Electric Fluid Heater

Abstract

A partially or fully electric fluid heater (14) is disclosed that is arranged to heat a fluid in a first circuit, the fluid including a heating fluid or tap water. The heater (100) comprises a first electric heating element (108) configured to heat the fluid in the first circuit, and a DC power source (120) configured to at least partially power the first heating element. The DC power source has a capacity of at least 1 kWh, and optionally at least 5 kWh.

Description

[Technical field]

[0001] The present invention relates to electric heaters for fluid heating systems, in particular but not exclusively to electric boilers for wet heating systems or electric furnaces for air heating systems, both of which can supply heated fluid (e.g. via a radiator) or heated tap water, or both, for a heated space. [Background technology]

[0002] Gas boilers can provide hot water and wet heating solutions for space heating needs. For example, domestic gas boilers often provide hot water to heating radiators in a heating system, and also provide on-demand hot water to a tap (e.g., for drinking, cleaning, washing). The two supplies (heating and tap) are kept separate because the heating water can become dirty as it passes through the radiator circuit, while tap water must be clean. Combination ("combi") boilers are popular because they provide all of this functionality within a sealed, high-pressure environment in a single boiler housing with a relatively small physical footprint. Other types of boilers with separate tanks or cylinders are also in use.

[0003] Gas boilers burn fossil fuels, so electric boilers are now emerging as a greener alternative. Electric boilers run water through an electric heating element.

[0004] Electric combi boilers use similar technology to electric kettles. They are plugged into a utility power supply and supplied with cold water from the mains. When hot water is demanded (e.g. the hot water tap is opened or the heating switched on), a heating element in the electric boiler generates heat and transfers this heat to the cold water. The heated water is then pumped to the tap or radiator where it is needed.

[0005] Storage electric boilers include a hot water tank (either an internal tank within the unit or an external tank) that allows water to be heated and stored when energy costs are lower (e.g., overnight) for subsequent use when energy costs are higher (e.g., the next day). Such systems take up a lot of space.

[0006] Along the same theme, but offering some of the advantages of a combi boiler, a Combined Primary Storage Unit (CPSU) has a central heating boiler and hot water cylinder combined in one large housing, which provides large amounts of hot water whenever required. However, a lot of space is required to house this system.

[0007] All of these electric boiler systems use a heating element that is powered by AC (alternating current) mains power. Summary of the Invention [Problem to be solved by the invention]

[0008] The inventors realised that a better electric boiler could be made and have developed the solution set out in the claims. [Means for solving the problem]

[0009] According to a first aspect of the present invention there is provided a fluid heater as claimed in claim 1.

[0010] Advantageously, a fully electric or hybrid electric fluid heater is provided that can rely solely on DC power (i.e., does not have to rely on AC input), and this type of heater is more environmentally friendly than pure gas-fired (or other combustible fossil fuel-fired) boilers.

[0011] Optional features of the present invention are as set forth in the dependent claims and provide various advantages as described in the detailed description of the invention. These optional features make the inventive heater setup more efficient and intelligent. Any of these optional features can be combined with any other optional features as will be appreciated by those skilled in the art.

[0012] Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0013] [Figure 1] 1 shows a schematic diagram of a boiler according to a first embodiment of the present invention. [Diagram 2] 1 shows a schematic diagram of a boiler according to another embodiment of the present invention. [Diagram 3] 1 shows a schematic diagram of a boiler according to yet another aspect of the present invention. [Figure 4] Figure 4a shows a rear view of a furnace according to yet another embodiment of the invention, Figure 4b shows a side view of a furnace according to yet another embodiment of the invention, Figure 4c shows a cross-sectional view (on line DD shown in the side view) of a furnace according to yet another embodiment of the invention, and Figure 4d shows a cut-away perspective view of a furnace according to yet another embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The exemplary embodiments described in the detailed description and claims are not meant to be limiting. Other embodiments can be used and other changes can be made without departing from the scope of the invention. Various embodiments have been described. The specific embodiments are not intended as exhaustive descriptions or as limitations on the aspects more broadly discussed and claimed. Features described in conjunction with a particular embodiment are not necessarily limited to that embodiment and can be incorporated in any other embodiment or embodiments. The protection afforded by the applicable doctrine of equivalents shall be retained to its fullest extent.

[0015] Terms such as upper, lower, top, bottom, left, right, inside, outside, vertical, upright, etc. are used to simply and clearly describe the present invention. These terms should not be construed as limiting. Those skilled in the art will envision other suitable embodiments within the scope of the present invention.

[0016] Referring to Figure 1, there is shown a hot water heater 100 (also referred to herein as a boiler) used to heat water for use in a standard fluid circuit, such as a radiator heated water circuit. Various aspects of boilers and boiler systems are described in detail with reference to non-limiting examples. Further details will be apparent to those skilled in the art. In particular, aspects of known boiler systems (including aspects not described) can be incorporated and used in the present invention by those skilled in the art.

[0017] In general, the boiler may be a tank-type boiler (also known as a system boiler), or a combi boiler, or any other known boiler type, or a furnace-type heater, such as a furnace-type air heater. Those skilled in the art can adapt the described embodiments to boiler types other than the described types. As is known, these boiler types can be used to provide heated water (e.g., to a radiator circuit), or drinking water (e.g., to a tap of the circuit), or both. In other examples, instead of heating radiator water, there may be another type of heating fluid flowing through the heating system, for example another liquid, another gas (e.g., air), or oil, or any combination thereof.

[0018] Such fluid circuits are well known in the art. Any or each fluid circuit may be a substantially sealed fluid circuit in use, or may optionally be pressurized. In a potable water circuit, pressure from a mains or gravity-fed source drives the water so that water flows from the tap in normal use when the tap / faucet is opened. Typically, a radiator circuit is substantially sealed in normal use. Bleed or pressure relief points may be provided at convenient locations to allow inspection or pressure relief or fluid relief for maintenance and repair. It is known to use expansion tanks or expansion vessels, which are small tanks used to protect sealed (i.e. not open to atmospheric pressure) fluid heating systems and domestic hot water systems from excessive pressure. Typically, the expansion tank is partially filled with air, the compressibility of which dampens the shock caused by water hammer and absorbs excess water pressure caused by thermal expansion. In an air heater, the fluid circuit usually comprises at least one vent for the exit of heated air to the space to be heated. In such circuits, the air within the circuit is not sealed from the environment, typically atmospheric or ambient pressure. In some such systems, during normal operation, air is drawn into the furnace, heated, and then blown around the heating network.

[0019] In this embodiment, the hot water heater 100 is a system boiler and includes a boiler housing 102 for housing the boiler components. In many cases, the boiler of the present invention will be required to fit within a small space. Even though the boiler of the present invention includes new components (as described in more detail below), in many embodiments, the present invention includes features that make the boiler compact and allow the boiler to fit within the same housing or space footprint as a typical known boiler.

[0020] The boiler 100 is arranged to heat water in a first circuit, the first circuit being a heated water circuit that comprises several components in addition to the boiler 100, including a standard domestic radiator (not shown). In this embodiment, water is used as the heating fluid in the first circuit, although in other embodiments other known heating fluids may be used.

[0021] Relatively cool water from the first circuit enters the boiler 100 through a cold water input pipe 104, is heated, and then relatively warm water leaves the boiler 100 through a hot water output pipe 106 to the first circuit.

[0022] The boiler 100 comprises an electric boiler vessel 110 located within a housing 102 between an input pipe 104 and an output pipe 106. The electric boiler vessel 110 is an enclosed vessel containing a first electric heating element 108 arranged to heat water passing through the vessel 110.

[0023] In accordance with the present invention, the first electric heating element 108 is powered by a DC power source, in this embodiment in the form of a battery pack 120 also located within the housing 102. In this embodiment, the boiler is a fully electric boiler, i.e., all of the heat sources are electrical. In other embodiments, the boiler may be partially electric, for example partially electric and partially gas, or partially electric and other combustible fuels, where suitable combustible fuels may be natural gas, hydrogen gas, or a combustible fluid such as propane or methane gas, or ethane or butane gas, or a suitable combustible oil or solid, or mulch such as wood chips or wood pellets, or any combination thereof. Thus, some of the heating power is provided by DC electrical components, while others are provided by more traditional combustion fuels. This can be useful to add redundancy within the system, or can be used to operate efficiently in environments where one or other power sources are scarce. In the present invention, the DC power source is large enough to provide nearly all of the power output of a typical boiler as needed.

[0024] In this embodiment, the DC power source has a capacity of 1 kWh.

[0025] In another example for a small gas-electric hybrid boiler system setup, the battery capacity may be about 1 kWh (which may be useful in a small residential facility, such as a small apartment block, or may be more useful in a larger residential facility as a boost to a regular hot water source).

[0026] In another embodiment for larger gas electric hybrid boiler system setups, the battery capacity may be about 3-5 kWh (this capacity may be useful in large residential facilities).

[0027] In another embodiment for a fully electric boiler system setup, the battery capacity may be about 5 kWh or more. In most cases, a capacity of 15 kWh to 20 kWh is sufficient to cover most of the hot water needs with only a boiler using DC power. For example, for a fully electric boiler in a small apartment block, the battery capacity may be about 10 kWh, for a medium house, about 15 to 20 kWh, and for a large house, about 25 to 30 kWh.

[0028] In some implementations, the battery capacity may be approximately 90 kWh, for example, to supply heating fluid and heated drinking water to a large building.

[0029] In this embodiment, in some embodiments, the peak power output of the DC power source is between 10 kW and 20 kW, and in some embodiments up to 200 kW. In low peak demand circuits, the peak power output may be 1 kW or 2 kW. Providing an appropriate peak power output can be made according to the particular circuit requirements and will be apparent to one of ordinary skill in the art. For example, in one exemplary situation, a 90 kWh battery can provide 350 kW for 10 minutes.

[0030] In this embodiment, the battery pack 120 comprises a stack of batteries in a compact cell ordered array.

[0031] In this example, the 1 kWh DC battery pack 120 includes 100 replaceable or rechargeable cylindrical cells, such as standard size 18650 type cells (18 mm diameter, 65 mm length), each cell having approximately 10 Wh capacity. In this example, the rechargeable cells are arranged in a 10×10 stack for compactness, and the entire stack can be removed from the battery pack 120 and recharged outside the housing 102. In another example, the stack may be a 5×20 stack. Other suitable stack configurations will become apparent depending on the available space in the battery pack. The stack is configured such that each cell in the stack can be used approximately consistently over time in a known manner, so that the stack effectively operates as a single unit. In some examples, the DC power source can also be charged from a renewable heat source, such as solar or wind power, or a heat pump, or any other suitable power source.

[0032] In other embodiments, the DC battery pack can be charged in situ, ie, without removing the battery from the housing 102, through a charging connection (not shown).

[0033] In this embodiment, charging is performed by a battery charging mechanism which in this embodiment comprises an AC-DC converter, and in embodiments where charging is performed in situ, the boiler further comprises an AC-DC converter disposed within the housing.

[0034] A typical 18650 type cell has a voltage of 3.6V. In this embodiment, the cells in the pack 120 are arranged in series, i.e., the effective voltage is about 3600V. The pack is well insulated. In other embodiments, the cells may be arranged in a different configuration, for example, all in series (so that the maximum voltage in any single path is 3.6V) or in parallel paths with several cells in series, for example 10 parallel paths with each path having 10 cells (36V) in series.

[0035] In some embodiments, the cells may be configured to provide a voltage approximately equal to the AC input supply voltage, allowing for easier AC / DC combinations and easier charging. For example, in the UK, a 240V battery pack may be provided. In some implementations, a slightly lower DC voltage battery pack may be provided, but still approximately equal to the AC input supply voltage, and appropriate values ​​can be determined by one of skill in the art.

[0036] In some embodiments, instead of a single battery pack, multiple battery packs or stacks are provided within the battery pack.

[0037] The boiler 100 housing also has an AC connection 130 to power small electronic components such as switching circuits, boiler display screen, boiler user interface, sensors, Wi-Fi, Bluetooth, sub-1 GHz communications, etc., LED lighting, and other standard boiler components (these have relatively low power demands compared to the power required to heat water during normal boiler operation). Other such components include an igniter or spark generator, ignition / ionization electrodes, pressure sensor / transmitter (water), water pressure switch, flow sensor / switch (ensuring the gas / air mixture is flowing properly before ignition can occur), combustion sensor (thermal switch, sometimes listed separately from temperature sensor by manufacturer), thermostat, thermocouple / PRT, control PCB, multimedia interface, power electronics for the power pack, pumps for water and gas (simple electric pumps, sometimes more complex pumps with drive electronics). In some embodiments, this power may also be provided by a renewable heat source such as solar or wind, or a heat pump, or any other suitable power source. In some embodiments, these small electronic components are powered directly from a DC power source, i.e., there is no AC connection to the boiler.

[0038] In this embodiment, the boiler 100 also includes an electrical control unit (not shown) arranged to control any one or more of the following: heating, battery charging, battery discharging, system requirements, switching of the DC power supply. In some embodiments, the controller is a computer controlled and arranged to control the amount of heating provided to the fluid based on or in response to any one or more control factors, including the amount of heating required, the fluid input temperature at an input point in one or more fluid circuits, the fluid output temperature at an output point in one or more fluid circuits, the fluid temperature at any given point in one or more fluid circuits, the amount of heat capacity available from the first heating element, the amount of heat capacity available from the combustible fuel burner, the instantaneous demand for heating fluid or potable water, the forecasted demand for heating fluid or potable water, and the flow rate of the fluid to be heated.

[0039] Additionally, in some embodiments, the fluid heater includes one or more sensors (not shown) configured to sense information related to one or more control factors and provide the control factor information to the controller. Some of the sensors are located inside the boiler housing (e.g., to measure water temperature or flow rate within the boiler). Some of the sensors are located outside the boiler housing (e.g., to measure water temperature or flow rate at a desired location outside the boiler and in the first circuit, such as in a room of the building). The controller is operative to direct heating of the fluid by the fuel burner and the electric heating element in response to information from such sensors.

[0040] In some examples, the controller may have a memory (not shown) associated with it (either integrally or separately), the memory configured to store information about any one or more aspects of the system, such as historical or sensory information related to any of the control factors, control factor information, sensory information from any of the sensors, desired output information (e.g., desired room temperature), etc. The controller can access the information from the memory in known manner. The controller and memory may be implemented in standard computer-controllable networks and systems.

[0041] The relatively large battery of the present invention generates heat. Other electrical components of the boiler also generate heat. The inventors have realized that there is a need for a compact and efficient non-standard cooling system.

[0042] The boiler 100 of this embodiment also includes a cooling system (not shown). Due to the desire for extra switching and intelligent use of DC-v-AC in conjunction with intelligent use of large capacity DC batteries (see below in some embodiments), the electronics may run hotter than in a normal boiler due to the large DC battery power. In some embodiments, the heater includes a high power switching module configured to efficiently switch high currents so that the power can be varied in the same resistive electric heating element and the fluid temperature can be smoothly changed. This is particularly important in potable water circuits. This feature allows pulse width modulation in the control circuit. The high power switching module may be configured to switch 30 amps or more.

[0043] In embodiments that include a battery charging mechanism, the inventors have further found that heat generation in the battery charging system, specifically in the AC-DC converter battery charging system that allows the voltage to charge the DC battery pack / cell, can be problematic. This type of battery charging mechanism is not yet in the boiler system or boiler housing and generates heat. Therefore, a further advantage of some embodiments of the present invention is to use a cooling system as a heat sink (or provide an additional separate cooling system) to also cool the battery charging mechanism. This system can be particularly useful since charging can (and should) occur when the battery charging mechanism's cooling system is not heating the building or providing hot drinking water (e.g., overnight). The cooling system of the present invention allows the heating system to run, which takes away the heat during charging. The controller may be configured to flow fluid through the fluid heater system to cool the battery charging mechanism even when heated fluid is not needed, for example, the controller may operate in response to predicting, being notified, or sensing (e.g., via feedback from a temperature sensor located near the battery charger or after the battery has been continuously charged for a threshold minimum period of time) that the battery charging system should be cooled. This battery charging mechanism cooling function may be implemented using any of the described embodiments, including the battery charger to create a novel embodiment of the present invention.

[0044] In some embodiments (e.g., where the flow of heated fluid / potable water is responsible for cooling), cooling is provided via the flow of heated fluid / potable water through the controller / battery / battery charger when the heating system is operational (e.g., when potable water or heated radiator fluid is required). However, when the heating system is not operational, the present invention allows the charger cooling system to operate (whether via the flow of heated fluid / potable water or via the cooling system's own dedicated refrigerant in its own dedicated refrigerant circuit) specifically for the purpose of cooling the battery charger.

[0045] In some embodiments, the cooling system uses a portion of the water output from the radiator, which reaches the cooling input pipes 104 (typically at about 35-40° C.) for cooling the electronic components, which are much hotter (ideally intended to keep the electronic components well below 100° C.). In some embodiments, elements of the cooling system include a first circuit piping from the inlet 104 in the boiler 100, located adjacent or near the components requiring cooling.

[0046] The cooling system of this example includes a refrigerant circuit having a sealed refrigerant piping system (not shown) through which refrigerant is routed. The sealed refrigerant piping system is configured to facilitate heat transfer between the refrigerant and the boiler's chilled water input to transfer heat to the refrigerant, and between the refrigerant and the battery cells or other components to transfer heat away from those components. This is accomplished by disposing the piping system near any one or more of the boiler components, the battery cells, and the chilled water input at suitable locations.

[0047] In the embodiment of Figure 1, the boiler is configured to be compact. The housing has dimensions of 400cm wide x 300cm deep x 700cm high and houses the first heater vessel 110 housing the first heating element 108, the DC power supply 102, and (in this embodiment) the cooling system. In other embodiments, the housing may have dimensions of 390mm wide, 270mm deep, 600mm high, or 400mm wide, 300mm deep, 724mm high, or 400mm wide, 310mm deep, 724mm high, or 440mm wide, 365mm deep, 780mm high, or 440mm wide, 364mm deep, 825mm high, or 440mm wide, 365mm deep, 780mm high, or any other suitable dimensions apparent to one skilled in the art.

[0048] In a more compact case, the DC power supply is located in the front side of the housing when in use, substantially filling the space between the front and rear ends of the housing, and substantially filling the space between the left and right sides of the housing. The boiler has walls on the left and right sides that are relatively inaccessible when in use. The front side is relatively accessible and is typically used to access the internal components during maintenance.

[0049] In some embodiments, the housing 100 includes an access door positioned to provide access to the internal components of the heater (e.g., for maintenance or repair), and the DC power supply is positioned within or integral with the access door, which also increases overall compactness and ensures that the DC battery does not need to be further removed or manipulated to access the internal boiler components (e.g., for repair / service).

[0050] In this embodiment, the boiler 100 also includes an insulating layer or heat shield (not shown) disposed between the DC power supply and the first heater vessel. The insulating layer or heat shield may include any one or any combination of an air gap, a gap filled (partially or completely) with an insulating material, a gap filled (partially or completely) with an infrared reflective material, a gap filled (partially or completely) with an insulator or a low thermal conductivity material.

[0051] In some embodiments, the heat shield may include an associated heat shield cooling mechanism positioned to transfer heat from a region of the heat shield towards another region where it is safer to dissipate the heat, the cooling mechanism comprising: A fluid material that carries heat away from an area (e.g., a heat shield area) to a heat dissipation area (i.e., another area where it is safer to dissipate heat than the heat shield area); Active cooling mechanisms such as Peltier elements (which actively move heat from one side to another, e.g., to another area where it is safer to dissipate heat than the heat shield area); A cooling cabinet (similar to a typical refrigerator) disposed within the boiler housing and positioned to substantially enclose the DC power supply; An airflow mechanism, such as a blower, arranged to draw air from outside the housing or from inside the housing to provide the required cooling effect; Any one or more of the following may be included.

[0052] The electric heating element can be wrapped around the pipe or component of the first circuit. Advantages of this include ease of manufacture, ease of reconfiguration / replacement / upgrade / repair if necessary (as the heating element is located outside the pipe / component and does not need to touch the wet side). The heating element is easily visible and therefore convenient to inspect (e.g. during routine maintenance) for deterioration. Such heating elements are also easier to clean. Such heating elements are not affected by sludge in the water circuit (a problem common in radiator water circuits).

[0053] In other embodiments, the electric heating element can be located inside the first circuit conduit / pipe, the advantages of which include compactness and low heat loss to the environment (heat is almost entirely retained within the desired water circuit during normal heating operation).

[0054] In other embodiments, the electric heating element may be incorporated into the walls of the water circuit conduits of the first circuit, the advantages of which include that these walls are more robust, less susceptible to damage from dirty water, and suffer less heat loss (than an equivalent wrapped heating element).

[0055] In other embodiments, heating may occur in a chamber (rather than in a pipe). In such an embodiment, the pipes of the first circuit may run in and out of the chamber, and one or more electric heating elements may be provided anywhere in the chamber, embedded in the walls of the chamber, wrapped around the walls of the chamber, or any combination thereof. The advantage of using such a chamber, rather than simply heating the water / heating fluid as it passes through the fluid pipes of the circuit, is that a longer or more bypass path can be provided, and this bypass allows the heating fluid to remain close to the heating element(s) for a longer period of time where more heat can be transferred (compared to a direct passage through a straight section of pipe).

[0056] In yet another embodiment, the types and arrangements of electric heating elements used may be combined depending on the particular application.

[0057] In a further embodiment (not shown), the boiler comprises a hybrid electric-gas boiler vessel instead of a vessel with only an electric heating element. In such an embodiment, multiple heating mechanisms are provided in the same sealed boiler vessel chamber. One is an electric heating mechanism and the other is a gas burner mechanism. The gas burner mechanism is of known type. The other mechanism may be a burner burning a different fuel (e.g. hydrogen gas, propane gas, oil) instead of natural gas. The electric heating mechanism may be in any suitable form. In this example, it is in the form of an electric heating element. In such an example, the DC power supply is still large enough to provide the electric heating element with enough power to obtain all or most of the required heated fluid / water. The boiler may be arranged to heat water in the first circuit (such as to heat water for supplying to a radiator circuit) in one example. The electric heating element or multiple such elements may be located anywhere in or around the burner vessel so that the water can be heated by either or both the gas and the electric heating mechanism. The heating element can be an electrical wire that can be heated by passing an electric current through it and appropriately positioned (e.g., wrapped around a water pipe, or a baffle (or any other component in the burner vessel)) to deliver heat to where it is needed.

[0058] There may be a heat exchanger in the gas burner vessel. The heat exchanger is positioned to focus heat from the combustion gases, the heated electric element(s), or both, to the or each water pipe. The heat exchanger may be metallic or ceramic. In one embodiment, the heat exchanger may be in the form of one or more plates (e.g., metal plates) positioned partially or completely around the water pipe. The electric heating element may be positioned between the plates. In another embodiment, there may be a block of suitable material (e.g., a ceramic block) positioned around the water pipe.

[0059] 2, in another embodiment, a hot water heater 200 comprises a combi boiler arranged to heat water in a second circuit (for heating and supplying drinking water) and a first circuit (for heating a heating fluid and supplying the radiator network), the second circuit having a different conduit arrangement, i.e. piping different from that of the first circuit, so that the fluids in the two circuits do not merge (so that the drinking water is not contaminated by the radiator water).

[0060] Some components of boiler 200 are similar to components of boiler 100 and have similar reference numbers in the format 2xx instead of 1xx.

[0061] The boiler 200 includes a housing 202 that contains a first heater vessel 210 that houses a first heating element 208, a DC power supply 202, and a cooling system (not shown).

[0062] Relatively cool water from the first radiator circuit enters the boiler 200 through a cooling radiator fluid input pipe 204, is heated, and then relatively warm water leaves the boiler 200 through a hot water output pipe 206 to the first radiator network circuit.

[0063] Boiler 200 comprises an electric boiler vessel 210 located within housing 202 between input 204 and output 206 pipes. Electric boiler vessel 210 is an enclosed vessel containing a first electric heating element 208 arranged to heat water passing through vessel 210.

[0064] According to the present invention, the first electric heating element 208 is powered by a DC power source, in this embodiment in the form of a battery pack 220 also located in the housing 202. In this embodiment, the boiler is a fully electric boiler, i.e., all of the heat sources are electric. In other embodiments, the boiler may be partially electric, for example partially electric and partially gas, or partially electric and partially other combustible fuels, where suitable combustible fuels may be hydrogen gas or propane gas, or suitable combustible oil, or wood chips or wood pellets, or any combination thereof. Thus, some of the heating power is provided by DC electric components, while others are provided by more traditional combustion fuels. This can be useful to add redundancy in the system, or can be used to operate efficiently in environments where one or other power sources are lacking. In the present invention, the DC power source is large enough to provide nearly all of the power output of a typical boiler as needed.

[0065] In some such embodiments, for example, embodiments in which the air intake is used to assist in the combustion process (e.g., when burning gas or combustible fuel), the cooling system may include using the air intake to cool the battery pack and / or electronic components because the air being drawn in will be relatively cool while at the same time the air is being heated, making the combustion process more efficient. This may be accomplished by locating the air intake path near the battery pack or components requiring cooling.

[0066] In this example, the DC power source has a capacity of 5 kWh.

[0067] Other variations (e.g., hybrid electric-gas power configuration, AC-DC controller configuration, cooling configuration, etc.) are similar to those described with reference to previous embodiments (e.g., with reference to FIG. 1).

[0068] In the embodiment of Figure 2, the hot water in the first boiler vessel 210 is also configured to heat water in the second circuit (without directly heating the water in the second circuit). The second circuit comprises a potable water circuit (e.g., providing tap water for washing, bathing, drinking, etc.). Relatively cooler water from the second circuit enters the boiler 200 through a main cold water input pipe 205 (supplied through a water main pipe) and is heated, and then the relatively warmer potable water leaves the boiler 200 through a hot water output pipe 207 to a second tap circuit.

[0069] The second circuit comprises a pipe section between the inlet 205 and the outlet 207, arranged for heat to be transferred from the first container 210 to the second circuit. In this embodiment, this is achieved by locating this pipe section in close proximity to the container 210 so as to effectively transfer heat to the section of pipe in use. The pipe section comprises a helical pipe wrapped around the container 210 to further aid in the transfer of heat between the pipe section and the container 210. In another embodiment, instead of or in addition to a helical pipe wrapped around the container, the water is heated via a wet heat transfer box. In this way, it is not necessary to heat the radiator water every time drinking water is heated. In such an embodiment, the water of either circuit can be heated separately, i.e. pipes from both circuits can enter the heat exchanger container to provide heating for either or both circuits.

[0070] The battery pack 220 is positioned at the top of the housing 202, spaced from the heating vessel 210, and is shielded from the heating vessel 210 by a heat shield (not shown), as described with respect to the other embodiments.

[0071] Referring to Fig. 3, in another embodiment, a hot water heater 300 comprises a combi boiler arranged to heat water in a second circuit (for heating and supplying drinking water) and a first circuit (for heating a heating fluid and supplying a radiator network). The system of Fig. 3 is similar to the system of Fig. 2, except that the drinking water in the second circuit is primarily heated through a different mechanism (similar reference numbers are in the format 3xx instead of 2xx). The combi boiler 300 includes an electric boiler vessel 310, which is located in the housing 302 between the input 304 pipe and the output 306 pipe. The electric boiler vessel 310 is a closed vessel housing a first electric heating element 308 arranged to heat water passing through the vessel 310.

[0072] In accordance with the present invention, the first electric heating element 308 is powered by a DC power source, in this embodiment in the form of a battery pack 320 also located within the housing 302. In this embodiment, the boiler is a fully electric boiler, i.e., all of the heat sources are electric. In other embodiments, the boiler may be partially electric, for example partially electric and partially gas, or partially electric and partially other combustible fuels, where suitable combustible fuels may be hydrogen gas or propane gas, or suitable combustible oil or combustible solids or mulch, or any combination thereof. Thus, some of the heating power is provided by DC electric components, while others are provided by more traditional combustion fuels. This can be useful to add redundancy within the system, or can be used to operate efficiently in environments where one or other power sources are lacking. In the present invention, the DC power source is large enough to provide substantially all of the power output of a typical boiler as needed.

[0073] In this embodiment, the DC power source has a capacity of 20 kWh.

[0074] In contrast to the embodiment of Figure 2, the electric heating arrangement of the embodiment of Figure 3 includes a second electric heating element configured to efficiently deliver heat to the water in the second circuit. In this embodiment, the boiler 300 includes a second electric boiler vessel 311 that houses the second electric heating element 309 in the path of the second circuit between the input pipe 305 and the output pipe 307. In this embodiment, the DC battery pack also powers the second electric heating element 309.

[0075] Various modifications can be made to the present invention without departing from the scope of the invention.

[0076] For example, although embodiments of the present invention have been described with respect to a water boiler, the same inventive concepts may be applied to other (partially or wholly) electric fluid heaters, e.g., air heaters (also known as furnaces) are common in North America. Typically, such systems include a fan for blowing out the heated air, but for clarity, a fan has not been shown in any of the drawings. Systems for heating other fluids will be apparent to those skilled in the art.

[0077] 4a-4d show one such embodiment, according to which a furnace heater 400 is arranged to supply heated (or cooled) air. The furnace 400 includes a housing 402, an air inlet 404, and a fan 406 arranged near the air inlet to draw air from the environment into the furnace housing 402. The housing also has an air outlet 408 through which the heated air exits the furnace housing. Between the air inlet 404 and the outlet 408 is an air duct 410. Those skilled in the art will be aware of variations of such furnace air heaters.

[0078] The furnace comprises a heat exchanger 412 configured to provide heat to air passing through a duct 410. In this embodiment, the heat exchanger is disposed within the duct (although in other embodiments, the heat exchanger may be disposed outside the duct). In this embodiment, a plurality of electric heating elements 414 are disposed within the body of the heat exchanger 412. The electric heating elements 414 are arranged to provide heat when powered by an electric current. The furnace comprises a large DC power source, in this embodiment in the form of six DC battery packs (other configurations will be apparent). The DC power source in this embodiment comprises a power source of the type previously described with respect to the boiler and is the only power source (i.e., there is no AC power source powering the heating element). In other embodiments, the heating element may also be powered by an AC power source. In this embodiment, the battery capacity is approximately 5 kWh, although this value may be different in other embodiments, as described in connection with the previous embodiment.

[0079] In this embodiment, the power packs provide surge and steady state power for the heating elements in the heated air delivery system. In some embodiments, a second fluid circuit for hot water is also provided, and in such embodiments, on-demand hot water may be managed in the furnace by the power electronics (used to power the furnace's electronic components). The number / power of DC power packs may be tailored to the requirements of a particular installation. In some embodiments, the power electronics may be cooled by circulating air or other fluid and may be used to preheat the air flowing through the ducts. The modular DC power packs are designed for easy replacement and are conveniently located on an accessible side of the housing.

[0080] In some such embodiments of the invention, the battery pack may comprise multiple modular battery sub-packs stacked together to form the battery pack (or in separate sections separated by boiler components or all of them). These sub-packs are configured to be manually handled, i.e., have a suitable weight for handling. These sub-packs may also be shaped for easy handling. The battery pack may be thermally managed or heat shielded as a whole (i.e., allowing heat from the cells of the battery pack to be removed to the appropriate location in the environment, but also not receiving undesired heat from other boiler components such as heat exchangers). The sub-packs may be individually thermally managed or heat shielded (i.e., allowing heat from the cells of the battery pack to be removed to the appropriate location in the environment, but also not receiving undesired heat from other boiler components such as heat exchangers).

[0081] The subpacks may be sized to fit within the boiler housing, i.e., the width of the subpack is about the same as, slightly less than, or significantly less than the width of the boiler housing. The height of the subpacks when stacked may be such that the combined height of the required number of subpacks is about the same as, just the same as, or much less than the height of the boiler housing.

[0082] In some embodiments, the subpack (or stack or other arrangement of subpacks) is equal to or smaller than the dimensions of a boiler housing, for example, width 390 or 440 cm or less, depth 270 or 365 cm or less, and height 600 or 825 cm or less.

[0083] There is very little wasted space within the furnace housing 402. Large, powerful battery packs are useful and fill space that would normally be empty.

[0084] In some embodiments, the heating element may be powered by both a DC power source and an AC power source. In such embodiments, the DC power source is configured to at least partially power the heating element. In some such embodiments, the DC power source may power the heating element fully at some times and partially at other times (depending on factors such as the time of day or the availability of power from renewable energy sources, etc.).

[0085] In an embodiment having multiple fluid circuits, e.g., a combi boiler, where there are other power sources in addition to the large DC power source, the first heating element may be configured to heat the fluid in one of the first and second circuits and the combustion heater may be configured to heat the fluid in the other of the first and second circuits, e.g., tap water is heated only by the power source and heating water is heated by a combustible fuel source.

[0086] There may be more than one heating element per heater vessel.

[0087] For any embodiment described as being solely electric, one skilled in the art will understand that the embodiment may also be provided in a combustible fuel format that is partially electric.

[0088] Any of the embodiments may include a DC power interface configured to accept a DC power source, the DC power interface configured to accept two or more types of DC power sources, such as any combination of Ni-MH battery cell packs, Ni-Cd battery cell packs, and Lithium battery cell packs, or hybrid packs containing a hybrid of any of these types of cells.

[0089] Any embodiment including a DC power battery may include a safety shut-off mechanism configured to disconnect the cell from powering the electric heating element. The safety shut-off mechanism may comprise a master switch or an automatic master switch, and in some embodiments the safety shut-off mechanism comprises a contactor. Advantageously, this provides a safe and simple DC switching mechanism.

[0090] Existing electric, gas (or other combustible fuel), or gas-electric hybrid (not known but described in applicant's co-pending applications) fluid heaters can be retrofitted with electric heating element(s) of the type described above, or batteries, or both, to provide a fluid heater within the scope of the present invention. The fluid heater of the present invention is more powerful, more efficient, and less dependent on the combustion of combustible fuel than the original fluid heaters. Such embodiments are particularly suited to introducing electric heating capabilities to existing gas boilers. For example, the electric heating element may be coated on, coated within, sprayed into, housed within, wrapped around, partially or fully embedded in, or otherwise associated with, a duct section or adjacent thereto, i.e., at the outlet from the gas burner vessel, the inlet to the burner vessel, or both. The heating element(s) may be powered by DC, AC, or a combination thereof. In some embodiments, a battery, such as a large battery of the type described above, may be attached to the burner vessel along with a control mechanism (e.g., control electronics and / or software) to control the amount of heating provided by the electric heating element(s) relative to the combustible fuel source, and the control mechanism may control the amount of heating provided by DC, AC, or a combination thereof.

[0091] In an embodiment in which the circuit comprises a heated water circuit, such as a radiator circuit, the boiler / heater may comprise a pump, such as a water pump (not shown for clarity of any of the drawings), as is known in the art.

[0092] In embodiments where the circuit comprises a potable water circuit, typically the inlet is from a water mains inlet, which is pressurized so no pump is required, in some embodiments a pump may be provided where the inlet is from a non-pressurized clean water source.

[0093] In some embodiments, the DC power source is located in the top of the housing. In such embodiments, wetted components (such as pipes or chambers that contain fluid) are located only below the DC power source. The DC power source may occupy about the top 80% of the space within the housing in some embodiments.

[0094] In some embodiments, a first heating element is arranged to heat only in a first fluid circuit and a second heating element is arranged to heat only in a second fluid circuit, or vice versa. For example, one heating element may be dedicated to heating a radiator circuit, while another heating element may be dedicated to heating a drinking water circuit. Thereby, suitable custom-made dedicated elements can be used for different circuits having different needs.

[0095] In any embodiment described, the or each heating element may be any element that emits heat when an electric current is passed through it, such as, for example, a resistive wire, or any wiring that emits heat when an electric current is passed through it, such as, but not limited to, Thin films (polyimide on conductive metal), Ceramic wire (ceramic sheath with nickel-chromium-aluminum embedded), Bare wire (nickel, nichrome, Kanthal, Stellite, etc., tungsten), Encapsulated wire (e.g., nichrome with silicone sheath), Inorganic insulated wires, such as copper sheath / nichrome, cupronickel / inconel, steel sheath / nickel, inconel sheath / nickel wire, and all kinds of hybrids of these (elements may be drawn to size or manufactured to finished size. Insulation is typically Al2O3 or MgO); Simple wire with elements wound between the wires, spiral wire, busbar wire, may be also possible.

[0096] In any embodiment where a single heating element is described, that heating element may be replaced by one or more different heating elements, as will be apparent to one of ordinary skill in the art.

[0097] For example, one or more of these electric heating elements may comprise an electrically conductive heating element coating on any one or more of an inner surface of at least one duct wall, an outer surface of at least one duct wall, and a surface of a combustion fuel heat exchanger, baffle, or any other component. One or more of the electric heating elements may comprise, for example, an inductive heating element that may be powered by induction (without direct contact).

[0098] In some cases, multiple separate electric heating elements are arranged to heat the fluid in separate sections of the duct. In some embodiments, multiple separate sections of heating elements are provided in the fluid duct, and each section may be controlled together or separately, for example to provide different levels of heating at different section locations. This may be effective when combustion heating levels are different at different locations of the burner vessel, and the electric heating element(s) may provide less heating in sections where the burner can provide more heating, and more heating in sections where the burner can provide less heating. In another use case, it may be desirable to provide different heating levels to different sections of the fluid path, such as at the initial start of heating when the fluid is first heated from a low temperature, e.g., when a tap is first turned on, and more heating may be provided at the beginning of the fluid path than at the end of the fluid path because the starting input fluid is particularly cold.

[0099] In some of these embodiments, the elements may be fully embedded within the fluid duct, such that no part of the element emerges or protrudes from the duct (eg, there are no external electrical connection points).

[0100] In some embodiments where heating elements are provided in separate zones (not continuous along the entire length of the duct), gaps between the separate zones may be formed by masking the gap portions of the pipe (e.g., with a spray mask) during the coating / spraying process.

[0101] In some embodiments, the present invention provides a single-housing fluid heater having an electric heating element configured to be powered by both a larger DC power source and an AC power source with an on-board controller and controller cooling system. The inventors have recognized that the components of this type of system have significantly different cooling needs.

[0102] In some embodiments (where it is possible to power the heating element via an AC power source), the controller may be configured to provide a shower saving algorithm, such as the following: if DC power is not available (e.g., battery level is low or zero), switch to powering the electric heating element only via AC power. In that case, direct (i.e., on-demand when the tap is turned on) hot water is provided only by AC power, which provides less power than a large DC power source can provide. Thus, the controller is programmed to ensure that some minimum threshold of DC capacity remains at all times, to allow, for example, high power showers. This feature can be selectively activated or deactivated by the user via a user interface that sends instructions to the controller. In some embodiments, the minimum threshold of DC capacity may be 5% of the total battery capacity held in the reservoir.

[0103] In some embodiments, the present invention provides a fluid heater that achieves the safe provision of a large modular power pack that is easily replaceable within the confines of the heater housing. The large power pack (which may be comprised of multiple sub-packs) has sufficient capacity to provide the entire heating load for a typical domestic dwelling via the mains. A power pack of this size is safely located within the confines of the housing using a heat shield as described above. Because the battery charger cooling mechanism may often be operated at different times relative to the controller and the battery cooling mechanism, the battery charger cooling mechanism may comprise or include a separate or distinct cooling mechanism relative to the controller and the battery cooling mechanism.

[0104] In some cases, there may be multiple cooling mechanisms, for example, at least one cooling mechanism associated with the controller, at least one cooling mechanism associated with the battery, and at least one cooling mechanism associated with the battery charger.

[0105] In some examples, the cooling system (alternatively or in addition to the cooling systems described above) may be a passive cooling system configured to transfer heat from a component to be cooled (such as a boiler electronics or a DC power source or a battery charger or any combination thereof). A passive cooling system may not include a flowing fluid. A passive cooling system may include a thermal heat sink (e.g., an aluminum block, such as a 20 mm x 40 mm x 80 mm aluminum block) with natural convection fins for heat dissipation to the environment. A passive cooling system may include a large thermal mass, such as a heater housing.

Claims

1. 1. A partially or fully electric fluid heater configured to heat a fluid in a first circuit, the fluid comprising a heating fluid or tap water, the heater comprising: a first electric heating element positioned to heat fluid in the first circuit; and a DC power supply configured to at least partially power the first heating element, the DC power supply having a capacity of at least 1 kWh, and optionally at least 5 kWh; and a heater housing configured to house the DC power supply.

2. 10. The heater of claim 1, further configured to heat a fluid in a second circuit, wherein the fluid in the first circuit comprises a heating fluid and the fluid in the second circuit comprises tap water, or vice versa, and the first heating element is configured to heat the fluid in the first circuit, the fluid in the second circuit, or both.

3. 10. The heater of claim 1, comprising an electrical control unit configured to control any one or more of heating, charging of the DC power supply, discharging of the DC power supply, system requirements, and switching of the DC power supply.

4. The heater of claim 3 , further comprising a cooling system configured to cool the electrical control unit, the DC power supply, or both.

5. 5. The heater of claim 4, further configured to heat a fluid in a second circuit, wherein the fluid in the first circuit comprises a heating fluid and the fluid in the second circuit comprises tap water, or vice versa, and the first heating element is configured to heat the fluid in the first circuit, the fluid in the second circuit, or both; the cooling system includes a refrigerant circuit having a refrigerant input pipe configured to carry an input refrigerant to the DC power source or the electrical control unit, or both; a refrigerant output pipe configured to carry an output refrigerant from the DC power source or the electrical control unit, or both; and a refrigerant radiator configured to receive the refrigerant output pipe and recirculate the refrigerant to the refrigerant input pipe after dissipating heat from the refrigerant output pipe, wherein the refrigerant output pipe, the radiator, or both are configured to transfer heat to any one or more of a fluid in the first circuit, a fluid in the second circuit, a heater chilled water inlet pipe, a heater cooling fluid inlet, and a heater heating fluid return pipe.

6. 10. The heater of claim 1, wherein the DC power source comprises a battery pack, optionally a compact battery pack.

7. 2. The heater according to claim 1, wherein the heater housing has dimensions of 390 to 440 cm in width, 270 to 365 cm in depth, and 600 to 825 cm in height.

8. The heater of claim 1 , wherein the heater housing is configured to house a first heater can that houses the first heating element and the DC power supply.

9. The heater according to claim 8, an electrical control unit configured to control any one or more of heating, charging of the DC power source, discharging of the DC power source, system requirements, and switching of the DC power source; a cooling system configured to cool the electrical control unit, the DC power supply, or both; Equipped with The heater housing is configured to house the cooling system.

10. 9. A heater according to claim 8, wherein the DC power supply is located on a front side of the housing when in use, or in an upper portion of the housing when in use.

11. 9. The heater of claim 8, wherein the DC power supply comprises: substantially filling the space between the front and rear ends of the housing; and A heater substantially filling the space between the left and right sides of the housing.

12. 9. The heater of claim 8, further comprising a heat shield disposed between the DC power supply and the first heater vessel.

13. 8. The heater of claim 7, wherein the housing includes an access door configured to allow access to internal components of the heater, and the DC power supply is located within or integral with the access door.

14. 3. The heater of claim 2, further comprising a combustion heater, such as a gas burner or an oil burner, positioned to heat fluid in the first circuit, the second circuit, or both.

15. 15. The heater of claim 14, wherein the first heating element is positioned to heat fluid in one of the first circuit and the second circuit, and the combustion heater is positioned to heat fluid in the other of the first circuit and the second circuit.

16. 3. The heater of claim 2, further comprising a second electric heating element positioned to heat fluid in the first circuit, the second circuit, or both.

17. 17. The heater of claim 16, further comprising an AC power source configured to at least partially power the second heating element, wherein the first heating element is configured to be powered solely by the DC power source and the second heating element is configured to be powered solely by the AC power source, or vice versa.

18. The heater of claim 16, wherein the heater housing is configured to house a first heater vessel that houses the first heating element and the DC power supply; The first heater enclosure houses the second heating element.

19. A heater as described in claim 16, wherein the heater housing is configured to accommodate a first heater container that accommodates the first heating element and the DC power supply, and the housing is configured to accommodate a second heater container that is configured to accommodate the second heating element.

20. 10. The heater of claim 1, further comprising: the capacitance of the or each heating element; and Capacity of the or each power source a controller configured to control distribution of power taking into account any one or more of:

21. 10. The heater of claim 1, comprising a DC power interface configured to accept the DC power source, and the DC power interface configured to accept two or more types of DC power sources, such as any combination of a Ni-MH cell battery pack, a Ni-Cd cell battery pack and a lithium ion cell battery pack, or a mixed cell type battery pack.

22. 22. A heater according to any preceding claim, comprising an AC-DC converter charger configured to charge the DC power source, optionally located within the housing.

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