US2223295A - Air conditioning system - Google Patents

Description

Filed Aug. 30, 1937 3 Sheets-Sheet l N INVENTOR Clarence WNe-ssel] ATTORNEY Nov. 26, 1940. c. w. NESSELL AIR CONDITIONING SYSTEM Filed Aug. 30, 1957 3 Sheets-Sheet 2 's'sll INTENTOR ClarenceW Ne ATTORNEY Nov. 26, 1940.

C. W. NESSELL AIR CONDITIONING SYSTEM Filed Aug. 30, 1937 3 Sheets-Sheet 3 an v EN a E 3 E Clarence WNessell INVENTOR ATTORNEY Patented Nov. 26, 1940 UNITED STATES PATENT OFFICE AIR CONDITIONING SYSTEM Application August 30, 1937, Serial No. 161,591

, 11 Claims.

. This invention is directed to a fluid circulating system and more particularly to a heating system. In a building having a plurality of spaces or zones to be heated, it is common to provide a warm air furnace connected by ducts to the various spaces to be heated, and a blower for circulating air through the furnace and through said spaces. Inorder to control the temperature in each space individually, each space may be provided with a thermostat, and a damper motor under the control of each thermostat, for operating dampers in the various warm air ducts, to permit or prevent the flow of air into each space, depending upon whether the thermostat in the particular space is calling for heat 01 is satisfied. In such a system, it is unnecessary to circulate air at as fast a rate when only one space is calling for heat as when more than one space is calling for heat. I therefore provide automatic means to operate the blower to circulate air at one rate when only one space is demanding heat, and to operate the blower to circulate air at a higher rate when more than one space is demanding heat, and also to stop the blower when none of the spaces are demanding heat, since, when none of the spaces are demanding heat, all the warm air ducts are closed by their respective dampers, and there is no necessity or advantage in operating the blower at this time. It may happen that one space in the building is larger than the others, or for some other reason, such as its exposure, may require a larger amount of heat to raise its temperature, and accordingly, I have provided means to operate the blower to circulate air at a higher rate when this particular space is calling for heat than when any other one space is calling for heat.

I have illustrated two common means for varying the amount of air circulated by the blower, but it should be understood that my invention is not limited to the two ways illustrated. In one form of the invention, a two-speed fan is illustrated, and in another form, adjustable dampers controlling the input to the fan are provided.

While my invention is illustrated in connection with a warm air heating system, it is equally applicable to any other type of heating system such as a hot water heating system, and to any other fluid circulating system, such as a cooling, 5 ventilating, r humidity controlling system, and it should therefore be understood that it is not limited to a warm air heatingsystem.

One of the objects or my invention is, therefore, to provide an improved fluid circulating 5! system.

Another object of my invention is to provide a fluid circulating system wherein fluid is circulated at varying rates of flow in accordance with the number of spaces being supplied with 5 fluid.

Another object of my invention is to provide a fluid circulating system wherein fluid is circulated at different rates of flow in accordance with the size and/or number f spaces being supplied with fluid.

More specifically, it is an object of my invention to provide a warm air heating systemwherein a pluralit of spaces are to be heated, and wherein one space requires more heat than the others, with thermostatic means for controlling the flow of air to the various spaces, together with means for circulating air at a high rate when any two spaces, or the aforementioned one space is calling for heat, for circulating air at a low rate when any other single space is calling for heat, and to stop the air circulation when none of the spaces are calling for heat.

Other objects will become apparent upon a study 01' the specification, claims and appended drawings, in which like reference characters represent like parts in the different views, and in which:

Figure 1 is a schematic view of one form of my invention,

' Figure 2 is a view of a second form of my invention, and

Figure 3 is a view of still another form of my invention.

Referrin now to Figure 1 a heating plantis illustrated, said plant comprising a warm air furnace I0 having a fuel supply line H, a warm air duct 12 havin branch ducts i3, I4, 15, and I8, communicating with registers l1, l8, I9, and 20 located in the spaces to be heated. A fan 2| is provided for circulating air through the furnace and spaces to be heated, there being a return air duct 22 communicating with the inlet of the fan. The furnace is also provided with the usual flue gas stack 21. I 5

For driving fan 2!, I have provided a motor 23 connected to the fan by means of a belt 24, said belt travelling over pulleys 25 and 26 on the motor and fan, respectively. The motor 23 is or the condenser induction type and comprises an armature 30, a field winding 3|, a second field winding 32, and a condenser 33. windings 3i and 32 are connected together at one end thereof and condenser 33 is connected to the other end of winding 32. An autotransformer 35 is provided for varying the current through winding 23, thereby varying the speed of the motor.

In the fuel supply line I I is a valve 38, said valve having an upstanding stem 39 to which is connected an armature 40, this armature being surrounded by a. solenoid 4i. Energization of solenoid 4I causes armature 40 to move upwardly and through the stem 39 causes the valve to move to open position. Any suitable means such as a spring (not shown) may be provided for moving the valve to closed position when solenoid 4i'is deenergized.

Mounted in the warm air chamber of the furnace is a bimetallic element 42 connected at one end to a rod 43, the other end of said element 42 being held against movement by being rigidly connected to the wall of the furnace or otherwise suitably securedagainst movement. The rod is connected to the mercury switches 44 and 45 in a known manner, so that rotation of rod 43 by the bimetallic element dflcauses switches 44- and 45 to be tilted. Switch 44 is provided with contacts 46 and 4t", and switch 513 provided with contacts 48 and 49. Switch 45 is designed to be closed at a lower temperature than is necessary to close switch 44.

For controlling the operation of the motor 23 and the energization of solenoid M, a relay generally indicated by the reference character 60 is provided. This relay comprises a coil GI, an armature 62, switch arms 63 and 64, and stationary contacts 65 and 68 cooperating with the switch arms 63 and 64, respectively. When coil IN is energized,'switch arms 63 and 64 are moved out of engagement with their respective contacts 65 and 66, and when deenergized the switch arms move into engagement with their respective contacts.

For controlling the speed at which motor 23 operates there is provided a second relay generally indicated by the reference character 50. This relay comprises a coil 5|, armature 52, a switch arm 53, and contacts 54 and 55. When coil 5| is deenergized, switch arm 53 is in engagement with contact 55,'and when said coil is energized the arm 53 is moved into engagement with contact 54.

For supplying power to the relays I have provided a transformer 10, said transformer having a high tension coil II and a low tension coil 12, the high tension side of the transformer being connected to lines I3 and I4 which are in turn connected to a suitable source of power (not shown).

The spaces to be heated are .designated by the maturei 41 drives'through suitable reduction being limited by the bottom of the slot I62 in which arm i8I travels. This damper motor operates until the damper is in wide open position, at which point it stalls, and maintains the damper in this position until the energizing circuit to the motor is broken. A spring I63 is provided for 'returning the damper and the motor to its original position after it has been deenergized.

Cams 30, 3I, IIO, IIl, I30, and Hi similar to cams E50 and I5! in space M0, are located in spaces 30, E00, and E20 as shown. Cooperating with the various cams are switch arms 92, 93, M2, M3, I32, 833, I52, and I53, theseswitch arms being held in engagement with contacts Q4, 95, Il i, Hi5, stop I34, contact I35, stop 55%, and contact l55, respectively, when the damper motors in each space are deenergized, When the cams are rotated through 180 the respective switch arms are moved into engagement respectively with contacts 55, 3?, H8, IIlI, I38, I32, E55, and

I5'l, and in this position, the dampers in the respective spaces are wide open.

OPERATION or SPECIES or FIGURE 1 With the parts in the positions illustrated none of the thermostats in the various spaces are calling for heat, the blade of each thermostat being out of engagement with its respective contact. Relay coil 6! is energized, thereby holding switch arms 63 and 64 out of engagement with contacts 65 and 66, the energizing circuit for this relay being as follows: from one side of low tension coil I2 of transformer I0 through conductors 200, 20 I, switch arm 93, contact 95, conductor 202, switch arm II3, contact II5, conductor 203, switch arm I33, contact I35, conductor 204, switch arm I53, contact I55, conductor 205, through the coil 65 and conductor 208 to the other side of transformer coil I2. Since switch arms 63 and 64 are out of engagement with their respective contacts it will be apparent that there is no circuit through solenoid M or motor 23.

Should the thermostat in any one of the spaces call for heat a circuit through the respective damper motor is established. Assume the thermostat in space is calling for heat, the damper motor in this space will be energized by the following circuit: from line I4 through conductors I10, I'II, I12, I13, I88, bimetallic element 82, am. 83, contact 84, conductor I80 through the field coil of the motor, and conductors I8I, I82, I83, and I84 back to the line I3. It will be obvious that the damper motor in any of the other spaces will 'be energized through a similar circuit upon a call for heat by the thermostats in those spaces,

Energization of the damper motor in space 80 causes rotation of cams and SI through at which time the. damper in said space is in open position and further movement is prevented, as described in connection with the damper motor I48 and'damper I45. Switch arms 92 and 93 are now in engagement with contacts 98 and 91 as will be apparent. The circuit through relay coil BI is now broken by reason of the opening of co tact 95, whereupon switch arms 63 and 64 move into engagement with their respective contacts 65 and 66. It will be obvious that the energization of any of the damper motors with the attendant shifting of the respective switch blades will likewise cause relay coil BI to become deenergized.

Engagement of switch blade 53 with contact 55 causes a circuit through solenoid M as follows: from line '54 through conductor Ziil, switch arm 63, contact 55, conductor 25 I, solenoid it, and conductor bacls to the line 13. Energization of solenoid 4| causes opening of valve 33 as previously described whereupon fuel is supplied to the furnace I3 through pipe II, the furnace thereby becoming hot.

When the temperature rises a suflicient the mercury therein and energy is supplied to motor 23. Autotransformer 35 is connected to the source of power from the line 14, through conductor 2|5, contacts 45 and 43 of switch 45, conductor 2I5, contact 55, switch arm 54, conductor 2I1, tap 2|5 on the transformer through the transformer coil to tap 2 I3, and through conductors 223, 22I to line 13. Relay 5| is at present deenergized, and switch 53 is in engagement with contact 55, and the voltage impressed on coil 3| is less than that impressed on the transformer, current flowing through the coil 3| through the following circuit: from the coil 3| through conductors 225, 223, terminal 2|3 of the transformer, through part of the transformer 35 to the tap 224, through conductor 225, contact 55, switch arm 53, and conductor 221 to the other side of field winding 3|. Field winding 32 and condenser 33 is connected to the transformer through the following circuit: from terminal 2|9 of .the transformer, through conductors 223 and 225, coil 32, condenser 33, to terminal 222 of the transformer.

winding 3| is considerably less-than the line voltage.

When relay coil 5| is energized and switch blade 53 is moved into engagement with contact 54 the voltage across coil 3| is increased whereupon the motor travels at high speed. The voltage on coil 3| is now greater than line voltage, the coil now being connected to transformer 35 as follows: from the fleld winding 3| through conductors 225, 223, terminal 2|5 of the transformer, through part of the transformer to tap 223, conductor 225, contact 54, switch arm 53, and conductor 221 to the other side of field winding 3|. It is therefore apparent that the voltage on coil 3| is increased upon energization of relay coil 5| and that the motor will operate at high speed.

Assume now that any other space also requires heat, as for example, space I23, the energization of the damper motor for this space causes cams I33 and III to move through 180 whereupon switch arms I32 and I33 are in engagement with contacts I35 and I31. After the temperature of the furnace rises to a high predetermined value at which contacts 45 and 41 are closed by the tilting of switch 44a circuit through relay coil 5| is established, this circuit being as follows: from the low tension coil 12 of transformer 13 through conductors 233, 23I, switch arm 33, contact 51, conductors I53, I5I, I34, contact I31, switch arm I33, conductor 233, contact H5, switch arm 3, conductors 252, 244, contact 55, switch arm 52, conductors 233, 232, contacts 45, 41, conductor 233, relay coil 5|, and conductor 234 back to the low tension coil 12. Energizationof relay coil 5| causes switch arm 53 to move into engagement with contact 54, whereby the high speed circuit through the motor, previously described, is established, and the motor drives the fan at high speed.

A call for heat by any combination of two zones will cause the energization of coil 5| through a circuit similar to that described above.

The motor now. operates at low speed since the voltage on field- Zone I43 is what is termed a Master zone." That is, it may require more air to be circulated therethrough when there is a. call for heat therein than any of the other zones, either by reason of its size or its exposure, for example. For this reason a circuit established through relay coil 5| should this space alone require heat. When switch arm i 43 of thermostat I4| moves into engagement with contact I44, cams I 53 and |5| are rotated through 183, as previously described, moving switch arms I52 and I-53 into engagement with contacts I55 and I51, thereby establishing the following circuit through relay coil 5|, it being assumed that the temperature of the furnace has risen to the value in which contacts 45 and 41 are closed, this circuit being as follows: from the low tension coil 12 through conductors 233, 24|, contact I55, switch arm I52, conductors 23I, 232, contacts 45, 41, conductor 233, through relay coil 5| and conductor 234 to the other side of low tension coil 12.

It will therefore be seen that upon a call for heat in any one zone, that the supply of fuel to the furnace is started. It will also be seen that upon a cail for heat by any single zone with the exception of zone I43 that the motor 23 is operated at low speed, after the switch 45 has closed because of a sufficient rise in temperature of the furnace, and that a call for heat by any two zones, the motor 23 is operated at high speed, assuming that switch 44 has been moved to closed position. It has also been pointed out that upon a call for heat by zone I43 alone the motor is operated at high speed. When all of the thermostats have become satisfied the damper motors are returned to their original positions as illustrated under the influence of their respective springs such as spring I 53 of damper motor I45, whereupon relay coil 5| is again energized through the circuit originally described, switch arms '53 and 54 are moved to open positions, the supply of fuel to the furnace is cut oi! by reason ,of the deenergization of solenoid 4|, relay coil 5| isdeenergized and the supply of power to the motor 23 is cut oil by the opening of switch 54.

Description of Figure 2 In Figure 2 I have illustrated a system similar to that of Figure 1 except that a single speed fan motor is provided and the change in rate 50 of circulation of air is controlled by suitable dampers provided in the return air duct 22 to the fan 2|.

The motor is represented by the reference character 253 and is provided with contacts 3|3 and 3, said motor being connected to the fan by a belt 24 passing over pulleys 25 and 25 of the motor and fan, respectively.

In the return air duct are shown dampers 255, connected to a. damper motor "I by means of link 252 pivotally connected at its other end to arm 253 connected to a shaft 254 which is driven by the motor 25I. Stops 255 and 255 are provided to limit the movement of arm 253, a spring 251 moving arm 253 against stop 255, arm 253 being held against stop 255 in which position the dampers 255 are in their wide open position when the motor is energized.

Switches 44 and 45 operated by the bimetallic element 42 are identical with those described in Figure 1. A third switch 25I operated by the with contacts 252 and 253 which are normally closed and which are opened when the temperatherefor are identical with those shown in Fig-' ure 1 and for this reason have not been illustrated in this figure.

OPERATION or SPECIES OF FIGURE 2 With none of the zones requiring heat, relay coil 6| is energized through the following circuit: from low tension coil 12 of transformer 10 through conductors 304, 303, switch arm 93, contact 95, conductor 302, switch arm II3, contact II5, conductor 30I', switch arm I33 and contact I35, conductor 300, switch arm I53, contact I55, and conductor 205 through relay coil 6| and conductor 206 back to the other side of transformer coil 12.

Switch arms 63 and 64 are accordingly held out of engagement with the contacts 65 and 66 and no current flows to the solenoid M or motor 250.

Upon a'call for heat in any one of the zones the damper motor for that particular zone operates to open the damper in the register for that zone whereupon the cams are rotated through 180 thereby breaking the energizing circuit for relay coil 5|. Solenoid 41 is now energized through the following circuit: from line 14 through conductor 2I0, switch arm 63, contact 65, conductor 2, solenoid 4I, conductor 2I2, contacts 252, 253 and conductor 2I2 back to line 13. Fuel is now supplied to the furnace I0 whereupon the temperature is increased until switch 45 is tilted to close contacts 48 and 49 and current through motor 250 flows as follows: from the line 14 through conductor 3I0, contacts 48, 49, conductor 3| I, contact 66, switch arm 54, conductor 3I2, terminal 3I3 through the motor winding, terminal 3I4 and conductor 3I5 back to the line 13. It is therefore apparent that upon a call for heat by any one zone fuel is supplied to the furnace and after a predetermined rise in temperature in the heating chamber thereof motor 250 operates to circulate air through the furnace and through the space in which the damper has been opened, or the space requiring heat. The amount of air circulated is at a low value as long as damper motor 26I is deenergized, holding dampers 260 in the positions as illustrated.

Should there be a call for heat in any two or more zones the damper motor 26I will be energized, or if zone alone, this zone being the master zone in this modification, is requiring heat, the damper motor ZBI willbe operated. Assume for the present "that zenes.l00 and I20 require heat. It will be understood that cams IIO, I I I, I30, and I3I have been rotated through 180 by their respective damper motors. If switch 44 has been tilted to close contacts 45 and 41 because of a suflicient rise in temperature in the heating chamber of the furnace, damper motor 26I will be energized through the following circuit: from low tension coil 12 through conductors 304, 303, switch arm 93, contact 95, conductor 302, switch arm II3, contact II1, conductors 33I, 335, 332, contact I31, switch arm I33, conductors 30I, 340, contact I I6, switch arm 2, conductor 331, contact 94,v switch arm 92, conductor 32I, contacts 46, 41 of switch 44, conductor 322 through the damper motor 26I to con-, ductor 323 and back to the other side of low tension coil 12. A similar circuit may be traced through the damper motor when any combination of two zones is calling for heat.

Assume now that zone 80 alone is calling for heat, this zone being the master zone," the damper motor 26I is. operated to move the dampers 260 to the open position, the circuit through the motor now being as follows it being understood of course that cams and 9I have been rotated through from the low tension coil 12 through conductors 304, 320, contact 95, switch arm 92, conductor 32I, contacts 46 and 41 of switch 44, conductor 322 through the damper motor, conductor 323 to the other side of low tension coil 312. It is assumed, of course, that the temperature of the heating chamber is suiiiciently high to cause switch 44 to be tilted to closed position,

Switch 25I is designed to open the circuit throughsolenoid 4| whereupon the flow of fuel to the furnace is cut off, upon the attainment of a high predetermined temperature in the furnace and is designed to prevent the furnace from becoming too hot.

It will thus be seen that the system illustrated in Figure 2 is similar to that shown in Figure 1 except that the two-speed motor illustrated in Figure 1 is substituted by a single speed fan motor and a damper motor by means of which the amount of air supplied to the fan may be varied.

Description of Figure 3 The structure shown by this figure is identical with that shown in Figure 1 except that in this figure the parts are so connected that no one zone alone will cause high'speed operation of motor 23. In other words, the master zone has been eliminated and substituted by a zone which is similar to the others. It is believed that further description of the apparatus shown is unnecessary in view of its similarity to Figure 1.

OPERATION OF SPECIES OF FIGURE 3 Solenoid 4| controlling the operation of valve 38 is energized as in Figure 1 when relay coil BI is deenergized. The energizing circuit for this coil when none of the zones are calling for heat is as follows: from low tension coil 12 through conductor 400, switch arm 93, contact 96, conductor 40I, switch arm H3, contact II5, conductor 402 switch arm I33, contact I35, conductor 403, switch arm I53, contact I55, conductor 4 through coil GI and back through conductor 420,

to the other side of low tension coil 12. This circuit is broken upon the moving of any one of the above named switch arms away from its respective contacts, which takes place when there is a i call for heat in any one of the zones, whereupon coil 6| is deenergized and a circuit through solenoid 4| identical to that described in Figure 1 is established. The motor 23 is now operated at low speed, assuming that switch 45 has been tilted to the position in which contacts 48 and 49 are closed by reason of the attainment of a predetermined temperature in the heating chamber of the furnace, and will continue to thus run as long as switch 64 is in engagement with contact 66 and switch 53 is in engagement with contact 55. The motor runs at high speed only when relay coil 5| is energized thereby moving switch arm 53 into engagement with contact 54 as in Figure 1. This will not take place until at least two of the zones are calling for heat, there being no single zone that when calling for heat will establish a circuit through this coil. If any two zones, as for example, zones 80 and I40 are calling for heat c'ams 90, 9|, I50, and I5I are moved through 180 and a circuit is established through coil 5| as follows, it being assumed that switch 44 aazaaee has been tilted to close contacts 48 and 4'! by the bimetallic element 42: from the low tension coil 12 through conductor 400, switch arm 93, contact 91, conductors M2, H6, H1, H8, 5, contact I51, 1

switch arm I53, conductor 403, contact I35, switch arm I33, conductor 402, contact H5, switch arm H3, conductors 4M, Mil, contact 95, switch arm 92 through conductor 435, contacts 48 and 41 of switch 44, conductor 233, relay coil 5|, and conductor 234 back to the other side oi, coil 12. ment of switch arm 53 into engagement with contact 54 and cause operation of the motor at high speed as described in connection with Figgure 1.

One more illustrative circuit will be traced through the relay coil 5!. Assuming now that zones 80 and I20 are calling for heat, the circuit through the coil 59 is now as follows: from transformer 12, conductor 400, switch arm 93, contact 91, conductors H2, H5, 4H, 4", contact I31, switch arm 133, conductor 402, contact H5, switch arm-| l3, conductors 40!, 401, contact 95, switch arm 92, conductor 435, contacts 43, 41, conductor 233, relay coil 5| and conductor 234 back to the other side of transformer coil 12.

It is therefore seen that I have devised a warm air heating system wherein damper motors to the various zones to be heated are under control of separate thermostats in each zone and wherein air is circulated at a low rate in response to a call for heat in any single zone, and is circulated at a high rate upon a call for heat for more than one zone. Also a master zone may be provided which causes operation of the air circulating means at a high rate upon a call for heat by that zone. It will be obvious that my invention is capable of many modifications and I wish it to be understood that the invention is to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a heating system, a heating chamber, means for heating said chamber, means for causing a forced circulation of fluid through said chamber and through a plurality of spaces to be heated at aplurality of predetermined rates of flow, temperature responsive means in each space, means controlled by the temperature responsive means for controlling the flow of fluid into each space, a plurality of electrical circuits for controlling the rate of flow or fluid by the circulating means, means responsive to the operation of the flow control means when said means is operated to admit fluid to any one space only to energize one electrical circuit to cause operation 01' the fluid circulating means-at aupredetermlned low rate of flow, means responsive to the operation of the flow control means when said means is operated to admit fluid to more than one space to energize a second electrical circuit to cause operation of the fluid circulating means at a predetermined high rate of flow, and means whereby all the energizing circuits to the fluid circulating means are deenergized when none of the temperature responsive means are calling for heat.

2. In a heating system, a heating chamber, means to supply heat to said chamber, means to caused a forced circulation or fluid through said chamber and into a plurality of spaces to be heated at any one of a plurality of predetermined rates, means to control the flow of fluid to the various spaces, there being one space having greater heat requirements than the other spaces, means responsive to the operation of the flow control means to admit fluidto the last mentioned space The energization of coil 5! will cause move to cause operation of the iiuid circulating means at a high predetermined rate, means responsive to the operation 01 the flow control means to admit fluid to any other single space to cause oper ation of the fluid circulating means at a low predetermined rate, and means responsive to the operation of the flow control means to admit fluid to any two spaces to cause operation of the fluid circulating means at a high predetermined rate. I

3. In a heating system, a heating chamber, means to supply heat to said chamber, means to cause a forcible circulation of fluid through said chamber and into any one or more of a plurality of spaces selectively at different predetermined rates dependent upon the spaces to be heated, means for controlling the flow oi" fluid into the various spaces, means for operating the fluid circulating means at a low predetermined rate in response to the operation of the flow control means to admit fluid to any one space only, means for operating the fluid circulating means at a high predetermined rate in response to the operation of the flow control means to admit fluid to more than one space, and means for stopping operation of the circulating means and the heating means in response to the operation of the flow control means to prevent flow of fluid to any of the spaces.

4. In an air circulating system, a fan for circulating air into a plurality 01' spaces, a motor for operating said Ian, said motor having high speed and low speed circuits, means for controlling the flow of air into said spaces, one of said spaces requiring a greater flow of air than any of said other spaces, means energizing a high speed circuit of the motor in response to operation of the controlling means to cause flow of air to the last mentioned zone, means energizing a low speed circuit of the motor in response to operation of the controlling means to cause flow of air to any other single zone, and means energizing a high speed circuit of the motor in response to operation 01' the controlling means to cause flow of air into any two spaces.

5. In an air circulating system, means for circulating air into a plurality oi spaces, a damper movable between two positions for varying the output oi. said air circulating means, in one position of which the damper permits minimum air flow and in the other position of which it permits maximum air flow, means for controlling the flow of air to the various spaces; means responsive to movement of the air flow controlling means to a position causing air flow into any one space only for causing operation of the air circulating means and for positioning the damper in the position of minimum air flow, means responsive to movement of the air flow controlling means to a position causing flow of air in more than one space for causing operation of the air circulating means and for positioning the damper in the position of maximum air flow, and means for stopping the air circulating means when the air flow controlling means is in a position preventing flow of air into any of the spaces.

6. In a heating system, a plurality of spaces to be heated, a heater, circulating means for circulating fluid through the heater and through the spaces to be heated at varying rates of flow, means controlling the flow of fluid into each of said spaces, a motor for operating each of said controlling means, temperature responsive means in each space for controlling the operation of the.

motor in that space, switch means operated by each of said motors, means normally maintaining the circulating means inoperative when none of the motors are operated to admit circulation of heating fluid through said spaces, circuit means for causing said circulating means to operate to circulate fluid at a low rate of flow in re sponse to the actuation of the switch means by one of said motors when said motor is actuated to admit circulation of fluid to the space controlled by said motor, and circuit means for causing operation of said circulating means to operate to. circulate fluid at a high rate of flow in response to the actuation of the switch means by any two or more of said motors when said motors are actuated to admit .circulation of fluid through the respective spaces. a

'7. In a heating system, a plurality of spaces to be heated, a heater, a two-speed fan for circulating air through the heater and the spaces to be heated, dampers for controlling the flow of air into each of said spaces, motors for operating said dampers, temperature responsive means in each space for controlling the motor in that space, switch means operated by each damper motor, means normally maintaining the fan inoperative when none of the damper motors are operated to open their respective dampers, circuit means for establishing a low speed circuit to the fan in response to the actuation of the switch means by one of the damper motors, and circuit means establishing a high speed circuit to the fan in response to the actuation of the switch means by any two of the damper motors when these motors are operated to open.

their respective dampers.

8. In a heating system, a heater, a motor fan unit having high and low speed circuits for circulating air through said heater and through the spaces to be heated, a damper in each space for controlling the flow of air into said spaces, a separate motor for operating each damper, cam means connected to each motor, a pair of switches operated by each cam means, each switch having a first position when its controlling motor is in a position wherein the damper operated thereby is closed to prevent the admission of air into the respective space, and each switch having a second position when its controlling motor' is in a position wherein the damper operated thereby is open to admit air into the respective space, means preventing operation of said motor fan unit when all of said switches are in the first positions, means connecting the low speed circuit of said motor fan unit to a source of power in response to the movement of a single pair of switches to the second position, and

- means connecting the high speed circuit of said motor fan unit to a source of power in responsev to movement of more than one pair of switches to the second positions.

the spaces to be heated, a damper in each space for controlling the flow or air into said spaces. a separate motor for operating each damper, temperature responsive means in each space controlling the operation of the respective damper a switch operated by each cam, each switch having a first position when its controlling motor is in a position wherein the damper operated thereby is closed to prevent the admission of air into the respective space, and each switch having a second position when its controlling motor is in a position wherein the damper operated thereby is open to admit air into the respective space, means preventing operation of said motor fan unit when all of said switches are in the first positions, means connecting the low speed circuit of said motor fan unit to a source of power in response to the movement of a single pair of switches to the second positions, and means connecting the high speed circuit of said motor fan unit to a source of power in response to movement of more than one pair of switches to the second positions.

10. In a conditioning system, means for causing a forced circulation of fluid through a plurality of spaces to be conditioned at varying rates of flow, means controlling the admission of fluid to each space, means operating said controlling means, space condition responsive means controlling said operating means, switch means, operated by said operating means, controlling a circuit through said fluid circulating meansto cause operation of said means to circulate fluid at a low rate when the controlling means is operated to admit air to one space only, and controlling a second circuit through said fluid circulating means to cause operation of said means to circulate fluid at a high rate when the controlling means is operated to admit fluid to any two or more spaces.

11. In a conditioning system, means for causing a forced circulation of fluid through a plurality of spaces to be conditioned at varying rates of flow, said spaces including one space requiring more fluid than the others, means controllin the admission of fluid to each space, means op- -motor, a pair oi'cams operated by each motor,

erating said controlling means, space condition responsive means controlling said operating means, switch means, operated by said operating means, controlling a circuit through said fluid circulating means to cause operation of said means to circulate fluid at a low rate when the controlling means is operated to admit fluid to any single space except said one space, controlling a second circuit through said fluid circulating means to cause operation of said means to circulate fluid at a high rate when the controlling means is operated to admit fluid to more than one space, and also when the controlling means is operated to admit fluid to said one space only.

CLARENCE W. NESSELL.

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