AU2016225782B2 - Water heating system - Google Patents

Abstract

A water heating system for a building, comprising: a plurality of 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 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 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. C'J -00 Coj Coj 00 OW q0 1.0 coo ..... .... ... coV 0c coCO 0 o co,

Description

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P10051.AU Specification -filed 5 Sept 2016

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.

Background of the Invention

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

.0 most applications.

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 through the heaters as cold

.5 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.

Summary of the Invention

According to one aspect of the present invention there is provided a water heating system for a

building, comprising:

a plurality of water heaters;

P10051.AU Specification -filed 5 Sept 2016

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 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 the bypass circuit to

.0 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 bypass circuit for opening the bypass 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

.5 location for supplying a sufficient amount of water to ignite the water heaters.

According to a preferred embodiment, the first and second flow/pressure 30 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.

O 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 10 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.

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 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.

P10051.AU Specification -filed 5 Sept 2016

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 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 30 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.

.0 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.

Preferably the water supply circuit is a return loop circuit for returning water from the circuit to an

.5 upstream location with respect to the water 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.

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 or an upstream portion in which cold 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.

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

P10051.AU Specification -filed 5 Sept 2016

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 5 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 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 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 bidirectional bypass circuit 40 is provided between the upstream portion 12a upstream side of the

.0 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 16a to 16c. In the event that demand for water is

.5 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 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.

O The first flow/pressure regulating device 180 is configured to allow flow from the 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 5 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 Specification -filed 5 Sept 2016

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 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.

.0 In some embodiments, 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 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.

A second water temperature sensor 151 may be provided downstream of the heaters 16a to 16c for

.5 monitoring the temperature of the water downstream of the heaters 16a to 16c. The temperature

sensor 151is 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 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 adead- end circuit, the pressure differential between the

P10051.AU Specification -filed 5 Sept 2016

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 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 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

.0 has risen sufficiently high to cause flow back through the loop 40 to the location U, thereby

maintaining the required 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

.5 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 and gas is supplied to O the heaters 16a to 16c to fuel the heaters via gas inlet 140.

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 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 31on 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.

Test gauge and plug 60 may also be provided in the hot water circuit 12.

P10051.AU Specification -filed 5 Sept 2016

Pressure Relief Valve 70 is provided in the hot water circuit 12 to protect the system pressure rating.

Individually heaters 16a to 16c will also require continuous single phase power for their normal

operation, such as a 240V/lPh/5OHz power supply.

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

.0 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

.5 various embodiments of the invention.

Claims (10)

P10051.AU Specification -filed 5 Sept 2016 The claims defining the invention are as follows:

1. A water heating system for a building, comprising:

a plurality of 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 the circuit upstream of the water heaters and a location downstream of the water heaters; and

.0 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 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 .5 second one way flow/pressure regulating device in the bypass circuit for opening the bypass 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.

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 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.

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.

P10051.AU Specification -filed 5 Sept 2016

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 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.

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.

.0

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.