WO2018225077A1

WO2018225077A1 - Electrically and gas-operated water heater

Info

Publication number: WO2018225077A1
Application number: PCT/IL2018/050634
Authority: WO
Inventors: Omer Eshed
Original assignee: Omer Eshed
Priority date: 2017-06-08
Filing date: 2018-06-10
Publication date: 2018-12-13

Abstract

A water heating unit, a water heating and storage system, and a method of heating water, in which the heating unit includes an electric heating element and a gas heating unit including a combustion chamber and gas burner within the combustion chamber mounted on a flange configured to be sealingly attached over an opening in a wall of an insulated water tank. A heat exchanger adapted to be located in the tank is in communication with the combustion chamber and an exhaust outlet is provided at a downstream end of the heat exchanger. A thermostat located in the water tank provides a temperature indication to a controller which operates the electric heating element and/or the gas burner. The electric heating element and the combustion chamber are configured to be at least partially disposed inside the tank when the flange is attached to the tank.

Description

Title: ELECTRICALLY AND GAS-OPERATED WATER HEATER

FIELD OF THE INVENTION

The present invention, in some embodiments thereof, relates to hot water heaters, and more particularly, but not exclusively, to water heating and storage systems that include both electric and gas-fired heating elements situated on a mounting structure which, in turn, is configured to be sealably attached to an opening in the wall of the water heater tank, and i s easily removable and replaceable when necessary.

RELATED APPLICATION

The present application is related to and claims priority to U. S. Provisional Application 62/516,693 filed 8 June 2017, the entire contents of which are incorporated herein by reference as if fully set forth. BACKGROUND OF THE INVENTION

Conventionally, the most common types of domestic hot water heaters are in the form of insulated tanks having electrically powered heating elements. A notable disadvantage of such arrangements is the inherently limited lifetime of electric heating elements. The elements must therefore be replaced at least once, and often, more than once, over the 10-20 year lifespan of a typical water tank.

Also, while electricity is generally the most available energy source, in areas where gas is readily available, it is often less costly than electricity. This can be an important consideration as water heating often represents about 15 percent of domestic electricity use in developed countries. Thus, systems which employ gas, mainly natural gas provided through urban gas mains, or less often, propane, LPG, or the like from refiilable tanks, as the energy source are advantageous when this option is available.

As the initial cost of solar-power systems has decreased, solar-powered water heaters have started to gain market share, especially in regions having generally sunny climates. In fact, in some countries such as Israel, the majority of water heaters are powered by solar energy.

Solar water heating systems are typically equipped with conventional electric heating elements as a backup energy source which can be used to heat the water on cloudy days or to speed up the heating of the water when necessary. Again, however, if gas is readily available, it can be an alternative as the energy source for backup in solar systems.

To permit the needed frequent maintenance of electric water heating elements, solar water heater tanks are sometimes equipped with a flange on which the heating element an often a thermostat are mounted. The flange is configured to cover a bottom opening in the tank with water-tight seals for heating element and for the flange itself.

Since solar water heaters having either gas or electric backup heating elements might be desired in a particular market, it would be desirable, e.g., in terms of inventory management, manufacturing convenience, etc. to readily and easily provide conventional water heating systems with both electric and gas heating elements. However, such systems are not commercially available, so far as applicant is aware. The present invention is intended to satisfy this need.

BRIEF DESCRIPTION OF THE INVENTION

According to an aspect of some embodiments of the invention, there is provided a water heating and storage system having an insulated hot water holding tank, a mounting flange configured to be sealingly attached over an opening in a wall of the tank, an electric heating element mounted on the flange, a gas heating unit including a combustion chamber and gas burner within the combustion chamber also mounted on the flange, with the burner being adapted for connection to a source of combustion gas, a heat exchanger in communication with the combustion chamber, an exhaust outlet at downstream end of the heat exchanger, a thermostat located in the water tank and typically mounted on the flange for controlling the heating element; and a control unit to operate the electric heating element and/or the gas burner, at the user desire. Alternatively, the control unit can be arranged to be responsive to a temperature indication from the thermostat and operate the electric heating element and/or the gas burner.

The electric heating element and the combustion chamber being mounted on the flange and configured and positioned to be at least partially disposed inside the tank when the flange is attached to the tank and including portions extending through the flange outside the tank. According to some embodiments, the thermostat is operative to provide an on- off indication to the control unit when the water in the tank is at a pre-selected temperature. According to some embodiments, the thermostat provides a continuous indication of the water temperature.

According to some embodiments, separate thermostats are provided which are operative to control the electric heating element and the gas burner.

According to some embodiments, provision is available for manual activation of one or both of the electric heating element and the gas heating unit.

According to some embodiments, the flange is attached to the outside of the tank and includes a portion of reduced size that fits into an opening in a wall of the tank to provide a water-tight seal.

According to some embodiments, an inlet end of the combustion chamber is open to the atmosphere to admit combustion air. According to some embodiments, the inlet end of the combustion chamber is closed, and further includes a source of combustion air connected to the combustion chamber.

According to an aspect of some embodiments of the invention, there is provided a heating unit for a hot water heating and storage system in the form of a mounting flange configured to be sealingly attached over an opening in a wall of an insulated water tank, an electric heating element mounted on the flange, a gas heating unit including a combustion chamber and gas burner within the combustion chamber also mounted on the flange, the burner being adapted for connection to a source of combustion gas, a heat exchanger in communication with the combustion chamber, an exhaust outlet at a downstream end of the heat exchanger, a thermostat located in the water tank; and a control unit responsive to a temperature indication from the thermostat to operate the electric heating element and/or the gas burner, with the electric heating element and the combustion chamber configured and positioned to be at least partially disposed inside the tank when the flange is attached to the tank and including portions extending through the flange outside the tank.

According to some embodiments, the thermostat is operative to provide an on- off indication to the control unit when the water in the tank is at a pre-selected temperature or to provide a continuous indication of the water temperature. According to some embodiments, the thermostat provides a continuous indication of the water temperature. According to some embodiments, separate thermostats control the operation of the electric heating element and the gas burner.

According to some embodiments, a manual control permits activation of one or both of the electric heating element and the gas heating unit.

According to some embodiments, the flange is configured to be attached to the outside of the tank and includes a portion of reduced size that fits into an opening in a wall of the tank provide a water-tight seal.

According to some embodiments, an inlet end of the combustion chamber is open to the atmosphere to admit combustion air. According to some embodiments the inlet end of the combustion chamber is closed, and is connectable to a source of combustion air.

According to an aspect of some embodiments of the invention, there is provided a method for heating water in a water heater having a tank, on which a flange is sealingly disposed over an opening the water heater tank, the flange including an electric heating element mounted on the flange; and a gas heating unit including a combustion chamber and gas burner adapted for connection to a source of combustion gas also mounted on the flange, the electric heating element and the combustion chamber being configured to extend into the water tank and back out through the flange and selectively activating the electric heating element and /or the gas heating unit.

According to some embodiments, the electric heating element and the gas heating unit are activated according to a temperature indication provided by a thermostat inside the water tank,

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a side elevation of a hot water heating and storage system in accordance with some embodiments of the present invention;

in side elevation, of a hot water heating and storage system in accordance with some embodiments of the present invention;

Figure 2 is a vertical section view partially exploded showing the interior of the water heater system of Figure 1 ;

Figure 3 is a side elevation of the heating unit of Figures 1 and 2 as a whole;

Figure 4 is a top view of the mounting flange for the heating unit showing the positioning of the heating unit parts located in the water tank; and Fig. 5 is a partially sectional view of the components shown in elevation in Fig.

3.

Throughout the drawings, like parts are given the same reference sign.

DETAILED DESCRIPTION OF THE INVENTION

Introductory Overview;

The present invention, in some embodiments thereof, relates to hot water heaters, and more particularly, but not exclusively, to water heating and storage systems that include both electric and gas-fired heating elements situated on a mounting structure, which, in turn, i s configured to be sealabiy attached to an opening in the wall of the water heater tank, and is easily and readily removable and replaceable when necessary .

According to a feature of some embodiments of the invention, the mounting structure, (which for convenience will be referred to herein as a "flange"), is configured to mate with an opening in the water tank and supports both an electri c heating element and a gas-fired heating unit in thermal contact with the interior of the tank.

In areas where gas is less expensive than electricity, some embodiments of the invention are constructed so the electri c heating element may be disabled completely allowing the use of gas as the sole heating source. Alternatively, the gas burning heating unit can be sel ectably operated to provide an additional source of energy for more rapid heating of water in the tank. Location of the gas heating unit on the flange along with the electric heating element facilitates easy assembly or removal, maintenance and replacement of the heating unit and/or the electric heating element, when required, and for retrofitting in existing water tanks.

According to some embodiments, the gas-fired heating unit includes a burner, a combustion chamber, an igniter for the burner, a connector configured for attachment to a source of combustion gas, and an exhaust pipe for combustion gasses connected to an outlet of the combustion chamber,

The system further includes a temperature control unit which controls the operation of the electri c heating element and the gas-fired burner. In some embodiments, the control unit operates the electric heating element and the burner separately according to a preset program. Alternatively, operation of the gas burner may be controlled manually at the discretion of the user. In either version, a single thermostat may be provided to activate and deactivate the electric heating element and to shut off the gas supply to the burner if it is used according to the water temperature in the tank. Alternatively, separate thermostats may be provided for the electric heating element and the gas burner. Optionally, the thermostat! s) may be preset when the water heater is installed (or factory pre-set). Alternatively, the thermostat(s) may be user-settable.

According to some embodiments, combustion fuel, e.g., propane, LPG, etc. may be provided from a refillabie gas tank. Optionally, the combustion fuel may be a combination of different gasses, provided from separate tanks. Alternatively, combustion fuel may be provided by an outside gas main. Optionally, a shut off valve for the burner may be provided separate from one associated with the gas source itself. Optionally, one or more other conventional safety features, such as a pressure relief valve for hot gas and a discharge pipe for hot water, etc., to prevent overheating of the water heater may al so be provided.

If the hot water tank is located outdoors, an outlet of the combustion chamber may be connected to an exhaust pipe that vents directly to the atmosphere. Otherwise, a suitable exhaust arrangement i s provided to move the hot exhaust from the combustion chamber outlet to the open air.

As will be understood, the combustion chamber serves the dual purpose of transferring the combustion heat to the water in the tank and containing the combustion products for safe disposal. The burner is therefore preferably located within the combustion chamber to maximize the efficiency of heat transfer and to confine the combustion gasses. Optionally, the burner and the igniter are located entirely within the water tank. Optionally, the combustion chamber may include a portion that extends through the flange to the outside the tank, and the burner and igniter may be located in the extension. In either case, the burner i s configured so that it i s in fluid communication with the atmosphere to provide oxygen for comb u stion . Detailed Description of Exemplary Embodiments:

Referring now to Fig. 1, there is shown a side elevation of a hot water heater heating and storage system, generally indicated at 10, according to some embodiments of the invention. System 10 includes a tank 12 optionally mounted on a base 14, a 5 heating unit generally indicated at 16, a water inlet pipe 18, a hot water outlet pipe 20, a gas inlet pipe 22 including an electrically controlled in-line shutoff valve 24, and a heating unit controller 26.

Briefly, heating unit 16 includes an electric heating element and a gas-powered heating sub-system, the latter including a burner, a combustion chamber, a heat 10 exchanger and a combustion gas exhaust. The details of the construction of heating unit 16 will be described below. Power to operate gas shutoff valve 24 (described below) is provided from controller 26 by an electrical cable 28 one wire 28a of which controls operation of valve 24. A second wire 28b provides power to operate an igniter of any suitable conventional and desired design (not shown) for the gas burner. A third wire 15 28c provides a connection between a thermostat and controller 26.

Controller 26 also provides electric power for the electric heating element, which may also be of any conventional desired construction through a wire 30.

As will be understood, for solar-powered water heaters, tank inlet pipe 18 is connected to the solar energy collector and is a source of preheated water. For 20 conventional water heaters, inlet pipe 18 provides unheated water from local water mains or other source such as a well. Correspondingly, water outlet pipe 20 is connected to the hot water distribution system of the dwelling or other building served by the system.

Tank 12 and base 14 may be configured for mounting on any convenient fiat 25 surface, either indoors or outdoors. When so mounted, heating unit 6 may be attached to the tank at an angle to the tank longitudinal axis as illustrated to provide access clearance for removal and reattachment for servicing if necessary. Alternatively, the tank may also be wall-mounted by means of a suitable support, in which case, heating unit 16 may be located at the bottom of the tank, e.g., along its longitudinal axis, if 30 desired.

Combustion gas, for example, natural gas, propane, or LPG, may be provided for heating unit 16 from a refillahle gas tank 32 through gas inlet pipe 22 and an extension 34 if necessary. Alternatively, gas may be provided by connection to an outside gas main if available.

Optionally, according to some embodiments, a combination of fuels may be used, for example, to produce a higher temperature flame. These may be provided from a single tank. If the primary fuel is supplied by an outside gas main, additional fuels may be supplied from separate tanks. Gas from the one or more additional sources may be fed through separate valves to control the amount of each gas in the mixture and connected to the gas line upstream of valve 24 in any suitable manner.

Electrical power is provided to controller 26 by a suitable connection to the power distribution system for the building.

Fig. 2 is a partially vertical section and partially exploded view of Fig. 1, which shows certain details of the inside of tank 12. In particular, heating unit 16 is shown partially axial ly withdrawn from its normal position, as illustrated in Fig. 1.

Details of the construction of heating unit 16 are best understood with reference to Figs. 3-5. Fig, 3 is a side elevation of the heating unit as a whole. Fig. 4 is a top view of flange 48 showing the positioning of the electric and gas heating units parts located inside in tank 12. Fig. 5 is a partially sectional view of the components shown in elevation in Fig. 3.

It should be noted that for clarity, and due to the rotational orientations of the figures, some of the components described below are not shown in all the figures. The figures showing the parts in question will be indicated in the discussion below for conveni ent reference ,

In a preferred embodiment, heating unit 16 is comprised of four major parts seen most comprehensively in Fig. 3. The heat unit includes an electric heating element 36, a gas burner 38, a combustion chamber 40, a heat exchanger 42, and an exhaust conduit 44 connected at an outlet of heat exchanger 42 for safe disposal of the combustion products produced by burner 38.

The components of heating unit 16 are mounted on a flange 48 (see Figs. 3-5) that is attached to tank 12 by a plurality of screws (not shown) that extend through holes 50 (see Fig. 4). As will be understood, flange 48 may be a flat plate if the portion of the tank to which it is attached is flat, or may have a curved contour to match the contour of the tank at the area of attachment. Flange 48 may include a reduced-size portion 52 (see Figs. 2 and 5) also configured to match the local contour of tank 12 that fits in the opening in tank 12 through which the parts of heating unit 16 located inside the tank are received. A gasket (not shown) may optionally be provided if necessary to assure a water-tight seal for the tank opening.

As will be also understood, the hot combustion products created by burner 38 in combustion chamber 40 pass into heat exchanger 42 whereby heat i s provided to the water in the tank. The heat exchanger also provides a safe and efficient conduit for disposal of the combustion products through exhaust conduit 44.

For both of these purposes, burner 38 i s therefore preferably located within or adjacent to an inlet end 54 of combustion chamber 40. In the illustrated embodiment, burner 38 and combustion chamber 40 are located outside of tank 12. In the illustrated embodiment, combustion chamber i s configured as a truncated cone with its open-end 54 extending through flange 48. This serves as an air inlet for the burner.

Electric heating element 36 is positioned to enter tank 12 through a suitably seal ed opening 56 (see Fig. 3) in flange 48 spaced apart from combustion chamber 40.

Optionally, combustion chamber 40, including inlet portion 54 may be configured as a sealed unit so that burner 38 and combustion chamber 40 essentially integral with heat exchanger 42. In any such embodiment, burner 38 may be located entirely within the water tank rather than on an extension outside of flange 48.

In such an arrangement, of course, combustion air must still be provided.

This may be accomplished using an air compressor or blower connected to the combustion chamber and operated by controller 26 when burner 38 is in use, or from a tank of compressed air or oxygen which may be refilled as necessary. Even when the inlet end 54 of combustion chamber 40 is open, a blower may be provided either as the sole or an additional source of combustion air for burner 38,

As noted above, heating unit 16 is operated by controller 26 which receives water temperature information from a thermostatic unit 58 (see Figs. 3 and 4) through an electric wire 38c. (see Figs. 1-3). Controller 26 may operate in various ways according to different embodiments of the invention. In its simplest form, with heating provided only by gas or electricity, controller 26 is operable to energize the electric heating element or the gas burner according to the temperature of the water in tank 12 as indicated by thermostat 58. In such an embodiment, thermostat 58 functions as a simple on-off device. The operating temperature of thermostat 58 may be pre-set at the time of installation or at the factor}', or manually by the user.

In other embodiments, if both gas and electric power are available, two on-off thermostats may be provided set for different temperatures with controller 26 operative to activate the electric heating element at one temperature and/or the gas burner at a different temperature or to activate the electric element normally, and to activate the gas burner upon command of the user.

In still other embodiments, thermostat 58 may be a thermocouple that provides continuous temperature information to controller 26. In such an embodiment, controller 26 is operative in any of the ways described above in response to the actual temperature reading.

An outer protective housing 60 (see Figs. 1 and 2) attached to the bottom of flange 48 provides a protective wail around the various connections to flange 48 and combustion chamber 40, and the connection between the outlet end 62 of heat exchanger 42 and exhaust conduit 44.

In a preferred construction, heat exchanger 42 is configured as a generally U- shaped structure, with a generally cylindrical inlet end 62 and an elongated helical portion 64 (see Figs. 3 and 5) that maximizes the surface area for heat transfer. Optionally, the heat exchanger is in the form of a simple U-shaped tube without a spiral portion, or may be of any other desired configuration.

As will be understood, water heater 10 may be located outdoors or indoors. If it is located indoors, suitable piping (not shown) will be connected to heat exchanger exhaust conduit 44 to c on duct the hot exhaust combustion gas to the open air.

Incoming water serves to cool flange 48 to some degree, but additional heat insulation on the outside of the flange and/or, on outer protective housing 60 can also be provided, if desired. Preferably, the various metal parts exposed to combustion products are formed of copper or stainless steel, although any other metal that can withstand the high temperature of the burning gas, on one hand, and is not susceptible to corrosion, on the other hand, can, alternatively, be utilized.

In some embodiments, a conventional quick-heating sleeve (not shown) optionally can be provided on flange 48 to enclose the electric heater and/or the combustion chamber inside the water tank. In such embodiments, water in the water tank fills the quick-heating sleeve and actuation of the heating elements heats the water in the quick-heating sleeve, which then flows out of the sleeve into the t o p p a r t o f t h e water tank. O p t i o n a l l y , the combustion chamber can be fully contained within the quick-heating sleeve, or the combustion chamber can pass into and out of the water tank outside of the quick-heating sleeve, or the combustion chamber can pass from the flange into the quick-heating sleeve and pass through an aperture in the sleeve into the body of the water tank, before extending out through the flange.

General Comments:

While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made. It will further be appreciated that the invention is not limited to what has been described hereinabove merely by way of example. Rather, the invention is limited solely by the claims which follow.

Claims

CLAIMS:

1 . A water heating and storage system comprising:

an insulated hot water holding tank;

a mounting flange configured to he sealingly attached over an opening in a wall of the insulated water tank;

an electric heating element mounted on the flange;

a gas heating unit including a combustion chamber and gas burner within the combustion chamber mounted on the flange, the burner being adapted for connection to a source of combustion gas; and,

an exhaust outlet at downstream end of the heat exchanger;

the electric heating element and the combustion chamber being configured and positioned to be at least partially disposed inside the tank, and the exhaust outlet being configured and positioned to be at least partially disposed outside the tank, when the flange is attached to the tank.

2. A water heating system according to claim 1, further including a heat exchanger in communication with the combustion chamber.

3. A water heating system according to claim 1 and 2, further including a thermostat located inside the water tank.

4. A water heating system according to claims 1-3, further including a control unit responsive to a temperature indication from the thermostat to operate the electric heating element and/or the gas burner.

5. A water heating system according to claim 1 -4, wherein the thermostat is operative to provide an on-off indication to the control unit when the water in the tank is at a pre-selected temperature or is operative to provide a continuous indication of the water temperature.

6. A water heating system according to claim 1, further including separate thermostats operative to control the operation of the electric heating element and the gas burner.

7. A water heating system according to claim 2 - 4, further including a manual control for activating one or both of the electric heating element and the gas heating unit.

8. A water heating system according to any one of claims 1-7, wherein the flange is attached to the outside of the tank and includes a portion of reduced size that fits into an opening in a wall of the tank to provide a water-tight seal.

9. A system according to any one of claims 1-8, wherein an inlet end of the combustion chamber is open to the atmosphere to admit combustion air,

10. A system according to any one of claims 1-9, wherein an inlet end of the combustion chamber is closed, and further includes a source of combustion air connected to the combustion chamber.

1 1. A heating unit for a hot water heating and storage system comprising: a mounting flange configured to be sealingly attached over an opening in a wall of an insulated water tank;

an electric heating element mounted on the flange,

a gas heating unit including a combustion chamber and gas burner within the combustion chamber also mounted on the flange, the burner being adapted for connection to a source of combustion gas;

a heat exchanger in communication with the combustion chamber, an exhaust outlet at a downstream end of the heat exchanger;

a thermostat located in the water tank; and

a control unit responsive to a temperature indication from the thermostat to operate the electric heating element and/or the gas burner,

the electric heating element and the combustion chamber being configured and positioned to be at least partially disposed inside the tank when the flange is attached to the tank and including portions extending through the flange outside the tank.

12. A heating unit according to claim 11 , wherein the thermostat is operative to provide an on-off indication to the control unit when the water in the tank is at a pre-selected temperature or to provide a continuous indication of the water temperature.

13. A heating unit according to claim 1 1, further including separate thermostats operative to control the operation of the electric heating element and the gas burner.

14. A heating unit according to claim 1 1-13, further including a manual control for activating one or both of the electric heating element and the gas heating unit.

15. A water heating system according to any one of claims 1 1-14, wherein the flange is configured to be attached to the outside of the tank and includes a portion of reduced size that fits into an opening in a wail of the tank to provide a water-tight seal.

16. A system according to any one of claims 1 1 -15, wherein an inlet end of the combustion chamber is open to the atmosphere to admit combustion air.

17. A system according to any one of claims 1 1 -16, wherein an inlet end of the combustion chamber is closed, and is adapted for connection to the combustion chamber.

18. A method for heating water in a water heater having a tank, the method comprising:

sealingly disposing a flange over an opening the water heater tank, the flange including:

an electric heating element mounted in the flange; and

a gas heating unit including a combustion chamber and gas burner adapted for connection to a source of combustion gas mounted on the flange,

the electric heating element and the combustion chamber being configured to extend into the water tank and back out through the flange; and

selectively activating the electric heating element and /or the gas heating unit.

19. A method according to claim 18, wherein the electric heating element and the gas heating unit are activated according to a temperature indication provided by a thermostat inside the water tank.