AU2007201101B1

AU2007201101B1 - Hot water system

Info

Publication number: AU2007201101B1
Application number: AU2007201101A
Authority: AU
Inventors: Ross Haysom; Ravindra Hiremath
Original assignee: Pump and Electrical Engineering Services Pty Ltd
Current assignee: Pump and Electrical Engineering Services Pty Ltd
Priority date: 2007-03-14
Filing date: 2007-03-14
Publication date: 2008-05-15
Anticipated expiration: 2027-03-14

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant(s): ROSS HAYSOM, RAVINDRA HIREMATH, ANN HAYSOM and NOELLA

HIREMATH

Invention Title: HOT WATER SYSTEM The following statement is a full description of this invention, including the best method for performing it known to me/us: 2 HOT WATER SYSTEM Field of the Invention This invention relates to a hot water system for supplying hot water (which term includes tempered and warm water) to a building in which relatively large numbers of hot water take-off points are required, and which may be dispersed over a considerable distance.

Background of the Invention Our Australian Patent 763394 discloses a hot water system suitable for the above-mentioned environment. The system of the above patent works very well in most applications.

The system of the previous patent uses continuous flow water heaters to heat the water. These heaters are operated upon demand when flow through the heaters is sufficient to activate the heaters. If demand is very small or flow is otherwise small, the water heaters may not be activated and therefore the water is not heated by the heaters and merely flows through the heaters as cold water. Furthermore, the system of the previous patent has some components which are relatively expensive.

The above problems may be exacerbated in some situations where the system includes infrastructure already installed in a building, such as a water supply circuit because the water supply circuit may not be properly designed or maintained, thereby making flow of water through the system more difficult.

Summary of the Invention The object of the present invention is to provide a hot water system which is less susceptible to problems concerned by low flow of water and which can be implemented using components which are relatively less expensive.

HR\Lial\Keep\peci\Pu.p Electrical Speci Hot Water System.doc 13/03/07 3 The invention may be said to reside in a hot water system for a building, comprising: water heating means for heating water; a water supply circuit for supplying water to a plurality of water outlets in the building; a pump for supplying water through the water heating means and through the circuit; a water loop circuit connected to the water supply circuit at a location on the circuit upstream of the water heating means and a location downstream of the water heating means; and a pressure regulating device in the loop circuit for opening the loop circuit, when a predetermined pressure differential exists between the downstream location and the upstream location, for allowing water to flow from the downstream location to the upstream location so water is supplied back to the upstream location to increase the pressure at the upstream location to thereby increase the flow of water through the heating means.

Therefore, if the pressure at the upstream location is low and that at the downstream location is high, water is able to be diverted back from the downstream location to the upstream location to ensure sufficient flow to activate the heating means if the heating means is in the form of a continuous flow water heater. Furthermore, the pump is not required to be a variable type pump which is activated dependent on water pressure and therefore a less expensive pump can be used in the system than in that of the aforesaid patent.

Preferably a water temperature sensor is provided for monitoring the temperature of water upstream of the water heating means so that if the temperature of the water upstream of the heating means rises above a predetermined temperature, a signal is provided to a controller for H.\Luisal\Keep\Speci\Pump 6 Electrical Speci Hot Water System.doc 13/03/07 4 switching off the pump.

Preferably the water supply circuit is a return loop circuit for returning water from the circuit to an upstream location with respect to the water heating means.

However, in other embodiments the circuit may be a deadend circuit which does not return water to the upstream location with respect to the water heating means.

Preferably a water flow compensating circuit is provided for supplying water from a cold water inlet to the circuit downstream of the water heating means when water flow requirements through the circuit exceed capability of supply through the water heating means.

The cold water inlet preferably comprises part of the water supply circuit upstream of the heating means.

In one embodiment of the invention the pump is located in the water supply circuit upstream of the water heating means and pumps water through the water heating means.

In another embodiment the pump is located in the water supply circuit downstream of the water heating means and draws water through the heating means.

Brief Description of the Drawings Preferred embodiments of the invention will be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic block diagram of a first embodiment of the invention; Figure 2 is a schematic block diagram of a second embodiment of the invention; and Figure 3 is a more complete circuit diagram of the first embodiment of the invention shown in Figure i.

H,\Luisal\Keep\Speci\Pump Electrical Speci Hot Water System.doc 13/03/07 5 Detailed Description of the Preferred Embodiments With reference to Figure 1, a water supply system 10 is shown which comprises a hot water circuit 12 which has an inlet branch 12a from a cold water supply 13, an outlet branch 12b for supplying hot water to a plurality of water outlets in a building (all of which are schematically represented by block 36 in Figure The outlet part 12b of the circuit 12 returns to the cold water inlet branch 12a via branch 12c.

At least one continuous flow hot water heater 16 is provided in the circuit 12 for heating water when water flows through the heaters 16. In the embodiment shown, three heaters 16a to 16c are provided. The circuit 12 has inlet and outlet branches 18 for supplying water to and from the various heaters 16a to 16c.

Thus, when water flows through the heaters 16a to 16c, the heaters are activated to heat the water and to supply the water to the outlet branch 12b and then to the outlets 36.

In the embodiment of Figure i, the circuit 12 is a return circuit for returning water back to the cold water inlet branch 12a and a pump 22 usually continually operates to circulate water through the heaters 16a to 16c so that hot water is continuously circulated ready to be drawn off from the outlets 36 upon demand.

A water flow compensating circuit 40 is provided between an upstream side of the heaters 16a to 16c and a downstream side of the heaters 16a to 16c so that in the event that demand for water is greater than that which can be supplied through the heaters 16a to 16c, additional water can be supplied through the circuit 40 to meet the required demand.

H,\Luisal\Keep\Speci\Pump Electrical Speci Hot Water Syetem.doc 13/03/07 00 6 0 O The circuit 40 has a non-return valve 42 which allows Swater to flow from the branch 12a to the outlet branch 12b when the pressure in the branch 12b drops to a predetermined value indicative of a requirement for more flow than can be supplied through the heaters 16a to 16c.

When the pressure differential reaches that value, the non-return valve 42 is opened to allow water to flow from the branch 12a to the branch 12b to compensate for the

C

required water flow.

SThe pump 22 is provided in the circuit 12 for pumping water through the heaters 12a and 12c. The pump 22 is controlled by a controller 50 to operate the pump 22 to circulate water through the heaters 16a to 16c and through the circuit 12 so that hot water is always available on demand.

A temperature sensor 150 is provided for monitoring the temperature at a location upstream of the heaters 16a to 16c and for providing an output of the monitored temperature to the controller A second water temperature sensor 151 is provided downstream of the heaters 16a to 16c for monitoring the temperature of the water downstream of the heaters 16a to 16c. The temperature sensor 151 is also connected to the controller 50. The purposes of the temperature sensor 151 is merely to provide a measure of the temperature of the hot water supplied by the system so that that temperature can be displayed on a display at the controller 50 or elsewhere as may be required.

The system 10 has a pressure regulating loop 70 which extends between an upstream location U of the heaters 16a to 16c and a downstream location D with respect to the heaters 16a to 16c. In the embodiment shown the loop uses part of the branch 12c. However, if desired, the N:\Melbourne\Caseo\Patent\71000-71999\P71694.AU\Specis\Hot Water System Amended pages.doc 14/04/08 00 7 Sloop 70 could be completely separate to the branch 12c.

SThe loop 70 includes a pressure regulating device 180 which is set to open when a predetermined pressure differential exists between the downstream location D with respect to the heaters 16a to 16c and the upstream location U with respect to the heaters 16a to 16c.

If the pressure at the location D exceeds the pressure at the location U by a predetermined amount which is set by the device 180, the device 180 is opened to allow water to flow through the branch 70 from the location D to the location U to increase the pressure of the water at the upstream side of the water heaters 16a to 16c, thereby enabling additional flow of water to be supplied through the heaters 16a to 16c to ensure that the water heaters are activated by the required flow to heat water as the water flows through the heaters 16a to 16c. In one embodiment of the invention the pressure differential may be in the order of 50Kpa. However, the pressure differential between the locations D and U will depend on the environment in which the water heating system is installed and the operating conditions required of the system. Typically, if the circuit 12 is a return circuit as shown in Figure 12, the required pressure differential is relatively high. If the circuit 12 is not a return circuit but rather is merely a dead-end circuit, the pressure differential between the locations D and U can be somewhat smaller, thereby enabling some return of water for continuous flow through the heaters 16a to 16c to maintain the required high temperature of the water in the circuit 12.

If the temperature sensed by the temperature sensor 150 is above a predetermined value, indicative of the fact that a reasonably large amount of hot water is being returned through the loop 70, the controller 50 can switch the pump 22 off so that water is not pumped through the heaters 16a N:\Melbourne\Caoes\Patent\71000-7199\P716 9 4 .AU\Specis\Hot Water System Amended pages.doc 14/04/08 8 to 16c. Generally, a relatively high temperature sensed by the temperature sensor 150 will be indicative of the fact that water is not being drawn off from the outlets 36 and the pressure at the location D has risen sufficiently high to cause flow back through the loop 70 to the location U, thereby elevating the temperature of the water in the cold water inlet 12a. In this circumstance, more flow through the heaters 16a to 16c is not required and therefore the pump 22 can be disabled.

When there is a demand for water from the outlets 36, the pressure at the location D will drop, thereby causing the regulating device 180 to close and the temperature at the location U will drop because cold water will be supplied into the branch 12a. This in turn will cause the pump 22 to be switched on by the controller 50 to supply water through the heaters 16a to 16c to meet the demand required by the opening of the outlets 36.

Figure 2 shows a second embodiment of the invention in which like reference numerals indicate like parts to those previously described. The only difference between the embodiments of Figures 1 and 2, is that in Figure 2 the pump 22 is downstream of the heaters 16a to 16c so that the pump 22 draws water through the heaters 16a to 16c rather than pushes water through the heaters 16a to 16c.

Otherwise, the operation of the embodiment of Figure 2 is identical to that of Figure 1.

Figure 3 shows a more complete circuit diagram relating to the embodiment of Figure 1. In Figure 3, cold water is supplied from cold water inlet 13 through valve 100 to circuit branch 12a. The branch 12a may have a plug and gauge cock 101. An isolation valve 102 is provided in the branch 12a upstream of the differential bypass device 180.

The non-return valve 80 is provided in parallel with the pressure compensating device 180. Thus, in the embodiment H\Luisal\Keep\Speci\Pump Electrical Speci Hot Water System.doc 13/03/07 9 of Figure 3 the circuit 40 and the loop 70 share a common conduit which separate between isolation valves 102 and 105 so that water can pass from the location U to the location D through the common conduit, then through the conduit marked 40 and device 80 if compensation flow is required, or pass from location D to location U through the common conduit, then the conduit labelled 70 and the pressure differential device 180 to location U if pressure flow back from the location D to the location U is required.

Water is supplied through the inlet branch 12a to the pump 22 for pumping through branches 18 to the water heaters 16a, 16b and 16c. Water is then supplied from the heaters 16a to 16c to the branch 12b for flow to the outlets 36.

Similarly, the branch 12c may also have isolation valves 113 and 115 as well as a one way valve 117. The valves 102, 105, 113 and 115 are provided as isolation valves to provide for maintenance.

Gas is supplied to the heaters 16a to 16c to fuel the heaters via gas inlet 150 which connects to the heater via branches 151. Hot water is supplied from the heaters to the branch 12b via branches 153.

The control of the pump 22 by the temperature sensor 150 overcomes friction losses inherent in the heaters 16a to 16c so it is the preferred flow path and may also provide an adjustable flow rate for the circulation of water through the circuit 12 via the setting of the differential bypass device 180, thus maintaining a constancy of temperature in the circuit branch 12b.

The system of the preferred embodiment therefore has the advantage that hot water can be supplied at a set temperature in relation to a specified flow rate, supply water pressure can be maintained over the specific flow H.\Luioa1\Keep\Speci\Pump Electrical Speci Hot Water System.doc 13/03/07 10 rates required and circulation of water through the circuit 12 and back to the heaters 16a to 16c ensures consistency of temperature throughout the circuit 12.

In some embodiments of the invention the pump 22 can be operated to reduce the flow of water through the heaters 16a to 16c to a flow rate above that required to activate the heaters, but of sufficiently low volume so that the water is heated in the heaters to a relatively high temperature, for example 70 0 C. Additional water can then be supplied through the branch 40 to compensate for the relatively low flow and mixed with the high temperature water to decrease the temperature of the water to that which is actually required, for example, 60*C. As the flow rate through the water heater(s) is less, the friction loss through the water heater(s) is less. This therefore enables the pump 22 to be a pump of less capacity than may otherwise be required, thereby also further reducing costs.

The controller 50 may be a conventional controller and is connected by wires 120 to the heaters 16a to 16c to operate the heaters, and to the temperature sensor 150 and pump 22 via wire 131 and 132, and also to the temperature sensor 151 via line 133 so that the required signals are supplied to and from the controller 50 to operate the system.

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 H.\Luisal\Keep\Speci\Pump Electrical Speci Hot Water Syste.doc 13/03/07 11 Simplication, the word "comprise", or variations such as "comprises" or "comprising", is used in an inclusive Ssense, i.e. 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.

HI\Luial\Keep\Speci\Pump Electrical Speci Hot Water System.doc 13/03/07

Claims

1. A hot water system for a building, comprising: water heating means for heating water; a water supply circuit for supplying water to a plurality of water outlets in the building; a pump for supplying water through the water heating means and through the circuit; a water loop circuit connected to the water supply circuit at a location on the circuit upstream of the water heating means and a location downstream of the water heating means; and a pressure regulating device in the loop circuit for opening the loop circuit, when a predetermined pressure differential exists between the downstream location and the upstream location, for allowing water to flow from the downstream location to the upstream location so water is supplied back to the upstream location to increase the pressure at the upstream location to thereby increase the flow of water through the heating means.

2. The system of claim 1 wherein a water temperature sensor is provided for monitoring the temperature of water upstream of the water heating means so that if the temperature of the water upstream of the heating means rises above a predetermined temperature, a signal is provided to a controller for switching off the pump.

3. The system of claim 1 wherein the water supply circuit is a return loop circuit for returning water from the circuit to an upstream location with respect to the water heating means.

4. The system of any one of claims 1 to 3 wherein a water flow compensating circuit is provided for supplying water from a cold water inlet to the circuit downstream of the water heating means when water flow requirements H.\Luisal\Keep\Speci\Pump Electrical Speci Hot Water Syatem.doc 13/03/07 13 through the circuit exceed capability of supply through the water heating means. The system of any one of claims 1 to 4 wherein the cold water inlet comprises part of the water supply circuit upstream of the heating means. S6. The system of any one of claims 1 to 5 wherein Sthe pump is located in the water supply circuit upstream of the water heating means and pumps water through the Swater heating means.

7. The system of any one of claims 1 to 5 wherein the pump is located in the water supply circuit downstream of the water heating means and draws water through the heating means. H,\Luisal\Keep\Speci\Pump Electrical Speci Hot Water System.doc 13/03/07