EP3418649B1

EP3418649B1 - Hot water appliance and hot water system using the same

Info

Publication number: EP3418649B1
Application number: EP18178917.3A
Authority: EP
Inventors: Lili Chen; Bo Wang; Wenjie CHENG; He Ting WANG
Original assignee: Vaillant Wuxi Heating Equipment Co Ltd; Vaillant GmbH
Current assignee: Vaillant Wuxi Heating Equipment Co Ltd; Vaillant GmbH
Priority date: 2017-06-21
Filing date: 2018-06-21
Publication date: 2020-11-04
Anticipated expiration: 2038-06-21
Also published as: EP3418649A1; CN107461933A; ES2847048T3

Description

FIELD OF THE INVENTION

The present invention relates to the field of hot water system, and more particularly to a water preheating circulation assembly suitable for domestic hot water system.

BACKGROUND OF THE INVENTION

When turning on a hot faucet to start a domestic hot water appliance, such as a gas water heater, a user often has to wait a long time for hot water output from the hot faucet. This is because, on one hand, there is a large amount of cold water remaining in water pipelines within or outside of the appliance, and this amount of cold water has to be drained out first and then hot water comes out; on the other hand, at the beginning of starting the gas water heater, for consideration of security, a blower will be first activated to exhaust residual gas within the combustion chamber and flue pipes, and the combustion burner will be ignited after the residual gas being all replaced by fresh air, during the period, hot faucet continuously outputs cold water. Obviously, the big volume of drained cold water causes the waste of water resources. In addition, this will lead to a poor user experience, for example, when the user desires to take a shower in winter, the user has to wait a long time to get hot water.
One of the applicants of present application has ever filed a patent application that has been published with the number CN 105299875 A and discloses a gas-fired water heating appliance having a preheat function. The appliance is provided with a water pump and a water tank for preheating cold water in the pipelines before a user can use it so that hot water can be supplied immediately when the user turns on the hot water faucet, thereby improving the user's experience. However, in this invention, the water pump is only mounted in the water preheating circuit, and it would not work when there is a need for providing domestic hot water at certain water consuming point.
The Chinese patent CN 103712329 B discloses a gas water heater with a preheat function. The gas water heater has a cold water incoming line 31 where a water pump 11 is mounted, one pipe section with a flow sensor 4 mounted therein connected between the cold water incoming line 31 and water mains, and another pipe section with an electromagnetic water valve 7 mounted therein connected between the cold water incoming line 31 and returning pipelines 10. When the incoming cold water is detected by the flow sensor 4, the water pump 11 is activated, and the electromagnetic water valve 7 is actuated to be open to allow water coming from the returning pipelines to enter the appliance for being preheated.
During supplying hot water, a user may feel the water sometimes hot and sometimes cold due to the instability of the water pressure, which obviously reduce the comfort for the user. In addition, in hot summer, the temperature of water output from the gas water heater may be higher than a preset outlet temperature. This is because, the inlet water temperature is relatively high as ambient temperature is high, therefore, even if the gas water heater works at a minimum workload, the temperature of water can readily reach and exceed the preset outlet temperature. Especially for a constant-temperature water heater that can output water with a constant temperature preset by the user. In this case, the temperature of water directly output from the hot faucet of certain water consuming point is often higher than the preset outlet temperature, which results in poor user's experience or even burn the user.
In view of this, it is necessary to improve the existing hot water appliance to solve the above problems.

SUMMARY OF THE INVENTION

It is an object of present invention to provide a hot water system using a hot water appliance capable of providing domestic hot water instantly when there is demand for hot water at a water consuming point, and at the same time ensuring that the temperature of output hot water can be stably maintained at a preset outlet temperature.
According to the present invention there is provided a hot water system including a hot water appliance, a cold water line connected to the first water inlet port of the hot water appliance, a hot water line connected to the water outlet port of the hot water appliance; and a return water line having one end connected to the second water inlet port of the hot water appliance and the other end connected with the hot water line. The hot water appliance including a housing, a heat source, and a hydraulic assembly. The housing has a first water inlet port, a second water inlet port, and a water outlet port. The heat source is disposed in the housing. The hydraulic assembly is disposed in the housing and including a heat exchange line for allowing water passing therethrough to absorb heat generated by the heat source, a first pipe section connected with the first water inlet port and communicating with the heat exchange line, and a second pipe section connected with the second water inlet port and communicating with the heat exchange line, wherein the first pipe section and the second pipe section are arranged in parallel. A circulation pump is disposed in the heat exchange line. A flow sensor is disposed in the first pipe section. An electrically actuated valve is provided in the second pipe section. Wherein the circulation pump is capable of operating in a normal mode and a boost mode; and the hot water appliance further includes a controller electrically connected with the circulation pump, the flow sensor, and the electrically actuated valve; and wherein the controller is configured to control the electrically actuated valve to be closed to block the flow of water in the second pipe section and to activate the circulation pump to operate in the boost mode when the controller detects there is a flow of water in the first pipe section through the flow sensor.
Wherein, the controller activates the circulation pump to operate in a normal mode on receiving a trigger signal, at this time, the electrically actuated valve is in an open state, and the water is pumped through the second pipe section into the heat exchange line.
In one embodiment, the hot water appliance further includes a timer electrically connected with the controller; when a preset time is reached, the controller receives the trigger signal from the timer.
In a preferred or an alternative embodiment, the hot water appliance further includes a wireless communication module electrically connected with the controller, and the controller receives the trigger signal through the wireless communication module.
Preferably, the hot water appliance further includes a temperature sensor disposed in the heat exchange line; and the controller is configured to detect the temperature of water within the heat exchange line through the temperature sensor and to deactivate the operation of the circulation pump when the detected temperature reaches a predetermined threshold.
Preferably, the controller includes an appliance control unit and a pump control unit electrically connected with the appliance control unit; wherein the appliance control unit is electrically connected to the flow sensor, and the pump control unit is electrically connected to the circulation pump and the electrically actuated valve.
In a preferred embodiment, the electrically actuated valve includes a motor electrically connected to the controller and a valve engaged with the motor, wherein the motor is driven by the controller to control the valve to open or close.
Compared with the state of art, the present invention has the advantages that: since the circulation pump is disposed in the heat exchange line, the stability of the pressure of cold water supplied can be assured. In addition, as the circulation pump is operated in the boost mode, it can create increased pressure to the cold water to further increase the supply of cold water. Therefore, even in a hot summer, when the ambient temperature is close to the outlet water temperature preset by the user, the temperature of hot water output from the gas water heater can be steadily kept at the preset value, thereby avoiding causing user's discomfort due to the overheating water.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a schematic working principle diagram of a hot water system in accordance with one embodiment of present invention;
Fig. 2 is a schematic working principle diagram of a hot water system in accordance with another embodiment of present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawing figures to describe the preferred embodiments of the present invention in detail. However, the embodiments can not be used to restrict the present invention. Changes such as structure, method and function obviously made to those of ordinary skill in the art are also protected by the present invention.
The hot water system of the present invention is suitable for home applications and can be used to provide domestic hot water and/or space heating. The hot water system includes a hot water appliance. The hot water appliance may be a gas water heater fired with combustible gas, or may be an appliance for heating water by heat exchangers, such as a solar water heater or a heat pump. Gas-fired water heating appliances are used to heat domestic water by burning combustible gas to meet the needs of hot water for users, such as gas water heaters that provide domestic hot water, or gas boilers that can provide both domestic hot water and needs of space heating. A gas water heater will be examplified to explain the present invention in details in the following embodiments.
Referring to Fig. 1, a hot water system 100 in accordance with a first embodiment of present invention, includes a gas water heater, a cold water line 81 connected to a water inlet of the gas water heater (a first water inlet port 11 that will be described in details later) to provide cold water. A hot water line 82 connected to a water outlet of the gas water heater (an outlet port 12 that will be described in details later) to output hot water, and a return water line 83 connected between the gas water heater and the hot water line 82. The return water line 83 is connected to a second water inlet port 13 (described in details later) of the gas water heater. The cold water line 81, the hot water line 82, and the return water line 83 may be formed by a single water pipe, or may be composed by a number of water pipes connected in series. The hot water line 82 is mainly provided to allow the flow of hot water discharged from the gas water heater when the gas water heater is in operation, and when the gas water heater is not in operation, the water remained in the hot water line gradually cools to the room temperature that equals to the temperature of water remained in the cold water line 81. The hot water system 100 also includes a number of water consuming points 91 (only one is shown in the figure), and the hot water line 82 is connected to pipe joints at the water consuming points.
The gas water heater includes a housing 10, and a heat source 20, a heat exchanger 30, a gas exhausting device 40, and a hydraulic assembly are all disposed in the housing. The housing 10 is provided at the bottom thereof with the first water inlet port 11, the second water inlet port 13, and a water outlet port 12. The first and the second water inlet ports and the water outlet port may take form of pipe joints. The heat source 20 may be a burner composed of a number of burner blades (not shown) arranged side by side. Each burner blade may be provided with a gas-air mixture passage where gas supplied through a gas line (not shown) mixes with primary air to form gas-air mixture that is further delivered to fire holes at the top of the burner blade to be burnt to generate heat. The heat exchanger 30 is mounted above the burner 20, and it can be in form of a finned tube heat exchanger, that is, a number of fins (not shown) are disposed in a heat exchanger shell with a heat exchange line 143 extending through the fins transversely. Similarly, the heat exchange line 143 may be formed by a single water pipe, or may be composed by a number of water pipes connected in series. The burner 20 burns the gas-air mixture and generates high-temperature flue gas. When the flue gas passes through the heat exchanger 30, the flue gas dissipates heat to the fins, and the heat is further transferred to the water flowing through the heat exchange line. The flue gas is then collected by the gas exhausting device 40 and discharged to outdoors.
The hydraulic assembly includes the heat exchange line 143 that has one end connecting to the water outlet port 12, a first pipe section 141 connected to the first water inlet port 11 and communicating with the heat exchange line 143, and a second pipe section 142 connected to the second water inlet port 13 and communicating with the heat exchange line 143. The water flowing through the heat exchange line 143 is heated by the heat exchanger 30 and then enters the hot water line 82 through the water outlet port 12, thereby outputting domestic hot water at the water consuming point 91. The first pipe section 141 and the second pipe section 142 are arranged in parallel. The first and the second pipe sections 141, 142 may be formed by a single water pipe or a part of the single water pipe, or may be composed by multiple water pipes connected in series.
A flow sensor 53 is provided in the first pipe section 141 to detect the flow of water in the first pipe section. An electrically actuated valve 54 is disposed in the second pipe section 142. In this embodiment, the electrically actuated valve 54 includes a motor and a valve engaged with the motor. The motor can be a step motor with a motor shaft engaged with the valve, thus the valve is driven by the rotation of the motor shaft to generate a linear movement, so as to make the valve open and close. In this embodiment, the electrically actuated valve 54 is in a normally open state. A circulation pump 51 is provided in the heat exchange line 143. The circulation pump 51 is a booster pump capable of operating in a normal mode and a boost mode. When being operated in the boost mode, the circulation pump creates increased pressure to the water flowing in the pipeline, which result in a water flow rate greater than that in the normal mode. A temperature sensor 52 is provided in the heat exchange line 143.
A controller is also provided in the housing 10. In this embodiment, the controller includes an appliance control unit 61 and a pump control unit 62 electrically connected with the appliance control unit 61. The appliance control unit 61 is configured to control the operation of most of the electrical devices of the gas water heater, such as controlling the ignition of the ignition unit (not shown) of the burner, the operation of the gas proportional valve (not shown), and so on. The appliance control unit 61 is also electrically connected with the flow sensor 53 and the temperature sensor 52. The pump control unit 62 is electrically connected with the circulation pump 51 and the electrically actuated valve 54 to control the operation of these two devices. The appliance control unit 61 and the pump control unit 62 each may be a logic control circuit formed by a number of electronic components connected in accordance with certain wiring patterns; or it may also be a microcontroller (MCU) storing program instructions; or it may be integrated chips with specific use, such as Field-Programmable Gate Arrays (FPGAs).
In this embodiment, a timer 71 and the appliance control unit 61 are electrically connected via electric wires or cables. The timer may be an electronic timer, which is disposed outside of the housing 10 and has a time setting interface. The user may preset a time for preheating water remaining in pipelines. When the preset time is reached, the timer 71 will transmit a trigger signal to the appliance control unit 61, then the appliance control unit 61 activates the circulation pump 51 to operate. A wireless communication module 72 is also connected to the appliance control unit 61 through electric wires or cables. In this embodiment, the wireless communication module 72 may be a Wi-Fi module, which can perform wireless communication with a mobile terminal (not shown) through a wireless router (not shown). For example, the mobile terminal may be a smart phone with installing an application (APP) suitable for the control of the gas water heater, and the user can start the preheating cycle of the hot water system at any time he or she desires through the application. In the meantime, the appliance control unit 61 receives the trigger signal from the user's smart phone through the wireless communication module 72, so as to activate the circulation pump 51 to operate. In this embodiment, the gas water heater is equipped with both the timer and the wireless communication module to allow the user to selectively trigger the operation of the circulation pump. However, in alternative embodiments, the gas water heater may only be equipped with one of the timer and the wireless communication module for the purpose of reducing costs.
When there is a need of hot water at the water consuming point 91, cold water in the cold water line 81 enters the heat exchange line 143 through the first water inlet port 11 and the first pipe section 141. The appliance control unit 61 sends a corresponding signal to the pump control unit 62 when the flow sensor 53 detects there is a flow of water in the first pipe section 141. In response to receiving the signal, the pump control unit 62 controls the electrically actuated valve 54 to be closed to shut off the flow of water in the second pipe section 142, and at the same time, to activate the circulation pump 51 to work in the boost mode. After being heated by the heat exchanger 30, the water flows out of the gas water heater through the water outlet port 12, and is supplied to the water consuming point 91 via the hot water line 82. Since the circulation pump 51 is disposed in the heat exchange line 143, the stability of the pressure of cold water supplied can be assured. In addition, as the circulation pump is operated in the boost mode, it can create increased pressure to the cold water to further increase the supply of cold water. Therefore, even in a hot summer, when the ambient temperature is close to the outlet water temperature preset by the user, the temperature of hot water output from the gas water heater can be steadily kept at the preset value, thereby avoiding causing user's discomfort due to the overheating water.
The user can preset the time to start the preheating cycle within the hot water system through the timer 71, or turn on the preheating cycle through specific application on the smart phone. When the appliance control unit 61 receives the trigger signal from the timer 71 or the wireless communication module 72, it sends a corresponding signal to the pump control unit 62, and then the pump control unit 62 activates the circulation pump 51 to operate in the normal mode. If the electrically actuated valve 54 is in the closed state at this time, the pump control unit 62 actuates the electrically actuated valve to open the valve; if the electrically actuated valve 54 is in the normally open state at this time, the pump control unit 62 does nothing to the electrically actuated valve. Therefore, the water in the second pipe section 142 flows through the heat exchange line 143 and enters the hot water line 82 via the water outlet port 12 after being heated by the heat exchanger 30, and then passes through the return water line 83 and goes back into the gas water heater again via the second water inlet port 13. In this way, the water remaining in the pipelines can be continuously heated by repeating the preheating cycle. At the same time, the appliance control unit 61 monitors the temperature of the water in the water preheating circuit through the temperature sensor 52. When the detected temperature reaches a predetermined threshold, the appliance control unit 61 deactivates the circulation pump 51 through the pump control unit 62, and cuts off the gas supply and stops the operation of the burner, thereby avoiding the water within the preheating circuit being overheated and preventing the user from being burned when the user turns on the hot faucet.
Fig. 2 shows a hot water system in accordance with a second embodiment of the present invention. The main difference from the above-described embodiments is that, the controller includes only the appliance control unit 61, in other words, the pump control unit 62 in the above embodiments is integrated into the appliance control unit 61. Since the operation performed by present controller is similar to that performed by the controller composed of the appliance control unit and the pump control unit as described in the above embodiments, the applicant will not repeat them hereinafter. In the present embodiment, the appliance control unit 61 is electrically connected to the circulation pump 51, the temperature sensor 52, the flow sensor 53, the electrically actuated valve 55, the timer 71, and the wireless communication module 72 via wires or cables. In addition, the electrically actuated valve 55 in this embodiment is in the form of a solenoid valve, i.e., it does not require a motor, instead, the operation of opening and closing of the valve is controlled by the electromagnetic force.
It is to be understood, however, that even though numerous, characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosed is illustrative only, and changes may be made in detail, especially in matters of number, shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broadest general meaning of the terms in which the appended claims are expressed.

Claims

A hot water system (100, 200), wherein the system comprises:
a hot water appliance comprising:
a housing (10) having a first water inlet port (11), a second water inlet port (13), and a water outlet port (12);

a heat source (20) disposed in the housing;

a hydraulic assembly disposed in the housing and comprising a heat exchange line (143) for allowing water passing therethrough to absorb heat generated by the heat source, a first pipe section (141) connected with the first water inlet port and communicating with the heat exchange line, and a second pipe section (142) connected with the second water inlet port and communicating with the heat exchange line; wherein the first pipe section and the second pipe section are arranged in parallel;

a circulation pump (51) disposed in the heat exchange line;

a flow sensor (53) disposed in the first pipe section; and

an electrically actuated valve (54) provided in the second pipe section;

and the hot water appliance further comprises a controller electrically connected with the circulation pump, the flow sensor, and the electrically actuated valve; wherein the hot water system further comprises;

a cold water line (81) connected to the first water inlet port (11) of the hot water appliance;

a hot water line (82) connected to the water outlet port (12) of the hot water appliance; and

a return water line (83) having one end connected to the second water inlet port (13) of the hot water appliance and the other end connected with the hot water line (82), characterized in that
the circulation pump (51) is capable of operating in a normal mode and a boost mode, and in that
the controller is configured to control the electrically actuated valve (54) to be closed to block the flow of water in the second pipe section (142) and to activate the circulation pump (51) to operate in the boost mode when the controller detects there is a flow of water in the first pipe section (141) through the flow sensor (53).
A hot water system according to claim 1, characterized in that the controller is further configured to activate the circulation pump to operate in a normal mode on receiving a trigger signal, at this time, the electrically actuated valve is controlled to be in an open state, and the water is pumped through the second pipe section into the heat exchange line.
A hot water system according to claim 2, characterized in that the hot water appliance further comprises a timer (71) electrically connected with the controller; when a preset time is reached, the controller is further configured to receive said trigger signal from the timer.
A hot water system according to claim 2 or 3, characterized in that the hot water appliance further comprises a wireless communication module (72) electrically connected with the controller, and the controller is further configured to receive said trigger signal through the wireless communication module.
A hot water system according to claim 1 or 2, characterized in that the hot water appliance further comprises a temperature sensor (52) disposed in the heat exchange line; and the controller is further configured to detect the temperature of water within the heat exchange line through the temperature sensor and to deactivate the operation of the circulation pump when the detected temperature reaches a predetermined threshold.
A hot water system according to claim 1, characterized in that the controller comprises an appliance control unit (61) and a pump control unit (62) electrically connected with the appliance control unit; wherein the appliance control unit is electrically connected to the flow sensor, and the pump control unit is electrically connected to the circulation pump and the electrically actuated valve.
A hot water system according to claim 1, characterized in that the electrically actuated valve comprises a motor electrically connected to the controller and a valve engaged with the motor, wherein the motor is driven by the controller to control the valve to open or close.