Patent Application
20150253038
Not Applicable
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The invention relates generally to water heaters and in particular to dual energy gas and electric water heaters and to safety circuits therefor. Traditionally, water heaters have been energized by a variety of sources, including electricity and combustion of natural gas, both drawn from local distribution networks. In most populated areas today, residences and other types of facilities including businesses, industrial plants, retail facilities, educational facilities, and government facilities, generally have access to local distribution networks of both electricity and natural gas, and thus the decision on whether to operate water heaters, furnaces, and similar energy intensive equipment is based on current economic conditions affecting the price and immediate availability of electricity and natural gas.
Energy price swings and supply interruptions can occur with little warning, and facilities operators have long sought to maintain dual energy systems that can be switched as necessary, for example, with water heaters that may be energized by either electricity or natural gas. The prior art teaches a number of dual energy water heater systems whose specialized adaptations are focused on rapid, automated, and unattended switching between energy supplies over timescales of seconds up to hours. However, such systems and their attendant management complexity are unnecessary where many homeowners and facility operators want to respond to energy price shifts and supply issues over longer timescales of days up to weeks, and have a more deliberate, manual, and cheaper transition. Such timescales are generally too short and frequent for the regular replacement of a single energy source water heater with another of the other type, but long enough where automated control systems are not necessary.
Dual energy systems in the field of water heaters will necessarily face the problem of disabling the not-in-use energy source when the other is in use, specifically disabling the ability of the system to burn gas while the electric heating system is active and vice versa. The prior art systems have generally addressed this by disabling the gas supply by providing automatic gas flow control. However, the gas igniter generally remains in electrical communication with the ignition point of the gas burner. This creates a potential safety hazard of an unnecessary spark from the unexpected activation of the igniter, even if the gas supply is disabled, whether electronically or manually.
The present invention aims to address these shortcomings of the prior art by providing a dual-energy gas and electric water heater equipped with a safety circuit that disables the gas igniter whenever the electrical heating system is connected to wall power, and where an electrical quick connect is provided for the purpose of easily powering and depowering the electrical heating system. The igniter is intended to be enabled whenever the electrical system is without power, either from being disconnected or from a power outage. The invention may be used in conjunction with manual enablement and disablement of the natural gas supply, or in combination with prior art systems that automatically disable and enable the gas supply.
Accordingly, the invention is directed to a dual energy electric and gas water heater with an igniter shutoff circuit. The water heater provides the user with a quick connect by which the electrical heating system may be selectively enabled or disabled. A transformer and relay limit the function of the gas igniter to only function when the electrical heating system is not energized, whether by manual disconnection or power loss.
Additional features and advantages of the invention will be set forth in the description which follows, and will be apparent from the description, or may be learned by practice of the invention. The foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention.
The accompanying drawings are included to provide a further understanding of the invention and are incorporated into and constitute a part of the specification. They illustrate one embodiment of the invention and, together with the description, serve to explain the principles of the invention.
Referring now to the invention in more detail, the invention is directed to a dual energy electric and gas water heater with an igniter shutoff circuit. The water heater 200 provides the user with a quick connect 102A and 102B, by which the electrical heating system may be selectively enabled or disabled. A transformer 117 and relay limit 118 the function of the gas igniter 108 to only function when the electrical heating system is not energized, whether by manual disconnection or power loss.
The water heater 200 itself provides a cylindrical water tank, overflow pipe 114, hot water output 115, and cold water input 116. The gas subsystem, apart from the igniter circuit of the invention, is standard comprising a gas burner 103 supplied with gas from a facility grid or tank via the gas supply 106 and the gas burner gas line 104, and with the gas flow regulated by the gas flow control 107, all standard off-the-shelf components.
The power lead 101 is linked to the facility power, preferably and as shown in
Powered via the quick connect second component 102B, and in electrical communication therewith, is the electric heating system, which is comprised of an upper heating element 110, upper thermostat 111, lower heating element 112, and lower thermostat 113. According to well-known designs, the upper thermostat receives a 240V difference between connections C8 at +120V and C7 at −120V in opposite phase. C8 links terminal X on the quick connect second component 102B to the upper thermostat 111, as shown. C7 links terminal Y on the quick connect second component 102B to the Upper Thermostat 111. The upper thermostat provides selective power at 240V AC across connections C9 and C11, which link the upper thermostat 111 to the upper heating element 112. The upper thermostat provides constant power at 240 AC across connections C10 to the lower heating element 112 and C12 to the lower thermostat 113. The lower thermostat provides selectively controls the flow of electricity over connection C13 to the lower heating element 112. The upper and lower thermostats 111 and 113, together with the upper and lower heating elements 110 and 112 together form an electric water heating system that is responsive to water temperature, according to well-known methods and structures.
A gas igniter shutoff circuit is provided. An igniter 108 is configured with a manually actuated igniter button 109. According to well-known structures and principles, pressing the igniter button 109 causes the igniter 108 to be energized, thereby creating a momentary DC voltage across its terminals. In a standard system, the positive terminal of the igniter would be linked to an ignition electrode located over a gas burner such that pressing the igniter button creates a spark between the ignition electrode and either a secondary electrode or conductive components of the gas burner itself, either of which may be wired to the igniter's negative terminal or to ground (with the igniter's negative terminal linked to ground as well). Generically, and as used in the claims, the ignition electrode 105 is understood to be positioned in proximity to the gas burner 103 such that the gas burner 103 may be ignited by spark emission at the ignition electrode 103, regardless of the exact configuration of the ignition circuit. In the present system of the invention, connection C5 links the igniter 108 to a relay 118, and connection C6 links the relay 118 to the ignition electrode 105, such that the igniter 108 and the ignition electrode 105 are in electrical communication that may be selectively interrupted by the relay 118 being in an energized state. Numerous alternative ignition circuits exist where the interrupt of the relay 118 is differently placed, and all are applicable in the present invention so long as the relay 118's open state prevents a spark from being created at the ignition electrode. The relay 118 is configured to be closed when not energized and open when energized, and is energized by current from a transformer 117 across connections C3 and C4. In the preferred embodiment, the relay 118 is configured to accept 24V and the transformer 117 is configured to output 24V; both DC and AC varieties of off-the-shelf transformers and relays may be used. In the preferred embodiment, the transformer 117 accepts 120V AC input provided across terminals Y and W (or, equivalently, X and W) of the quick connect second component 102B over connections C1 and C2 (or, equivalently, C2 and a connection from terminal X to the transformer 117). Together, the upper and lower thermostats 111 and 113, the upper and lower heating elements 110 and 112, the transformer 117, and the relay 118 form the “electrical heating system” as used in the Claims. Generically, the electrical heating system may be said to be energized whenever it is receiving source power on the quick connect second component 102B, and that the relay 118 is understood to be configured so as to be energized whenever the electrical heating system is energized, regardless of the actual configuration of the transformer 117 and connections C3 and C4.
The invention is used according to at least two methods of operation. In the first method of operation, the user wishes to operate the water heater 200 primarily from burning gas; for example, the user may be motivated by the current local price of energy from natural gas relative to the current local price of energy from electricity. In this scenario, the user disconnects or leaves disconnected the quick connect first component 102A from the quick connect second component 102B. The user enables the flow of gas, for example by setting the gas flow control 107 on an on position, or by enabling a main gas valve in-line with the gas supply 106. This has the effect of disabling the electrical heating system and ensuring that connections C3 and C4 through the relay 118 are not energized, and thus the relay 118 will be closed. This will enable operation of the igniter 108 via the manual igniter button 109. The user presses the igniter button, which momentarily applies a voltage on the igniter electrode 105, which sparks to the gas burner 103 (or, equivalently, a secondary electrode) in conjunction with the flow of gas through the gas burner gas line 104, thereby igniting the gas burner 103. Because the electrical systems are disconnected via the quick connect 102A and 102B, there is no risk of double-heating or energy waste resulting from both systems being simultaneously operational.
In the second method of operation, the user wishes to operate the water heater 200 primarily from electricity; for example, the user may be motivated by the current local price of energy from electricity relative to the current local price of energy from natural gas. The user connects the quick connect first component 102A to the quick connect second component 102B, thereby energizing the electrical system (or, in embodiments not having a quick connect, allowing the electrical heating system to be energized). In particular, connections C3 and C4 through the relay 118 will be energized, thereby closing the relay. The closed relay will render the igniter 108 inoperable by electrically isolating connection C5 from connection C6, regardless of user operation of the igniter button 109, and the gas burner cannot receive an ignition spark. The user may then separately disable the supply of gas or leave gas supplied to the system. When gas is allowed to be supplied to the system, the gas system will be enabled automatically in the event of a power failure, because the state of C3 and C4 not being energized will result in the relay 118 closing, thereby enabling operation of the igniter 108 via the igniter button 109.
In alternative configurations, the ignition disabling system of the invention may be combined with existing systems that automatically enable and disable the gas supply in response to the electrical system being energized, thereby providing an additional layer of safety,
Components, component sizes, and materials listed above are preferable, but artisans will recognize that alternate components and materials could be selected without altering the scope of the invention.
While the foregoing written description of the invention enables one of ordinary skill to make and use what is presently considered to be the best mode thereof, those of ordinary skill in the art will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should, therefore, not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention.
