AU2021204162A1

AU2021204162A1 - Hot water system

Info

Publication number: AU2021204162A1
Application number: AU2021204162A
Authority: AU
Inventors: Ravindra Hiremath; Shalitha Lokuliyana
Original assignee: Pump and Electrical Engineering Services Pty Ltd
Current assignee: Pump and Electrical Engineering Services Pty Ltd
Priority date: 2021-06-21
Filing date: 2021-06-21
Publication date: 2023-01-19

Abstract

A water heating system for a building, comprising: a plurality of continuous flow electric water heaters; 5 a water supply circuit for supplying water from the heaters to a plurality of water outlets in the building, the water supply circuit including an upstream portion in which cold water from a cold water supply is received and a downstream portion which is downstream from the heaters; a pump for supplying water through the water heaters and through the circuit; a .0 bidirectional bypass circuit connected to the water supply circuit at a location on the circuit upstream of the water heaters and a location downstream of the water heaters; and a first one way flow/pressure regulating device in the bypass circuit, being configured to allow flow from the cold water inlet to the downstream location and to open only once a predetermined pressure differential has been exceeded so as to create resistance within .5 the bypass circuit to encourage flow through the heaters before flowing through the bypass circuit when water flow requirements through the supply circuit exceed capability of supply through the water heaters, a second one way flow/pressure regulating device in the loop circuit for opening the loop circuit when a predetermined pressure differential exists between the downstream location .0 and the upstream location, for allowing water to flow between the downstream location and the upstream location for supplying a sufficient amount of water to ignite the water heaters. P10051.AU.1 Specification -I Dec 2020

Description

Water heating system

Field of the invention This invention relates to a water heating system for a building. For example, the present invention relates to heating potable water and 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.

.0 Background The present applicant's Australian Patent nos. 763394 and 2007201101 disclose a hot water system suitable for the above-mentioned environment. The system of the above patents work very well in most applications. .5 The system of the previous patents 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 .0 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.

Australian Patent no. 2007201101 addresses these problems by providing a water loop circuit between locations upstream and downstream of the heaters for allowing water to flow from the downstream location to the upstream location when a predetermined pressure differential exists for supplying a sufficient amount of water to ignite the water heaters.

Related Australian patent application no. 2016225782 envisages the use of continuous flow gas water heaters for systems of the present type. As solar electricity

P10051.AU.1 Specification -I Dec 2020 generation and storage becomes more commonly available and used for energy requirements, it is desirable that water heaters of systems of the present type be operable on other forms of energy.

Summary According to one aspect of the present invention there is provided a water heating system for a building, comprising: a plurality of continuous flow electric water heaters; .0 a water supply circuit for supplying water from the heaters to a plurality of water outlets in the building, the water supply circuit including an upstream portion in which cold water from a cold water supply is received and a downstream portion which is downstream from the heaters; a pump for supplying water through the water heaters and through the circuit; .5 a bidirectional bypass circuit connected to the water supply circuit at a location on the circuit upstream of the water heaters and a location downstream of the water heaters; and a first one way flow/pressure regulating device in the bypass circuit, being configured to allow flow from the cold water inlet to the downstream location and to open .0 only once a predetermined pressure differential has been exceeded so as to create resistance within the bypass circuit to encourage flow through the heaters before flowing through the bypass circuit when water flow requirements through the supply circuit exceed capability of supply through the water heaters, a second one way flow/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 between the downstream location and the upstream location for supplying a sufficient amount of water to ignite the water heaters.

According to a preferred embodiment, the first and second flow/pressure regulating devices are in the form of variable resistance spring loaded one way flow/pressure compensating valves.

Preferably, the first and second flow/pressure regulating devices are oppositely orientated and mounted in parallel to permit flow in either direction within the bypass circuit.

P10051.AU.1 Specification -I Dec 2020

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 speed 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.

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

The system can further comprise a water temperature sensor provided for monitoring the temperature of water upstream of the water heating means so that if the .5 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.

The system can further comprise a water temperature sensor provided for monitoring the temperature of water upstream of the water heating means so that if the .0 temperature of the water upstream of the heating means falls below a predetermined temperature, a signal is provided to a controller for switching on the pump.

In preferred embodiments, the cold water inlet comprises part of the water supply circuit upstream of the heating means. Also, the pump is preferably located in the water supply circuit upstream of the water heating means and pumps water through the water heating means.

The water heating system can further comprise a check valve on the suction side of the pump and the pump may be positioned in the system to prevent gravitational draining of the system.

Further the systems may also include an automatic electricity supply interruption, operable for a brief period to reset and/or reboot the water heaters, each water heating means being reset and/or rebooted independently of the other water heating means and on a randomly selected and/or randomly timed basis.

P10051.AU.1 Specification -I Dec 2020

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.

Brief description of the drawings In order that the invention may be more easily understood, an embodiment will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic block diagram of a first embodiment of the invention. .0

Detailed description 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 or an upstream portion in which cold .5 water from a cold water supply 13 is received, and an outlet branch 12b or downstream portion which is downstream of the heaters for supplying hot water to a plurality of water outlets in a building (all of which are schematically represented by block 36 in Figure 1). The outlet branch 12b of the circuit 12 returns to the cold water inlet branch 12a via branch 12c.

.0 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, though it will be appreciated that embodiments having more than three heaters are possible and, in fact, commercial embodiments are likely to have as many heaters as required, with heaters being banked with as many heaters as required for large scale applications. The circuit 12 has inlet and outlet branches 18 for supplying water to and from the various heaters 16a to 16c. The heaters 16a to 16c are continuous flow electric water heaters.

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 downstream portion 12b and then to the outlets 36.

In the embodiment of Figure 1, the circuit 12 includes a return circuit 12c for returning water back to the upstream portion 12a. In some embodiments, the pump 22

P10051.AU.1 Specification -I Dec 2020 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 bi-directional bypass circuit 40 is provided between the upstream portion 12a upstream side of the heaters 16a to 16c and the downstream portion 12b downstream side of the heaters 16a to 16c for allowing water to flow between the upstream location (inlet branch 12a) and the downstream location (branch 12b) for supplying water from the cold water inlet 13 to the circuit 12 downstream of the water heaters 16a to 16c when water flow requirements through the circuit 12 exceed capability of supply through the water heaters .0 16a to 16c. 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.

Within the bypass circuit 40 are first and second flow/pressure regulating devices .5 180, 190. The first and second flow/pressure regulating devices 180, 190 are configured for one-way operation and are oppositely orientated to allow bidirectional flow in the bypass circuit 40.

The first flow/pressure regulating device 180 is configured to allow flow from the .0 upstream location 12a to the downstream location 12b and to open once a predetermined pressure level has been exceeded so as to create resistance within the bypass circuit 40 to encourage flow through the heaters 16a to 16c before flowing through the first flow/pressure regulating device 180. In this regard, the first flow/pressure regulating device 180 creates artificial friction in the bypass circuit to prevent water flowing through the first flow/pressure regulating device 180 before flowing through the heaters 16a to 16c. Advantageously, wasted energy is minimised and a smaller pump is used, thereby saving costs. In a preferred form, the flow/pressure regulating device is in the form of a variable resistance spring loaded flow/pressure compensating valve.

In use, 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, the first flow/pressure regulating device 180 opens to allow water to flow from the branch 12a to the branch 12b to compensate for the required water flow.

P10051.AU.1 Specification -I Dec 2020

The second flow/pressure regulating device 190 is in the form of a differential pressure by-pass valve in parallel with the first flow/pressure regulating device 180 to permit flow in either direction within the loop circuit 40 to allow water to be supplied back to the upstream location 12a when a predetermined pressure differential exists for supplying a sufficient amount of water to ignite the water heaters 16a to 16c. In a preferred form, the second differential pressure by-pass valve 190 is a variable resistance spring loaded differential pressure by-pass valve.

The pump 22 is provided in the circuit 12 for pumping water through the heaters 16a .0 to 16c. 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.

In some embodiments, a temperature sensor 150 is provided for monitoring the .5 temperature at a location upstream of the heaters 16a to 16c and for providing an output of the monitored temperature to the controller 50. It will be appreciated that embodiments without a temperature sensor 150 are also possible and that in such embodiments, a controller 50 will not be provided.

.0 A second water temperature sensor 151 may be 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. 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.

In the embodiment shown the loop 40 uses part of the branch 12c. However, if desired, the loop 40 could be completely separate to the branch 12c. Branch 12c also includes a check valve 30 and strainer 32.

If the pressure at the location D exceeds the pressure at the location U by a predetermined amount which is set by the second differential pressure by-pass valve 190, the valve 190 is opened to allow water to flow through the loop 40 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

P10051.AU.1 Specification -I Dec 2020 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 60KPa. 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, the set resistance for bypass valve 190 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 with set lower resistance for bypass valve 190, thereby enabling some return of water for continuous flow .0 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 required minimum temperature of hot water is being .5 returned through the loop 40, the controller 50 can switch the pump 22 off so that water is not pumped through the heaters 16a 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/or the pressure at the location D has risen sufficiently high to cause flow back through the loop 40 to the location U, thereby maintaining the required .0 temperature of the water in the circuit 12 through 36 and/or through 40. In this circumstance, 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, with required set resistance the regulating device 180 to remain closed 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.

The inlet 13 may also have an isolation valves 113 to provide for maintenance. The system 10 may also include a loss of inlet pressure switch 130 to act as a safety and prevent dry operation of the pump 22. The controller 50, where used, may be a conventional controller and is connected by wires 120 to the pump 22 to operate the pump, and to the

P10051.AU.1 Specification -I Dec 2020 temperature sensors 150 and 151 so that the required signals are supplied to and from the controller 50 to operate the system.

In the described embodiments, the pump is preferably positioned in the system to prevent gravitational draining to reduce the chances of the pump running dry and becoming damaged. Although a check valve may be provided on the pressure side of the pump, this is preferably replaced with a check valve 31 on the suction side of the pump to prevent gravitational draining, thereby trapping water within the pump to prevent damage from dry running of the pump. .0 Test gauge and plug 60 may also be provided in the hot water circuit 12.

Pressure Relief Valve 70 is provided in the hot water circuit 12 to protect the system pressure rating. .5 Individually heaters 16a to 16c will also require continuous single phase or three phase power for their normal operation, such as a 240V/lPh/5Hz or 415V/3ph/5Hz power supply.

.0 The water heating system may also include an automatic electricity supply interruption, operable for a brief period to reset and/or reboot the water heaters, the system preferably being configured so that each water heater can be reset and/or rebooted independently of the other water heaters and on a randomly selected and/or randomly timed basis.

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, 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.

P10051.AU.1 Specification -I Dec 2020

Claims

CLAIMS 1. A water heating system for a building, comprising: a plurality of continuous flow electric water heaters; a water supply circuit for supplying water from the heaters to a plurality of water outlets in the building, the water supply circuit including an upstream portion in which cold water from a cold water supply is received and a downstream portion which is downstream from the heaters; a pump for supplying water through the water heaters and through the circuit; a bidirectional bypass circuit connected to the water supply circuit at a location on .0 the circuit upstream of the water heaters and a location downstream of the water heaters; and a first one way flow/pressure regulating device in the bypass circuit, being configured to allow flow from the cold water inlet to the downstream location and to open only once a predetermined pressure differential has been exceeded so as to .5 create resistance within the bypass circuit to encourage flow through the heaters before flowing through the bypass circuit when water flow requirements through the supply circuit exceed capability of supply through the water heaters, a second one way flow/pressure regulating device in the loop circuit for opening the loop circuit when a predetermined pressure differential exists between the downstream location .0 and the upstream location, for allowing water to flow between the downstream location and the upstream location for supplying a sufficient amount of water to ignite the water heaters.
2. A water heating system as claimed in claim 1, wherein the first and second flow/pressure regulating devices are in the form of variable resistance spring loaded one way flow/pressure compensating valves.
3. A water heating system as claimed in claim 1 or claim 2, wherein the first and second flow/pressure regulating devices are oppositely orientated and mounted in parallel to permit flow in either direction within the bypass circuit.
4. The system of any preceding claim, 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

P10051.AU.1 Specification -I Dec 2020 predetermined temperature, a signal is provided to a controller for switching off the pump.
5. The system of any preceding claim, 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 falls below a predetermined temperature, a signal is provided to a controller for switching on the pump.

.0
6. The system of any one of claims 1 to 5 wherein the cold water inlet comprises part of the water supply circuit upstream of the heating means.

7. The system of any one of claims 1 to 6 wherein the pump is located in the water supply circuit upstream of the water heating means and pumps water through the .5 water heating means.

8. The system of any preceding claim, further comprising a check valve on the suction side of the pump and wherein the pump is positioned in the system to prevent gravitational draining of the system. .0

9. A water heating system according to any preceding claim, further comprising an automatic electricity supply interruption, operable for a brief period to reset and/or reboot the water heating means, each water heating means being reset and/or rebooted independently of the other water heating means and on a randomly selected and/or randomly timed basis.

10. The system of any preceding claim, wherein the water supply circuit includes a return line from the water outlets to the upstream portion of the supply circuit.

P10051.AU.1 Specification -I Dec 2020

16a 16b 16c 60 70 120 18 18 18 140 12 18 18 18 12a 120 120 1/1

151 31 22 180 150 130 40 D 1 b 13 40 U 36 190 113 12c 12c

30 32 FIGURE 1