US2411731A - Steam heating system - Google Patents

Description

NOV. 26, 1946. w. JONES v 2,411,731

' I STEAM HEATING SYSTEM Filed May 25, 1942 :3 Sheets-Sheet 1 Nov. 26, 1946. w. T. JONES STEAM HEATING SYSTEM 3 Shets-Sheei 2 Filed May 25, 1942 Nov. 26, 1946; ON 1 2,411,731

STEAM HEATING SYS TEM Filed May 25, 1942 3 Sheets-Sheet 3 Patented Nov, 26, 1946 UNITED sTAT s PATENT OFFICE f -William T. Jones, Newton, Mass, assignor to Barnes & Jones Incorporated, Jamaica Plain,

Mass, a corporation of Massachusetts Application May 25, 1942, Serial No. 444,313

This invention pertains to heat exchange systems,'for instance, heating or cooling systems wherein a hot or cold fluid gives up or receives heat during the operation of the system ;In many such systems, the fluid is condensable and is condensed, during the operation, from vaporous or gaseous form in order that its heat units may be available as a source of heat; or, in other instances, the fluid, in vaporous or gaseous form,

' ment and usually under pressure, by the direct admission of hot 'steam;' textile tenter-frames, cloth or. other drying apparatus or the like where steam is admitted'to a; bank of pipes constituting a single large ra'diatorjsteam heating systems for heating buildings where many radiatorsare usually employed; condenser apparatus for condensing steam in steam power plants; and stills for alcohol, petroleum products, etc. In certain more specific applications of the invention, for example in drying apparatus, heating systems and some types of power-plant condenser, the rate of condensation may depend to a substantial degree upon some variable and, in some instances, wholly uncontrollable condition, for instance, the temperature or the outside atmosphere; and for such conditions the present invention contemplates" a dual type of control whereby, if desired, the supply of fluid to be condensed or the amount of refrigerant employed may be varied automatically in response to such conditions, thereby producing a substantially uniform amount of condensate regardless of such varying factors, I I

In accordance with the present invention the supply of heat (which may be derived from a hot vapor' orgas or from the burning of a liquid'or gaseousfuel) is varied in accordance with the effects produced. Thus the amount of one of thefluids delivered to heat exchange apparatus, wherein one fluid-is condensed by loss of heat to another, is so varied in' accordance with variations in the amount of condensate produced as to maintain a substantially predetermined ratio between the quantity of available heat delivered (for instance, in the form of a hot' fluid) and the amount of condensate produced per unit of time; for specific instance, in'a steam condenser the 11 Claims.

, {crest-9) V e 2 amount of steam supplied may be varied in accordance with therate at which thesame steam is condensed to water by the action of a refrigerant fluid such as water or. atmospheric air.

While the invention is of broader utility as just above suggested, it is herein specifically disclosed for purposes'of illustration andby Way of example as employed in a novel and improved method of controlling the amount of steam supplied to the radiator or radiators of a steam heating system, and to novel apparatus for use in the practice of such a method.

In the early days of steam heating one of the most urgent problems. was to devise eflicient means for transferring the heat from the steam generated in the boiler to the air in theroom to be heated, but that early problem has been so well solved that the heating engineer is now confronted with the problem of controlling the emission of heat from the radiators so as to avoid overheating;

In heating systems for buildings the radiators are customarily of such capacity as to warm the room toapproximately F. during the coldest weather which may be expected in the locality in which the system is installed. However, such extreme cold, weather prevails for only a few days during the entire heating season, and thus the rooms will be overheated most of the time unless some means be provided for restricting the heat output of the radiators during the milder weather. For example; in Boston, Massachusetts, it is customary to design the heating system to have sufficient radiating capacity to warm the building to approximately 70 F. inside when the outside temperature is 0, although the average outdoor temperature in that locality for the season between October '1 and May 1 is 38.1 (American Society of Heating and Ventilating Engineers Guide for 1941). Since the heating capacity of the systemremains constant, it is obvious that the building will be very much overheated most of the time unless the heat output from the radiators can be controlled proportion-' ately to variations in-heat loss from the building;

Several continuous-flow systems now commercially available regulate the amount of steam admitted to the system so as to vary the heat output from the radiators, but all such systems, so far as known to me, depend upon the accurate control of pressure differential between the supply and return sides of the radiator.

Such control systems make use of orifices in the radiators orin the steam mains and risers; to

balance distribution and also to; maintain the requisite pressure difierential between the supply side and the return sides of the radiators. By varying the steam pressure in accordance with the demand (for example as determined by a thermostat outside of the building), a controlled differential is maintained and steam in varying amounts is supplied to the radiators. Some such systems use a variable vacuum to circulate the steam at a subatmospheric pressure and thus at a reduced temperature, thereby restricting the heat output of the radiators. However, in all such systems as just above referred to it is necessary to control the pressure differential for any definite condition, within very narrow'limits, and

this is sometimes very difi'lcult. This is particularly the case where a vacuum pump forms a part of the heating system. Electrically driven vacuum pumps start on a low limit control and stop when the vacuum reaches the high setting of the control device. A common setting for the vacuum pump controls causes the pump to start automatically when the vacuum drops to four inches of mercury and to stop when the vacuum reaches eight inches. This four-inch variation equals about two pounds per square inch gauge pressure, and any such variation will destroy the effectiveness of a continuous-flow steam heating system based on the principle of constant differential.

The above discussion has reference to systems of the continuous-flow type. Such systems are much to be preferred to the intermittent or ofi-and-on type of system since they not only provide more uniform temperature within the building but the heating system itself is less exposed to mechanical strains due to expansion, etc, than when the steam is intermittently turned on and shut off.

In a steam heating system all of the heat emitted from the radiators must necessarily come from the steam which is supplied. While initial pressure of the steam may afiect the velocity of flow of the steam in the supply mains, it has but little direct effect upon the number of heat units emitted by the. radiator, the latter depending, in any given case, almost entirely upon the quantity, that is to say, the number of pounds of steam which condenses in the radiator and from which the heat units are obtained. Thus it is obvious that by varying the quantity of steam supplied to the radiators, the amount of heat emitted may be controlled. In calculating radiation, it is customary to consider that radiators will condense one-quarter pound of steam per square foot, per hour, in a room where the temperature is 70 F. Thus a radiator having forty square feet of radiating surface will condense ten pounds of steam per hour when it is hot all over. Manifestly if only live pounds of steam per hour were admitted to the radiator, only one-half of the capacity of the radiator would be required to condense it, or, in other words, the original radiatorv would be only half heated. Thus, for example, considering a fortyfoot radiator, if the entire radiator is necessary to heat a given room, on a zero day, then onequarter pound of steam per square foot of-radiator will be condensed each hour or, in other words, ten pounds of steam per hour must besupplied to the radiator to keep it hot all over. On the other hand, when the outdoor temperature is 35, only one-half the capacity of radiator is required to maintain the same inside temperature of 70, and the admission of five pounds of steam per hour to the radiator 4 would be sufficient. It is thus highly desirable to provide some variable control of the amount of steam supplied to the radiator in order not only to avoid overheating and discomfort to the occupants of the building, but also for economy in operation.

One object of the present invention is to provide a very simple, inexpensive and Jefifective method and means whereby, in a steam heating system, the proper output of heat to maintain a predetermined and healthful temperature condition in the room is automatically attained. A further object is to provide a novel method and apparatus whereby, in a steam heating system, a substantially constant supply of heat units is delivered to the room for any given outdoor temperature. A.f urther object of the invention is to provide a novel method and apparatus whereby, in a steam heating system, the proper amount of radiation for any given outdoor temperature is automatically maintained regardless of variations in the steam supply pressure or in the pressure differential between the inlet and delivery sides of the radiator, even though the pressure inthe supply conduit drop below that of the atmosphere. A further object is to provide a novel method and apparatus for use in a steam heating system which is readily applicable to and can be installed in existing systems even though they employ vacuum pumps, without necessitating expensive alterations in the existing piping or other adjuncts and appliances.

In accordance with the present invention the amount of condensate from a key radiator or a group of radiators is metered and the amount of steam admitted to the system may be varied in substantially exact proportion to the amount of steam which condenses in this key radiator or group of radiators. The improved system of the present invention will automatically adjust itself to such an extreme condition as results from the starting or stopping of a vacuum pump. It is thus very desirable in buildings where it is customary tostart the vacuum pump early in the morning to hasten circulation of steam through a heating system from which the steam has been shut off during the night, for after the building has been warmed the vacuum pump may be set to operate only as a condensate pump without creating any vacuum. Furthermore, the arrangement of the present invention permits delivering the steam at three or four pounds gauge pressure, for example, into the steam mains, while at the same time the vacuum pump is creating from four to eight inches of vacuum in the return mains in orderthereby to warm the building rapidly, since the operation of the control device of thepresent invention is enentirely unaffected by such a pressure difierential. Thus after the initial warming of the building in the morning and as the sun reaches a higher altitude, the heat loss from the building will decreaseand under these circumstances the device of the present invention automatically reduces the amount of steam admitted to the supply pipes but its proper functioning is not aifected, even if, as the result of such reduction in the steam supplied, the inlet pressure at the radiator drops to subatmospheric. Likewise as the sun declines and more heat is needed, the arrangement of the present invention automatically admits more steam to the radiators without requiring the adjustment of any valves or other part by an operator.

Other objects. and advantages of the invene tion wil1 be pointed out-hereinafter: in the following moredetailed description and by reference to the accompanying drawings, wherein .Fig. 1 is a fragmentary elevation showing one preferred embodiment of the invention associated with heating units, for example radiators,

certain elements of the apparatus being diagrammatically indicated;

Fig. 2 is a sectional view illustrating a preferred form of orifice valve employed for controlling the discharge of condensate from the apparatus;

Figs. 3 and 4 are electrical wiring diagrams illustrative of certain features of the invention; and.

Fig. 5 is a diagram, showing in elevation and partly in section a modified arrangement wherein pneumatic valve-actuating motors are employed.

In accordance with that embodiment of the invention herein specifically disclosed, the amount of heat emitted by the radiator is controlled by gradually closing a steam-admission valve in direct response to increase in the amount of liquid condensed per unit of time in the radiator and gradually opening the steam-admission valve in direct response to decrease in the amount of liquid condensed per unit of time in the radiator, and automatically varying such unit of time in response to some other selected 6 the other, the arm 6 of the potentiometer likewise swings.

The steam which condenses in the radiator "flows out through the delivery pipe 8 (Fig. 1)

assumed to be located within a building or portion of a building to be heated. It is contemplated that the control apparatus herein disclosed may be associated with one or a plurality of radiators. When hereinafter reference is made to a radiator, it is intended by this term to designate heating means of the fluid condensing type, whether such heating means be a single radiator, or aplurality of radiators or other. steam-condensing appliances connected in sired type, although it is contemplated that it will be so devised that less than a 360 turn of the stem 4 wil1 move the valve from full open to fullclosed position and vice versa. The stem 4 is turned back and forth by a reversible electric motor 5, preferably of a type commonly employed for actuating dampers or the like and wherein the motor shaft rocks through an arc of less than360 and usually only approximately 180. While as illustrated in Fig. 1, the valve stem 4 is directly connected to the motor shaft, it is obvious that motion-transmitting means of conventional type, for instance gears or cams, may be interposed between the valve stem and motor shaft ,if, it be desired to turn the valve stem in other than a one-to-one ratio relative to the'turningof the motor shaft. As indicated in Fig. 3, the, shaft 4 of this motor carries the swinging control arm '6 of a potentiometer or voltage-divider, 1 which is preferably built into the motor casing'the arrangement being such that astheinotor shaftturns in one direction or which leadsto a casing 9 of any suitable ma-' terial, for example, cast iron, which provides the float chamber 1.: Within this chamber I0 is arranged afloat ll mounted on an arm l2 which is fixed to a rock shaft I3. One end of this shaft 13 extends to the outside of the casing and has fixed thereto the swinging control arm l4 of a potentiometer or voltage-divider 15. Thus, as the float H rises and falls within the chamber III in response to variations I in the level of liquid within said chambenthe' arm M of potentiometer l5 likewise swings;

'As diagrammatically illustrated in Fig. 3, both of the potentiometers 'Iand I5 are connected as voltage-dividers across the same source of potential." For any given position of the arm l4 of the potentiometer 15 there will be a corresponding position of the arm 6 of thepotentiometer 1 at which the two arms will be equipotential. When this condition is attained by the turning of the arm 6, no current will flow through the coils of the polarized relay 35 and the contacts of the relay 35 will be open so that no power will be delivered to the motor. However, until this condition is reached, there will be a current flow through-the relay 35, whose contacts willbe closed in such a way that the motor will move the arm 6 toward a position corresponding to that of the arm 14, that is to say, to a position such that current will no longer flow through the relay to the motor. Thus the motor will stop and the admission valve will have been properly set in accordance with the position of the float.

From the lower part of the casing 9 a delivery pipe I6 extends downwardly and preferably delivers the liquid into a strainer or filter IT. This strainer or filter may be of any desired construe tion and is designed to remove solid particles from the liquid in order that such solid particles may not clog the control orifice. While as here shown it is below the casing 9, it may, if preferred, be placed above casing 9. However, this strainer is not an essential feature of the invention and may be omitted if desired. The strainer discharges the liquid into a pipe [8 whose lower end is connected to the orifice valve [9. This orifice valve may be of any appropriate type operative accuratelyto control the flow of liquid downwardly through it. A valve appropriate for the purpose is disclosed in the patent to Jones et al., No. 2,247,090, June 24, 1941. As illustrated in Fig. 2, this valve l9 has the valve head 22 comprising the conical plug portion 23 which is located within a control orifice formed in the orifice member 24. The valve head is moved axially by means of a rotary stem 25. From the valve casing IS a pipe 20 extends downwardly pressures in the chamber I 0 andin the pipe 20.

The valve stem 25 is connected, preferably di-. rectly, to the shaft of a reversible motor'26 which,

may be of the same type as the motor 5 above referred to, that is to say, an electric motor having a shaft which rocks through an angle less than 360 and usuallyonly approximately 180.

thereto the movable control arm 21 of a potentiometer or voltage-divider 28, and thus when the motor shaft is rocked on one direction or the other, the arm 2'! is likewise rocked. As above suggested with reference to the motor'5 and stem 4, suitableratio-varying connections of conventionaltype may, if desired, be interposed between the valve stem 2-5 and the shaft of motor 26.

The control bulb 29 (Fig. 4) of a thermostat device (typical of any secondary control) is pref erably located outside of the building which is heated by this system, and this bulb is;cnnected to the motor element 30 of the thermostat. This motor is here shown as a metallic bellows and is designed to move the control arm 3| of a potentiometer or voltage-divider 32. The potentiometers 32 and 28 are connected through the polarized relay 34 so that the position of arm 3| determines that of arm 21 in exactly the same way that arm 6 controls arm I4, as above described.

The valve I9 is located at a distance below the normal liquid level in the chamber I0 such as thereby to provide a predetermined fluid head at the valve orifice under normal conditions. For instance, the orifice may be located at a distance of approximately 27.68" below the horizontal plane of the shaft I3, thereby providing substantially one pound pressure head at the valve orifice when the float arm I2 is horizontal.

Assuming that the system is totake care of outdoor temperature variations between 0 and approximately 70 F., and assuming that the interior of the building is at the desired temperature while the temperature outside is 35 F., and that under these conditions the water level in the float chamber I0 is such that the float. arm I2 is horizontal, the potentiometer arm I4 will be at such a point that no current is supplied to the motor and the valve 3 is partly open. Just enough steam is now being supplied to the radiator to equal the condensate which is discharged through the orifice valve I9 under the normal pressure head. If it now be assumed that for the above temperature conditions the valve 3 has not yet been properly set and that moresteam than necessary is entering the radiatonthu causing over-l1eat-' ing and waste, more condensate will be delivered to the chamber 9 than will pass through the orifice valve I9 under the above head and in consequence the water level in chamber 9 will rise and the float II will rise with the water, thus moving the potentiometer arm I4 to a new position, thus energizing the relay 35 and supplying current to the motor 5. This causes the motor 5 to turn the valve stem 4 andthus close the steam admission valve to some further extent. As the valve stem turns, the arm 6 also is moved, and this movement continues until the arms I4 and 5 are at the equipotential point, thus deenergizing the relay, cutting oif current from the motor 5, and leaving the admission valve 3 more nearly closed. This restricts the flow of steam to the radiator and less condensate thereforereaches the chamber 9 per unitof time and the Water level gradually drops.

If, on the other hand, insufilcient steam is being supplied to the radiator than is proper, under the assumed temperature conditions, the water level in the float chamber will drop and the lowering of the float will move the potentiometer arm It to such a setting as to energize the relay-35 and permit current to flow to the motor 5 in a direction such as to turn the motor shaft 4 so as to open the valve 3. g

-. .If und he -9Qndifi9nsabove. su gested the temperature outsideof' thebuilding should drop, then the thermostat 29, 3-!) would movethe arm 3! of the potentiometer 32 in such adirection as to cause-current to flow through the leads of the relay 34 andthus energize the motor '26. .The motor shaft 25 and potentiometer arm'Z'I would then turn in such-a direction as gradually to open the orifice valve I9, thus establishing a faster rate of discharge of liquid from the float chamber II]. In practice these changes are sufficiently frequent so that the water level in the float chamber actually varies but slightly in height, the apparatus being very sensitively responsive to such changes in level and thus con stantly maintaining substantially the exact steam supply proper to provide the necessary heat under varying conditions of outside temperature.

Obviously the twoicontrols, that is to say, the float control and the outdoor thermostat, while independent of each other so far as their control of the motors 5 and 26 is concerned, nevertheless cooperate automatically to maintain a substantially uniform temperature within the building. It is further obvious that both of these devices may be operating at the same time and that under certain conditions the action of one may neutralize that of the other so that there is no actual variation in the amount of steam delivered to the radiator. While the thermostat bulb 23 will usually be placed outside of the building, it may be otherwise located if desired, It is to be understood that a secondary control, for example an indoor thermostat, may be pro vided for controlling the admission of steam to the system, for instancefdu'ring' the early part of the day when it is necessary rapidly to build up the temperature in the room, and that such secondary control may be of any usual 'type' and may be cut in and out of action by the engineer in charge at the proper time, or automatically, for example, by such a well known device as a program clock. In Fig. 3 there is indicated diagrammatically at 33 a manually actuable switch device which may be employed for cutting out of actionand fully'op'ening the float-controlled valve, if desired. Obviously other usual 'adjunctive features of "a heating system may be supplied, such, for example, as vacuum or condensate valves or the like, all in accordance l with usual practice and which have no necessary relation to the control device of the present invention. One desirable adjunct is a manually operated rheostat whereby to modify, at will, the setting of valve I?! as called for by the automatic control. In order to permit of the use of alternating current for actuating the valve motors, and to permit a simple type of reversible motor to be employed, the controlling circuit includes the polarized alternating current relays 34 and 35 above described, but since the type of motor here suggested is well known, and the electrical circuits used in controlling such motors are well known, it seems unnecessary herein to describe such circuits in greater detail.

It may again be noted that in accordance with this arrangement the control of the admission of steam to the radiator is wholly independent of the pressure in the steam supply main or in the illustrated, such float control responding to variations "in. the. volume of. condensate delivered; it is to be understood that equivalent means responsive to the quantity of condensate delivered may be substituted for such float control. For example, suitable means for actually weighing the condensate delivered may be substituted for the float control within the purview of the present invention, as well as other and equivalent means for measuring the volume of the liquid.

Fig. illustrates .a heat exchange system of modified construction wherein pneumatic motors replace the electric motors in the system hereinabove described. As shown in Fig. 5, the condensable fluid, for example hot steam, is supplied through the supply main 2 tothe admission valve 3. i This admissionvalve controls the delivery of thehot steam to the distributing main 2 from which pipes 2 2 etc., lead to radiators or banks of radiators suitably arranged in the structure whichisto be heated. As here illustrated the pipe 2 leads to a radiator I? which is a key or control radiator and which may be located at any suitable point in the'structure which is to be heated, in particular ,at a point where it will be subjectedto typical or selected conditions of exposure. From this key radiator I a return pipe 8 leads to a float. chamber 9 such as hereinabove described, Within this float chamber is a movable float ll carried by a swinging arm I2 fixed to a shift l3 to which is also secured gear M This gear- M mesheswith a gear l5, which may be of the same or different diameter, as desired, and which is mounted upon the actuating shaft or, stem of an, air control valve V. The system comprises an aircompressor Cor other source of compressed airand, from this source, pipes, including the pipe I5, leadthe compressed air to the valve V. From this valve an air delivery pipe Lif= leadsto a pneumatic motor 5 of any conventional or appropriate typepperative to open and close-the steam admission valve, 3. v

'Ihe condensate which collects in the float chamber}! is. drained off through the pipe I8 into the casing of the orifice valve l 9 which discharges arranged to actuate anair control valve 30 which receives air from the source Cand which delivers air throughthe, pipe SUP-to, a pneumatic motor 26 of conventional type which isarranged toposition the orifice valve 19.

' Since this apparatus functions in substantiale 'ly the same wayand with the same object in view as thatabove described, it is apparently unnecsary to describe its mode of operation specifically, other than to pointv out that the thermostat 29,

controls the orificevalve l9. by means of pneu-.. Y

matic motor 26% in accordance. with variations in,

outside atmospheric conditions, while the pneumatic motor 5?, controlled by the float, determines the admission of. steam by valve 3 in accordance with variations in the level of condensate in the chamber 9.

- When several radiators are included in the systemyall being supplied by valve 3, each radiator should be provided with an inlet orifice in order kier or still is a, condenser, and when herein reference is made to a condenser without qualification, the term is to be regarded as broadly inclusive of any heat-exchanger which functions to reduce a'relatively hot vaporous or gaseous substance to a relatively cooler liquid state.

While certain desirable embodiments of the invention have herein been disclosed by way of example, it is to be understood that the invention is not necessarily limited .to these precise embodiments but is to be regarded as broadly inclusive of any and all equivalent constructions falling within the scope of the appended claims.

I claim:

1. In a steam-heating system having a radiator and an adjustable steam-admission valve for varying the quantity of steam delivered by the radiator, a receptacle for the collection of liquid condensed in the radiator, a float in the receptacle, a reversible electric motor for adjusting the steam-admission valve, means controlled by the float for determining the direction in which the motor shaft turns, an orifice-valve operative to determine the rate of escape of liquid from the receptacle, a thermostat remote from the radiator and exposed to outdoor temperatures, and a re-v versible electric motor controlled by the thermostat for setting the orifice-valve.

2. In a steam-heating system having a radiator,

an adjustable steam-admission valve, a receptaclefor collecting liquid condensed in the radiator, an orifice-valve for determining the rate of escape of liquid from the receptacle, a reversible electric motor for actuating each of said valves and circuits for supplying current to each motor, respectively, each of said circuits including a polarized relay and a potentiometer, each potentiometer comprising a control arm operatively connected to the respective motor shaft, a movable float within the receptacle, one of said circuits also including a potentiometer having a control arm operatively connected to the float, and a thermostat, the other circuit including a potentiometer having a control arm actuable by the thermostat, the parts being so constructed ply valve motor to turn in one direction or the other.

3. In a steam-heating system having a radiator,'

an adjustable steam-admission valve, a receptacle for collecting liquid condensed in the radiator, an orifice-valve for determining the rate of escape of liquid from the receptacle, a reversible electric motor for actuating each of said valves, and circuits for supplying current to each motor, respectively, each of said circuits including a potentiometer comprising a control arm fixed to the respective motor shaft, a movable float within the receptacle, one of said circuits also including a potentiometer having a control arm operatively connected to the float, and a thermostat, the other'circuit also including a potentiometer having a control arm actuable by the thermostat, the parts being so constructed and arranged that movement of the last-named potentiometer arm bythe thermostat in one direction or the other causes the orifice-valve motor to turn in one direction or the other, while movement of the float-actuated potentiometer arm in one direction or the other causes the steam-supii ply valve motor to turn in onedire'ction or the other, each of said circuits including a polarized, alternating current relay.

4. In a steam-heating system having a radiator, an adjustable steam-admission valve, a receptacle for collecting liquid condensed in the radiator, an orifice-valve for determining the rateof escape of liquid from the receptacle, a reversible electric motor for actuating each of said valves and circuits for supplying current to each motor, respectively, each of said circuits including a polarized relay and a potentiometer, the latter comprising a control arm fixed to the respective motor shaft, a movable float within the receptacle, one of said circuits including a second potentionieter having a control arm operatively connected to the float, and a thermostat, the other circuit including a second potentiometer having a control arm actuable by the thermostat, the parts being so constructed and arranged that movement of the last-named potentiometer arm by the thermostat in one direction or the other causes the orifice-valve motor to turn in one direction or the other, while movement of the float-actuated potentiometer arm in one direction or the other causes the steam-supply valve motor to turn in one direction or the other, one at least of said circuits including a switch whereby the delivery of current to either motor may be manually controlled at will.

5. In a steam heating system having a radiator, a steam supply main, a steam-admission valve operative to control the delivery of steam from the supply main to the radiator, a pneumatic motor for closing and opening the admission valve, a source of compressed air, a receptacle for collecting liquid which condenses in the radiator, an orifice valve for determining the rate of escape of liquid from the receptacle, a pneumatic motor for closing and opening the orifice valve, an air control valveoperative to determine the flow of compressed air from the source to the admission valve motor, a movable float within the receptacle operatively connected to said air control valve for actuating the latter, a thermostat, an air control valve operative to determine the how of air from the source to the orifice valve motor, and means actuated by the thermostat for operating said latter air valve.

6. In a heat-exchange system wherein radiators are supplied with a condensable fluid, a supply main for said fluid, a plurality of radiators, one of which is.a key radiator, pipes leading to and from the several radiators, a main admission valve operative to control the passage of the fluid from the supply main to the pipes which lead to the radiators, a pneumatic motor for closing and opening the admission valve, a source of compressed air, a receptacle for condensate from the key radiator, an orifice-valve for determining the rate of escape of liquid from the receptacle, a pneumatic motor for closing and opening the orifice-valve, air control valves operative, respectively, to admit air from the source of compressed air to the admission and orifice-valve motors, a movable float in the receptacle, means actuable by the float for operating the air valve which supplies air to the admission-valve motor, a thermostat, and means actuable by the thermostat for operating the air valve which supplies air to the orifice-valve motor. 1

7. In a heat exchange system wherein radiators are supplied with a condensable fluid, a

supply main for said fluid, a plurality of radiators one of which is a, key radiator, pipes leading to and from the several radiators, a main admission valve operative to control the passage of the fluid from the supply main to the pipes which lead to the radiators, a motor for closing and opening the admission valve, a source of energy for driving the motor, a receptacle for condensate from the key radiator, an orifice valve for determining the rate of escape of liquid from the receptacle, a motor for closing and opening the orifice valve, control means operative to admit energy from the source to the admission and orifice valve motors, a movable float in the receptacle, means actuated by the float for operating the control means which admits driving energy to the admission valve motor, a thermostat, and means actuated by the thermostat for operating the control means which admits driving energy to the orifice valve motor.

8. In a heat exchange system including a radiator, a steam supply conduit, a steam admission valve operative to control the amount of steam admitted to the radiator from the supply conduit, a reversible motor for' actuating the steam admission valve, a receptacle for collecting the liquid which condenses in the radiator, 21 motor-actuated orifice-valve operative to determine the rate of escape of the liquid from the receptacle, means operative to energize the orificevalve motor to open or close the orifice-valve in proport1on to variations in outdoor temperature, and means operative to energize the steam admission valve motor to move in a direction to close the steam admission valve whenever the liquid level in the receptacle rises above normal and to move in a direction to open the steam admission valve whenever the liquid level in the receptacle drops below normal.

9. In a steani-heating system having a radiator and an adjustable steam-admission valve for varying the quantity of steam delivered to the radiator, said valve having a casing defining inlet and delivery chambers, a second casing having therein a condensate chamber for the collection of liquid condensed in the radiator and in which the pressure never exceeds that in'the delivery end ofthe radiator, a pipe for conducting steam from the delivery chamber of the steamadmission valve to the supply end of the radiator,

a pipe for conducting condensate from the deliV-' valve, means controlled by the float for determining the direction in which-the motor shaft 60 turns, an orifice-valve operative to determine the.

rate of escape of liquid from the condensate chamber, a thermostat remote from the radia-, tor and exposed to outdoor temperatures, and

means controlled by the thermostat for setting 65 the orifice-valve.

10. In a heat exchange systemwherein radiators are supplied with a condensable fluid, a supply main for said fluid, a plurality of radiators one of which is a key radiator, pipes leading 70 to and from the several radiators, a main admission valve operative to control the passage of the fluid from the supply main to the'pipes which lead to the radiators, a motor for closing and opening the admission valve, a'sour'ce of energy 75 for driving the motor, a casing remote from the 1'3 admission valve and having therein a condensate chamber for the collection of condensate from the key radiator, one of said pipes conducting.

steam fromthe steam-admission valve to the supply end or the key radiator and another of said pipes conducting condensate from the delivery end of the key radiator to said condensate chamber, the key radiator providing the only path for the flow of fluid from the steam supply main to the condensate chamber whereby the pressure in the condensate chamber never exceeds that at the delivery end of the radiator, an orifice-valve for determining the rate of escape of liquid from the condensate chamber, a motor for closing and opening the orifice valve, control means operative to admit energy from the source to the admission and orifice-valve motors,

a movable float in the condensate chamber, means actuated by the float for operating the control means which admits driving energy to the admission valve motor, a thermostat, and means actuated by the thermostat for operating the control means which admits driving energy to the orifice-valve motor.

11. In a heat exchange system including a radiator, a steam supply conduit, a steam-admission valve having a casing and a movable valve stem, said valve being operative to control the 14 amount of steam admitted to the radiator from a supply conduit, a reversible motor for actuating the stem of the steam-admission valve, a casing independent of the valve casing defininga condensate chamber for collecting the liquid which condenses in the radiator, a pipe for conducting steam from the casing of the admission valve to the supply end of the radiator, a pipe fOr conducting condensate from the delivery end of the radiator to the condensate chamber, the

radiator providing the only path for the flow of fluid from the supply conduit to the condensate chamber whereby the pressure in the condensate chamber never exceeds that at the delivery end of the radiator, a motor-actuated orifice valve operative to determine the rate of escape of the liquid from the condensate chamber, means operative to energize the orifice-valve motor to open or close the orifice-valve in proportion to variations in outdoor temperature, and means operative to energize the steam-admission valve motor to move in a direction to close the steam-admission valve whenever the liquid level in the condensate chamber rises above normal and to move in a direction to open thesteam-admission valve whenever the liquid level in the condensate chamber drops below normal,

WILLIAM T. JONES.

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