Water heater

Abstract

To suppress combustion vibration when a first combustion unit is ignited while a second combustion unit is being burned.SOLUTION: A hot water supply heater 1 comprises: a hot water supply combustion unit 4A having a hot water supply burner 6A; a heating combustion unit 5A having a heating burner 6B; a gas pipe 17 for supplying gas to the gas burners 6, the gas pipe 17 having a common pipe 17A through which gas supplied to each gas burner 6 flows in common, and a plurality of gas branch pipes 18 branching from a downstream end of the common pipe 17A and connected to the gas burners 6; a gas proportional valve 21 provided in the common pipe 17A; a gas solenoid valve 19 provided for each gas branch pipe 18; and a control board 79. When the hot water supply combustion unit 4A is ignited while the heating combustion unit 5A is burning, the control board 79 closes the gas solenoid valve 19 of the heating combustion unit 5A during pre-purge that is performed before the ignition of the hot water supply combustion unit 4A, and after the pre-purge is completed, while the gas solenoid valve 19 of the heating combustion unit 5A is closed, the gas solenoid valve 19 of the hot water supply combustion unit 4A is opened to ignite the hot water supply combustion unit 4A.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The technology disclosed in this specification relates to a water heater.

Background Art

[0002] Conventionally, there is known a water heater including a first combustion part having a gas burner, a second combustion part having a gas burner, a gas pipe for supplying gas to the gas burner, a common pipe through which the gas supplied to each gas burner flows in common, a plurality of gas branch pipes branched from the downstream end of the common pipe and connected to the gas burner, a gas amount adjustment valve provided in the common pipe, and a gas switching valve provided for each gas branch pipe (see, for example, Patent Document 1).

[0003] Specifically, the water heater with a post-combustion function described in Patent Document 1 includes a water heating combustion part, a post-combustion part, and a fuel supply part. The fuel supply part branches into three directions and supplies fuel gas to two burners (a first water heating burner and a second water heating burner) of the water heating combustion part and a post-combustion burner of the post-combustion part. A proportional valve for adjusting the gas amount is provided in a section before the three-way branch in the fuel supply part. And a first water heating on-off valve for interrupting the supply of fuel to the first water heating burner, a second water heating on-off valve for interrupting the supply of fuel to the second water heating burner, and a post-combustion on-off valve for interrupting the supply of fuel to the post-combustion burner are provided. When a hot water supply instruction is given during the post-combustion operation, the water heater with a post-combustion function described in the same document opens the first water heating on-off valve and, if necessary, the second water heating on-off valve, and sets the gas amount supplied to the post-combustion burner to a predetermined amount, and sets the gas amount to an amount that makes it easy for the first and second water heating burners to ignite.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the water heater with a post-combustion function described in Patent Document 1, for example, when the first and second water heating burners are ignited during post-combustion operation, there is a risk of combustion vibration occurring. Combustion vibration is likely to occur when the first and second water heating burners are cold, and also tends to occur even if there is a fluctuation in the gas amount immediately after ignition. One aspect of the present invention aims to suppress combustion vibration when igniting the first combustion part during the combustion of the second combustion part.

Means for Solving the Problems

[0006] The water heater of the present disclosure includes a first combustion part having a gas burner, a second combustion part having a gas burner, a gas pipe that supplies gas to the gas burner, a common pipe through which the gas supplied to each gas burner flows in common, a plurality of gas branch pipes that branch from the downstream end of the common pipe and are connected to the gas burner, a gas amount adjustment valve provided in the common pipe, a gas switching valve provided for each gas branch pipe, and a controller. When the controller ignites the first combustion part while the second combustion part is burning, the gas switching valve of the second combustion part is closed during the purge performed before ignition of the first combustion part, and after the purge is completed, with the gas switching valve of the second combustion part closed, the gas switching valve of the first combustion part is opened to ignite the first combustion part.

Effects of the Invention

[0007] According to the above configuration, it is possible to suppress combustion vibration when igniting the first combustion part during the combustion of the second combustion part.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0009] [Outline of Embodiment] First, the outline of the embodiment of the present disclosure will be listed and described.

[0010] (1) The water heater according to the embodiment includes a first combustion unit having a gas burner, a second combustion unit having a gas burner, a gas pipe for supplying gas to the gas burner, a common pipe through which the gas supplied to each gas burner flows in common, a plurality of gas branch pipes branched from the downstream end of the common pipe and connected to the gas burner, a gas amount adjustment valve provided in the common pipe, a gas switching valve provided for each gas branch pipe, and a controller. When the controller ignites the first combustion unit while the second combustion unit is burning, before igniting the first combustion unit, during the purge performed before ignition, the gas switching valve of the second combustion unit is closed, and after the purge is completed, with the gas switching valve of the second combustion unit closed, the gas switching valve of the first combustion unit is opened to ignite the first combustion unit.

[0011] The above-mentioned purge means discharging the unburned gas accumulated in the combustion chamber by rotating the combustion fan before ignition. According to the water heater described in the above (1), when igniting the first combustion unit while the second combustion unit is burning, by closing the gas switching valve of the second combustion unit before igniting the first combustion unit (that is, during the purge) to stop the combustion of the second combustion unit, the occurrence of combustion vibration can be suppressed. In the above water heater, since the common pipe of the gas pipe and the gas volume adjustment valve provided in the common pipe are shared by the two combustion parts, if the gas switching valve of the first combustion part is opened and the gas switching valve of the second combustion part is closed at the same time, fluctuations in the gas volume will occur instantaneously (or a change in the gas flow will occur instantaneously), and combustion vibration is likely to be induced. According to the above water heater, since the combustion of the second combustion part is stopped before the ignition of the first combustion part, there is also an advantage that the induction of combustion vibration can be suppressed compared to the case of opening and closing at the same time.

[0012] (2) The water heater according to (1) above, wherein the controller may open the gas switching valve of the second combustion part and re-ignite the second combustion part after igniting the first combustion part.

[0013] In the water heater according to (2) above, re-ignition is performed on the second combustion part after igniting the first combustion part. When re-igniting the second combustion part, the temperatures of both the first combustion part and the second combustion part are somewhat high. The temperature of the combustion part mentioned here refers to, for example, the ambient temperature in the combustion chamber in which the combustion part is accommodated. Combustion vibration is likely to occur when the combustion part to be ignited is cold (in other words, when the ambient temperature in the combustion chamber is low). Therefore, combustion vibration is less likely to occur when both temperatures are somewhat high. For this reason, combustion vibration when re-igniting the second combustion part is also suppressed.

[0014] (3) The water heater according to (2) above, wherein the controller may open the gas switching valve of the second combustion part and re-ignite the second combustion part when a specified time has elapsed since the first combustion part was ignited, or when a specified time has elapsed since the gas switching valve of the second combustion part was closed.

[0015] When a certain amount of time has elapsed since the first combustion part was ignited (or when the gas switching valve of the second combustion part was closed), the temperature of the first combustion part exceeds the temperature at which combustion vibration of the first combustion part is likely to occur. For this reason, when a certain amount of time has elapsed, combustion vibration when restarting the combustion of the second combustion part becomes less likely to occur. According to the water heater described in (3) above, by measuring in advance the time until the temperature of the first combustion part exceeds the temperature at which combustion vibration of the first combustion part is likely to occur and setting it as a specified time, combustion vibration when reigniting the second combustion part can be more reliably suppressed.

[0016] (4) The water heater according to (2) or (3) above, when defining the control to burn only the second combustion part as the normal control of the second combustion part, the controller ignites the second combustion part when the temperature of the heat medium of the second combustion part is less than a predetermined ignition start temperature in the normal control, and when the gas switching valve of the second combustion part is closed to ignite the first combustion part, the predetermined ignition start temperature may be set higher than the normal control.

[0017] According to the water heater described in (4) above, when the gas switching valve of the second combustion part is closed to ignite the first combustion part, since the predetermined ignition start temperature is set higher than the normal control, the temperature drop of the heat medium while combustion has stopped is compensated. For this reason, the usability of the user is not impaired.

[0018] (5) The water heater according to (2) or (3) above, wherein the second combustion part may be a combustion part for heating or for reheating a bath.

[0019] In the water heater described in (5) above, when igniting the first combustion part, the combustion of the combustion part for heating or for reheating temporarily stops, but if it is temporary, the temperature of the heat medium does not significantly decrease due to the residual heat of the combustion part. In the case of the combustion part for heating or for reheating, if the temperature of the heat medium does not significantly decrease, it is difficult for the user to notice the temperature change, so the usability of the user is not impaired.

[0020] [Details of Embodiment] Details of the embodiment of the present disclosure will be described. The present disclosure is not limited to these examples, is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. Embodiments of the present disclosure can be implemented in various forms such as apparatuses, methods, computer programs for realizing the functions of these apparatuses or methods, and recording media on which the computer programs are recorded.

[0021] <Embodiment 1> Embodiment 1 of the present disclosure will be described with reference to FIGS. 1 to 5. In the following description, the reference numerals in the drawings may be omitted for some of the same components.

[0022] (1) Overall structure of the water heater and heater Referring to FIG. 1, an overview of the water heater and heater 1 as a water heater according to Embodiment 1 will be described. The water heater and heater 1 has a water heating function of heating the supplied tap water and supplying hot water to the outside, and a heating function of supplying hot water to radiators installed outside in the room or under the floor to heat the room or the floor. The water heater and heater 1 includes a front cover 72. The front cover 72 has an exhaust port 73 for accommodating an exhaust pipe 16 described later, an air supply port 74 for taking in outside air, and the like.

[0023] As shown in FIG. 2, the water heater and heater 1 includes a housing 70, an inner cylinder 2 accommodated in the housing 70, a control board 79 (an example of a controller), and the like. The housing 70 includes a box-shaped housing main body 71 having an opening 71A on the front surface, and a front cover 72 (see FIG. 1) that closes the opening 71A of the housing main body 71.

[0024] The housing main body 71 includes a bottom plate 71B located on the lower side in a front view, a left side plate 71C located on the left side in a front view, a right side plate 71D located on the right side in a front view, a top plate 71E located on the upper side in a front view, and a rear wall 71F located on the rear side. The inner cylinder 2 is provided with a hot water supply combustion chamber 4, a heating combustion chamber 5, a hot water supply primary heat exchanger 11, a heating primary heat exchanger 13, a hot water supply secondary heat exchanger 12, a heating secondary heat exchanger 14, an exhaust hood 15, etc. The inner cylinder 2 is partitioned into left and right by a partitioning member 3 (see FIG. 3) to be described later. A hot water supply combustion chamber 4, a hot water supply primary heat exchanger 11, and a hot water supply secondary heat exchanger 12 are provided on the right side, and a heating combustion chamber 5, a heating primary heat exchanger 13, and a heating secondary heat exchanger 14 are provided on the left side.

[0025] As shown in FIG. 3, the hot water supply and heating machine 1 has a hot water supply circuit A, a heating circuit B, and a bath circuit C. The hot water supply and heating machine 1 has a hot water supply combustion chamber 4 and a heating combustion chamber 5 formed by partitioning inside the inner cylinder 2 by a partitioning member 3, and a gas burner 6. The gas burner 6 includes a plurality of hot water supply burners 6A arranged at the lower part of the hot water supply combustion chamber 4 and a plurality of heating burners 6B arranged at the lower part of the heating combustion chamber 5. An ignition plug 8 and a flame rod 9 are respectively provided in each combustion chamber 4, 5. A combustion fan 10 for supplying combustion air to each gas burner 6A, 6B is provided at the lower part of the inner cylinder 2.

[0026] At the upper part inside the hot water supply combustion chamber 4, a hot water supply primary heat exchanger 11 and a hot water supply secondary heat exchanger 12 through which the combustion exhaust of the hot water supply burner 6A passes are provided. At the upper part of the heating combustion chamber 5, a heating primary heat exchanger 13 and a heating secondary heat exchanger 14 through which the combustion exhaust of the heating burner 6B passes are provided. Each secondary heat exchanger 12, 14 is housed in an exhaust hood 15 provided at the upper part of the inner cylinder 2. An exhaust pipe 16 for discharging the combustion exhaust that has passed through each secondary heat exchanger 12, 14 is formed in the exhaust hood 15.

[0027] In the following description, the hot water supply burner 6A, the hot water supply primary heat exchanger 11, and the hot water supply secondary heat exchanger 12 are referred to as a hot water supply combustion part 4A, and the heating burner 6B, the heating primary heat exchanger 13, and the heating secondary heat exchanger 14 are referred to as a heating combustion part 5A. The hot water supply combustion part 4A is an example of a first combustion part, and the heating combustion part 5A is an example of a second combustion part.

[0028] A gas pipe 17 to which an external gas pipe is connected is connected to a gas inlet provided in the bottom plate 71B of the housing 70. The gas pipe 17 has a common pipe 17A through which the gas supplied to each gas burner 6 commonly flows, and a plurality of gas branch pipes 18 that branch from the downstream end of the common pipe 17A and are connected to each gas burner 6. The common pipe 17A is provided with an original gas solenoid valve 20 and a gas proportional valve 21 (an example of a gas amount adjustment valve) from the upstream side. Each gas branch pipe 18 is provided with a gas solenoid valve 19 (an example of a gas switching valve) that opens and closes the gas flow path.

[0029] A water supply pipe 22 connected to the water inlet 78 of the bottom plate 71B is connected to the inlet of the heat absorption pipe of the secondary hot water heat exchanger 12. The water supply pipe 22 is provided with a strainer 23 having a drain plug, a hot water supply water amount sensor 24 that detects the amount of water flowing through the water supply pipe 22, a hot water supply inlet thermistor 25 that detects the temperature of the water (inlet water temperature) supplied from the water inlet 78, and a water amount control valve 26 that controls the amount of water flowing through the water supply pipe 22 from the upstream side.

[0030] The outlet of the heat absorption pipe is connected to the inlet of the heat transfer pipe of the primary hot water heat exchanger 11, and a hot water outlet pipe 27 connected to the hot water outlet of the bottom plate 71B is connected to the outlet of the heat transfer pipe. The hot water outlet pipe 27 is provided with a hot water heat exchanger thermistor 28 that detects the outlet temperature from the primary hot water heat exchanger 11, and a hot water outlet thermistor 29 that detects the hot water outlet temperature from the appliance on the downstream side of the hot water heat exchanger thermistor 28. A bypass pipe 30 that bypasses the primary and secondary hot water heat exchangers 11 and 12 is connected between the upstream side of the hot water outlet thermistor 29 in the hot water outlet pipe 27 and the downstream side of the water amount control valve 26 in the water supply pipe 22, and the bypass pipe 30 is provided with a bypass valve 31 that controls the bypass flow rate. In this way, a hot water supply circuit A is formed in the housing 70, in which water from the water supply pipe 22 passes through the secondary hot water heat exchanger 12 and the primary hot water heat exchanger 11 in this order, exchanges heat with the combustion exhaust gas of the hot water supply burner 6A, is heated, and then hot water is discharged from the hot water outlet pipe 27.

[0031] On one side, a heating return pipe 32 connected to the heating return port 76 of the bottom plate 71B is connected to the inlet of the heat absorption pipe of the heating secondary heat exchanger 14. The heating return port 76 is connected to the downstream ends of the pipes extending from the high-temperature radiator 33 and the low-temperature radiator 34 outside the hot water heating machine 1. The high-temperature radiator 33 is, for example, a heating blower that blows warm air into the room. The low-temperature radiator 34 is, for example, floor heating. The outlet of the heat absorption pipe of the heating secondary heat exchanger 14 is connected to an intermediate pipe 35 (intermediate pipes 35A and 35B). A heating tank 69 and a heating circulation pump 36 are provided in the intermediate pipe 35.

[0032] The downstream end of the intermediate pipe 35 is connected to the inlet of the heat transfer pipe of the heating low-temperature forward pipe 38 and the heating primary heat exchanger 13. A thermostatic valve 39 is arranged on the downstream side of the heating low-temperature forward pipe 38, branching the heating low-temperature forward pipe 38. The downstream end of the thermostatic valve 39 serves as the heating low-temperature forward port 77. The heating low-temperature forward port 77 is connected to the low-temperature radiator 34.

[0033] The outlet of the heat transfer pipe of the heating primary heat exchanger 13 is connected to the heating high-temperature forward pipe 40. The downstream end of the heating high-temperature forward pipe 40 serves as the heating high-temperature forward port 75 provided on the bottom plate 71B. The heating high-temperature forward port 75 is connected to the high-temperature radiator 33. A heating high-temperature thermistor 41 is provided in the heating high-temperature forward pipe 40. The heating high-temperature forward pipe 40 and the heating return pipe 32 are connected by a bath heating pipe 42. A supplementary boiling flow control valve 43 is provided in the bath heating pipe 42. A heating bypass pipe 44 that bypasses the heating primary and secondary heat exchangers 13 and 14 is connected between the upstream side of the heating tank 69 in the intermediate pipe 35 and the heating high-temperature forward pipe 40, and a bypass thermostatic valve 45 for controlling the bypass flow rate is provided in the heating bypass pipe 44.

[0034] Therefore, in the heating circuit B, the hot water heated by the heating secondary heat exchanger 14 circulates through the intermediate pipe 35, the heating tank 69, the heating low-temperature outgoing pipe 38, and the low-temperature radiator 34 to the heating return pipe 32, and at the same time, it flows into the heating primary heat exchanger 13 through the intermediate pipe 35. The hot water heated by the heating primary heat exchanger 13 returns to the heating return pipe 32 through the heating high-temperature outgoing pipe 40 and the high-temperature radiator 33, and circulates through the heating secondary heat exchanger 14, the intermediate pipe 35, and the heating tank 69 to the heating primary heat exchanger 13.

[0035] The bath circuit C is provided with a bath heat exchanger 46 into which a bath heating pipe 42 is inserted. The inlet of the bath heat exchanger 46 is connected to a bath return pipe 47 connected to the bath return port of the bottom plate 71B. The bath return port is connected to the bathtub 49 through an external bath return pipe 48. A bath circulation pump 50 is provided on the downstream side of the bath return pipe 47. A bath return thermistor 51 for detecting the bath return temperature is provided on the upstream side of the bath circulation pump 50. A water flow switch 52 and a water level sensor 53 are provided on the downstream side of the bath circulation pump 50. The outlet of the bath heat exchanger 46 is connected to a bath outgoing pipe 54 connected to the bath outgoing port of the bottom plate 71B. The bath outgoing port is connected to the bathtub 49 through an external bath outgoing pipe 55. A bath outgoing thermistor 56 for detecting the bath outgoing temperature is provided on the bath outgoing pipe 54.

[0036] Between the downstream side of the bypass pipe 30 in the hot water outlet pipe 27 and the upstream side of the bath circulation pump 50 in the bath return pipe 47, a dropping pipe 57 is connected. In this dropping pipe 57, from the upstream side (the hot water outlet pipe 27 side), a dropping water solenoid valve 58 for opening and closing the dropping pipe 57 and a bath water volume sensor 59 for detecting the amount of water flowing through the dropping pipe 57 are respectively provided. The dropping pipe 57 enables the hot water heated in the hot water supply circuit A to be supplied to the bathtub 49. On the downstream side of the bath water volume sensor 59, three check valves 60, 60, 60 are provided. Between these check valves 60, an edge-cut valve 61 is connected. This edge-cut valve 61 is connected to a drain pipe 62 connected to an overflow discharge port provided on the bottom plate 71B and an introduction pipe 63 connected to the downstream side of the strainer 23 in the water supply pipe 22. When the internal pressure of the hot water (an example of a heat medium) in the dropping pipe 57 increases due to the back pressure from the bath return pipe 47 and becomes greater than the back pressure from the introduction pipe 63, the edge-cut valve 61 discharges the hot water flowing back from the dropping pipe 57 to the overflow discharge port via the drain pipe 62. In this way, a bath circuit C for circulating the hot water in the bathtub 49 is formed by the bath heat exchanger 46, the bath forward pipe 54, the bath return pipe 47, and the like.

[0037] Inside the housing 70, a neutralizer 64 for neutralizing the drain generated in the hot water supply secondary heat exchanger 12 and the heating secondary heat exchanger 14 is provided. This neutralizer 64 is connected to a drain receiver 66 provided on the bottom surface of the exhaust hood 15 via a drain introduction pipe 65 and is connected to the drain pipe 62 of the edge-cut valve 61 via a drain discharge pipe 67. The neutralizer 64 is provided with a water level electrode 68 for detecting the water level.

[0038] Referring to FIG. 2, the control board 79 will be described. The control board 79 has a control unit and various electronic components mounted thereon. The control unit is, for example, a CPU, a microcomputer (so-called microcontroller), an FPGA (Field Programmable Gate Array), etc. The control board 79 receives detection signals from various thermistors, sensors, etc., and operates various valves, etc., to perform hot water temperature control, hot water filling control for the bathtub 49, temperature control related to heating, etc. Although not shown, the water heater 1 is provided with a remote control, etc., that is communicably connected to the control board 79.

[0039] (2) Control for igniting the water heating combustion part when the heating combustion part is burning In the following description, ignition may also be referred to as ignition. That is, in the following description, ignition and ignition have substantially the same meaning. When the control board 79 ignites the water heating combustion part 4A when the heating combustion part 5A is burning, it closes the gas solenoid valve 19 of the heating combustion part 5A during the pre-purge performed before the ignition of the water heating combustion part 4A to stop the combustion of the heating combustion part 5A. Pre-purge means discharging the unburned gas accumulated in the combustion chamber by rotating the combustion fan before ignition. After the pre-purge is completed, the control board 79 opens the gas solenoid valve 19 of the water heating combustion part 4A to ignite the water heating combustion part 4A while the gas solenoid valve 19 of the heating combustion part 5A is closed. Then, after igniting the water heating combustion part 4A, the control board 79 opens the gas solenoid valve 19 of the heating combustion part 5A to re-ignite the heating combustion part 5A.

[0040] (2-1) Sequence for igniting the water heating combustion part Referring to FIG. 4, an example of the sequence for igniting the water heating combustion part 4A when the heating combustion part 5A is burning will be described. The following sequence starts when the water supply to the heat exchangers (the primary water heating heat exchanger 11 and the secondary water heating heat exchanger 12) of the water heating combustion part 4A is started.

[0041] In S101, the control board 79 detects the water supply to the heat exchanger of the hot water combustion section 4A by the hot water supply amount sensor 24. When the control board 79 detects the water supply, it determines whether the heating combustion section 5A is in combustion. In the example shown in FIG. 4, it is determined that the heating combustion section 5A is in combustion.

[0042] In S102, the control board 79 starts the purge. In the purge, the control board 79 changes the rotation speed of the combustion fan 10 to the specified rotation speed. Here, the rotation speed refers to the number of rotations per unit time (i.e., the rotation speed). The purge is performed for a certain period of time. During this purge, the control board 79 closes the gas solenoid valve 19 of the heating combustion section 5A. As a result, the combustion of the heating combustion section 5A stops. In other words, the heating combustion section 5A is extinguished. In S103, after the purge is completed and the gas solenoid valve 19 of the heating combustion section 5A is closed, the control board 79 starts the igniter discharge to ignite the hot water combustion section 4A. And in S103, the control board 79 checks for the extinction of the heating combustion section 5A.

[0043] In S104, the control board 79 opens the gas solenoid valve 19 of the hot water combustion section 4A to ignite the hot water combustion section 4A. And in S104, the control board 79 determines that the extinction of the heating combustion section 5A is completed. In S105, the control board 79 detects the ignition of the hot water combustion section 4A. In S106, the control board 79 ends the igniter discharge.

[0044] As described above, the sequence shown in FIG. 4 is an example, and there may be a timing deviation after S103 depending on the operations of the hot water combustion section 4A and the heating combustion section 5A. For example, if it takes time to check for the extinction of the heating combustion section 5A (S103), the completion of the extinction of the heating combustion section 5A may occur after S105.

[0045] (2-2) Re-ignition of the heating combustion section When the control board 79 ignites the hot water combustion unit 4A (in other words, when the ignition of the hot water combustion unit 4A is detected at S105), it reignites the heating combustion unit 5A after a specified time (for example, 5 seconds) has elapsed. The specified time is a time that has been previously measured as the time until the temperature of the hot water combustion unit 4A exceeds the temperature at which combustion vibration of the hot water combustion unit 4A is likely to occur. However, there are cases where the control board 79 does not reignite the heating combustion unit 5A. This will be specifically described below.

[0046] Here, the control of burning only the heating combustion unit 5A while the combustion of the hot water combustion unit 4A is stopped is defined as the normal control of the heating combustion unit 5A. In the normal control of the heating combustion unit 5A, when the control board 79 starts the hot water supply operation to the heating combustion unit 5A, it detects the temperature of the hot water by the heating high-temperature thermistor 41 before igniting the heating combustion unit 5A, and ignites the heating combustion unit 5A when the temperature of the hot water is less than the predetermined ignition start temperature. The ignition start temperature is a temperature that is lower than the heating set temperature (target temperature) set by the user by a first predetermined temperature (for example, 10°C). Then, the control board 79 stops the combustion when the temperature of the hot water in the heating combustion unit 5A becomes higher than the predetermined combustion stop temperature. The combustion stop temperature is a temperature that is higher than the heating set temperature by a second predetermined temperature (for example, 5°C).

[0047] For example, when the heating set temperature is 60°C, the first predetermined temperature is 10°C, and the second predetermined temperature is 5°C, the control board 79 ignites the heating combustion unit 5A when the temperature of the hot water drops below 50°C (=60°C - 10°C), and stops the combustion when the temperature of the hot water exceeds 65°C (=60°C + 5°C) during combustion.

[0048] When the control board 79 stops the combustion of the heating combustion unit 5A to ignite the hot water combustion unit 4A, after the specified time has elapsed since the hot water combustion unit 4A was ignited, it determines whether the temperature of the hot water in the heating combustion unit 5A is less than the ignition start temperature, and if it is less than the ignition start temperature, it reignites the heating combustion unit 5A.

[0049] When the temperature of hot water is equal to or higher than the ignition start temperature, the control board 79 does not re-ignite the heating combustion unit 5A at that time, but waits for the temperature of the hot water to drop below the ignition start temperature and then re-ignites. However, before the temperature of the hot water drops below the ignition start temperature, the user may stop the heating or the supplementary heating. Alternatively, the heating or the supplementary heating may be stopped before the elapse of a specified time after the water heating combustion unit 4A is ignited. In that case, the heating combustion unit 5A is not re-ignited. That is, when the combustion of the heating combustion unit 5A is stopped to ignite the water heating combustion unit 4A, the heating combustion unit 5A is not necessarily re-ignited thereafter.

[0050] When the control board 79 stops the combustion of the heating combustion unit 5A to ignite the water heating combustion unit 4A, the control board 79 sets the ignition start temperature of the heating combustion unit 5A higher than the normal control. However, the ignition start temperature is not set higher than the combustion stop temperature. For example, when the ignition start temperature in normal control is 50°C, when the combustion of the heating combustion unit 5A is stopped to ignite the water heating combustion unit 4A, the control board 79 sets the ignition start temperature to 55°C, for example. Ignition is performed with the ignition start temperature set higher than the normal control only when ignition is first performed after raising the ignition start temperature, and thereafter, the control returns to the normal control.

[0051] (3) Effects of the Embodiment According to the water heater 1 according to Embodiment 1, when igniting the water heating combustion unit 4A while the heating combustion unit 5A is burning, by closing the gas solenoid valve 19 of the heating combustion unit 5A and stopping the combustion of the heating combustion unit 5A before igniting the water heating combustion unit 4A, the occurrence of combustion vibration can be suppressed. According to the water heater and heater 1, since the combustion of the heating combustion unit 5A is stopped before ignition of the hot water supply combustion unit 4A, there is also an advantage that the induction of combustion vibration can be suppressed. This will be specifically described with reference to the comparative example shown in FIG. 5. In the comparative example shown in FIG. 5, the opening of the gas solenoid valve 19 of the hot water supply combustion unit 4A and the closing of the gas solenoid valve 19 of the heating combustion unit 5A are performed simultaneously. In the water heater and heater 1, since the common pipe 17A of the gas pipe 17 and the gas proportional valve 21 provided in the common pipe 17A are shared by the hot water supply combustion unit 4A and the heating combustion unit 5A, when the opening of the gas solenoid valve 19 of the hot water supply combustion unit 4A and the closing of the gas solenoid valve 19 of the heating combustion unit 5A are performed simultaneously, a fluctuation in the gas amount occurs instantaneously (or a change in the gas flow occurs instantaneously), and combustion vibration is likely to be induced. On the other hand, if the combustion of the heating combustion unit 5A is stopped before ignition of the hot water supply combustion unit 4A, a fluctuation in the gas amount is less likely to occur compared to the case of simultaneous opening and closing, so there is also an advantage that the induction of combustion vibration can be suppressed.

[0052] According to the water heater and heater 1, after ignition of the hot water supply combustion unit 4A, re-ignition is performed on the heating combustion unit 5A. When re-igniting the heating combustion unit 5A, the temperatures of both the hot water supply combustion unit 4A and the heating combustion unit 5A are relatively high to some extent. Combustion vibration is likely to occur when the combustion unit to be ignited is cold, so combustion vibration is less likely to occur when the temperatures of both are relatively high to some extent. Therefore, the combustion vibration when re-igniting the heating combustion unit 5A is also suppressed.

[0053] According to the water heater and heater 1, by measuring in advance the time until the temperature at which combustion vibration is likely to occur is exceeded and setting it as a specified time, the combustion vibration when re-igniting the heating combustion unit 5A can be more reliably suppressed.

[0054] According to the water heater and heater 1, when the combustion of the heating combustion unit 5A is stopped to ignite the hot water supply combustion unit 4A, the ignition start temperature is set higher than normal control, so the temperature drop of the hot water during the period when the combustion has stopped is compensated. Therefore, the usability of the user is not impaired.

[0055] In the hot water supply and heating unit 1, when igniting the hot water supply combustion section 4A, the combustion of the heating combustion section 5A temporarily stops. However, if it is only temporary, the temperature of the hot water will not significantly decrease due to the residual heat of the heating combustion section 5A. In the case of the heating combustion section 5A, if the temperature of the hot water does not significantly decrease, it is difficult for the user to notice the change in temperature, so the usability of the user is not impaired.

[0056] <Other Embodiments> (1) In the above embodiment, the case where the hot water supply combustion section 4A is the first combustion section and the heating combustion section 5A is the second combustion section is illustrated. In contrast, the heating combustion section 5A may be the first combustion section and the hot water supply combustion section 4A may be the second combustion section. That is, when igniting the other combustion section while one of the combustion sections is burning, the combustion of the one combustion section may be stopped regardless of whether the one combustion section is the hot water supply combustion section 4A or the heating combustion section 5A.

[0057] (2) In the above embodiment, the case where the heating combustion section 5A is reignited after a specified time has elapsed since ignition of the hot water supply combustion section 4A is illustrated. That is, the case where the start point of counting the specified time is when the hot water supply combustion section 4A is ignited is illustrated. In contrast, the start point of counting the specified time may be when the gas solenoid valve 19 of the heating combustion section 5A is closed.

[0058] (3) In the above embodiment, the case where the heating combustion section 5A is reignited after a specified time has elapsed since ignition of the hot water supply combustion section 4A is illustrated. In contrast, without waiting for the specified time to elapse, the heating combustion section 5A may be reignited immediately after ignition of the hot water supply combustion section 4A.

[0059] (4) In the above embodiment, the case where the ignition start temperature of the heating combustion section 5A is made higher than the normal control when the combustion of the heating combustion section 5A is stopped to ignite the hot water supply combustion section 4A is illustrated. In contrast, even when the combustion of the heating combustion section 5A is stopped to ignite the hot water supply combustion section 4A, the ignition start temperature may be the same as the normal control.

[0060] (5) In the above-described embodiment, an example was given in which when a specified time has elapsed since ignition of the hot water combustion unit 4A (or when a specified time has elapsed since the gas solenoid valve 21 of the heating combustion unit 5A was closed), the gas solenoid valve 21 of the heating combustion unit 5A is opened to reignite the heating combustion unit 5A. In contrast, a temperature sensor for measuring the temperature inside the hot water combustion chamber 4 may be provided, and when the temperature detected by the temperature sensor exceeds a specified temperature (a temperature at which combustion vibration of the hot water combustion unit 4A is likely to occur), the heating combustion unit 5A may be reignited.

Explanation of Signs

[0061] 1: Hot water and heating machine (an example of a water heater) 4A: Hot water combustion unit (an example of a first combustion unit) 5A: Heating combustion unit (an example of a second combustion unit) 6: Gas burner 17: Gas pipe 17A: Common pipe 18: Gas branch pipe 19: Gas solenoid valve (an example of a gas switching valve) 21: Gas proportional valve (an example of a gas quantity adjustment valve)

Claims

1. A water heater, comprising: a first combustion part having a gas burner; a second combustion part having a gas burner; a gas pipe for supplying gas to the gas burner, the gas pipe including a common pipe through which the gas supplied to each of the gas burners flows in common, and a plurality of gas branch pipes branched from a downstream end of the common pipe and connected to the gas burner; a gas flow rate adjustment valve provided in the common pipe; a gas switching valve provided for each of the gas branch pipes; a controller; When the controller ignites the first combustion part while the second combustion part is burning, before ignition of the first combustion part, during purging performed before ignition, the gas switching valve of the second combustion part is closed, after the purging is completed, with the gas switching valve of the second combustion part closed, the gas switching valve of the first combustion part is opened to ignite the first combustion part. A water heater.

2. The water heater according to Claim 1, wherein after igniting the first combustion part, the controller opens the gas switching valve of the second combustion part to re-ignite the second combustion part.

3. The water heater according to Claim 2, wherein when a specified time has elapsed since ignition of the first combustion part, or when a specified time has elapsed since the gas switching valve of the second combustion part was closed, the controller opens the gas switching valve of the second combustion part to re-ignite the second combustion part.

4. The water heater according to Claim 2 or Claim 3, when control for burning only the second combustion part is defined as normal control of the second combustion part, the controller, in the normal control, ignites the second combustion part when the temperature of the heat medium of the second combustion part is lower than a predetermined ignition start temperature, when the gas switching valve of the second combustion part is closed to ignite the first combustion part, sets the predetermined ignition start temperature higher than in the normal control.

5. The water heater according to Claim 2 or Claim 3, wherein the second combustion part is a combustion part for heating or for reheating a bath.

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