Water heater

Abstract

To provide a water heater capable of enhancing corrosion resistance of a heat exchanger.SOLUTION: A water heater comprises: a heat source machine 2; a water supply pipe 7; a heat exchanger 6 for heating water from a water supply pipe 7 by heat generated by the heat source machine 2; a hot water supply pipe 8 for delivering hot water by the heat exchanger 6; flow rate measurement means 12 for measuring the flow rate of hot water flowed into the hot water supply pipe 8; water temperature measurement means 38 for measuring the temperature of hot water in the heat exchanger 6; a control part 22 for controlling operation of the heat source machine 2; a corrosion resistance electrode 70 disposed so as to come into contact with hot water inside the hot water supply pipe 8 or the heat exchanger 6, for inhibiting a metal material of the hot water supply pipe 8 or the heat exchanger 6 from dissolving into the hot water and corroding; and a counter electrode 71 of the corrosion resistance electrode 70. The control part 22, when a value detected by the flow rate measurement means 12 is less than a first flow rate and a value detected by the water temperature measurement means 38 is equal to or more than a first temperature, makes a corrosion resistance current flow between the corrosion resistance electrode 70 and the counter electrode 71 for a predetermined time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water heater. [Background technology]

[0002] Conventionally, this type of device has been equipped with a burner as a heat source, a water supply pipe, a heat exchanger that uses heat generated by the burner to heat the hot water from the water supply pipe, and a hot water outlet pipe that outputs the hot water from the heat exchanger, the water supply pipe is provided with a flow rate sensor that detects the flow rate, the burner is equipped with a vaporization heater that heats the fuel oil to an ignition temperature and vaporizes it, and when the operation switch is turned on, electricity is passed through the vaporization heater, and the device goes into a standby state where the temperature at which the fuel oil can be vaporized, for example the vaporizer temperature is maintained at 200°C to 250°C (for example, Patent Document 1).

[0003] In addition, a hot water supply device uses one burner to heat a hot water supply circuit having a water supply pipe, a heat exchanger, and a hot water outlet pipe, and a bath reheating circuit connected to a bathtub. During reheating operation, this hot water supply device ignites the burner and drives a circulation pump provided in the bath reheating circuit to circulate and heat the hot water in the filled bathtub. (For example, Patent Document 2) [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6826932 [Patent Document 2] JP 2002-191080 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in the conventional hot water supply device of Patent Document 1, the heater is preheated in standby mode so that hot water can be supplied immediately in response to a heat request. Due to this preheating, the water temperature in the heat exchanger rises to about 60°C to 70°C, and the inner wall of the heat exchanger is exposed to temperatures that are prone to pitting corrosion while in contact with still hot water.

[0006] Furthermore, in the conventional hot water supply device of Patent Document 2, during reheating operation, the burner is burned and a circulation pump in the bath reheating circuit is driven to circulate and heat the hot water in a filled bathtub, but when hot water is not being discharged from the hot water supply circuit, the burner is shared, so the water temperature in the hot water supply circuit rises partially, and the inner walls of the hot water supply circuit come into contact with still hot water and are exposed to temperatures that are prone to causing pitting corrosion.

[0007] In both types of water heating devices, the inner walls of the hot water circuit are in contact with still hot water and cold water and are exposed to temperatures that are prone to pitting corrosion. It is known that pitting corrosion is particularly likely to occur when the water temperature is around 70°C. Pitting corrosion can lead to water leaks, so there was room for improvement.

[0008] The present invention has been made in view of the above background, and has an object to provide a water heater capable of improving the corrosion resistance of a heat exchanger. [Means for solving the problem]

[0009] The present invention has been made to achieve the above-mentioned object, and claim 1 relates to a heat source unit, a water supply pipe, a heat exchanger that heats hot water from the water supply pipe using heat generated by the heat source unit, a hot water outlet pipe that outputs hot water from the heat exchanger, a flow rate measuring means that measures the flow rate of hot water flowing from the water supply pipe to the hot water outlet pipe, a water temperature measuring means that measures the temperature of the hot water in the heat exchanger, a control unit that controls the operation of the heat source unit, a corrosion-resistant electrode that is arranged in contact with the hot water inside the water outlet pipe or the heat exchanger and prevents the metal material of the hot water outlet pipe or the heat exchanger from dissolving into the hot water and corroding, and a counter electrode for the corrosion-resistant electrode, and the control unit is characterized in that when the detection value by the flow rate measuring means is less than a first flow rate and the detection value of the water temperature measuring means is equal to or higher than a first temperature, it flows a corrosion-resistant current between the corrosion-resistant electrode and the counter electrode for a predetermined time.

[0010] In claim 2, the heat source machine is a kerosene vaporization burner having a vaporizer with a vaporization heater that heats fuel oil to an ignition temperature to vaporize it, a vaporizer temperature detection means that detects the temperature of the vaporizer, and a fuel pump that supplies fuel oil to the vaporizer, and the vaporization heater is arranged below the heat exchanger, and the control unit is capable of preheating the vaporizer by passing electricity through the vaporization heater when the detection value of the flow measuring means is less than the first flow rate, and drives the heat source machine to dispense hot water when the detection value of the flow measuring means is equal to or greater than the first flow rate.

[0011] Claim 3 features a bath re-heating circuit equipped with a circulation pump for circulating and heating the hot and cold water in the bathtub, a bath heat exchanger connected to the bath re-heating circuit and heated by the heat source unit common to the heat exchanger, and a re-heating start means electrically connected to the control unit, wherein when the control unit is instructed by the re-heating start means to start re-heating, it drives the heat source unit and the circulation pump to circulate and heat the hot and cold water in the bathtub. Effect of the Invention

[0012] According to the present invention, a hot water supply device capable of improving the corrosion resistance of a heat exchanger can be provided. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic diagram of a water heater according to a first embodiment of the present invention; [Diagram 2] Block diagram of a water heater according to a first embodiment of the present invention. [Diagram 3] FIG. 2 is a flow chart of the water heater according to the first embodiment of the present invention. [Figure 4] FIG. 1 is a schematic diagram of a water heater according to a second embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A first embodiment of the present invention will be described with reference to FIGS.

[0015] Reference numeral 1 denotes a water heater of the first embodiment, 2 denotes a kerosene vaporization burner (hereinafter simply referred to as burner) as a heat source that burns fuel such as kerosene to generate a flame, 3a and 3b denote hot water taps provided in a kitchen, bathtub or the like, 4 denotes an operation remote control provided outside the bathroom as an operating means for remotely controlling the water heater 1, 5 denotes an operation remote control provided in the bathroom, and 50 denotes a bathtub.

[0016] Reference numeral 2a denotes a vaporization heater for heating the fuel oil supplied to the burner 2 to the ignition temperature and vaporizing it, reference numeral 2b denotes a vaporizer that incorporates the vaporization heater 2a and vaporizes the fuel oil, and reference numeral 2c denotes a nozzle that sprays the fuel oil into the vaporizer 2b. Reference numeral 2f denotes a fuel pump for sending fuel to the nozzle 2c, 2e denotes an ignition plug for igniting vaporized fuel, 2h denotes an igniter for discharging the spark plug 2e, and 2k denotes a carburetor temperature detection means such as a thermistor for detecting the temperature of the carburetor 2b. Reference numeral 41 a denotes a blower motor for blowing combustion air to the burner 2 .

[0017] Reference numeral 6 denotes a fin-and-tube type heat exchanger equipped with heat exchange fins 44 on a copper tube. Upstream of the heat exchanger 6 is a water supply pipe 7 connected to a water pipe, and downstream of the heat exchanger 6 is a hot water outlet pipe 8 having hot water taps 3a and 3b at their ends. Evaporation heater 2a is disposed below heat exchanger 6 in the installed state.

[0018] Reference numeral 9 denotes a bypass pipe that branches off from the water supply pipe 7, connects the water supply pipe 7 and the hot water outlet pipe 8, and bypasses the heat exchanger 6. At the connection between the hot water outlet pipe 8 and the bypass pipe 9, a mixing valve 10 is provided that mixes the hot water heated in the heat exchanger 6 with the water from the bypass pipe 9. The mixing valve 10 adjusts the valve opening of the internal valve body to adjust the mixture ratio of hot water and water, thereby discharging hot water at the desired temperature.

[0019] Reference numeral 11 denotes a supply water temperature sensor provided in the supply water pipe 7 for detecting the temperature of the supply water, 12 denotes a flow measuring means such as a flow rate sensor provided in the supply water pipe 7 for detecting the supply water flow rate of the heated fluid, and 13 denotes a heat exchanger outlet temperature sensor provided in the outlet water pipe 8 upstream of the connection between the outlet water pipe 8 and the bypass pipe 9, and the heat exchanger outlet temperature sensor 13 detects the temperature of the hot water flowing out of the heat exchanger 6. Reference numeral 38 denotes a water temperature detection means such as a thermistor for detecting the temperature of hot water in the heat exchanger 6 . Reference numeral 14 denotes an outlet hot water temperature sensor serving as outlet hot water temperature detection means for detecting the temperature of the hot water mixed by the mixing valve 10 .

[0020] The operation remote control 4 is equipped with a hot water temperature setting switch 19 which sets the hot water set temperature at which hot water is to be discharged from the mixing valve 10 and supplied to the hot water tap 3a and the hot water tap 3b, and an operation switch 47 which detects a push operation to turn on power to the evaporative heater 2a, and the operation remote control 5 is also equipped with switches similar to those on the operation remote control 4.

[0021] 70 is a corrosion-resistant electrode that is provided on the hot water outlet pipe 8 and is positioned and fixed so as to be in contact with the hot water inside the hot water outlet pipe 8, and prevents the metal material constituting the hot water outlet pipe 8 or the heat exchanger 6 from dissolving into the hot water and corroding. Reference numeral 71 denotes the counter electrode of the anticorrosive electrode 70, and specifically denotes the copper tube of the heat exchanger 6 which is the body to be protected from corrosion. The anticorrosive electrode 70 may be attached to the heat exchanger 6 with the attachment portion insulated.

[0022] Reference numeral 22 denotes a control unit that is connected wirelessly or by wire to operation remote controls 4 and 5 for mutual communication, receives signals from each sensor in water heating device 1 and signals from operation remote controls 4 and 5, and controls the drive of each actuator.

[0023] This control unit 22 has a target temperature setting means 23 that sets the heat exchange outlet target temperature of the hot water flowing out from the heat exchanger 6, and when hot water of the set temperature set by the hot water temperature setting switch 19 is discharged, it controls the combustion amount of the burner 2 so that the temperature of the hot water detected by the heat exchange outlet temperature sensor 13 becomes the heat exchange outlet target temperature set by the target temperature setting means 23. In other words, the amount of heat provided to the water flowing through the heat exchanger 6 by the burner 2 is controlled, and the opening degree of the mixing valve 10 is controlled so that the hot water temperature detected by the outlet hot water temperature sensor 14 becomes the set temperature set by the hot water temperature setting switch 19.

[0024] In the present invention, the control unit 22 is capable of executing an anticorrosion measure of passing an anticorrosion current between the anticorrosive electrode 70 and the counter electrode 71 for a predetermined time (e.g., 1 hour) when the value detected by the flow rate measuring means 12 is less than a first flow rate (e.g., 3 liters per minute) and the value detected by the water temperature measuring means 38 is equal to or higher than a first temperature (e.g., 60°C). Specifically, a voltage (e.g., DC 15 V) that cancels the pitting potential is applied.

[0025] Next, the operation of the first embodiment will be described.

[0026] When operation switch 47 is turned on, the system goes into a standby state in which vaporization heater 2a is preheated so that hot water can be supplied immediately in response to a heat request made by opening hot water taps 3a and 3b. As a result, the temperature of vaporizer 2b is maintained at 200°C to 230°C. Then, when the hot water taps 3a and 3b are opened and the detection value of the flow measuring means 12 becomes equal to or greater than a first flow rate (e.g., 3 liters per minute), it is determined that there is a heat request, and the combustion fan 41, igniter 2h, and fuel pump 2f are driven to proceed with the ignition operation. When the hot water taps 3a and 3b are opened, the fire is extinguished and the device goes into a standby state in which the evaporative heater 2a is preheated so that hot water can be supplied immediately in response to the next heat request.

[0027] Due to preheating of evaporation heater 2a, heat exchanger 6 is located above evaporation heater 2a in the installed state, so the temperature of heat exchanger 6 also rises, and the water temperature in heat exchanger 6 rises to about 60°C to 70°C.

[0028] The details will be explained based on FIG. First, when operation switch 47 is turned on (step S1), electricity is applied to vaporization heater 2a, and vaporizer 2b is heated to a temperature at which fuel oil is vaporized (step S2). If the detection value of the flow rate measuring means 12 is less than a first flow rate (e.g., 3 liters per minute) (step S3), that is, the standby state continues, and then it is determined whether the detection value of the water temperature measuring means 38, which is the temperature of the heat exchanger 6, is a first temperature (e.g., 60°C) or higher (step S4), and if it is the first temperature or higher, it is determined that corrosion prevention measures are necessary, and the process transitions to step S5. If the value detected by the water temperature measuring means 38 is less than the first temperature, the process proceeds to step S3 without taking any anti-corrosion measures.

[0029] In step S4, if the detection value of the water temperature measuring means 38 is equal to or higher than the first temperature, it is determined that anti-corrosion measures are necessary, a first timer is started (step S5), and an anti-corrosion current is applied between the anti-corrosion electrode 70 and the counter electrode 71 (step S6). Then, after the anticorrosive current is applied until the first timer reaches a predetermined time (for example, one hour) or more (step S7), the application of the anticorrosive current is stopped in step S8 (step S8), and the process transitions to step S3. It should be noted that, if the detection value of the flow rate measurement means 12 becomes equal to or greater than the first flow rate before the predetermined time has elapsed in step S7, the application of the anticorrosive current may be stopped.

[0030] If, in step S3, the detected value of the flow rate measuring means 12 is equal to or greater than the first flow rate (for example, 3 liters per minute) (step S3), it is determined that there is a heat request, and the process proceeds to step S9 to perform an ignition operation. That is, in step S9, the combustion fan 41 is driven, the igniter 2h is driven to discharge the ignition plug 2e (step S10), the fuel pump 2f is driven to spray the fuel into the carburetor 2b (step S11) to ignite the fuel, and the igniter 2h is turned off in step S12. This starts the combustion of the burner 2.

[0031] In step S13, if the detected value of the flow rate measuring means 12 again falls below the first flow rate (for example, 3 liters per minute), it is determined that the heat demand has disappeared, and the burner 2 is extinguished. That is, in step S14, the fuel pump 2f is stopped, and after a post-purge is performed (step S15), the combustion fan 41 is stopped (step S16), and the process transitions to step S3.

[0032] In the conventional technology, the evaporative heater 2a is preheated in standby mode so that hot water can be supplied immediately in response to a heat request. Due to the heat from this preheating, the water temperature in the heat exchanger 6 rises to approximately 60°C to 70°C, and the inner wall of the heat exchanger 6 is exposed to temperatures that are prone to pitting corrosion while in contact with still hot water.

[0033] In the present invention, the control unit 22 flows an anticorrosion current between the anticorrosion electrode 70 and the counter electrode 71 for a predetermined time (e.g., 1 hour) when the detection value by the flow rate measuring means 12 is less than a first flow rate (e.g., 3 liters per minute) and the detection value by the water temperature measuring means 38 is equal to or higher than a first temperature (e.g., 60°C). As a result, when the detection value by the water temperature measuring means 38 is equal to or higher than the first temperature and the detection value by the flow rate measuring means 12 is less than the first flow rate, an anticorrosive current is passed, thereby improving the corrosion resistance of the heat exchanger 6. Furthermore, when the detection value by the flow measuring means 12 is equal to or greater than the first flow rate, new tap water continues to be supplied from the water supply pipe 7, so it is believed that pitting corrosion is less likely to occur, and the hot water supply device can be operated economically without applying an anticorrosive current. Furthermore, when the detection value of the water temperature measuring means 38 is less than the first temperature, it is in a temperature range of 60°C or less where pitting corrosion is unlikely to occur, so the water heating apparatus can be operated economically without applying an anticorrosive current. This makes it possible to improve the corrosion resistance of heat exchanger 6, and provide a hot water supply device that can be used safely.

[0034] Next, a second embodiment will be described with reference to FIG.

[0035] The second embodiment is the first embodiment equipped with a bath reheating circuit 25 and a water filling pipe 15. The bath reheating circuit 25 is composed of a bath heat exchanger 24 heated by the same burner 2 that heats the heat exchanger 6, a bath return pipe 33 through which the bath water heated by the bath heat exchanger 24 flows into the bathtub 50, a circulation pump 27 provided on the bath return pipe 33, and a bath supply pipe 34 through which the bath water in the bathtub 50 flows into the bath heat exchanger 24. The burner 2 in the second embodiment may be a kerosene vaporization burner like the first embodiment, or may be another type of burner, for example, a pressure spray burner.

[0036] The filling pipe 15 branches off from the outlet pipe 8 downstream of the mixing valve 10 and supplies hot water to the bathtub 50. The filling pipe 15 is equipped with a filling valve 16 which starts and stops filling the bathtub 50 with hot water, a bath flow rate sensor 17 which detects the amount of hot water filling the bathtub 50 per hour, and a double check valve 18 which prevents backflow of bath water from the bathtub 50.

[0037] Reference numeral 26 denotes a bath water flow sensor that detects whether the bath water is flowing in the piping, 27 denotes a circulation pump that forcibly circulates the bath water in the bath reheating circuit 25, 28 denotes a bath temperature sensor that detects the temperature of the circulating bath water, 29 denotes a water level sensor that detects the water level of the bath water in the bathtub 50, and 30 denotes a branch check valve installed midway on the water filling branch pipe 35, which branches off from the water filling pipe 15 and connects to the bath return pipe 33. Reference numeral 36 denotes a reheating start means, such as a reheating switch mounted on the operating remote control 4. When the reheating start means 36 is turned on, it drives the burner 2 and the circulation pump 27 of the bath reheating circuit 25 to circulate and heat the hot water in the bathtub 50.

[0038] In the present invention, the control unit 22 is capable of executing an anticorrosion measure of passing an anticorrosion current between the anticorrosive electrode 70 and the counter electrode 71 for a predetermined time (e.g., 1 hour) when the value detected by the flow rate measuring means 12 is less than a first flow rate (e.g., 3 liters per minute) and the value detected by the water temperature measuring means 38 is equal to or higher than a first temperature (e.g., 60°C). Specifically, a voltage (e.g., DC 15 V) that cancels the pitting potential is applied.

[0039] Next, the operation of the second embodiment will be described.

[0040] When the operation switch 47 is turned on and the reheating start means 36 is turned on while the bathtub 50 is filled with hot water, the burner 2 and the circulation pump 27 of the bath reheating circuit 25 are driven to circulate and heat the hot water in the bathtub 50 until it reaches a preset boiling temperature.

[0041] Here, as the temperature of the hot water in the bath heat exchanger 24 rises due to the combustion of burner 2 during the re-heating operation, the temperature of the heat exchanger 6 also rises, and the water temperature in the heat exchanger 6 partially rises to around 60°C to 70°C.

[0042] In the prior art, during reheating operation, burner 2 is burned and circulation pump 27 provided in bath reheating circuit 25 is driven to circulate and heat the hot water in the filled bathtub 50. However, when hot water is not discharged through outlet pipe 8, the burner 2 is shared, so the water temperature in heat exchanger 6 rises, and the inner wall of heat exchanger 6 comes into contact with non-flowing hot water and is exposed to temperatures that are prone to causing pitting corrosion.

[0043] In the present invention, the control unit 22 flows an anticorrosion current between the anticorrosion electrode 70 and the counter electrode 71 for a predetermined time (e.g., 1 hour) when the detection value by the flow rate measuring means 12 is less than a first flow rate (e.g., 3 liters per minute) and the detection value by the water temperature measuring means 38 is equal to or higher than a first temperature (e.g., 60°C). As a result, when the detection value by the water temperature measuring means 38 is equal to or higher than the first temperature and the detection value by the flow rate measuring means 12 is less than the first flow rate, an anticorrosive current is passed, thereby improving the corrosion resistance of the heat exchanger 6.

[0044] The other configurations used in the present embodiment are presented as examples, and are not intended to limit the scope of the invention, and may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the invention and its equivalents described in the claims. [Explanation of symbols]

[0045] 1: Hot water supply equipment 2: Burner (heat source) 2a: Evaporation heater 2b: Carburetor 2f: Fuel pump 6: Heat exchanger 7: Water supply pipe 8: Tap pipe 12: Flow rate measuring means 22: Control section 24: Bath heat exchanger 25: Bath reheating circuit 27: Circulation pump 36:Means for starting additional firing 38: Water temperature measurement means 50: Bathtub 70: Corrosion-resistant electrodes 71: Opposite

Claims

1. A heat source machine, A water supply pipe, A heat exchanger that heats hot water from the water supply pipe using heat generated by the heat source device; A hot water outlet pipe for outletting hot water from the heat exchanger; A flow rate measuring means for measuring a flow rate of hot water flowing from the water supply pipe to the hot water outlet pipe; A water temperature measuring means for measuring the temperature of the hot water in the heat exchanger; A control unit that controls the operation of the heat source device; a corrosion prevention electrode arranged in contact with hot water inside the outlet pipe or the heat exchanger to prevent a metallic material of the outlet pipe or the heat exchanger from being dissolved in the hot water and corroded; A counter electrode of the anticorrosive electrode; Equipped with The control unit is When the detected value by the flow rate measuring means is less than a first flow rate and the detected value by the water temperature measuring means is equal to or greater than a first temperature, A corrosion protection current is passed between the corrosion protection electrode and the counter electrode for a predetermined time. A water heating apparatus characterized by the above.

2. The heat source machine is A vaporizer having a vaporization heater for heating and vaporizing the fuel oil to an ignition temperature; a vaporizer temperature detection means for detecting the temperature of the vaporizer; a fuel pump for supplying fuel to the carburetor; A kerosene vaporizing burner having the vaporization heater is disposed below the heat exchanger, The control unit is When the detected value of the flow rate measuring means is less than the first flow rate, the vaporization heater is energized to preheat the vaporizer, When the detected value of the flow rate measuring means is equal to or greater than the first flow rate, the heat source device is driven to dispense hot water.

2. The hot water supply device according to claim 1 .

3. A bath reheating circuit equipped with a circulation pump to circulate and heat the water in the bathtub; A bath heat exchanger connected to the bath reheating circuit and heated by the heat source unit common to the heat exchanger; A reheating start means electrically connected to the control unit; Equipped with When the reheating start means issues an instruction to start reheating, the control unit drives the heat source device and the circulation pump to circulate and heat the hot water in the bathtub.

2. The hot water supply device according to claim 1 .

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