices in the same zone.

Another object is to provide a heating and cooling system having separate valves controlling heating and cooling with an automatic changeover arrangement for shifting from heating to cooling in response to outdoor conditions, the changeover requiring either valve to be in a minimum position in order to shift to the other. Numerous other objects and advantages of my invention will become apparent from the following detailed description and annexed drawing.

Referring to the drawing, a portion of a building is represented, having apparatus therein consttliting that necessary for one zone of a zone type of arrangement embodying my invention.v Numeral Ill represents diagrammatically the floor of the building .or ctherstructure in which the air is to be conditioned. Within the space to be the valve is opened on an increase in temperature for the purpose of controlling the flow of cooled water to the radiator during the cooling season.

During the heating season the hand valve 2l6 will be open and the hand valve 22| will be closed, and during the cooling season the hand valve 216 will be'closed and the hand valve 22l will be open. It will be obvious that the two valves 2|! and 222 could be replaced by a single automatic valve whose connections could be reversed for getting direct and reverse action. Suchan arrangement is shown in the patent of Frederick D. Joesting,

conditioned are heat exchange devices H and l2 which. as disclosed, take the form of rad ators. The radiator II is supplied'with water through a pipe l3 and one or the otherof the two parallel pipes 2M and 2|. The pipe 2 is provided with a hand valve 2|! and an automatic valve prises a thermal bulb 223 connected to a pressure motor 224 by means of capillary tubing 225. The valve 222 is of the reverse actingtyp'e, that is,

Water is supplied to the radiator l2 through pipe [1 and either one or the otherof the two parallel pipes 230 and 23L The pipe 230 is provided with a hand valve 232 and a direct acting thermostatically controlled valve 233 similar to the valve 211. The pipe 23l is provided with a hand valve 234 and a reverse acting thermostatically operated control valve 235 which is a duplicate of the valve 222. It is obvious that these two valves could be replaced by the re.- versible valve of the aforementioned Joestin patent.

The supply pipes l3'and' ll are connected to a, distributing header 24 and water is forced to the. header by' a motor driven circulating pump 25. The radiator II has an outlet pipe 26 and the radiator l2 has an outlet pipe 21 and these pipes are connected to a return main 28.

As pointed out, the apparatus as disclosed on the drawing may represent the apparatus necessary for one zone of a zone type system and the distributing header 24 and the return main 28 may have branches 2! and 30 respectively for serving other similar zones.- The radiators H and I2 are intended as exemplary disclosures of any type of heat exchange devices suitable for heating or cooling air in the space. That is, unit air conditioners might be used instead, these conditioners being of a type adapted to have. either hot or cold water circulated therethrough with the supply of water to each either being modulated or controlled in an on and of! manner, the

supply water being heated or cooled depending on whether or not it is winter or summer. The

invention of course comprehends reversing the controls of the heat exchangers in the space to rovide for winter and summer operation, the valves opening on low temperature in winter and opening on high temperature in summer.

Connected to the inlet of the circulator 25 is a pipe 35 and connectedbetween this pipe and the return main 26 is a water heater 36. At

the juncture of the outlet pipe from the heater 36 and the pipe 35 is disposed a three-way valve 31 of a type known in the art. Also connected between the pipe 35 and the return main 281 is a by-pass pipe 38 and at the juncture of this pipe with the pipe 35 is another three-way valve 39. The three-way valve 31 controls the proportions of water passing through the .water heater 35 and through the by-pass 38, that is, the threeway valve 31 takes a position permitting a certain proportion of the water to pass through the water heater 36 and the remainder passing through the by-pass 38, the three-way valve 39 being in a position at the time to permit water to pass freely from pipe 38 to pipe 35.

The water heater 36 may be any suitable type heat exchanger. For instance, it may be a tank the valve 37 or the valve 39. This controller is of a differential pressure type and it is designated by the numeral 51. The pressure differential is established by means of an orifice member 58 connected in the pipe 35 ahead of the circulator 25. The orifice is, of course, of fixed cross-sectional area and of course, there will be a pressure drop through the orificedepending and tube type with an arrangement for supplying steam to the tubes for heating the water.

The return main 2B is connected to a branch return pipe 42 and the pipe 22 is connected to a water cooler 53. The lower end of the pipe 35 is connected to another distributing pipe M which is also connected to the water cooler 53. The branch pipes 42 and 44 may be connected with other zones so that the water cooler 63 can serve all of the zones. As will now be apparent, water being returned through the return main 28 can either pass through the by-pass pipe .38 or. through the pipe 42, the water cooler 43 and pipe 64 back to pipe 35. The three-way valve 39 controls the proportions of water which can pass through the by-pass 38 and to the water cooler.

The water cooler 43 may be any suitable type of heat exchanger with the coil of a direct expansion refrigerating system, for example, supplying the necessary cooling.

As will presently be explained, either one or the other of the three-way valves 3 and 39 is in control at any given time. When the valve 37 is in control, the valve 39 is in a minimum position, ordinarily an extreme position, wherein water can freely pass from by-pass pipe 38 to pipe 35. In this position'of valve 39, water is .prevented from going through the water cooler and then upwardly through the pipe 35.

However, water from other zones may freely circulate through the water cooler. When the three-way of the plurality of zones may have apparatus including a water heater, circulator, radiators and so on, as disclosed on the drawing, but with a single water cooler for supplying the necessary cooled water for all zones.

The three-way valve 31 is actuated by a proportioning type motor 50 of the type disclosed in the patent of D. G. Taylor, No. 2,028,110, this patent also disclosing a proportioning control system in detail. The motor 56 drives a shaft on which is mounted a crank arm 5| which is connected to the valve member of the three-way valve 31 by a stem 52. The three-way valve 39 is driven by a similar motor 53 having a crank arm 54 connected to the stem 55 of the valve.

A single proportionin'g controller is provided which may be connected so as to control either upon the rate at which water is being circulated, that is, upon the volume of water being circulated. The differential controller comprises a pivoted slider member 59 adapted to slide over a slide wire resistance 66 so as to form a potentiometer. The slider 59 is actuated by two bellows devices, one of which designated by the numeral 6! is connected to the pipe 35 on the up-stream side of the orifice 58 by a tube 62.

The other bellows device designated 53,is connected to the pipe 35 on the down-stream side of the orifice 58 by a tube 54. The bellows devices are arranged to act on the slider 59 in direct opposition to each other so that the slider will take a position depending on the difference in pressures on opposite sides of the orifice 58. that is, the controller 51 will respond to the rate of flow of water being circulated. In other words, for example, when more radiators have their valves closed, the resistance to flow between the supply header 24 and the return main 28 will be increased and as a result there will bean increase in pressure beyond the orifice 58 relative to the pressure on the -up-stream side of the orifice. Under these circumstances the force exerted by the bellows 63 will preponderate over that of bellows 6i and slider 59 will be adjusted downwardly along resistance 60. On the other hand, when more radiator valves are opened, the pressure difierential will change in the opposite directionand slider 59 will move upwardly along resistance 65.

The controller 51 may be connected so as to control either the motor 55 or the motor 53, the connections being automatically changed by means of a relay designated by the numeral 65. The relay 65 comprises a first winding 66 and an armature 65' associated therewith connected to movable switch blades 6'5, 58, 69 and T0. The relay includes a second winding H which when energized produces a magnetic-motive force completely neutralizing that of winding 66. When only winding 66 is energized the armature is attracted and the blades 67, 68, 69 and 70 are moved to the right into engagement with fixed electrical contacts 12, 13, T4 and 15 respectively.

When the winding H is energized, it neutralizes the effect of winding 66 and the armature moves in the opposite direction, either under the infiuence of gravity or a spring, and blade 61 moves out of engagement with contact 12 and the blades 58, 69 and 16 move to the left into engagement with fixed electrical contacts ll, 18 and 19.

With the parts in the position shown, winding 66 alone of relay 55 is energized and with the relay in this position, the controller 51 is connected to the motor 50 so as to control the three-way valve 31. Under these circumstances the lower end of slide wire resistance 60 is connected to motor 56 by wire 80, blade 68, contact 13, and Wire Bl. The slider 59 is connected to motor 50 by wire 82,-blade 69. contact 14 and the wire 83. The upper end of slide wire resistance 60 is connected to motor 50 by wire 85, blade 10, contact I5, and wire 85.

When the relay 55 is in its other position, the controller 51 is connected to motor 53 for controlling the three-way valve 39. Under these circumstances, the lower end of slide wire resistance 60 is connected to motor 53 by wire 00, blade, contact 11, and wire 30. The slider 59 is connected to motor 53 by wire 02, blade 39, contact 18 and wire 81. The upper end or slide wire resistance 60 is connected to motor 53 by wire 04, blade 10, contact 19,- and wire 30.

The relay 55 is controlled by a temperature responsive controller 93 responsive to outdoor temperature. The controller 93 comprises an ex- 7 pansible and contractible bellows 94 filled with a vaporizable liquid which causes the bellows to expand and. contract inaccordance with outdoor temperature. The movable end of the bellows carries a stem which engages a pivoted switch carrying lever 95 carrying a double ended mercury switch 90. The lever 95' is normally biased in a counter-clockwise direction by a coil spring 91. The mercury switch 96 has electrodes'at its left end which are bridged by the mercury when the outdoor temperature is below a predetermined value. The mercury switch 90 also has electrodes at its right end which are bridged when the outdoor temperature rises to a predetermined value causing the bellows to expand rotating the lever 95 in aclockwise direction.

Power for operation of the relay 85 is su l ed by a step-down transformer I having primary winding I 0| and a secondary winding I02, the primary winding having the greater number of turns.

As will presently become more clear, the controller 93 shifts control from one to t"e other of the three-way valves 31 and 39 by energiz ng and being shifted from, it must be in a position wherein little or no .water is being passed through the water heater before the shift can be accomplished. To provide for this feature, the system includes auxiliary switches I03 and I94. The auxiliary switch I03 comprises a cam I mounted on the shaft of the motor 50. The cam I05 has a single dwell and this cam actuates a pivoted switch carrying lever-I06 carrying a mercury switch I01. The mercury switch I01 is normally open and is closed by the cam I05 when motor 50 has positioned valve 31 to a minimum or extreme position wherein little or no water is allowed to pass t rough the water heater 3 The auxiliary switch I00 comprises a cam I mounted on the shaft of motor 53. The'czni 103 has a single dwell and this cam operates a pivoted switch carrying lever I09 carrying a mercury switch IIO which is closed by the cam when motor 53 has positioned valve 39 to a minimum or extreme position wherein little or no water can pass from return main 28 through the water cooler 43 to pipe 35, this position of three-way valve 39 permitting water to pass freely through by-pass 38 into pipe 35.

The outdoor temperature controller 93 may be adjusted so as to cause the electrodes atthe right end of mercury switch 36 to be bridged at an outdoor temperature of 70, for example. With the parts in the position shown on the drawing, the outdoor temperature is below 70 and th: system is operating on the heating part of the cycle. Valve 39 is in its minimum position and mercury switch I I0 is'closed. Winding I of that effecting bellows BI.

relay 05 is energized through the following circuit: from secondary through wire H5, mercury switch H0, wire "0, the left end of mercury switch 90, wire II1, wire II8, winding 65, and wire' H9 back to secondary I02. Engagement of blade 61 with contact 12 reduces a maintaining circuit for winding 06 as follows: from secondary I02 through wire [20, blade 61, contact I2, wire I2I, wire II8, winding 69 and wire I I9 back to secondary I02.

The system is now operatin to produce heat in the spaces being served with the, three-way valve 31 under control of controller 51. temperature adjacent the thermal bulb 2l8 tends to rise, valve 2I1 throttles down, thereby reducing the demands for heated water. Radiator I2 may be controlled by valve 233 in a similar manner. The throttling action of one or more valves as pointed out above will tend to increase the resistance between the supply header 20 and the retum main 28 and this will result in an increased pressure effecting bellows 63 relatve to The result of thisis that the force exerted by bellows 63 preponderates moving slider 59 downwardly along slide wire resistance 60. This tends to produce a shunt between wires BI and 83 connected to motor 50 and, the motor will now operate in a direction to position the three-way valve 31 to cause less water to pass through the water heater and more through the by-pass 38. (The operaton' of a motor of this type is described in detail in the above referred to Taylor patent.) The effect of this operation of the three-way valve is therefore to reduce the temperature of the water being supplied to the radiation without changing the volume, that is, the rate of flow. On the other hand, when valves 2I1 and 233 are moved toward open position by their thermal bulbs, the

resistance between the supply header 24 and return main 28 is reduced and consequently, the pressure affecting bellows 63 will be reduced relative to that affecting bellows BI. In other words. the differential will vary in the opposite direction and slider 59 will be moved upwardly along resistance 60. This tends to produce a shunt between wires 83 and 85 of motor 50 and the motor will now operate in a direct on to move the threeway valve 31 to a position causing more water to pass through the water heater 3S and less through the by-pass 38. In other words, the temperature of the water will be raised without change in volume.

From the foregoing it can be seen that the con troller 51 measures the load demands on the system as determined by the number of radiators demanding heated water and the amount demanded by each radiator. Thecontroller 5'! thus measures the load on the system as a whole and adjusts the heat content of the water being supplied accordingly. Thus, as the load decreases. water will be supplied at *a. lower temperatue and as respects the controller 51 this will have a rebalancing effect. In other words. as the load decreases and less heat is; demanded, the controller will cause water at a lower temperature to be suppl ed and thus the demands of the rad I02 of transformer I If the rather than heating will be required in the spaces.

However, the mercury-switch 96 may be thus shifted before the temperature in the spaces reaches a value such that cooling is actually required. That is, the electrodes at the right end of mercury switch 96 may becom bridged while some heating is still required in the spaces. Thus, the system does not shift over to cooling until the three-way valve 31 has been positioned to a minimum or extreme position wherein little or no water is being heated. This indicates of course, that there is no further demand for heat in the spaces. When valve 31 has been so positioned mercury switch I01 will be closed and winding H of relay 65 will be energized through the following circuit: from secondary m2 of transformer I 60 through wire H9, wire I25, winding 1|, wire I26, mercury switch I01, wire I21, the right end of mercury switch 96, wire H1, wire l2l, contact 12, switch blade 61, and wire I29 back to secondary J02. When winding II is thus energized it neutralizes the effect of I winding 66 and the armature moves to the left as valves 222 and 235 may have their control mechanisms reversed so as to throttle towards closed position as the temperature falls. Or as also pointed out, unit air conditioners may be used in lieu of radiators which are turned on and ofl individually in accordance with cooling demands. As the demand for coldwater decreases, the differential affecting controller 5? will vary in the same manner as described above to cause slider 69 to move'downwardly along resistance 66. This will tend to produce a shunt between wires 86 and 81 connected to motor 53 and the motor will operate in a direction to move valve 39 toward a position permitting" more water to flow through the by-pass 36 and less through the water cooler 43. On the other hand, upon increased demands for cooling water slider 59 will move upwardly tending to produce a shunt between wires 81 and 88 and valve 39 will be moved toward a position causing less water to pass through by-pass 38 and more to pass through water cooler 43. Thus, the temp'erature oi the water will be varied in accordance with the load demands for cooling water.

When the control shift from cooling to heating, valve 39 must be in its minimum position indicating that there is no further need for cooling before the shift is brought about. That is,

mercury switch I in must be closed as already described.

Various other arrangements may be used for 1 varying the temperature of the water delivered tothe. radiators although I prefrer the three-way valve and by -pass arrangement as described above.

From the foregoing, those skilled in the art will appreciate that I have provided a very ember of radiators in an individual zone, the load demands, that is,- the demands for heating or cooling water may vary considerably. My arrangement provides an accurate measurement of 6 the demands and adjusts the heating or cooling accordingly.

The single embodiment of my invention is exemplary of one of its preferred forms. There are many modifications and variations which fall within the realm and scope of the. invention and therefore the invention is to be limited only in accordance with the terms .of the claims appended hereto.

I claim a my invention:

i. In apparatus of the character described, in combination, a water circulating system, heating means and cooling means for, the water, a valve controlling the temperature of the water when heating is required of the system, a valve controlling the temperature of the water when cooling is required, condition responsive means for automatically controlling the valves, means for automatically shiftlng'controi from one valve to the other depending upon outdoor temperature, and control means operated as a result of valve movement for preventing a shift to one valve until the other valve is in its minimum position.

2. In apparatus of the character described, in combination, heating means including a control device therefor, cooling means including a control device therefor, control apparatus including means responsive to a condition representative of temperature changing load requirements, said control apparatus including means whereby each device can assume a position dependent on the said load, changeover means for shifting between the heating means and cooling means to render one or the other effective depending upon outdoor temperature, and means operated as a re- 0 suit of the movement of one control device to prevent said shift until said one control device is in a position representative of a minimum temperature changinglo'ad with reference to that device.

3. In apparatus of the character described, in combination, a fluid circulating system including supply and return pipes, means providing communication between said pipes including heating means for the fluid, cooling means for the fluid. and lay-pass means, flow control apparatus including three-way valve means for selectively adjusting the proportions of fluid passed through the heating means and by-pass means or the proportion of fluid passed through the cooling condition representative of temperature changing load requirements in a space being served by the system for adjusting the three-way valve .means, and means responsive to outdoor conditions for rendering either the heating means or cooling means efiective.

4. In apparatus of the character described. means for circulating a temperature changing medium to a space, means forselectively heating or cooling the medium, means responsive to temperature in the space, means varying the rate of flow of medium to said space in. accordance with the demand as measured by said temperature responsive means, and means for adjusting the temperature of the-medium in accordance with said rate offlow.

5. In apparatus of the character described. in combination, a fluid circulating system including supply and return pipes, means providing commeans and by-pass means, means responsive to a munication between said pipes including heating I means for the fluid, cooling means for the fluid, and by-pass means, flow control apparatus including a three-way valve for controlling the proportions of fluid heated and passed through the by-pass means, a three-way valve for controlling the proportions of fluid cooled and passed through the by-pass means, means responsive to a condition representative of temperature changing load demands for fluid in a space served by the system, and means whereby said condition responsive means may control each of the three-way valves depending upon the outdoor temperature.

6. In apparatus of the character described, in combination, a fluid circulating system including supply and return pipes, means providing communication between said pipes including heating means for the fluid, coolingmpans for the fluid, and by-pass means, flow control apparatus including a three-way valve for controlling the proportions of fluid heated and passed through the by-pas's means, a three-way valve for controlling the proportions oi fluid cooled and passed through the by-pass means, means responsive to a condition representative of temperature changing load demands for fluid in aspace served by the system, and control means whereby the condition responsive means is rendered eflective to control one or the other of the three-way valves depending uponvthe outdoor temperature, the said control means embodying mechanism whereby in order for control to be shifted from one valve'to another the valve being shifted from must be in a position representative oi minimum temperature changing load re.- quirements with reference to that particular valve.

7. In apparatus of the character described, in combination, a fluid circulating system including supply and return pipes, means providing communication between said pipes including heating means for the fluid, cooling means for the fluid, and by-pass means, flow control apparatus including a three-way valve for controlling, the

proportions of fluid heated and passed through the by-pass means, a three-way valve for controlling the proportions of fluid cooled and passed through the by-pass means, means responsive to a condition representative of temperature changing load demands for fluid in a space served by the system, and means responsive to outdoor temperature for causing said condition responsive means to control either 01' the three-way valves.

WILLIAM L. McGRATI-I.

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