AU2004100696A4 - Thermal isolating device and water heater including such a device - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT Applicant(s): Donald McPherson Invention Title: THERMAL ISOLATING DEVICE AND WATER HEATER INCLUDING SUCH A DEVICE The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 THERMAL ISOLATING DEVICE AND WATER HEATER INCLUDING SUCH A

DEVICE

Field of the Invention The present invention relates to a thermal isolating device and to a water heater including such a device.

Background of the Invention Hot water systems which include a storage compartment in which a volume of heated water is maintained suffer from the problem of escape of heat, thereby requiring additional energy in order to maintain the water in the compartment hot or to reheat water in the compartment.

Many attempts have been proposed for insulating hot water compartments to reduce loss of heat, and therefore waste of energy to reheat water to maintain the supply of hot water within the compartment.

Summary of the Invention The object of the present invention is to provide a device to further reduce the loss of heat from a hot water storage compartment, and thereby reduce the energy required to maintain a volume of hot water within the compartment.

A first aspect of the invention provides a thermal isolating device for a water heater having a hot water storage compartment and a water outlet, comprising: a body having a fluid flow passage; a first connector on the body for coupling the body to the hot water storage compartment; a second connector on the body for coupling the body to the water outlet, so that the thermal isolating device is locatable between the storage compartment and the water outlet; H \Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04 3 the body being formed from or having a heat insulating material to prevent conduction of heat from the storage compartment to the water outlet; a valve element in the body; a valve seat in the body for receiving the valve element; a biasing element for biasing the valve element against the seat so that the valve element prevents flow of hot water through the flow passage.

Thus, the device can be used in a water heater to prevent the flow of hot water into the water outlet, such as a pressure relief valve, under normal pressure conditions and heat isolates the valve from the hot water compartment so that heat is not conducted by the hot water passed the device to the water outlet and any conduit which leads from the water outlet. Because such water outlets and conduits are usually formed from metal material, they form a good heat conducting path which results in heat dissipating out of the hot water storage compartment. The device of the invention prevents the heat conduction to the water outlet when installed and therefore reduces the amount of energy needed to maintain the temperature of the hot water within the storage compartment ready for use by a user.

In one embodiment, the water outlet is a pressure relief valve and the device is locatable between the pressure relief valve and the storage compartment so that under normal pressure conditions, heat conduction to the relief valve is prevented and water is shut off from entering the relief valve and if there is an over-pressure condition within the water storage compartment, movement of the valve element against the bias of the biasing element allows escape of the over-pressure through the device and the pressure relief valve when the device is installed in the water heater.

H.\Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04 4 In another embodiment, the water outlet comprises a hot water delivery pipe for delivering hot water to a premises, and when all taps for supplying hot water from the pipe are closed, the device prevents heat conduction to the pipe and also shuts off flow of water to the pipe, and when a tap is opened, the reduction in pressure downstream of the device allows the valve element to move away from the seat against the bias of the biasing element so water can be delivered through the device and the pipe to the tap.

Preferably the body is completely formed from a plastic heat insulating material.

However, in other embodiments, the body could be formed from a heat conducting material but include an insulating section to prevent heat conduction along the entire length of the body.

Preferably the valve element is also formed from a plastic heat insulating material.

Preferably the valve element is a ball and the valve seat is an annular valve seat formed on a reduced diameter portion of the flow passage.

Preferably the biasing means comprises a spring for biasing the ball against the valve seat.

Preferably the spring is located between the ball and a retainer within the body.

Preferably the retainer comprises a shoulder formed on a second reduced diameter portion of the flow passage.

H:\Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04 5 Preferably the first connector comprises an external screw thread on the valve body.

Preferably the second connector comprises an internal screw thread tapped into a peripheral wall of the flow passage within the body.

The invention also provides a water heater comprising: a hot water storage compartment; a water outlet from the hot water storage compartment; a thermal isolating device located between the storage compartment and the water outlet for thermally isolating the water outlet from the hot water storage compartment to prevent heat conduction from the storage compartment to the water outlet during normal operating pressure within the water storage compartment.

In one embodiment the water outlet comprises a pressure relief valve and the thermal isolating device is located between the pressure relief valve and the water outlet.

In another embodiment, the water outlet is a water delivery pipe for delivering hot water to a premises and the thermal isolating device is located between the storage compartment and the water delivery pipe.

In still further embodiments, the water heater includes a first water outlet provided by a pressure relief valve and a second water outlet provided by hot water delivery pipe and respective thermal isolating devices are located between the pressure relief valve and the storage compartment and the hot water delivery pipe and the storage compartment.

Preferably the thermal isolating device comprises: a body having a fluid flow passage; H;\Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04 6 a first connector on the body coupling the body to the hot water storage compartment; a second connector on the body coupling the body to the water outlet; the body being formed from or having a heat insulating material to prevent conduction of heat from the storage compartment to the water outlet; a valve element in the body; a valve seat in the body for receiving the valve element; a biasing element for biasing the valve element against the seat so that the valve element prevents flow of hot water through the flow passage.

Preferably the body is completely formed from a plastic heat insulating material.

However, in other embodiments, the body could be formed from a heat conducting material but include an insulating section to prevent head conduction along the entire length of the body.

Preferably the valve element is also formed from a plastic heat insulating material.

Preferably the valve element is a ball and the valve seat is an annular valve seat formed on a reduced diameter portion of the flow passage.

Preferably the biasing means comprises a spring for biasing the ball against the valve seat.

Preferably the spring is located between the ball and a retainer within the body.

Preferably the retainer comprises a shoulder formed on a second reduced diameter portion of the flow passage.

H,\Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04 7 Preferably the first connector comprises an external screw thread on the valve body.

Preferably the second connector comprises an internal screw thread tapped into a peripheral wall of the flow passage within the body.

Brief Description of the Drawings A preferred embodiment of the invention will be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a view of a hot water system according to one embodiment of the invention; and Figure 2 is a cross-sectional view of a thermal isolating device used in the embodiment of Figure 1.

Detailed Description of the Preferred Embodiment With reference to Figure i, a water heater 10 is shown which has a hot water storage compartment 12, a pressure relief valve 14 and an overflow conduit 16 extending from the pressure relief valve 14. A water delivery pipe 18 is also provided for supplying hot water to a home or building (not shown). The pressure relief valve 14 and delivery pipe 18 form water outlets from the storage compartment 12.

The hot water storage compartment 12 may be heated by electric heating or gas fired heating or any other suitable form of heating.

The above water heater 10 conventional in design and well known, and colloquially referred to as a hot water service.

The storage compartment 12 maintains a volume of hot water ready for supply to a house or building through the pipe H.\Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04 8 18. If an over-pressure situation occurs, escape of pressure is allowed through the pressure relief valve 14 and the conduit 16.

Usually the valve 14 and conduit 16 are formed from metal and are in heat conducting contact with the storage compartment 12 and the water within the storage compartment 12, so heat can be conducted through the valve 14 and the conduit 16 and is therefore lost to atmosphere.

This therefore necessitates additional energy input to maintain the temperature of the water in the storage compartment 12. Furthermore, normally water in the storage compartment 12 can flow into the valve 14 and conduit 16, thereby creating a thermo-cycle in which hot water can heat up the metal valve 14 and conduit 16, then cool slightly, and be siphoned back into the tank 12 which causes even further heat losses from the hot water stored in the compartment 12.

In accordance with the preferred embodiment of the invention, a thermal isolating device 20 is located between the valve 14 and the storage compartment 12 for thermally isolating the compartment 12 from the valve 14 and the conduit 16. Thus, heat is not able to be conducted through to the outlet formed by the valve 14 and 16, thereby reducing heat loss from the water in the compartment 12, and thereby reducing the amount of energy which is needed to maintain the temperature of the water within the compartment 12.

In one embodiment of the invention, the water pipe 18 may also be separated from the compartment 12 by a device which is the same as the device 20, so that when water is not being drawn off through the pipe 18, the pipe 18 is thermally isolated to further reduce heat losses from the hot water within the storage compartment 12.

Hs\Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04 9 The use of the device 20' in the pipe 18 is not as critical as the device 20 between the pressure relief valve 14 and the storage compartment 12 because normally the pipe 18 is insulated, and therefore heat losses are considerably lower than heat losses associated with the valve 14 and conduit 16.

Figure 2 shows the device 20 (and also 20') in detail.

With reference to Figure 2, the device 20 comprises a housing 21 which is formed from plastic material or any other thermally insulating material to prevent heat conduction from an inlet end 22 to an outlet end 29 of the body 21. The body 21 has a fluid flow passage 23 extending between the inlet end 22 and the outlet end 29.

The inlet end 22 has an external screw thread 26 for connecting the device 20 to the storage compartment 12 by way of a mating screw thread on a stem 25 (see Figure 1) of the compartment 12, and an internal screw thread 24 tapped into internal wall 27 of the passage 23 for screwing onto a mating screw thread of the valve 14.

Thus, by simply removing the pressure relief valve 14 off the stem 25, an internal screw thread in the stem 25 is exposed and an external screw thread on the valve 14 is exposed. Thus, the device can be located in place, as shown in Figure i, between the compartment 12 and the pressure relief valve 14 by screwing the screw thread 26 into the screw thread in the stem 25 and screwing the screw thread on the pressure relief valve 14 into the screw thread 24.

The flow passage 23 has a first reduced diameter portion which has an annular valve seat 31. A second reduced diameter portion 33 is provided with a shoulder 34 which receives one end of a coil spring 36. The other end of the coil spring 36 engages a ball valve 38 and forces the ball valve 38 into a closed position on the seat 31.

Hi\Luisa\Keep\Speci\McPherson Thermal Isolating Devicedoc 23/08/04 10 Preferably the ball valve 38 is also formed from heat insulating plastic material, such as nylon or the like.

The spring 36 may be formed from stainless steel.

When the device 20 is installed in the system 10 as shown in Figure i, and normal operating pressures exist within the compartment 12, the ball 38 is seated against the seat 31, thereby preventing flow of water through the device to the valve 14 and conduit 16. The device 20 also thermally isolates the compartment 12 from the valve 14 and the conduit 16. Thus, because the water is not able to pass through the device in normal operating conditions, the valve 14 and conduit 16 are not heated, and therefore heat escaped from those components does not take place.

Furthermore, because those components are not heated, they are maintained cool and therefore can be easily handled when it is necessary to repair or change the valve 14.

If an over-pressure situation occurs within the compartment 12, the over-pressure pushes the ball valve 38 against the bias of the spring 36 so the ball valve 38 moves away from the seat 31 to allow escape of fluid through the passage 23 and then to the valve 14 and through the valve 14 and conduit 16 to prevent a dangerous over-pressure condition occurring within the compartment 12.

When the device 20 is installed in place, the end 22 of the device in the vicinity of the screw thread 26 will warm up because it is in communication with the compartment 12. However, the heat is not conducted because of the insulating qualities of the material from which the body 20 is formed, and also because the insulating ball valve 38 prevents the water from entering further into the body 20. However, in other embodiments, the body 20 could be formed in two halves and divided by an insulating plate schematically shown at 75 in Figure 2 Hi\Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04 11 to prevent heat conduction from the end 22 through to the end 29. The two halves on either side of the plate 25 can be secured together by any appropriate means such as bolts (not shown). Thus, the body apart from the plate 75 could be formed from a heat conducting material. Whilst such an arrangement is possible and will improve heat loss, the heat loss would probably be more than the preferred form of the embodiment in which the entire body 21 is formed from insulating material because the end 22 of the body will be able to significantly warm up, which would create some heat loss.

If the device 20 is not installed in the system, and the system shown in Figure 1 is conventional, the heat created by the hot water in the compartment 12 is conducted from the compartment 12 through the metal outlet 25 to the ball valve 14 and conduit 16 which effectively form a heat sink for dissipation of the heat to atmosphere. Thus, additional energy is needed to maintain the temperature of the water within the compartment 12 at the required temperature for delivery through the outlet 18. This in turn results in a waste of energy in overcoming the losses caused by the heat dissipation from the valve 14 and conduit 16. Furthermore, hot water in normal operating conditions can enter the valve 14 and conduit 16 and form a thermo-cycle. This generally circulates hot water into the valve 14 and conduit 16 and draws cooler water back into the tank which further exacerbates the heat loss from the water in the compartment 12 through the valve 14 and conduit 16.

By providing the isolating device 20, the device effectively shuts off heat conduction to the valve 14 and 16 by way of direct conduction through the metal components, or by way of hot water entering the outlet and flow into the valve 14. Thus, heat losses are significantly reduced.

H.\Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04 12 Tests have shown that the amount of energy which is saved by inclusion of the device 20 in a hot water system for heating domestic hot water is in the order of about 20 to 50 watts continuously depending on the size of the water outlet and the temperature of the water. The loss reduces as the water temperature drops.

If the device 20' is used in the outlet 18, when a hot water tap is turned on, the flow of water through the outlet 18 downstream of the device 20' is sufficient to create a low pressure environment which will draw the valve 38 away from the seat 31, thereby allowing water to flow through the passage 23 and the outlet 18 to the open hot water tap to supply hot water. When the tap is closed, the spring 36 is able to bias the valve 38 back into engagement with the seat 31 so that the device again forms the heat stop for preventing heat conduction and water flow into the conduit 18, thereby further reducing heat losses from the hot water stored within the compartment 12.

Since modifications within the spirit and scope of the invention may readily be effected by persons skilled within the art, it is to be understood that this invention is not limited to the particular embodiment described by way of example hereinabove.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise", or variations such as "comprises" or "comprising", is used in an inclusive sense, ie. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

H;\Luia\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04

Claims (28)

1. A thermal isolating device for a water heater having a hot water storage compartment and a water outlet, comprising: a body having a fluid flow passage; a first connector on the body for coupling the body to the hot water storage compartment; a second connector on the body for coupling the body to the water outlet, so that the thermal isolating device is locatable between the storage compartment and the water outlet; the body being formed from or having a heat insulating material to prevent conduction of heat from the storage compartment to the water outlet; a valve element in the body; a valve seat in the body for receiving the valve element; a biasing element for biasing the valve element against the seat so that the valve element prevents flow of hot water through the flow passage.

2. The device of claim 1 wherein the water outlet is a pressure relief valve and the device is locatable between the pressure relief valve and the storage compartment so that under normal pressure conditions, heat conduction to the relief valve is prevented and water is shut off from entering the relief valve and if there is an over-pressure condition within the water storage compartment, movement of the valve element against the bias of the biasing element allows escape of the over-pressure through the device and the pressure relief valve when the device is installed in the water heater.

3. The device of claim 1 wherein the water outlet comprises a hot water delivery pipe for delivering hot water to a premises, and when all taps for supplying hot Ht\Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04 14 water from the pipe are closed, the device prevents heat conduction to the pipe and also shuts off flow of water to the pipe, and when a tap is opened, the reduction in pressure downstream of the device allows the valve element to move away from the seat against the bias of the biasing element so water can be delivered through the device and the pipe to the tap.

4. The device of claim i, 2 or 3 wherein the body is completely formed from a plastic heat insulating material.

The device of any one of claims 1 to 4 wherein the body is formed from a heat conducting material but include an insulating section to prevent heat conduction along the entire length of the body.

6. The device of any one of claims 1 to 5 wherein the valve element is also formed from a plastic heat insulating material.

7. The device of any one of claims 1 to 6 wherein the valve element is a ball and the valve seat is an annular valve seat formed on a reduced diameter portion of the flow passage.

8. The device of any one of claims 1 to 7 wherein the biasing means comprises a spring for biasing the ball against the valve seat.

9. The device of any one of claims 1 to 8 wherein the spring is located between the ball and a retainer within the body. The device of any one of claims 1 to 9 wherein the retainer comprises a shoulder formed on a second reduced diameter portion of the flow passage.

H'\Luisa\Keep\Speci\McPheron Thermal Isolating Device.doc 23/08/04 15

11. The device of any one of claims 1 to 10 wherein the first connector comprises an external screw thread on the valve body.

12. The device of any one of claims 1 to 11 wherein the second connector comprises an internal screw thread tapped into a peripheral wall of the flow passage within the body.

13. A water heater comprising: a hot water storage compartment; a water outlet from the hot water storage compartment; a thermal isolating device located between the storage compartment and the water outlet for thermally isolating the water outlet from the hot water storage compartment to prevent heat conduction from the storage compartment to the water outlet during normal operating pressure within the water storage compartment.

14. The heater of claim 13 wherein the water outlet comprises a pressure relief valve and the thermal isolating device is located between the pressure relief valve and the water outlet.

The heater of claim 13 wherein the water outlet is a water delivery pipe for delivering hot water to a premises and the thermal isolating device is located between the storage compartment and the water delivery pipe.

16. The heater of claim 13 wherein the water heater includes a first water outlet provided by a pressure relief valve and a second water outlet provided by hot water delivery pipe and respective thermal isolating devices are located between the pressure relief valve and the storage compartment and the hot water delivery pipe and the storage compartment. H:\Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04 16

17. The heater of any one of claims 13 to 16 wherein the thermal isolating device comprises: a body having a fluid flow passage; a first connector on the body coupling the body to the hot water storage compartment; a second connector on the body coupling the body to the water outlet; the body being formed from or having a heat insulating material to prevent conduction of heat from the storage compartment to the water outlet; a valve element in the body; a valve seat in the body for receiving the valve element; a biasing element for biasing the valve element against the seat so that the valve element prevents flow of hot water through the flow passage.

18. The heater of claim 17 wherein the body is completely formed from a plastic heat insulating material.

19. The heater of claim 17 wherein the body is formed from a heat conducting material but includes an insulating section to prevent head conduction along the entire length of the body.

The heater of any one of claims 17 to 19 wherein the valve element is also formed from a plastic heat insulating material.

21. The heater of any one of claims 17 to 20 wherein the valve element is a ball and the valve seat is an annular valve seat formed on a reduced diameter portion of the flow passage. HS\Luia\Keep\Speci\McPheron Thermal Isolating Device.doc 23/08/04 17

22. The heater of any one of claims 17 to 21 wherein the biasing means comprises a spring for biasing the ball against the valve seat.

23. The heater of any one of claims 17 to 22 wherein the spring is located between the ball and a retainer within the body.

24. The heater of claim 23 wherein the retainer comprises a shoulder formed on a second reduced diameter portion of the flow passage.

The heater of any one of claims 17 to 24 wherein the first connector comprises an external screw thread on the valve body.

26. The heater of any one of claims 17 to 25 wherein the second connector comprises an internal screw thread tapped into a peripheral wall of the flow passage within the body.

27. A thermal isolating device substantially as hereinbefore described with reference to the accompanying drawings.

28. A water heater substantially as hereinbefore described with reference to the accompanying drawings. H!\Luisa\Keep\Speci\McPherson Thermal Isolating Device.doc 23/08/04