NZ212873A - Tempering valve for hot water supply, fail safe system - Google Patents

Description

2 1287 (•vie Complete Speci.'-cstion Fiied:^r?...). am: fA.6)S.»l /OO;. f Publication Date: !???..... P.O. Journal, No: Patents Form No. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION "FAIL SAFE TEMPERING VALVE" -I-,WE ACTROL INDUSTRIES, PTY. LTD. a company incorporated under th elaws of the State of Victoria, Australia, of ,<BHP House, 14 0 William Street, Melbourne, Victoria 3000, Australia, hereby declare the invention, for which -f-/we pray that a patent may be granted to -roe-/-us, and the method by Which it is to be performed, to be particularly described in and by the following statement 212873 This invention relates to tempering valves as used in hot water supply systems to provide some measure of control over the temperature of the water at the supply outlet.

Tempering valves have a mixing chamber which is connected to both hot and cold water supplies and have a thermostat device which controls the introduction of cold water to that chamber. An outlet of the chamber is connected to a tap or other draw-off point. If the hot water reaching the valve has a temperature below a predetermined level, the operation of the thermostat device is such that cold water is prevented from entering the mixing chamber. The temperature of the water at the draw-off point is therefore the same as that of the hot water at the tempering valve, except for heat loss as may occur between the draw-off point and that valve. If however, the temperature of the hot water is above the predetermined level when it reaches the valve, the thermostat device functions to open the cold water supply port so that mixing cold and hot water occurs within the valve. The water then supplied to the draw-off point has a temperature less than that of the hot water entering the valve.

The thermostat device for tempering valves generally includes a tubular body containing a temperature responsive medium which expands with increased temperature, and a push rod which responds to expansion and contraction of that medium and which may project out of one end of the tubular body. Such devices are known to fail because of leakage of the medium through a faulty seal or fracture of the tubular body, for example. That can have disasterous consequences in a tempering valve because the cold water inlet will then be cut off from the mixing chamber and water discharged at the associated service outlet will be at maximum temperature.

In a typical hot water tank installation, the cold 2 ? 1 2873 •supply is connected to the bottom of the tank and is also connected to the cold water inlet port of the tempering valve. The hot water inlet of that valve is in turn connected into an upper region of the tank. The aforementioned problem results from the fact that under normal ambient temperature conditions the valve may be constructed in such a way that it functions in the same manner as if the thermostat device had failed and consequently it is open to free flow of cold water through the valve orifice to the hot water inlet. As a result, cold water will enter the empty tank through the lower cold water inlet as intended and will also enter the tank by way of the hot water inlet of the tempering valve. That dual flow situation leads to the possibility of air being trapped within the tank and complete filling of the tank is thereby hindered.

Another problem with tempering valves in use is that an undesirable water flow through the valve from the hot to the cold water inlet can arise due to a thermosyphon effect.

It is an object of the present invention to provide an improved form of tempering valve having a fail-safe facility but which enables the above problems to be overcome or alleviated.

According to the present invention there is provided a tempering valve including, a hollow body having a chamber therein, an outlet and a hot water inlet each of which communicates with said chamber, a cold water inlet which communicates with said chamber through an orifice provided within said body, a valve member mounted within said body for movement towards and away from a position at which it closes said orifice and therby prevents said communication between v-fehe^hamber and the cold water inlet, temperature responsive mearis operable to cause said valve member to move in one ©^direction away from said orifice closing position when exposed ■^Wo a temperature above a particular temperature, fail-safe S/jifeans which operates in response to said temperature responsive .means failing so as to provide communication between said chamber and said cold water inlet, and closure means for clo.sing of the communication between the cold water inlet and theriot water inlet of the valve when flow between the cold water inlet and the hot water inlet is otherwise possible. ?12B73 In one possible embodiment the fail-safe means may be further operative in response to being exposed to a temperature below said particular temperature to provide communication between said chamber and said cold water at least when said closure means is not preventing communication between the cold water inlet and the hot water inlet. In this particular embodiment the closure means may be selectively adjustable to adopt either of two positions at which it allows and prevents respectively operation of the fail-safe means.

That is, communication between the cold and hot water inlets can be blocked during filling of an associated hot water tank even though under those conditions the thermostat would normally function to open such communication. After filling of the tank, the adjustable means can be returned to an inoperative position at which it allows the valve to function in a normal manner.

In a further possible embodiment the closure means may include a non-return valve located between "the hot water inlet and said chamber and operative to inhibit or prevent 20 water flow from said chamber to said hot water inlet.

It will be convenient to hereinafter describe the invention as applied to one particular type of fail-safe tempering valve, but that is not the only possible application of the invention.

The essential features of the invention, and further optional features, are described in detail in the following passages of the specification which refer to the accompanying drawings. The drawings however, are merely illustrative of how the invention might be put into effect, so that the specific foFnF^id arrangement of the features (whether they be essential Z-^^r optjional features) shown is not to be understood as limiting Sn\the. invention.

In the drawings: o:| f»lj Figure 1 is a diagrammatic view showing a typical H ^ .^^installation to which a valve according to the invention is •v^ J* t i'-r *■ • applicable; • , Figure 2 is a cross sectional view of one form of valve incorporating an embodiment of the invention; 39 Figure 3 is a view similar to figure 2 but showing the , 21287 valve open as a consequence of normal operation of the thermostat; Figure 4 is a view similar to figure 3 but showing the valve open as a consequence of abnormal operation of the thermostat; Figure 5 is a view similar to figure 4 but showing the valve prevented from adopting the figure 4 posistion by appropriate adjustment of stop means; Figure 6 is a view similar to figure 2 and showing the invention applied to another fbrm of valve; Figure 7 is a view of part only of the figure valve in a condition corresponding toithat shown by figure 5; Figure 8 is a view of yet another form of valve to which an embodiment of the invention has been applied.

Figure 9 is a view of a further form of valve embodying the invention.

In the typical arrangement of figure 1 a cold water supply 1 is connected to the bottom region of the storage tank 2 and is also connected to the cold water inlet 3 of a tempering valve 4. The hot water inlet 5 of the valve 4 is connected to an upper region of the tank 2 and the outlet 6 of the valve 4 is connected to a service outlet or the like through a conduit 7. A valve according to the invention is applicable to such a typical arrangement and may have other applications. The valve 4 shown in figure 1 is one form of valve to which the invention can be applied and that valve is shown in greater detail in figure 2. As will be apparent from figure 2, the valve 4 includes a hollow body 8 having an outlet port 6, a cold water inlet port 3 and a hot water inlet port 5. The outlet port 6 and the cold water inlet port 3 are preferable in substantialL_ alignment as shown and the hot water inlet port 5 is arranged transverse to the two aligned ports 6 and 3. An internal wall 9 of the body 8 forms a separation between a cold water inlet section 10 and a mixing chamber 11, both of which are formed within the interior of the valve body 8, and an orifice 12 through the wall 9 enables communication between the inlet section 10 and the chamber 11. The hot water inlet port 5 and the outlet port 6 are in combined communication with the chamber 11 and the cold water inlet port 3 is in continuous communication with the inlet section 10.

CT 212873 A valve member 13 is mounted within the body 8 for movement towards and away from a position as shown in figure 2 at which it closes the orifice 12 and therby prevents communication between the inlet section 10 and the chamber 11. In the arrangement shown, the valve member 13 is secured to the body 14 of a thermostat device 15 which is located within a passage 16 connecting the hot water inlet port 5 to the chamber 11 of the valve body 8.

The body 14 of the thermostat device 15 is preferably aligned with the valve orifice 12 and may be guided for axial movement relative to the valve body 8 by a member 17 located within the passage 16. In the example shown, the guide member 17 has a central opening 18 within which the thermostat body 14 is slidably located and at least one other opening 19 located radially outwards of the central opening 18 and through which the inlet port 5 communicates with the valve chamber 11. The valve member 13 is attached to one end of the thermostat body 14 and a biasing spring 20 is disposed between that member 13 and the guide member 17 so as to urge those members 13 and 17 apart. As shown, separation of the valve and guide members 13 and 17 may be limited by engagement between a stop 21 and part of the thermostat device.

Thermostat devices 15 of the kind shown are well known and include within.the body 14 a quantity of material such as wax which expands and contracts with rising and falling temperature respectively. A stem 22 projects out of one end of the thermostat body 14 and responds to expansion and contraction of the wax by respectively moving further out of or withdrawing into the thermostat body 14. In the construction under considferation, the stem 22 projects out of the end of the ^hexrmo?stat body 14 to which the valve member 13 is attached and its outer end located in engagement with the stop 21. The arrangement is therefore such that the position of the valve briber 13 relative to the valve orifice 12 is determined by the extent to which the stem 22 projects out of the thermostat body 14.

The valve member 13 is arranged to pass completely through the orifice 12 and closes the orifice 12 when at a particular axial position or within a small range of axial positions. When the temperature of the hot water passing across the thermostat 15 is above ambient temperature the thermostat stem 22 extends out of the body 14 and by reaction with the stop 21 pushes the valve member 13 in a direction towards the inlet port 5. If the temperature of the water exceeds that at which the orifice 12 is closed as shown in figure 2, the valve member 13 will be pushed towards the position shown in figure 3 and thereby causes opening of the orifice 12. If the thermostat 15 fails for any reason or is exposed to a temperature below the aforementioned closing temperature so that the stem 22 withdraws into the thermostat body 14 beyond the position shown in figure 2, the valve member 13 will be moved through the orifice 12 to ithe cold water inlet side shown in figure 4 and thereby open the orifice 12 to flow. The last mentioned result is achieved if there is no hot water flowing over the thermostat 15, such as when the valve 4 is first installed on a tank 2.

The stop 21 is adjustable between two positions, one of which is adopted for normal operation of the valve 4 and the other is adopted for tank filling purposes. In the particular construction shown, the stop 21 is formed by the inner end of a screw 23 which is arranged coaxial with the thermostat stem 22 and is located on the cold water inlet side of the orifice 12. According to one arrangement as shown, the stop screw 23 is located in a plug 24 which is removably secured within an opening through a wall of the valve body 8. It is usually convenient to have screw threaded engagement between the plug 24 and the valve body 8 and an O-ring 25 or other sealing means may be provided between!.the two parts.

The stop screw 23 has an enlarged head 26 at the outer end thereof and that head 26 is slidably arranged within an axial bore 27 of the plug 24. An O-ring 28 or other sealing means may be provided between the head 26 of the stop screw 23 and the bore 27. The threaded shank of the stop screw 23 cooperatively engages with a nut 29 having a non-circular peripheral shape and which is slidable axially within a complementary counter-bore 30 at the inner end of the plug 24. In the normal position of the stop screw 2 3 as shown in figures 2 to 4, the nut 29 engages against the shoulder 31 formed by the counter—bore 30 and the relative axial positions of the nut 29 and stop screw 23? are preselected to hold the valve member 13 in CT the orifice closed position for a particular temperature or temperature range.

Adjusting means is associated with the stop screw 23 and is operable to extend the stop screw 23 beyond its normal position as shown in figures 2 to 4 and thereby relocate the outer end of the thermostat stem 22 so that the valve member 13 will close the orifice 12 under cold conditions - i.e., there is no hot water flowing over the thermostat 15. That adjusting means is preferably a screw 32, as shown, located axially outwards of the stop screw 23 and threadably engaging within an outer extension of the plug bore 27. The adjusting screw 32 is arranged so that it can be moved against the outer end of the stop screw 23 and by further adjustment can push that screw 23 and its associated nut 29 inwards from the normal position previously described. A shoulder 33 of the adjusting screw 32 may contact an opposed shoulder 34 of the plug bore 27 when the stop screw 23 has reached the tank filling position as shown in figure 5. The adjusting screw 32 is accessible from the outer end of the plug 24 for adjusting purposes and means may be provided to prevent complete withdrawal of the adjusting screw 32 from the plug 24.

It will be apparent from the foregoing description that the valve 4 can be simply set to close the orifice 12 during a tank filling operation. That is, the adjusting screw 32 is turned so as to push the stop screw 23 inwards to the position at which it holds the valve member 13 in an orifice closed position even though the thermostat 15 is subjected to a cold environment. When filling of the tank 2 is completed, the adjusting screw 32 can then be returned to its normal position and thereby allow the stop screw 2 3 to adopt its normal position at which the valve 4 will operate in the normal manner.

The particular valve construction described is only one possible form of tempering valve having a fail safe facility. The present invention is applicable to valves of the same kind having different details of construction.; By way of example, figure 6 shows another form of valve to which the invention can be applied and components of that valve corresponding to components of the previously described valve will be given like reference numerals except that they are in the number CT - 8 - series 100 to 199. In the figure 6 construction, the valve member 113 is mounted on the thermostat stem 122 for movement with that stem 122 and is moved to the hot water inlet side of the orifice 112 when the thermostat 115 fails or is in a cold environment. The adjusting means is therefore arranged to prevent that movement of the stem 122 for tank filling purposes and, as shown, may comprise a screw 123 threadably engaging with the outer end of the stem 122 and being engagable with an abutment 135 to hold the stem 122 against movement from the orifice closed position. Figure 6 shows the screw 123 in the normal position-and"-it will be moved further onto the stem 122 as shown in figure 7 for tank filling purposes. The screw 12 3 could engage within rather than over the stem 122 as shown.

Figure 8 shows still another valve construction in \hich components of the valve corresponding to those previously described are given like reference numerals.:; except that they are in the number series 200 - 299. In the figure 8 construction the valve member 213 does not pass through the orifice 212 and the fail-safe means includes a passage 236 formed through the valve member 213 and a closure member 217 connected Ito the thermostat stem 222 and being operable to open and close the passage 2 36 as required. The tank filling mode is achieved by appropriate adjustment of a screw 223 which is attached to the stem 222 and is engagable with an abutment 235.

In yet another valve arrangement (not shown), the hot and cold water inlets are in axial alignment and the thermostat device is located on the same axis. It is therefore not convenient to gain access to an end of the thermostat stem as in the previously described constructions. For this type of construction the adjusting means may comprise a screw which extends transversely to the aforementioned axis and ;is accessible from the outside of the valve body to be moved into and out of a position at which it obstructs movement of the closure member from the orifice closed position when the thermostat is cold.

That may be achieved by engagement between the screw and any appropriate movable component within the valve body.

In figure 9 there is shown a further form of valve embodying the invention and components of that valve corresponding to components of the previously described valves are given like CT ?! 2873 reference numerals except they are in the number series 300-399. In the figure 9 valve, the thermostat device 315 is mounted and operable generally as described in relation to figures 2 to 4 although in this embodiment it is mounted in the mix outlet 306.

The closure means for closing of the communication between the cold water inlet 303 and the hot water inlet 305 of the valve when flow between those two inlets is possible, e.g., when the thermostat device 315 is exposed to a low temperature and the valve member 313 opens orifice 312 generally as in figure 4, includes a non-return valve 345. This non-return valve 345 is located between the hot water inlet 305 and the chamber 311 and includes a valve member 346 resiliently biased by spring 347 into engagement with valve seat 348 in the valve body 308. The stem 349 mounting the valve member 346 is slidably in apertured collar 350. If Valve member 313 opens orifice 312 upon exposure of the thermostat device 315 to a low temperature, or upon thermostat failure, in either case generally as in figure 5, non-return valve 345 will prevent reverse flow of cold water from the cold water inlet 303 to the hot water inlet 305. The valve 345 will also prevent flow from hot water inlet 305 to cold water inlet 303 under thermosyphon effects when orifice 312 is open generally as in figure 3, since spring 347 is sufficiently strong to prevent such flow.

The valve in figure 9 further includes a selectively adjustable stop member 360 to which the end of the stem 322 remote from the thermostat body 314 is secured. The stop member 360 is selectively movable relative to the valve body 308 by being in threaded engagement with the body 308 so as to enable adjustment of the position of the valve member 313 relative to the orifice 312. This may be for the purpose of calibration or setting of the temperature at which the thermostat device 315 will be operative to open the orifice 312 to cold water flow during normal operation generally as""ln figure 3. The selective movement 9!2873 of the stop member 360 may also enable user closure of the orifice 312 even if the thermostat device"315 is exposed to a low temperature and the orifice would otherwise be open as in figure 4, such as during initial filling of the associated tank 2 (figure 1). That is, the stop member 360 may be operable in the same way as the stop 21 in figures 2 to 5 to close the orifice 312 during tank filling generally as in figure 5.

Various alterations,modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the spirit or ambit of the invention as defined by the appended claims. 11

Claims (15)

1. WHAT */WE CLAIM 1S:-1. A tempering valve including a hollow body having a chamber therein, an outlet and a hot water inlet each of which communicates with said chamber, a cold water inlet which communicates with said chamber through an orifice provided within said body, a valve member mounted within said body for movement towards and away from a position at which it closes said orifice and thereby prevents said communication between the chamber and the cold water inlet, temperature responsive;10 means operable to cause said valve member to move in one direction away from said orifice closing position when exposed to a temperature above a particular temperature, fail-safe means which operates in response to said temperature responsive means failing so as to provide communication between said chamber and said cold water inlet, and closure means for closing of the communication between the cold water inlet and the hot water inlet of the valve when flow between the cold water inlet and the hot water inlet is otherwise possible.;20
2. 2. A tempering valve according to claim 1 wherein said fail-safe means is further operative in response to being exposed to a temperature below said particular temperature to provide communication between said chamber and said cold water inlet at least when said closure means is not preventing communication between the cold water inlet and the hot water inlet.;
3. 3. A tempering valve accordinq to claim 2 wherein said closure means is selectively adjustable to adopt either of two positions at which it allows and prevents respectively;3t)" operation of the fail-safe means.;
4. 4. ?! A tempering valve according to claim 3 wherein said i fa ^ i;Ovalve1 member forms part of said fail-safe means and is movable;■1 .;thorough said orifice so as to be capable of movement away frorr,;^PRi9S7sa?id orifice closing position in a direction opposite said one , direction when said temperature responsive means fails or is;=3^=^-"* exposed to a temperature below said particular temperature.
5. 5. j A tempering valve according to claim 4 wherein said adjustable means is operable in one said position to prevent 39 movement of said valve member in said opposite direction away from said orifice closing position.
6. 6. A tempering valve according to claim 4 or 5, wherein said temperature responsive means includes a thermostat body which is mounted within said valve body for relative movement in the axial direction of said orifice, said valve member being secured to said thermostat body against relative movement, spring means which acts between the two said bodies so as to urge said valve member to move in said opposite direction, and a stem which, projects beyond one end of said thermostat body and is movable axially relative to that body.
7. 7. A thermostat valve according to claim 4 or 5, wherein said temperature responsive means includes a thermostat body which is secured within said valve body against movement relative thereto, a stem projecting beyond one end of said thermostat body and being movable axially relative to that body, said valve member being secured to said stem for movement therewith., and spring means acting between said valve member and said valve body so as to urge said valve member to move in said opposite direction.
8. 8. A tempering valve according to any one of claims 3 to 7 wherein said adjustable means includes a stop member which adopts a different position relative to another member when in each of two said positions thereof.
9. 9. A tempering valve according to claim 8 when appended to claim 6, wherein said stop member engages end to end with said stem and is adjustable relative to said valve body.
10. 10. A tempering valve according to claim 8 when appended to claim 7 wherein said stop member is connected to said stem for movement therewith and is adjustable relative to that stem.
11. 11. A tempering valve according to claim 3, wherein said fail-safe means includes ..passage through said valve member and a closure member operable to open and close said passage according to circumstances, said temperature responsive means includes a movable stem, and said closure member is secured to said stem for movement therewith.
12. 12. A tempering valve according to claim 1 or 2 wherein said closure mea,ns includes a non-return valve located between the hot water inlet and said chamber and operative to inhibit DW - 13 - lte212273 or prevent water flow from said chamber to said hot wal inlet and also to prevent flow as a result of the thermosyphon effect from said hot water inlet to said cold water inlet.
13. 13. A tempering valve according to claim 12 wherein said nonreturn valve includes a valve member resiliently biased into engagement with a valve seat provided in the valve body between the hot water inlet and the chamber.
14. 14. A tempering valve according to claim 12 or 13 wherein said temperature responsive means includes a thermostat body which is mounted within said valve body for relative movement in the axial direction of said orifice, said valve member being 10 secured to said thermostat body against relative movement, spring means which acts between the two said bodies so as to urge said valve member to move in said opposite direction, and a stem which projects beyond one end of said thermostat body and is movable axially relative to that body, said valve further including a selectively adjustable stop member to which the end of said stem remote from said thermostat body is secured, the stop member being movable relative to the valve body to enable selective adjustment of the position of the valve member relative to the orifice. 20
15. 15. A tempering valve substantially as herein particularly described with reference to any one of the embodiments shown in the accompanying drawings. N £i CAREY Af r LICAHTS 30