WATER LEAKAGE DETECTION AND MITIGATION SYSTEM AND METHOD

Abstract

An air inlet duct connected to an air inlet of a burner assembly of a water heater system includes an outlet connected to the air inlet of the burner assembly, a duct inlet for receiving air, a main conduit connecting the duct inlet and the outlet, a branch connected to the main conduit, and a pressure relief mechanism connected to the branch. The pressure relief mechanism opens when the main conduit reaches a predetermined pressure value. The air inlet duct is adapted to mitigate effects from leaks that develop in the water heater system.

Description

BACKGROUND

The present disclosure relates to leakage detection and mitigation systems and methods. In some examples, the leakage detection mitigation systems and methods are used with water heater apparatus, for example a tank water heater. This disclosure incorporates by reference U.S. Pat. No. 11,573,148 entitled “Leakage Detection in Condensing Water Heater,” which was filed as U.S. application Ser. No. 16/538,514 on Aug. 12, 2019.

SUMMARY

In a combustion tank water heater, the point of failure is often a leak that develops in the heat exchanger coil or flue that is contained within the tank. The flue has a glass lining that protects the flue, which is typically steel, from corrosion. Over time, the glass lining that protects the flue can become compromised, and water from the tank can corrode the underlying steel material to the point where a leak develops. Water from the tank can then leak into the flue. When the leak is large enough and/or when the supply water pressure is sufficiently high, the leaking water can propagate throughout the combustion system. In some cases, the water pressure can be sufficiently high to allow the leaking water to propagate upstream in the gas system that feeds the combustor, and into other gas appliances that are also connected to the gas system. This propagation of water can lead to substantial water damage.

One purpose of the leakage detection and mitigation systems and methods described herein is to detect a major water leak into the combustion system of a tank water heater. Another purpose of the leakage detection and mitigation systems and methods described herein is to mitigate any damage resulting from the leak.

In one aspect, an assembly for use in heating water in a water heater system includes a burner assembly and an inlet air duct. The burner assembly includes a gas inlet, an air inlet, and a flue gas outlet. The burner assembly is configured such that gas passing through the gas inlet and air passing through the air inlet are combusted before passing through the flue gas outlet. The inlet air duct is connected to the air inlet such that air passes through the inlet air duct prior to passing into the air inlet. The inlet air duct includes an outlet connected to the air inlet, a duct inlet configured to receive air, and a main conduit connecting the duct inlet and the outlet. The main conduit includes a branch connected to a pressure relief mechanism. The pressure relief mechanism is configured to open when the main conduit reaches a predetermined pressure value.

In another aspect, which is combinable with any other aspect, a water leakage detection system for a water heater system includes a flue gas circuit, a condensate drain line, and a pressure relief opening. The flue gas circuit extends through a tank of the water heater system and includes a burner, an inlet air duct, a heat exchanger, and a condensate trap. The inlet air duct is arranged to provide combustion air to the burner. The heat exchanger is arranged downstream of the burner. The condensate trap is arranged downstream of the heat exchanger. The condensate drain line is coupled to the condensate trap and a pressure relief opening is configured to discharge water leaking from the tank of the water heater system into the flue gas circuit. The pressure relief opening is provided in one of the inlet air duct and the condensate drain line. The fluid flow through the pressure relief opening is prevented during normal operation of the water heater system.

In another aspect, which is combinable with any other aspect, an inlet air duct is configured to connect to an air inlet of a burner assembly of a water heater system. The inlet air duct includes an outlet, a duct inlet, a main conduit, a branch, and a pressure relief mechanism. The outlet is connected to the air inlet of the burner assembly. The duct inlet is configured to receive air. The main conduit connects the duct inlet and the outlet. The branch is connected to the main conduit. The pressure relief mechanism is connected to the branch and is configured to open when the main conduit reaches a predetermined pressure value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view of a water heater according to a construction of the present invention, the water heater including a heat exchanger and a vent pipe in connection with the heat exchanger.

FIG. 2 is a perspective view of a condensate collector for a water heater.

FIG. 3 is a schematic view of an installation of a water heater condensate drain line.

FIG. 4A illustrates normal operation of a 180° branch extension.

FIG. 4B illustrates failure operation of a 180° branch extension.

FIG. 5 is a perspective view of a burner assembly of the water heater of FIG. 1.

FIG. 6 illustrates a portion of an air inlet structure according to an embodiment of the invention.

FIG. 7 is a cross-sectional view of a portion of the air inlet structure of FIG. 6.

Before any embodiments are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Use of “including” and “comprising” and variations thereof as used herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Use of “consisting of” and variations thereof as used herein is meant to encompass only the items listed thereafter and equivalents thereof. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings.

The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (for example, it includes at least the degree of error associated with the measurement of the particular quantity). The modifier “about” should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4”. The term “about” may refer to plus or minus 10% of the indicated number. For example, “about 10%” may indicate a range of 9% to 11%, and “about 1%” may mean from 0.9-1.1. Other meanings of “about” may be apparent from the context, such as rounding off, so, for example “about 1” may also mean from 0.5 to 1.4.

DETAILED DESCRIPTION

In general, a condensing combustion tank water heater includes a tank to hold water, a combustion system that burns a liquid or gaseous fuel, and a heat exchanger or flue arranged within the tank to transfer heat from the products of combustion to the water within the tank. To extract the maximum available heat energy from the products of combustion, the flue is designed such that the transfer of heat from the combustion products to the water cools the combustion products down below the dew point of the water vapor within those combustion products. This allows for the recovery of the latent heat of the water vapor into the water within the tank, thereby increasing the water heater's thermal efficiency. While the vapor products of combustion can be exhausted through an exhaust vent piping system, the liquid condensate must be allowed to drain by gravity from the flue into a suitable drain. Such a system is illustrated in FIG. 1.

FIG. 1 illustrates a water heater 10 including a heat exchanger 12, a tank 14, a gas burner 18, and an exhaust assembly 30. The illustrated heat exchanger 12 includes a combustion chamber 22 and a flue 26. The water heater 10 also includes a flue gas circuit 34 and a control system (shown in FIG. 3).

The tank 14 includes a water inlet 42 for the supply of cold water from a source of water. The tank 14 also includes a water outlet 46 for delivery of hot water from the tank 14 to a hot water consuming device (e.g., faucet, shower, dishwasher, etc.). A sacrificial anode 48 may extend from the water outlet 46 to protect the tank 14 from corrosion. The tank 14 defines an interior space 50 configured to receive the water. A hot water draw occurs when the water is exiting the tank 14 (i.e., through the water outlet 46) and is delivered to the hot water consuming device.

The gas burner 18 burns a combustible mixture of fuel (e.g., natural gas) and air to generate hot flue gases in the combustion chamber 22. The water heater 10 may be defined as being in a heating mode when the gas burner 18 is operating. The water heater 10 may be further defined as being in a standby mode when the gas burner 18 is not operating. There is an absence of flue gases flowing through the water heater 10 when the water heater 10 is in the standby mode. The flue gas circuit 34 includes an air delivery portion (not shown) to deliver the combustion air to the gas burner 18.

In the illustrated embodiment, the gas burner 18 is positioned near the top of the tank 14 with respect to gravity, and the combustion chamber 22 extends from the burner 18 into the tank 14. In particular, the burner 18 may extend partially into the combustion chamber 22 through a top of the combustion chamber 22. The illustrated burner 18 fires downwardly into the combustion chamber 22 and may therefore be defined as a down-firing burner. In other embodiments, the gas burner 18 may be positioned at the bottom of the tank 14 and fired upwardly into the combustion chamber 22. The combustion chamber 22 is defined by an upper portion of the flue 26. The combustion chamber 22 and flue 26 are positioned within the interior space 50 defined by the tank 14. The flue gases generated by the gas burner 18 flow through the flue 26. The water within the interior space 50 is heated as the hot flue gases flow through the flue 26. As such, the flue 26, and the combustion chamber 22, may be collectively referred to as the heat exchanger 12 for transferring heat from the flue gases to the water in the tank 14.

With continued reference to FIG. 1, the flue 26 includes a plurality of sections forming the flue 26. In the illustrated embodiment, the flue 26 includes a wider upper section which defines the combustion chamber 22, a narrowing section 54a, a vertical section or riser 54b, and a coil section 54c. The narrowing section 54a and the vertical section 54b are connected by a first elbow 58. The vertical section 54b and the coil section 54c are connected by a second elbow 62.

The flue 26 is in fluid connection with the exhaust assembly 30. The exhaust assembly 30 includes an intermediate section 66 and a vent pipe 70. The illustrated intermediate section 66 is in connection with the coil section 54c through a wall of the tank 14. The intermediate section 66 is positioned between the coil section 54c and the vent pipe 70. In the illustrated embodiment, the coil section 54c and the intermediate section 66 are connected by a third elbow 74, which is part of the flue 26. The vent pipe 70 is in fluid connection with the outside atmosphere (e.g., outside of a room).

The flue gas circuit 34 includes the combustion chamber 22, the flue 26, and the exhaust assembly 30. The flue gases are configured to flow along the flue gas circuit 34 from the combustion chamber 22, through the flue 26 and the exhaust assembly 30, and to the outside atmosphere. In particular, the flue gases are generated by the gas burner 18 and flow from the combustion chamber 22 to the narrowing section 54a. The narrowing section 54a communicates between a lower end of the combustion chamber 22 and the first elbow 58. The narrowing section 54a is shaped as a nozzle and causes the velocity of the flue gases to increase as they are delivered to the first elbow 58. A bottom end 78 of the vertical section 54b receives the flue gases from the narrowing section 54a (via the first elbow 58). The flue gases rise in the vertical section 54b and are delivered to a top end 82 of the vertical section 54b. Subsequently, the flue gases are received in the coil section 54c (via the second elbow 62). The coil section 54c guides the flue gases along a downward spiral path to the intermediate section 66. The bends of the first and second elbows 58, 62 change the direction of flow of the flue gases. For example, the first elbow 58 turns the direction of flow of the flue gases from downward (as received from the narrowing section 54a) to upward (as delivered to the vertical section 54b).

With continued reference to FIG. 1, the intermediate section 66 of the exhaust assembly 30 receives the flue gases from the coil section 54c and guides the flue gases horizontally to the vent pipe 70 where the flue gases are vented to the outside atmosphere. The bend of the third elbow 74 changes the direction of flow of the flue gases from coiling (as guided along the coil section 54c) to horizontal (as delivered to the intermediate section 66).

As the flue gases travel along the flue gas circuit 34 from the combustion chamber 22 to an end 86 of the coil section 54c, heat is transferred from the hot flue gases to the water within the interior space 50 defined by the tank 14. Specifically, the flue gases are in contact with the interior surfaces of the combustion chamber 22 and the flue 26, and the water is in contact with the outer surfaces of the combustion chamber 22 and the flue 26 such that the heat is transferred from the flue gases to the water by conduction. As the flue gases lose heat to the water, a temperature of the flue gases may fall below a predetermined temperature limit (e.g., 130 degrees Fahrenheit). Condensate from the flue gases forms within the coil section 54c once the temperature of the flue gases falls below the predetermined temperature limit. Subsequently, the condensate is guided along a downward spiral path from the coil section 54c to the intermediate section 66 (i.e., by gravity).

In other embodiments, the heat exchanger 12 (e.g., combustion chamber 22 and flue 26) may include separate flue tubes, instead of the coil section 54c, that extend vertically through the tank 14. These flue tubes received the flue gases from the gas burner 18. Each of the flue tubes may further include baffles to enhance heat transfer from the flue gases to the water. In still other embodiments, the tank 14 may be configured to receive the hot flue gases from the gas burner 18 (instead of the water), and the water flows through a coil (e.g., coil section 54c). In this alternative embodiment, the gas burner 18 and the exhaust assembly 30 are in fluid connection with the tank 14, and the water inlet 42 and the water outlet 46 are each in fluid connection with the heat exchanger coil (e.g., the coil section 54c). As such, in this alternative configuration, the water heater 10 is a tankless water heater. Furthermore, the water heater 10 may further include flue gas flow members (e.g., baffles, plates, etc.) positioned within the tank 14 to facilitate the flow of the flue gases proximate the heat exchanger coil receiving the water. This may increase the heat transfer between the water and the flue gases. The intermediate section 66, in this embodiment, is in fluid connection with the tank 14. The flue gas flow members may direct the condensate toward the intermediate section 66.

With continued reference to FIG. 1, the exhaust assembly 30 further includes a condensate collector or drain assembly 90 in fluid connection with the intermediate section 66. The drain assembly 90 includes a condensate collector 94 and a drain line 98. After having rejected heat from the combustion products to the water with the tank 14 by way of the heat exchanger within the tank 14, the gaseous components of the combustion products are exhausted by way of an exhaust vent 70, while the liquid condensate is removed to a drain by way of the condensate drain line 98. The condensate flows (e.g., by gravity) to the condensate collector 94 from the intermediate section 66. The condensate collector 94 functions as a trap to prevent the gaseous exhaust products from venting out through the condensate drain. Condensate will collect in the collector 94 until it reaches the height of the drain line 98, after which the condensate will drain away through the drain line 98 by gravity. The gaseous exhaust products, which are lighter than air, will rise unobstructed through the vertical vent 70.

With continued reference to FIG. 1, the intermediate section 66 may include a first portion 106 and a second portion 110. The illustrated first portion 106 is formed by a first material, and the second portion 110 is formed by a second material different than the first material. For example, in the illustrated embodiment, the first material of the first portion 106 is metal (e.g., aluminum), and the second material of the second portion 110 is a non-heat conducting material such as rubber. Furthermore, the vent pipe 70 is formed of a third material such as plastic piping (polyvinyl chloride (“PVC”) pipe). The first, second, and third materials are configured to withstand the temperatures of the condensate stream and the flue gases as both exit the water heater 10 (through the drain line 98 and the vent pipe 70, respectively).

FIG. 2 illustrates the condensate collector 94 for a water heater 10 according to some embodiments. In the exemplary embodiment of FIG. 2, the condensate collector 94 is formed of a fourth material such as cast aluminum or polyvinyl chloride (PVC). The vent pipe 70 and the condensate drain line 98 are connected to the condensate collector 94 at the time of installation.

In order to detect a condition where water under pressure is entering the combustion system (i.e., the heat exchanger 12, the combustion chamber 22, the gas burner 18, pipe sections 54a, 54b, and 54c, and/or the exhaust assembly 30), such as through a crack or hole in the heat exchanger 12, a branch extension 150 extending a short distance (e.g. about one inch) vertically from the condensate drain line 98 is added, as shown in FIG. 3. The branch extension is for example a T-fitting along the drain line 98, where two ends of the “T” connect to and form part of the drain line 98, and the third end of the “T” is open to the atmosphere, i.e., the opening 152. The opening 152 shown in FIG. 3 extends upwards with respect to gravity. Alternatively, the vertical branch extension 150 can, after extending upward for a sufficient distance, extend in another direction so that the opening 152 does not face upward with respect to gravity. As shown in FIGS. 4A and 4B, the branch extension 150 can include a bend 156 that is 180° such that the opening 152 extends downwards. This can reduce the likelihood that dust, debris, etc. will drop into the condensate line 98 via the opening 152. The other structure shown in FIG. 3, such as the vent pipe 70, the condensate collector 94, and the water heater 10 remains the same.

The branch extension 150 forms the opening 152, which is open to atmospheric pressure, but during normal operation (with no water leak into the combustion system) there is no condensate flow out of the opening 152. Since the pressure of the exhaust downstream of the heat exchanger 12 is very low—near atmospheric pressure—there is insufficient head pressure in the condensate to provide the vertical lift that would be necessary to direct water through the condensate trap and out of the opening 152 of the branch extension 150. As a result, during normal operation the condensate will pass directly through the condensate drain line 98. An example of this normal operation is shown in FIG. 4A.

If a large enough leak develops in the heat exchanger 12, then pressurized water from the tank 14 will flow into the heat exchanger 12 through that leak. The pressurized water will very rapidly fill the entire combustion system, including the condensate collector 94. The condensate drain line 98 is insufficient in size (i.e., a diameter of the drain line 98 is too small) to drain away all of this pressurized water, and water will accumulate within the condensate collector 94 to a height that exceeds the elevation of the opening 152. As a result, the head pressure at the branch extension 150 will be sufficient to provide the necessary rise such that water passes through and out of the opening 152. Generally, the pressure of the pressurized water will be enough to cause water to spray out of the opening 152. An example of this failure operation is shown in FIG. 4B.

With reference to FIG. 3, a moisture sensor 160 may be arranged at a location where it will detect the spray of water through the opening 152. Various types of moisture sensors 160 are available for use. Such a moisture sensor 160 can include two conductive elements that are part of a low-voltage circuit. The two conductive elements are spaced a short distance apart from one another to create a normally electrically open condition in the circuit. When water is present at the sensor 160, the water (due to its substantially greater electrical conductivity than air) will electrically short together the two conductive elements, thereby completing the low-voltage circuit.

A controller 170 is electrically connected to the low-voltage circuit, and the controller 170 is configured to detect that the low-voltage circuit in the sensor 160 has been completed. The controller 170 can also be electrically connected to an electronic shut-off valve 180 arranged upstream of the water heater inlet line 42. The shut-off valve 180 is shown in FIG. 1. In response to determining that the low-voltage circuit has been completed, the controller 170 engages the shut-off valve 180 to mitigate the damage that would otherwise result from the pressurized water if water were allowed to continue to flow through the water inlet 42 and into the leaking heat exchanger 12. Once the shut-off valve 180 has closed, the pressure of water from the tank 14 will almost immediately drop to atmospheric pressure as water flows out of the tank 14 (such as through the condensate drain line 98 or the exhaust vent pipe 70). The controller 170 can also be configured to generate and transmit an alert indicating that a failure has occurred. Once the shut-off valve 180 has engaged, in some embodiments it remains in that state until the water heater 10 has been serviced or replaced.

With continued reference to FIG. 3, the water heater 10 can be placed into a drain pan 196 that extends to the location of the opening 152. In some embodiments, the moisture sensor 160 can be arranged within the drain pan 196 directly underneath the branch extension. Alternatively, the moisture sensor 160 can be integrated into the branch extension 150 at or near the opening 152. The branch extension 150 (and, optionally, the moisture sensor 160) can alternatively be provided as part of the drain assembly 90 or condensate collector 94.

FIG. 4A illustrates normal operation of the water heater 10, such that condensate 190 flows within the drain line 98 but does not erupt through the opening 152. FIG. 4B illustrates failure operation of the water heater 10, where a leak has occurred and pressurized water 192 erupts through the opening 152.

An additional aspect of the invention is depicted in FIGS. 5-7. FIG. 5 depicts a burner assembly for the water heater 10, including the burner 18 that is received into the combustion chamber 22. A blower 202 is coupled to the burner 18 in order to deliver a mixture of gas and air thereto, the mixture of air and gas being combusted in the burner 18 to produce the flue gases 212, which are then directed through the flue 26. The gas (depicted by arrow 211) is delivered to the blower 202 by way of the gas valve 203, and the air (depicted by arrow 210) is delivered to the blower 202 by way of a flexible coupling 204 (such as a coupling produced by Fernco, Inc.). An inlet end 205 of the flexible coupling 204 is connected to an inlet air duct 220, a portion of which is depicted in FIG. 6.

In at least some preferable embodiments, the inlet air duct 220 is constructed from polyvinyl chloride (PVC) components rated for drain, waste and venting (DWV) applications. The inlet air duct 220 includes a fitting 221, generally referred to as a “wye” fitting, having a main conduit 224 and a branch 223 arranged at an angle to, and in fluid communication with, the main conduit 224. An outlet 222 of the fitting 221 connects to the inlet end 205 of the flexible coupling 204, for example with a worm gear clamp. An inlet end 229 of the fitting 221 is coupled to ductwork 225. The ductwork 225 can be field-installed as part of the installation of the water heater 10, and can be solvent welded to the inlet end 229 when the water heater 10 is installed. The exact arrangement of the ductwork 225 will vary with the requirements of each installation, but will generally extend to a location from where ambient air needed for combustion can be drawn. In many cases, this ductwork 225 will need to extend vertically upward to, for example, penetrate through a roof of the building that houses the water heater 10. The inlet air duct 220 and the ductwork 225 form part of the flue gas circuit 34.

The branch 223 of the inlet air duct 220 is provided with a pressure relief mechanism 230. The exemplary pressure relief mechanism 230 includes an orifice 234 which is closed off during normal operation by a pivoting door 231. A spring mechanism 232 maintains the door 231 in a closed position against a seat 233 that surrounds the orifice 234 in order to prevent flow through the branch 223. During normal operation, since the entire inlet air duct 220 is arranged on the suction side of the blower, the pressure in the fitting 221 will be sub-atmospheric. The pressure relief mechanism will therefore also operate as a check-valve during normal operation, to prevent air in the ambient space surrounding the water heater 10 from entering through the open end 226 of the branch 223.

In the event that the previously-described leak in the heat exchanger 12 occurs, the pressurized water from the interior space 50 of the tank can fill the burner assembly 201 and, potentially, propagate through the gas valve 203 and into the gas distribution system. In order to prevent such an occurrence, the spring mechanism 232 can be configured to allow the door 231 to displace off of the seat 233 under an acting pressure that is less than the pressure that the gas valve 203 is capable of withstanding. By way of example, the gas valve 203 may have a back pressure rating of 50 mbar. Such a back pressure may be exceeded when the inlet air duct fills with leaking water to a height exceeding twenty inches in the ductwork 225. By having the pressure relief mechanism 230 actuate at a lower pressure (for example, at a pressure of 45 mbar, or 40 mbar, or 35 mbar, etc.), the leaking water 192 will pass through the orifice and be discharged out the open end 226 of the branch 223. The branch 223, the orifice 234, and the spring mechanism 232 can all be sized such that the leaking water 192 can be effectively dissipated and the threshold back-pressurization of the gas valve 203 can be prevented. By way of example, on a water heater requiring three inch internal diameter air inlet ducting to the provide the combustion air, a two inch internal diameter branch 223 can be sufficient to protect the gas valve with even a relatively large leak in the heat exchanger.

It should be understood that the open end 226 need not be arranged immediately adjacent the pressure relief mechanism 230, as shown in FIG. 7. Additional ductwork can be connected to continue the branch 223, for example to direct leaking water to a drain.

The described inlet air duct 220 can be provided as a sole means for mitigating the leakage resulting from a heat exchanger failure, or can be combined with one or more aspects previously described herein. By way of example, the inlet air duct 220 can be combined with the condensate line branch extension 150, to provide for a leaking water relief path in cases where the heat exchanger leak is of a size that results in a water leakage rate in excess of that which the condensate line can accommodate. As another example, the moisture sensor 160 can be arranged within the branch 223 to detect the leakage condition.

Although aspects have been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects as described.

Claims

1. An assembly for use in heating water in a water heater system, the assembly comprising: a burner assembly, the burner assembly including a gas inlet, an air inlet, and a flue gas outlet, the burner assembly configured such that gas passing through the gas inlet and air passing through the air inlet are combusted before passing through the flue gas outlet, andan inlet air duct connected to the air inlet such that air passes through the inlet air duct prior to passing into the air inlet,wherein the inlet air duct includes an outlet connected to the air inlet, a duct inlet configured to receive air, and a main conduit connecting the duct inlet and the outlet, andwherein the main conduit includes a branch connected to a pressure relief mechanism, the pressure relief mechanism configured to open when the main conduit reaches a predetermined pressure value.

2. The assembly of claim 1, wherein the gas inlet includes a gas valve having a backpressure rating, wherein the predetermined pressure value is less than the backpressure rating, and wherein the pressure relief mechanism is configured to flow water from the main conduit when pressure in the main conduit reaches the predetermined pressure value.

3. The assembly of claim 1, wherein the branch includes an orifice, and wherein the pressure relief mechanism operates to selectively seal the orifice.

4. The assembly of claim 3, wherein the air inlet is connected to ductwork, and wherein the main conduit is configured to reach the predetermined pressure value as a result of pressure created by water within the ductwork.

5. The assembly of claim 3, wherein the pressure relief mechanism includes a door extending between a seat and a spring, and wherein the spring biases the door against the seat to seal the orifice.

6. The assembly of claim 5, wherein the spring is configured such that, when the predetermined pressure value is met or exceeded, pressure in the main conduit pushes the door off of the seat so that fluid can escape past the door and through the orifice.

7. The assembly of claim 5, wherein the burner assembly includes a blower arranged such that a suction side of the blower creates a vacuum in the main conduit, and wherein the vacuum in the main conduit operates to hold the door against the seat.

8. The assembly of claim 1, wherein the inlet air duct is formed from polyvinyl chloride (PVC).

9. The assembly of claim 8, wherein the air inlet of the burner assembly is connected to the outlet of the inlet air duct via a flexible coupling.

10. A water leakage detection system for a water heater system, comprising: a flue gas circuit extending through a tank of the water heater system, the flue gas circuit comprising: a burner;an inlet air duct arranged to provide combustion air to the burner;a heat exchanger arranged downstream of the burner; anda condensate trap arranged downstream of the heat exchanger;a condensate drain line coupled to the condensate trap; anda pressure relief opening configured to discharge water leaking from the tank of the water heater system into the flue gas circuit, the pressure relief opening being provided in one of the inlet air duct and the condensate drain line, wherein fluid flow through the pressure relief opening is prevented during normal operation of the water heater system.

11. The water leakage detection system of claim 10 further comprising a moisture sensor, and wherein the moisture sensor is configured to detect water passing through the pressure relief opening.

12. The water leakage detection system of claim 11, wherein the water leakage detection system is installed within the water heater system, wherein the moisture sensor is used as an input for controlling a shutoff valve, and wherein the shutoff valve is configured to, after the moisture sensor detects the water passing through the pressure relief opening, shut off a water supply to the water heater system.

13. The water leakage detection system of claim 10, wherein the water leakage detection system is configured to allow fluid flow through the pressure relief opening when a pressure at the pressure relief opening exceeds a predetermined pressure value.

14. The water leakage detection system of claim 13, further comprising a spring mechanism, wherein the predetermined pressure value is determined by the spring mechanism.

15. The water leakage detection system of claim 13, wherein the predetermined pressure value is determined by an elevation distance between the pressure relief opening and the condensate trap.

16. An inlet air duct configured to connect to an air inlet of a burner assembly of a water heater system, the air inlet duct comprising: an outlet connected to the air inlet of the burner assembly,a duct inlet configured to receive air,a main conduit connecting the duct inlet and the outlet,a branch connected to the main conduit, anda pressure relief mechanism connected to the branch,wherein the pressure relief mechanism is configured to open when the main conduit reaches a predetermined pressure value.

17. The inlet air duct of claim 16, wherein the pressure relief mechanism is configured to flow water from the main conduit when the main conduit reaches the predetermined pressure value.

18. The inlet air duct of claim 16, wherein the branch includes an orifice, and wherein the pressure relief mechanism operates to selectively seal the orifice.

19. The inlet air duct of claim 16, wherein the duct inlet is connected to ductwork, and wherein the main conduit is configured to reach the predetermined pressure value as a result of pressure created by water within the ductwork.

20. The inlet air duct of claim 18, wherein the pressure relief mechanism includes a door extending between a seat and a spring, and wherein the spring biases the door against the seat to seal the orifice.

21. The inlet air duct of claim 20, wherein the spring is configured such that, when the predetermined pressure value is met or exceeded, pressure in the main conduit moves the door off of the seat so that the water can escape past the door and through the orifice.

22. The inlet air duct of claim 16 further comprising a moisture sensor, and wherein the moisture sensor is configured to detect moisture in the branch.

23. The inlet air duct of claim 22, wherein the air inlet duct is configured such that air passing through the air inlet duct is used by the burner assembly to heat water in the water heater system, wherein the moisture sensor is configured to be used as an input for controlling a shutoff valve, and wherein the shutoff valve is configured to, after the moisture sensor detects moisture in the branch, shut off a water supply to the water heater system.