[001] The present invention relates to a system for detecting and preventing dry fire events in water heaters.
BACKGROUND AND PRIOR ART:
[002] Storage water heaters are used to heat and store a quantity of water in a storage tank in both residences and commercial buildings. Electric water heaters typically utilize one or more electric resistance heating elements to supply heat to the tank-stored water under the control of a thermostat which monitors the temperature of the stored water.
[003] There exists a possibility that the water heater can be "dry fired" / "dry heat" / "dry boil" i.e., have its electric resistance type heating elements energized before the storage tank is filled with water or otherwise in a condition in which the heating elements are not covered in water. When such dry heating occurs, the electric resistance heating elements may overheat, and the heating element and water tank temperature rise very drastically. This normally leads to element failure and melting of insulation material attached with the tank. As well, in those water heaters including bodies formed by plastic materials, damage to the body from excessive heat can render the water heater irreparable.
[004] Storage water heaters of various capacities are protected against dry heating damage, by measuring the rate of rise of temperature inside the tank, using temperature sensor and microcontrollers. However, the conventional system prevents the dry heating situation of the water heaters based upon an undesirable operation of thermal cutout, since due to dry heating, there is a heat inertia built up inside the tank which leads to temperature at which thermal cutout normally operates. If the thermal cutout operates, the power supply to the heating element and rest of the electrical components are cutoff. To again restore the power, the cutout needs to be reset always.
[005] US Patent Publication No. US4493981 provides a Boil dry protection system for cooking appliance, wherein a power control arrangement for a cooking

appliance incorporating an automatic surface unit for automatically detecting the occurrence of a boil dry condition for a utensil placed on the surface unit when operating in the Boil mode is disclosed. In accordance with one form of the invention a boil dry condition is indicated when the rate of increase of sensed utensil temperature exceeds a predetermined reference rate, or the sensed utensil temperature exceeds a predetermined threshold temperature.
[006] US Patent Publication No. US8867906 provides a dry fire protection system for a water heater. The water heater includes a body having an elongated hollow for holding water to be heated, an inlet opening and an outlet opening in communication with the hollow for flowing water there through. A heating element is coupled to the body for heating the water within the hollow. The dry fire protection system comprises a sensing element disposed in the hollow of the body for detecting the presence of water in the hollow. The sensing element is spaced from and operably connected to the heating element. The sensing element is configured to generate a voltage in response to a temperature of the sensing element. A controller is operably connected to the sensing element for monitoring the generated voltage across the sensing element. The controller is configured to prevent a supply of electrical power to the heating element as a function of the generated voltage.
[007] However, the aforementioned prior arts provide conventional solutions having operation and function that are not similar to the subject matter of the present disclosure.
OBJECTS OF THE INVENTION:
[008] The principal objective of the present invention is to provide a dry heat prevention system distinct from all conventional solutions.
[009] Another object of the present invention is to prevent dry heating condition of a storage water heater without initiating a thermal cutout.

SUMMARY OF THE INVENTION:
[0010] In accordance with the said objectives, the present invention provides a dry heat prevention system for a storage water heater. The dry heat prevention system includes a Negative Temperature Coefficient (NTC) voltage sensor coupled to a heating element of the storage water heater; and a monitoring unit coupled to the NTC voltage sensor and the heating element, wherein the monitoring unit is configured to cut-off power supply to the heating element, without initiating a thermal cutout of the storage water heater, based on a thermal profile provided by the NTC voltage sensor, the thermal profile being indicative of a dry heat condition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0012] Figure 1 illustrates a block diagram depicting a dry heat prevention system for a storage water heater in accordance with an embodiment of the present disclosure; and
[0013] Figure 2 illustrates a flow chart associated with working of a monitoring unit of the dry heat prevention system.
[0014] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from

the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAIL DESCRIPTION OF THE INVENTION
[0015] The present invention will be described in detail below with reference to an embodiment as shown in the drawing.
[0016] Figure 1 illustrates a block diagram depicting a dry heat prevention system 102 for a storage water heater 100 in accordance with an embodiment of the present disclosure. As shown, the storage water heater 100 is an electrically operated receiving power from supply PS. Alternatively, the storage water heater 100 may be gas fired or inductive water heater. The dry heat prevention system 102 includes a Negative Temperature Coefficient (NTC) voltage sensor 104 coupled to a heating element 106 of the storage water heater 100. Resistance of the NTC voltage sensor 104 decreases as temperature rises.
[0017] The dry heat prevention system 102 further includes a monitoring unit 108 coupled to the NTC voltage sensor 104 and the heating element 106. In an embodiment, the monitoring unit 108 may be any state of the art computing device known to a person skilled in the art. The NTC voltage sensor 104 is configured to evaluate a thermal profile associated with working or operation of the heating element 106. In an example, the thermal profile includes a gradient of temperature. Further, the thermal profile of the heating element 106 corresponds to a dry heat condition in case the gradient of temperature is more than a threshold value. The dry heat condition is indicative of a low or no water in the storage water heater 100.
[0018] In operation, the monitoring unit 108 is configured to cut-off the power supply to the heating element 106, without initiating a thermal cutout of the storage water heater 100, based on the thermal profile provided by the NTC voltage sensor 104, the thermal profile being indicative of the dry heat condition. Further, based on the identification of the dry heat condition, the monitoring unit

108 is provides an alert to a user of the storage water heater 100, the alert being indicative of the dry heat condition. In example, the alert may be a warning signal including an audio, video, wireless, tactile, etc. signal know to a person skilled in the art. In an example, the alert may be error codes provided on a seven-segment 5 display having LED indicators. Further, based on the alert, the user may switch off the storage water heater 100. However, in an embodiment, the monitoring unit 108 is configured to prevent reheating of the storage water heater 100 in case the user switches off, and switches on just after the dry heat condition.
[0019] In an embodiment, the monitoring unit 108 is configured to detect the dry 10 heat condition at a relatively low temperature, and is also configured to monitor thermal or heat inertia associated with the storage water heater 100. In an example, the threshold value for deducing the dry heat condition is based upon a comparison between the thermal profile of the heating element 106 and the thermal or heat inertia, to enable the monitoring unit 108 not to initiate the thermal 15 cutout of the storage water heater 100.
[0020] Figure 2 illustrates a flow chart 200 associated with working of a monitoring unit 108 of the dry heat prevention system 102 in accordance with an embodiment of the present disclosure. At block 202, the monitoring unit 108 enables power supply PS to the storage water heater 100. At block 204, the 20 monitoring unit 108 evaluates whether the heating element 106 is turned on. At block 206, the monitoring unit 108 monitors whether the heating element 106 has been turned on for a predetermined time.
[0021] At block 208, the monitoring unit 108 determines temperature inside the storage water heater 100. At block 210, the monitoring unit 108 determines the
25 thermal profile based on the gradient of temperature. At block 212, the monitoring unit 108 checks whether the thermal profile is greater than the threshold value. At block 214, the monitoring unit 108 turns off the heating element 106 and alerts the user based on the identification of the dry heat condition. At block 216, the monitoring unit 108 performs power reset of the storage water heater 100 in case
30 the user switches off the storage water heater 100.
6

[0022] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the 5 same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various assembly that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the
10 reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation,
15 together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0023] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be 20 noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0024] It will be further appreciated that functions or structures of a plurality of 25 components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other 30 dimensions or geometries are possible. In addition, while a feature of the present
7

invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of "comprising" or "including" also contemplates embodiments that "consist essentially of or "consist of the recited feature.
[0025] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

WE CLAIM:

1.A dry heat prevention system (102) for a storage water heater (100), the dry heat prevention system (102) comprising:
a Negative Temperature Coefficient (NTC) voltage sensor (104) coupled to a heating element (106) of the storage water heater (100); and
a monitoring unit (108) coupled to the NTC voltage sensor (104) and the heating element (106), wherein the monitoring unit (108) is configured to cut-off power supply to the heating element (106), without initiating a thermal cutout of the storage water heater (100), based on a thermal profile provided by the NTC voltage sensor (104), the thermal profile being indicative of a dry heat condition.

2. The dry heat prevention system (102) as claimed in claim 1, wherein the thermal profile provides that a gradient of temperature is more than a threshold value.

3. The dry heat prevention system (102) as claimed in claim 1, wherein the monitoring unit (108) is configured to provide an alert to a user of the storage water heater (100), the alert being indicative of the dry heat condition.

4. The dry heat prevention system (102) as claimed in claim 1, wherein the monitoring unit (108) is configured to detect the dry heat condition at low temperature.

5. The dry heat prevention system (102) as claimed in claim 1, wherein the dry heat condition is indicative of a low or no water in the storage water heater (100).

6. The dry heat prevention system (102) as claimed in claim 1, wherein the monitoring unit (108) is configured to monitor thermal or heat inertia associated with the storage water heater (100).

7. The dry heat prevention system (102) as claimed in claim 3, wherein the monitoring unit (108) is configured to prevent reheating of the storage water heater (100) in case the user switches off, and switches on just after the dry heat condition.
, Description:FIELD OF INVENTION:
[001] The present invention relates to a system for detecting and preventing dry fire events in water heaters.
BACKGROUND AND PRIOR ART:
[002] Storage water heaters are used to heat and store a quantity of water in a storage tank in both residences and commercial buildings. Electric water heaters typically utilize one or more electric resistance heating elements to supply heat to the tank-stored water under the control of a thermostat which monitors the temperature of the stored water.
[003] There exists a possibility that the water heater can be “dry fired” / “dry heat” / “dry boil” i.e., have its electric resistance type heating elements energized before the storage tank is filled with water or otherwise in a condition in which the heating elements are not covered in water. When such dry heating occurs, the electric resistance heating elements may overheat, and the heating element and water tank temperature rise very drastically. This normally leads to element failure and melting of insulation material attached with the tank. As well, in those water heaters including bodies formed by plastic materials, damage to the body from excessive heat can render the water heater irreparable.
[004] Storage water heaters of various capacities are protected against dry heating damage, by measuring the rate of rise of temperature inside the tank, using temperature sensor and microcontrollers. However, the conventional system prevents the dry heating situation of the water heaters based upon an undesirable operation of thermal cutout, since due to dry heating, there is a heat inertia built up inside the tank which leads to temperature at which thermal cutout normally operates. If the thermal cutout operates, the power supply to the heating element and rest of the electrical components are cutoff. To again restore the power, the cutout needs to be reset always.
[005] US Patent Publication No. US4493981 provides a Boil dry protection system for cooking appliance, wherein a power control arrangement for a cooking appliance incorporating an automatic surface unit for automatically detecting the occurrence of a boil dry condition for a utensil placed on the surface unit when operating in the Boil mode is disclosed. In accordance with one form of the invention a boil dry condition is indicated when the rate of increase of sensed utensil temperature exceeds a predetermined reference rate, or the sensed utensil temperature exceeds a predetermined threshold temperature.
[006] US Patent Publication No. US8867906 provides a dry fire protection system for a water heater. The water heater includes a body having an elongated hollow for holding water to be heated, an inlet opening and an outlet opening in communication with the hollow for flowing water there through. A heating element is coupled to the body for heating the water within the hollow. The dry fire protection system comprises a sensing element disposed in the hollow of the body for detecting the presence of water in the hollow. The sensing element is spaced from and operably connected to the heating element. The sensing element is configured to generate a voltage in response to a temperature of the sensing element. A controller is operably connected to the sensing element for monitoring the generated voltage across the sensing element. The controller is configured to prevent a supply of electrical power to the heating element as a function of the generated voltage.
[007] However, the aforementioned prior arts provide conventional solutions having operation and function that are not similar to the subject matter of the present disclosure.
OBJECTS OF THE INVENTION:
[008] The principal objective of the present invention is to provide a dry heat prevention system distinct from all conventional solutions.
[009] Another object of the present invention is to prevent dry heating condition of a storage water heater without initiating a thermal cutout.

SUMMARY OF THE INVENTION:
[0010] In accordance with the said objectives, the present invention provides a dry heat prevention system for a storage water heater. The dry heat prevention system includes a Negative Temperature Coefficient (NTC) voltage sensor coupled to a heating element of the storage water heater; and a monitoring unit coupled to the NTC voltage sensor and the heating element, wherein the monitoring unit is configured to cut-off power supply to the heating element, without initiating a thermal cutout of the storage water heater, based on a thermal profile provided by the NTC voltage sensor, the thermal profile being indicative of a dry heat condition.

BRIEF DESCRIPTION OF THE DRAWINGS
[0011] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0012] Figure 1 illustrates a block diagram depicting a dry heat prevention system for a storage water heater in accordance with an embodiment of the present disclosure; and
[0013] Figure 2 illustrates a flow chart associated with working of a monitoring unit of the dry heat prevention system.
[0014] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAIL DESCRIPTION OF THE INVENTION
[0015] The present invention will be described in detail below with reference to an embodiment as shown in the drawing.
[0016] Figure 1 illustrates a block diagram depicting a dry heat prevention system 102 for a storage water heater 100 in accordance with an embodiment of the present disclosure. As shown, the storage water heater 100 is an electrically operated receiving power from supply PS. Alternatively, the storage water heater 100 may be gas fired or inductive water heater. The dry heat prevention system 102 includes a Negative Temperature Coefficient (NTC) voltage sensor 104 coupled to a heating element 106 of the storage water heater 100. Resistance of the NTC voltage sensor 104 decreases as temperature rises.
[0017] The dry heat prevention system 102 further includes a monitoring unit 108 coupled to the NTC voltage sensor 104 and the heating element 106. In an embodiment, the monitoring unit 108 may be any state of the art computing device known to a person skilled in the art. The NTC voltage sensor 104 is configured to evaluate a thermal profile associated with working or operation of the heating element 106. In an example, the thermal profile includes a gradient of temperature. Further, the thermal profile of the heating element 106 corresponds to a dry heat condition in case the gradient of temperature is more than a threshold value. The dry heat condition is indicative of a low or no water in the storage water heater 100.
[0018] In operation, the monitoring unit 108 is configured to cut-off the power supply to the heating element 106, without initiating a thermal cutout of the storage water heater 100, based on the thermal profile provided by the NTC voltage sensor 104, the thermal profile being indicative of the dry heat condition. Further, based on the identification of the dry heat condition, the monitoring unit 108 is provides an alert to a user of the storage water heater 100, the alert being indicative of the dry heat condition. In example, the alert may be a warning signal including an audio, video, wireless, tactile, etc. signal know to a person skilled in the art. In an example, the alert may be error codes provided on a seven-segment display having LED indicators. Further, based on the alert, the user may switch off the storage water heater 100. However, in an embodiment, the monitoring unit 108 is configured to prevent reheating of the storage water heater 100 in case the user switches off, and switches on just after the dry heat condition.
[0019] In an embodiment, the monitoring unit 108 is configured to detect the dry heat condition at a relatively low temperature, and is also configured to monitor thermal or heat inertia associated with the storage water heater 100. In an example, the threshold value for deducing the dry heat condition is based upon a comparison between the thermal profile of the heating element 106 and the thermal or heat inertia, to enable the monitoring unit 108 not to initiate the thermal cutout of the storage water heater 100.
[0020] Figure 2 illustrates a flow chart 200 associated with working of a monitoring unit 108 of the dry heat prevention system 102 in accordance with an embodiment of the present disclosure. At block 202, the monitoring unit 108 enables power supply PS to the storage water heater 100. At block 204, the monitoring unit 108 evaluates whether the heating element 106 is turned on. At block 206, the monitoring unit 108 monitors whether the heating element 106 has been turned on for a predetermined time.
[0021] At block 208, the monitoring unit 108 determines temperature inside the storage water heater 100. At block 210, the monitoring unit 108 determines the thermal profile based on the gradient of temperature. At block 212, the monitoring unit 108 checks whether the thermal profile is greater than the threshold value. At block 214, the monitoring unit 108 turns off the heating element 106 and alerts the user based on the identification of the dry heat condition. At block 216, the monitoring unit 108 performs power reset of the storage water heater 100 in case the user switches off the storage water heater 100.
[0022] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various assembly that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0023] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0024] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0025] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.