US2159624A - Valve system - Google Patents

Description

3 Sheets-Sheet l l5 1 3 14 I9 I816 SylvanuS G'Shipley May 23, 1939. s. c. SHIPLEY VALVE SYSTEM Filed Nov. 19. 1934 s Sheets-Sheet 2 S ylvanus C. Shipley S. C SHIPLEY VALVE SYSTEM Filed No v. 19, 1934 3 Sheets-Sheet 3 Sylvanus C. Shipley 167 Patented May 23, 1939 UNITED STATES PATENT OFFICE VALVE SYSTEM Application November 19,1934, Serial No. 753,557

g 14 Claim. This invention relates to valve systems for heaters wherein a control valve is operated by an electric motor which is responsive to a condition such as temperature.

There are in existence at the present time, heating systems that employ a heater delivering heat to a space and having a main heating burner, a pilot burner and a safety pilot control cooperating with the pilot burner". It is usual to control the main burner by means of a control valve which is operated by an electric motor in response to change in a condition such as temperature as reflected by a room'thermostat; The motor receives its energy in such systems from an electrical powor line. In somesystems, it is usual to have a secondary air controlling device including a lever extending outwardly through the control valve casing which is operated by the electric motor by being operatively connected with the control as valve for the main burner.

terns. when the'thermostat calls for heat,- the motor is energized to open the control valve to supply fluid to the main burner which is ignited by the pilot burner. Provision is made by means 25 of the safety pilot control whereby the motor may not be energized to open the control valve when the pilot burner is extinguished. In the above described systems, the power lines which deliver energy to the electric motor are subject so to power failure and when the thermostat calls for heat during this period of power failure, the motor cannot be energized to open the control valve. 1

It.often happens that heat is required during 35 this period of power failurean'd some means must be provided'to open the control valve to deliver fluid to the main burner. In the case of the system utilizing a secondary air control mechanism, the means for controlling the secondary 40 air control mechanism, which is operatively connected to the main control valve and which extends outwardly through the casing thereof, forms a convenient means whereby the control 'valve' may be manually opened. In the case opened. Users of such systems have been properly instructed how to open thecontrol valvevmanually during the period of power failure and they In the above sys-" where no such secondary air control mechanism have become so accustomed to dose that it has become practically automatic on their part.

In many instances, the failure of the control valve to open at the command of the thermostat is due to extinguishment of the pilot burner as reflected by the safety pilot control. Under such circumstances, if the control valve should be.

manually opened in the manner pointed out above, the main burner would not ignite due to the pilot burner being extinguished, causing large amounts of combustible fluid to accumulate in the heater.

Since the user has been properly instructed to manually open the control valve during periods of power failure in the manner pointed out above, it is entirely possiblethat he would attempt to open the control valve in the same manner during the period of extinguishment of the pilot burner and in the past such manual operation has occurred. Having thus opened the control valve and seeing that the main burner was not ignited, he would probably determine that the pilot was not burning. The chances are that he would attempt to light the pilot burner and in so doling, he would unconsciously ignite the large amounts of combustible fluid accumulated in the heater caused by the previous opening of the control valve.- Under such conditions, explosions of no mean proportion are liable to occur much to the damage of the heater and possible injury to the user.

Therefore, an object of this invention is to provide a manual means for opening the control valve which is not readily accessible to the user thereof and which requires the manual opening of the valve to be made by a properly instructed service man or prevents the haphazard opening thereof by the user.

Another object is to provide a motorized control valve having a cover enclosing the same and requiring the cover to be removed before said control valve may be'manually opened.

Still another object is to provide a motorized control valve having'a cover enclosing the same K and an auxiliary control element extending outwardly therefrom forming a convenient means for manually opening the valve with means located within the cover preventing fmanual opening of the valve without first removing the cover.

A further object is to provide a motorized control valve having a pawl connecting said motor and said control valve whereby said control valve is opened by energization of said motor and to provide means on said pawl to permit manual opening of said valve.

. control whereby a control valve may not be automatically or manually opened while the pilot is extinguished except by releasing said latching mechanism.

A further object is to provide a manual con-- trol means for a valve in combination with the systemto be disclosed hereafter.

- Further objects and advantages will become apparent to those skilled in the art by reference to the accompanying description and drawings in which:

Fig. 1 is a vertical sectional view of the control valve assembly taken substantially on the line II of Fig. 2,

Fig. 2 is an end elevational view of the same looking from the left in Fig. l and showing the cover in section,

Fig. 3 is a sideelevational view looking from the right in Fig. 2, the cover being shown in section and the terminal block and binding posts being shown in broken lines as if transparent,

Fig. 4 is a diagrammatic view of the structure shown in Figs. 1 to 3 and including the electrical control system therefor,

Fig. 5 is a diagrammatic view similar to Fig. .4 but showing a modified form of the invention,

Fig. 6 is a schematic view of a system including the present invention associated with a gas burner.

The invention contemplates the use of the after-described control system in combination with a heater, preferably a gas heater, having a main burner, a pilot burner combined with a safety pilot control and a secondary air control which are old in the art and need not be specifically shown and described, it being sufficient to state that the control valve 9 controls the main burner, that the safety pilot control operates the safety pilot switch arm |3| and that the lever 58 controls the secondary air supply.

Referring now to Figs. 1 to 4, the control valve generally designated at 9 has a valve casing |8 having inlet and outlet openings II and I2 respectively. The valve casing ID has a transverse wall l3 having a port opening l4 therein which isencompassed by an annular shoulder to form a valve seat l5. The valve member comprises a valve disc l6 adapted to seat on the annular seat l5, reinforcing washers I! and I8 flanking the valve disc l6, said valve disc I 6 and said reinforcing washers I1 and I8 being securely clamped together by means of a plug l9 and a nut 29 screwed thereon.

Extending into the plug |9 of the valve member is a valve stem 2|, the plug I9 and the valve stem 2| having holes to receive a pin 22 to secure the valve stem 2| and plug |9 together in fixed relation. Mounted in an annular groove in' the valve stem 2| is a split ring 23 which supports a spring retainer member 24. A spring 25 rests in the spring retainer member 24 and abuts against an abutment plate 26 to normally urge the valve member toward its seat. Located adjacent the upper portion of the valve casing H] are a disc 21, a packing washer 28 and a support 29 which are secured together and to the abutment disc 26 by means of rivets 38. 3| designates a clamping nut, screw-threaded on the upper portion of the valve casing H! to hold the. support 29 in fixed relation to the valve casing l8.

through which the valve stem 2| slidably extends outwardly from the valve casing H]. In order to effectively seal the valve I0 against leakage of fluid therefrom, a diaphragm 31 is secured to the outer end of the valve stem 2| by clamping the diaphragm 31 between a nut 34 and a washer 35, the clamping action being efiected by a nut 36 screwed on the screw-threaded portion 33 of the valve stem 2|. The outer edge of the diaphragm 31 is clamped between the support 29 and a base 38 by means of screws 39.

Mounted on the base 38 by means of screws 42 are two upright, spaced parallel plates 48' and 4|, the plates 48 and 4| being held in spaced relation by bolts 43 cooperating with nuts 45 to clamp the plates 40 and 4| against spacer members 44.

A motor of any known type, generally designated at 48, is secured to and spaced from the vertical plate 48 by means of screws 41 and spacers 48. The motor shaft extends through the '.,plate 48 and has a motor pinion 49 located on the end thereof. Located between the plates 48 and 4| and driven by the motor pinion 49 is a reduction gear train, comprising a gear 58 engaging the motor pinion 49, a gear 52 engaging a pinion 5| integral with the gear 58 and a gear 54 engaging a pinion 53 integral with the gear 52. The gears and pinions are suitably mounted and spaced between the upright parallel plates 40 and 4| by means of bearings 55.

By means of a pivot pin 59 and spacers 50, a lever 58 is pivoted between the plates 48 and 4| and by means of a pivot pin BI and spacers 32 the lever 58 is pivoted to a U-shaped bracket 63, which bracket 83 is secured to the valve stem 2| by a nut 64 screwed on the screw-threaded portion 33 of the valve stem 2| whereby movement of the lever 58 in a clockwise direction about its pivot pin 59 causes opening of the valve 9.

Pivoted to the lever 58 by means of a pin 65 is an upwardly extending pawl 66, havinga concave portion 61 to'engage and coact with a pin 68 se-.

cured to the gear 54. The pawl 86 is urged inwardly by means of a spring 18 engaging the pawl 66 and a pin 1| located on the lever 58 and inward movement of the pawl 86 1s limited by means of a stop pin 692 The outer end of the lever 58 is provided with holes 12 in which there may be attached means for controlling a secondary air supply to the heater.

The upright plate 40, has an inwardly extending flange 18 to which is secured a screw I6 by means of a nut 19. A cover 15 encloses the moving mechanism and is held in place by a knurled nut 11 screw-threaded on the screw 16. The cover I5 has a slot 88 through which the lever 58 extends outwardly so that the lever 58 may actuate the secondary air control.

A sleeve 8| is suitably secured to the upright plate 4| and has slidably mounted therein a latch pin 82, having an annular flange;83 at the inner end thereof and a fibre disc 85 secured intermediate the ends thereof to be engaged by a spring 84'to maintain the latch pin 82 in its outward position, the latch pin 82 extends outwardly through'a slot 86 in the cover 15 for external manual manipulation.

From the above description of the structure,

.it will be seen that when the motor 48 is energized, it operates through the gear train to angularly move the pin 88 to engage the concave surface 61 of the pawl 68 to raise the pawl 88 and thereby pivotthe lever 58 about its pivot 59 to open the control valve 9. Upward movement of the valve member and the pivoted lever 58 is arrested by the lever 58 engaging against the stop pin 69 whereupon the motor is stalled and the valve 9 is maintained in open positionas long as the motor 46 is energized. When the motor 46 is deenergized, the spring 25 closes the valve 9 and returns the parts to their original positions.

61 designates an insulating terminal block which is secured to and spaced from the vertical plate H by means of screws 88 and spacers 89. Mounted onthe terminal block 81 are binding posts90, 9|, 92, 93, 94 and 95. The-binding posts 90 and 9I are the power terminals and are nor-' mally connected to the secondary terminals of a step-down transformer, not forming part of the valve structure per se. The binding post 92 is connected to a contact l30 of a safety pilot control and the binding" post 93 is connected to an upper stationary binding post I31 ofa room thermostat I36. The binding post 94 is connected to an upper contact I 35 of a room thermostat I36 and the binding post 95 is connected to a lower contact I33 of a room thermostat I36 and to a switch arm I3I of the safety pilot control. 96 and 91 designate motor lead wires which are connected respectively to binding posts 90 and 94,

- these motor lead wires being extended through a conduit tube 98 located between the spaced upright plates 40 and 4|.

The shaft of the large gear 54 has an outwardly extending extension 99 which is flattened to slidably receive two friction discs I so that when the shaft extension 99 is rotated, the friction discs are also rotated. Rotatably mounted on the extension 90 and located between the discs I00 is a friction cam IOI which is held in frictional engagement with the friction discs I00 by means of a spring I02 abutting against the outer friction disc I00 and a collar I03 secured to the extension 99 by means of a pin I04. I05 designates a stop pin secured to the upright plate 4| which coacts with abutments I06 and I0I of friction cam I M to limit the angular movement of the friction cam IOI.

The friction cam I 0| has a cam surface I08 which coacts with a cam follower I09 secured to a rocker IIO which is pivoted to the binding post 93 and spaced from the terminal block 8I'by means of a spacer I II. Secured to the rocker I I0 is a leaf spring II2 which engages a stationary pin II3 secured to the terminal block 81 to urge the rocker H0 in a clockwise direction to maintain the cam follower I09 against the cam surface I08 of the friction cam IOI. Also secured to the rocker H0 is a contact arm II4 having a contact III which engages at certain times with a coacting stationary contact II 6 secured to a bus bar III which bus bar III is secured to the terminal block 81 by means of a screw H8.

The bus bar III is connected to the binding postv 94 and its lower end is bent inwardly and it has a stationary recycling contact II 9 on this end which engages at predetermined times with a coacting movable recycling contact I located on a spring bus bar I2I. The spring bus bar I2I connects the binding post 9| and 92 and normally urges the contact I20 against contact H9. The fibre disc 85 of the latching pin 82 being spring pressed outwardly normally separates the contacts H9 and I20 as is clearly shown in Fig. 2.

Located midway of the pawl 66 is a lug I which, under certain conditions of operation, coacts with the stationary stop pin 69 to prevent upward movement of the lever 58 as will be more fully pointed out hereafter, A handle I42 is formed on the upper end of the pawl 66.

Fig. 4 is a diagrammatic showing of the essential elements of this invention, along with a wiring diagram showing the complete system. In Fig. 4, it has been attempted to use the same reference characters as in Figs. 1 to 3 wherever possible. I22 and I23 are line wires carrying a supply of electrical energy which are connected to the primary I25 of a step down transformer I24. One end of the secondary I26 of the step down transformer I24 is connected by a wire IT! to the field coil I28 of the motor, generally designated at 46, and the other end of the secondary I26 is connected by a wire I29 to a stationary contact I30 of the safety pilot control. The contact I30 is engaged by a switch arm I3I of the safety pilot control when the pilot burner .is burning and the switch arm I3I is connected to the stationary contact H6 and the movable contact H5 is connected by a line wire I38 to the stationary binding post I31 of the room thermostat I36. engaged sequentially by movable contacts I39 and I 40 secured to the room thermostat I36 since the distance between contacts I33 and I39 is less than the distance between contacts I35 and I40.

Assume that'the control valve 9 is closed and the parts are in the position shown in Figs. 1 to 3 and that the pilot burner is burning whereby the safety pilot control causes the switch arm I 3| to engage the contact I30. The room thermostat calls for heat moving the contacts I39 and I40 to the left but since the distance between contacts I33 and I39 is less than the distance between contacts I35 and I40, contact I39 will first engage contact I33. Since the contacts H5 and II6 are open, the circuit to the motor is not completed. Upon further drop in temperature, contact I40 engages contact I35 completing a circuit from the secondary I26 through wire I29, contact I30 and switch arm I3I of the pilot safety control, bus I2I, wire I32, contacts I33 and I39, contacts I40 and I35, wire I34, wire 91, coil I28, and wire .I2'I back to the secondary I26 of the transformer I24, thereby energizing the motor 46 to begin its movement to open the valve 9. Upon this moven'et of the valve, cam IN is rotated in a clockwise direction and causes the cam surface I08 to' engage the cam follower I09 to close contacts H5 and H6 thereby completing a second and holding circuit from the secondary I26 of the transformer- I24, through the wire I29, contact I30 and switch arm I3I of the pilot safety control, bus I2I, wire I32, contacts I33 and I39, thermostat I36, binding post I3'I, wire I38,.contacts H5 and H6, bus II'I, wire 91, field coil I28 and wire I2I back to the secondary I26 of the transformer I24. Continued movement of the motor 46 caused by this circuit raises the arm 58 about its pivot 59 to completely open the valve thereby delivering fluid to the heater which is ignited by the pilot burner. When the valve is completely opened, the arm 58 engages the stop pin 69 to prevent further movement and to stall the motor. As long as the room thermostat I36 calls for heat, the motor will be energized and Stationary contacts I33 and I35 are will remain in this stalled position and maintain the valve 9 fully opened. When the temperature of the room rises sufficiently, the thermostat I35 moves the contacts I45 and I39 to the right, breaking the above mentioned circuits to deenergize the motor and allows the spring 25 to move the valve 9 to its closed position and to restore the parts to the position shown in Figs. 1 and 3.

If the pilot burner is extinguished, the safety pilot control moves the switch arm I5I away from the stationary contact I3 and prevents the above circuits from being completed. Therefore, when the pilot burner is extinguished, automatic opening of the valve by means of the motor 45 is entirely prevented.

Assume that there is a power failurein the lines I22 and I23 and the room thermostat calls for heat, the valve 9 cannot be opened by the motor 55. Since the lever 58 extends outwardly through the slot 55 in the cover I5 to control secondary air to the heater, this'extension of the lever 58 affords a convenient means for manually opening the valve by pressing down on the outward end of the lever 58 which swings the lever 58 about its pivot 59 to open the valve 9. In order to maintain this valve 9 in its open position, the latch pin 82 is thrust inwardly and engages under the lever 58 to hold the lever 55 in this shifted position and maintain the valve partially open such position being shown in broken lines in Fig. 3. Latch pin 82 is, prevented from being forced outwardly by the spring 84 by means of the flange 83 of the pin 82 engaging the lever 58. By so moving the pin 82 inwardly, the fibre disc 85 also moves inwardly allowing the recycling contact I25 to engage contact II9. whereby a circuit is completed from the secondary I25 of the transformer l24, wire i29, contact I35 and switch arm i3I of the safety pilot control, wire I2I, recycling contacts I25 and M5, wire 95, field coil I28 and wire i211 back to the secondary I25 of the transformer I25. When the power failure period ends and power is again restored to the lines I22 and H3, current will flow through this circuit to energize the motor to movethe lever 58 in clockwise direction about its pivot 55 which permits the annular flange of the latch pin 82 to disengage from the lever 58 to permit the sprin 84 to return the latch pin 82 to its outer position.

When the latch pin 82 is so returned to its outer position, the fibre disc 55 separates the contacts H9 and I25 to break the above circuit and if the room thermostat I35 is not calling for heat in the manner outlined above, no other circuits will be completed and the spring 25 will then close the valve I5 and return the parts to their relative positions as shown in Figs. 1 and 3.

As pointed out above, great danger occurs from manually opening the control valve when the pilot burner is extinguished because of the permitting of large amounts of explosive fluid to flow into and accumulate in the heater. In order to prevent the haphazard manual opening of the valve 9 bythe user of the heater without thought on his part in determining the cause of the failure of the control valve '9 to open whether it be power failure or the action of the safety pilot control, the lug MI is provided on the pawl 55. This lug is so located with relation to the stationary stop pin 59 that when the pin 58 of the gear 54 engages the concave surface 51 of the pawl 55, the

pawl 55 is angularly moved so that the lug I4I will not engage the stationary pin 59 which allows free easy opening movement of the valve I5 by the motor 45 as shown in broken lines in Fig. 4. However, manual manipulation of the lever 55 in the manner pointed out above is prevented because the pawl 55 is urged inwardly by means of spring I5 and by pushing down on the outward end of the lever 58 in the manner pointed out above, lug II of the pawl 55 engages the pin 59 which prevents movement of the lever 55 and consequent opening of the control valve 9. Therefore, in order to manually open the control valve 9, the cover I5 must be removed and the handle I52 of the pawl55 must be grasped to first swin the lug I4I to the left against the action of the spring I5 to clear the pin 69 to permit upward movement of the pawl 55 and consequent opening of the valve 9.

By use of this construction, it is impossible for the user of the heater and this system of control to manually open the valve in a haphazard manner. The user must do one of two things either call a properly instructed service man who will be instructed to determine whether or not the pilot burner is burning before he attempts to open the'main control valve 9 or he must remove the cover l5 himself which will make him think twice of what he is doing which will invariably make him look to see if the pilot burner is burning before he attempts to manually open the valve.

From the above, it will be seen that I have provided a control system wherein there are manual means for opening the control valve which are not easily accessible to the user of the system diagrammatically a modified form of my invention wherein like parts are indicated by like references. This modification employs the same motor 55, the same gear train, the same lever 55 and the same valve 9. The control system comprises the same transformer I25, the same room thermostat I35, the same friction cam 551i and the same recycling contacts H9 and I25. However, in this modification, the safety pilot control having the contact I35 and the switch arm M is not placed in series as above but is placed in parallel to operate a latching mechanism I5l which is secured to a stationary bracket E55. The pilot safety control embodying the contact I35 and the switch arm- I3I and the coil I55 is connected in parallel to the rest of the control system by a wire E53 connecting contact I35 with' the wire I29 by a wire I55 connecting the switch arm 856 with a coil I 55 and by a wire I55 connecting the coil I55 with the wire I21. Bracket I55 is adapted to receive a solenoid coil I55 so that when the coil I55 is energized, the latch arm I5I is attracted thereby in a clockwise direction to remove it from the path of lever 55. A spring I52, located between the latch arm I5I and the support bracket I52, normally urges the latch arm I5I in the path of movement of the lever 58.

The manner of operation of this modification is identical to the operation above when the room thermostat I35 calls for heat so a detailed decontrol valve 9 because the latch arm II is drawn out of the path of movement of the lever 58' by the coil I55. However, when the pilot light is extinguished, switch arm I3I disengagescontact I30 to break the magnetic effect of coil I55 and the spring I52 urges the' latch arm I5I into the path 01 movement of the lever 58, preventing manual opening of the control valve 9 and also preventing automatic opening of the control valve 9. Further, this modification contemplates the use of a pawl I49 which is not provided with the lug I 4I and the handle I42 described above since the latching action is taken care of by the latch arm I5I.

From the above, it is seen that in this modification I have devised means whereby it is impossible to manually open the control valve 9 or to automatically open it by means of the motor 45 when the pilot burner is extinguished unless the cover 15 is removed and the latch arm I5I is manually manipulated to remove it from the path of movement of the lever 58.

In Fig. 6 the valve system of the present invention has been shown in connection with a gas burning furnace. 'The valve 9 is shown in this figure as controlling the flow of gas through a pipe I66 to a gas burner I61, this gas burner being located in a furnace generally designated by the reference numeral I68. Primary air is admitted to the gas in the conventional manner by a suitable mixing chamber I69. A secondary air damper I10 is provided which permits the closing off of the secondary air upon the termination of burner operation to conserve heat in the furnace. This secondary air damper is pivotally mounted and biased inwardly. Connected to the damper is a chain "I, or other similar device, which extends over pulleys I12 to the secondary air damper arm 58. It will be obvious that upon the valve being operated, as previously explained, so that the damper arm 58 is moved downwardly the secondary air damp er I10 is permitted to move downwardly through the action of gravity.

pilot burner I14 which is connected to the gas line I56 behind the valve 9 so that it is normally constantly supplied with gas and hence constantly lighted. The pilot burner previously referred to and shown in highly schematic form is illustrated here. The pilot burner is shown as comprising the bimetallic contact member I3I exposed to the heat of the pilot flame and which cooperates with thecontact I30. The room thermostat I35 and the transformer I24 are shown in schematic form, such a showing being considered to be adequate in view of the more detailed showing in Figs. 4 and 5.

As many changes could be made in the above construction, installation and mechanism and as many apparent widely difierent embodiments of this invention could be made without departing from the scope thereof, it is intended'that all matter contained in the drawings or described in the specification shall be interpreted as illustrative only and not in a limiting sense.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In a device of the character described, a normally closed valve, automatic means associated with said valve for opening said valve, a

cover enclosing said .automatic means, means associated with said automatic means and ex- Located adjacent the main burner I61 Isasaid valve may be manually opened, and latch means within said cover to prevent manual opening of said valve, said latch means being ineffective to restrain manual opening of said valve.

after a predetermined initial opening movement thereof. a

2. In a device of the character described, a normally closed valve, means mounting on said valve and including an electric motor for opening said valve, a cover enclosing said means, means connected to said means and extending outwardly through said cover providing manual means for opening said valve, and releasable latch means within said cover to prevent manual opening of said valve when said cover is in place, said latch means being ineffective to restrain manual opening of said valve after a predetermined initial opening movement thereof.

3. In a device of the character described, a normally closed valve automatic means associated with said valve for opening said valve including a movable pin, a pawl associated therewith and a lever connected between said pawl and said valve, and means associated with said pawl to prevent manual opening of said valve by manual manipulation of said lever, said last named means having no effect on the opening of said valve by said automatic means.

4. In a device of the character described, a normally closed valve, automatic means associated with said valve for opening said valveineluding a movable pin, a pawl associated therewith and a lever connected between said pawl and said valve, and means associated with said pawl to prevent manual opening of said Valve by manuaimanipulation of said lever but permitting manual opening of said valve by manual manipulation of said pawl, said last named means having no eifect on the opening of said valve by said automatic means.

5. In a device of the character described, a normally closed valve, a lever connected to said valve for operating the same, a pawl carried by said lever andhaving a lug thereon, an abutment in the path of movement of said lugto prevent opening of said valve by manipulation of said lever, and a pin for engaging said pawl to swing said lug clear of said abutment to move said lever to open said valve.

6. In a device of ,the character described, a normally closed valve, automatic meansassooiated with said valve for opening said valve including a movable pin, a pawl associated therewith and a lever connected between said pawl and said valve, and releasable latch means associated with said lever to prevent manual opening of said valve by manual manipulation of said lever, said latch means being inefiective to restrain manual opening of said valve after a predetermined initial opening movement thereof.

'1. In a device of the character described, a normally closed valve, automatic means associated with said valve for opening said valve including a movable pin, a pawl associated therewith and a lever connected between said pawl and said valve, releasable latch means associated with said leverto prevent automatic opening of said valve by said automatic means and to prevent manual opening of said valve by manual manipulation of said lever, and means to release said releasable means to permit automatic or manual opening of said valve, said latch means being ineffective to restrain manual opening of said valve after a predetermined initial opening movement thereof.

8.- In a control system comprising a heater a valve biased to closed position for controlling said fuel inlet, power means associated with said valve for automatically opening said valve in response to a condition indicative of a demand for heat, means associated with said power means and operatively connected to said secondary air damper to control the position of the same in accordance with the position of the valve; and forming a convenient means for manually opening said valve, and releasable means to prevent manual opening of said valve by'manual manipulation of said last named means, said releasable means having no eflect upon the opening of said valve by said power means.

9. In a control system comprising a heater having a fuel inlet and a secondary air damper, a valve biased to closed position for controlling said fuel inlet, power means associated with said valve for automatically opening said valve in response to a condition indicative of a demand for heat, a cover enclosing said power means, means positively connected to said valve and extending through said cover and operatively connected to said secondary air damper to control the position of the same in accordance with the position of the valve, said last named means forming a convenient means for manually opening said valve, and means to prevent manual opening of said valve by manual manipulation of said last named means without removing said cover.

10. In a control system comprising a heater having a fuel inlet and a secondary air damper, a valve biased to closed position for controlling said fuel inlet, power means associated with said valve for automatically opening said valve in response to a condition indicative of a demand for heat, said power means including a movable .pin, a pawl associated therewith and a lever connected between said pawl and said valve, said lever being operatively connected to said secondary air damper and providing aconvenient means for manually opening said valve and means associated with said pawl to prevent manual opening of said valve by manual manipulation of said lever but permitting manual opening of said valve by manual manipulation of said pawl.

11. In a control system comprising a heater having a fuel inlet and a secondary air damper, a valve biased to closed position for controlling said fuel inlet, power means associated with said valve for automatically opening said valve in response to a condition indicative of a demand for heat including a lever connected to said valve, said lever being operatively connected to said secondary air damper and providing a convenient means for manually opening said valve, releasable means to prevent opening of said valve by said power means or by manual manipulation of said lever and means to release said releasable means to permit opening of said valve, said releasable means being ineffective to restrain opening movement of said valve after an initial opening movement thereof.

12. In adevice of the class described, a normally closed valve, operating mechanism for said valve including a motor and connecting means between said motor and said valve, a housing inclosing said operating mechanism, amember operatively connected and movable with said apparatus, said member providing manual means for opening said valve, and a releasable latch efiective to prevent opening movement of said valve by actuation of said member but ineffective to prevent opening movement of said valve by said operating mechanism.

13. In a control system comprising a heater having a fuel inlet and a secondary air damper, a valve biased to closed position for controlling said fuel inlet, power means associated with said valve for automatically opening said valve in response to a condition indicative of a demand for heat, a cover enclosing said power means, means operatively connected to said valve and extending through said cover and connected to said secondary air damper to control the position of the same in accordance with the position of the valve, said last named means forming means for manually opening said valve, means to prevent opening of said valve by manual manipulation" without first removing said cover, said last named means having no effect upon the opening of said valve by said motor means.

14. In a control system comprising a heater having a fuel inlet and a secondary air damper, a valve biased to closed position for controlling said fuel inlet, power means associated with said the position of the valve, said lever means also forming a means for manual operation of said valve, means within said cover to normally prevent opening of said valve by manual manipulationof said lever means, said last named means having no effect upon the opening of said valve by said motor means.

SYLVANUS C. SHIPLEI.

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