JP3792312B2 - Water heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water heater having a hot water supply burner and a heat exchanger for transferring heat from the hot water supply burner to the water supply.
[0002]
[Prior art]
Conventional water heaters detect the flow of water to the heat exchanger with a flow sensor, and when the flow sensor detects opening, the hot water burner is ignited to heat the heat exchanger and water supply is set It is designed to raise the temperature.
[0003]
In this way, when heating is started at the same time as opening, since it takes time until the set temperature of hot water is discharged after opening, water or lukewarm water comes out for a while after opening and is uncomfortable. Not only that, it was uneconomical to throw away water until the set temperature was reached. Accordingly, various hot water heaters have been proposed which have been improved so that hot water at a set temperature is discharged in a short time after opening.
[0004]
Japanese Patent Application Laid-Open No. 7-167493 discloses a water heater that can discharge hot water at a set temperature in as short a time as possible when the hot water is discharged again after a certain time has elapsed after the combustion of the water heater is stopped. Yes. In this water heater, the temperature of the hot water inside the heat exchanger after the hot water supply burner is stopped is detected by a temperature sensor, and the temperature drop from the set temperature is monitored. When the temperature falls to the lower limit of the allowable temperature limit, the hot water supply burner is ignited in a state where the plug is not opened, that is, the water flow confirmation means such as a flow sensor as a safety device is turned off. The hot water temperature in the heat exchanger is raised to the vicinity of the set temperature. For example, the hot water in the heat exchanger is kept at a temperature near the set temperature, for example, until 5 minutes have passed after closing.
[0005]
[Problems to be solved by the invention]
However, in such a conventional technique, the hot water in the heat exchanger is kept near the set temperature only after a predetermined time elapses after the hot water is discharged and closed, for example, get up in the morning, In the case of opening for the first time, there is a problem that it still takes time until the hot water at the set temperature is discharged. As a method of solving this, the hot water temperature in the heat exchanger is raised in advance at the time when the remote control operation switch is turned on or when the time set by the timer arrives, regardless of whether or not there has been hot water immediately before. It can be considered.
[0006]
However, there is no guarantee that water is present inside the heat exchanger when the hot water inside the heat exchanger is kept warm regardless of whether or not it has been previously opened. For example, in cold regions, water inside the water heater may be drained before going to bed to prevent freezing. In addition, immediately after installing the water heater, the water heater may be turned on before passing water into the heat exchanger. In this way, there may be no water in the heat exchanger, and a hot water supply burner even in a closed state (with the water flow confirmation means turned off), regardless of whether or not it has been previously opened. When igniting, there is a possibility that the air will burn.
[0007]
The present invention has been made paying attention to such problems of the prior art, and provides a water heater capable of preventing emptying when a hot water burner is ignited in a closed state. The purpose is that.
[0008]
[Means for Solving the Problems]
The gist of the present invention for achieving the object lies in the inventions of the following items.
[1] In a water heater (10) comprising a hot water supply burner (12) and a heat exchanger (14) for transferring heat from the hot water supply burner (12) to the water supply,
Temperature detection means (15) for detecting the temperature inside the heat exchanger (14);
Combustion control means (52) for burning the hot water supply burner (12) for a predetermined time without being opened;
When the temperature rise in the heat exchanger (14) is within a predetermined range at a point in time after the combustion control means (52) burns the hot water supply burner (12) for a predetermined time. Residual water confirmation means (54) for determining that a certain amount or more of water is present in the heat exchanger (14);
A water heater (10) characterized in that a water heater is provided.
[0013]
[2] The temperature detecting means (15) is a place where heat from the hot water supply burner (12) is not directly applied but is conducted by convection of the medium existing in the heat exchanger (14). The water heater (10) according to [1], wherein the water heater (10) is arranged.
[0014]
[3] When it is determined by the residual water confirmation means (54) that water is present inside the heat exchanger (14), the water inside the heat exchanger (14) until the water reaches a predetermined target temperature. The hot water supply burner (12) is burned and heated, and when it is determined by the residual water confirmation means (54) that no water is present in the heat exchanger (14), the hot water supply burner (12) The water heater (10) according to [1] or [2], further comprising a heating control means (56) for stopping the heating.
[0015]
[4] The combustion control means (52) burns the hot water supply burner (12) for heating the heat exchanger (14) over the entire surface thereof [1], [2] or [3] The water heater (10) described.
[0016]
The present invention operates as follows.
When the remaining water confirmation means (54) starts to heat the water in the heat exchanger (14) to a predetermined target temperature without being opened, first, the residual water confirmation means (54) puts water into the heat exchanger (14). Whether or not exists is detected. The residual water check is performed before the temperature in the heat exchanger (14) rises to the target temperature. The heating control means (56) reaches the target temperature when the water remaining in the heat exchanger (14) is detected by the residual water confirmation means (54). The hot water supply burner (12) is burned and heated up to.
[0017]
On the other hand, when it is detected by the residual water confirmation means (54) that no water is present inside the heat exchanger (14), heating by the hot water supply burner (12) is stopped to prevent emptying.
[0018]
When the heating of the heat exchanger (14) is started in such a state that the plug is not opened, it is first checked whether water is present in the interior. Even when there is no water inside, it is possible to prevent emptying and to improve the safety of the water heater (10).
[0019]
The remaining water can be confirmed as follows. That is, the combustion control means (52) first ignites the hot water supply burner (12) without being opened. The temperature detection means (15) detects the temperature inside the heat exchanger (14), and the difference in temperature rise characteristics inside the heat exchanger (14) after the hot water supply burner (12) is ignited. Thus, it is determined whether or not water is present inside the heat exchanger (14).
[0020]
The heat capacity of the heat exchanger (14) is greater when water is present inside. Therefore, the rate of temperature increase when water is present inside is smaller than the rate of temperature increase when no water is present inside, so that the water inside the heat exchanger (14) is obtained by examining the temperature rise characteristics. It can be determined whether or not it exists.
[0021]
Further, the combustion control means (52) burns the hot water supply burner (12) for a predetermined time without being opened, and then, based on the temperature rise inside the heat exchanger (14) at the time when a certain time has passed. It is detected whether water is present inside the heat exchanger (14).
[0022]
As described above, since the combustion is stopped for a predetermined time, it is possible to prevent the heat exchanger (14) from being deteriorated even when there is no water in the heat exchanger (14). Moreover, since temperature measurement is performed after a certain period of time has elapsed after combustion, a difference in temperature rise at the location of the temperature detection means (15) caused by a difference in heat capacity due to the presence or absence of water or a difference in thermal conductivity is appropriately detected. can do.
[0023]
Further, when the temperature rise in the heat exchanger (14) is within a predetermined range at a point in time after the hot water burner (12) is burned for a predetermined time without being opened, the heat exchange is performed. It may be determined that a certain amount or more of water is present in the vessel (14).
[0024]
When there is no water inside the heat exchanger (14) and air is present, the temperature rise is small, and when the state is almost full, a certain degree of temperature rise is shown. On the other hand, when a small amount of water is present, the temperature rise is greater than when the water is full because the heat capacity is small and steam is generated immediately. Thus, when the temperature rise is within a certain range, it is determined that there is a certain amount or more (close to full water) inside the heat exchanger.
[0025]
The temperature detection means (15) is arranged at a location where heat from the hot water supply burner (12) is not directly applied but is conducted by convection of the medium existing inside the heat exchanger (14). Thereby, it becomes difficult to receive the influence of the heat applied directly from the hot water supply burner (12), and the difference in the temperature rise characteristics due to the difference in heat capacity and heat conduction can be detected more accurately.
[0026]
In addition, the heating for detecting the temperature rise is performed by burning the entire surface of the hot water supply burner (12). Thereby, since the heat exchanger (14) is heated in a wide range, the time required for heat to be transferred to the location of the temperature detection means (15) by heat conduction is shortened, and the presence or absence of water is confirmed in a short time. It becomes possible.
[0027]
In addition, as the amount of heat applied increases, the temperature difference caused by the difference in heat capacity increases, so if the entire surface of the hot water supply burner (12) is burned and a large amount of heat is applied in a short time, the discrimination based on the temperature difference can be accurately performed. It can be carried out. Furthermore, since the heat exchanger (14) is heated over a wide range, even when there is no water, it is possible to prevent the heat exchanger (14) from being partially overheated and deteriorating the durability performance. it can.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Each figure shows an embodiment of the present invention.
As shown in FIG. 1, the water heater 10 includes a hot water supply burner 12 and a hot water supply heat exchanger 14 that transfers heat from the hot water supply burner 12 to the hot water. The hot water supply burner 12 includes three combustion surfaces, a first combustion surface 16a, a second combustion surface 16b, and a third combustion surface 16c, from the left in the drawing.
[0029]
A gas pipe 18 for hot water supply is connected to the hot water supply burner 12 of the water heater 10, and a gas on / off valve 20 is interposed in the gas pipe 18 and a gas detection sensor 22 is provided. The first to third combustion surfaces 16a, 16b and 16c are provided with first to third gas amount control valves 24a to 24c for adjusting the amount of gas supplied from the gas pipe 18, respectively. Whether or not to burn the combustion surface and the amount of combustion can be individually controlled. The hot water supply burner 12 is ignited by the second combustion surface 16b disposed in the center, and an ignition device 25 is provided in the vicinity of the center combustion surface 16b.
[0030]
A heat exchanger temperature sensor 15 is provided at a location on the outlet side of the heat exchanger 14 that is not directly heated by the hot water supply burner 12. Here, a thermistor is used as the heat exchanger temperature sensor 15. In addition, a thermocouple or the like can be used as a temperature sensor.
[0031]
Below the hot water supply burner 12, a combustion fan 26 for supplying and exhausting the hot water supply burner 12 is provided. A rotation speed sensor 26 a that detects the rotation speed of the combustion fan 26 is attached.
[0032]
A water supply pipe 28 is connected to the inlet side of the heat exchanger 14, and a water supply temperature sensor using a flow sensor 30 which is a water flow confirmation means for detecting the water supply flow rate and a thermistor for detecting the water supply temperature is connected to the water supply pipe 28. 32 and an electromagnetic water supply valve 34 are provided. A hot water supply pipe 36 is connected to the outlet side of the heat exchanger 14.
[0033]
A bypass path 38 that bypasses the heat exchanger 14 and directly connects the water supply pipe 28 and the hot water supply pipe 36 is provided in parallel with the heat exchanger 14. In the middle of the bypass path 38, a mixing valve 40 is provided for adjusting the ratio of the amount of water supplied to the heat exchanger 14 and the amount of water supplied to bypass the bypass path 38. The bypass path 38 may not be provided depending on specifications.
[0034]
The hot water supply pipe 36 is extended to use positions in various places, and a water faucet (not shown) is provided at the end thereof. Usually, a plurality of faucets are provided as needed. Further, a water amount control valve 42 for regulating the hot water is provided in the middle of the hot water supply pipe 36 downstream from the junction of the hot water supply pipe 36 and the bypass path 38, and further downstream, the hot water temperature for detecting the temperature of the hot water to be discharged. A sensor 44 is provided.
[0035]
The water heater 10 includes a control unit 50 as a circuit part that performs overall control of its operation, an operation unit 60 for receiving various operations such as setting a set temperature, and a display unit 62 for displaying an operation state and setting contents. And. The operation unit 60 and the display unit 62 are a main remote controller installed in a kitchen or the like and a bath remote controller installed in a bathroom.
[0036]
The water heater 10 has a standby mode in which the water inside the heat exchanger 14 is heated to a predetermined temperature and kept warm in a state where the faucet is not opened. When the standby mode is set, hot water at a set temperature can be discharged in a short time after opening. Whether to set the standby mode is selected by a switch (not shown) provided on the operation unit 60. In addition, it is possible to reserve the time for shifting to the standby mode by setting a timer.
[0037]
The control unit 50 includes a combustion control unit 52 that ignites the hot water supply burner 12 without being opened, and water is present inside the heat exchanger 14 when the hot water supply burner 12 is ignited without being opened. And a remaining water confirmation unit 54 for detecting whether or not. In addition, the control unit 50 includes a heating control unit 56 that controls the subsequent heating by the hot water supply burner 12 depending on whether or not water is present inside the heat exchanger 14.
[0038]
FIG. 2 illustrates a circuit configuration in the control unit 50 of the water heater 10. The control unit 50 includes a CPU (central processing unit) 71 that performs a central function of various controls. Various circuit devices are connected to the CPU 71 via various buses 72 such as a data bus and an address bus.
[0039]
Among these, a ROM (Read Only Memory) 73 is a read only memory for storing programs executed by the CPU 71 and various kinds of fixed data. A RAM (Random Access Memory) 74 is a working memory for storing data that is temporarily required for executing a program.
[0040]
The timer unit 75 is a circuit part that keeps time. In addition to managing the transition time to the standby mode such as 7:00 every morning, the timer unit 75 manages various times necessary for combustion control of the water heater 10 in seconds.
[0041]
The operation unit 60 and the display unit 62 are as described above. Connected to the bus 72 are an input port 76 for fetching various electrical information into the CPU 71 and an output port 77 for sending various electrical commands from the CPU 71 to various components such as an electromagnetic on-off valve. Yes.
[0042]
The heat exchange temperature sensor 15, the feed water temperature sensor 32, the hot water temperature sensor 44, the flow sensor 30, the gas detection sensor 22, the rotation speed sensor 26a, and the like are connected to the input port 76. The output port 77 is connected to first to third gas amount control valves 24a to 24c, a combustion fan 26, an ignition device 25, a gas on-off valve 20, and the like.
[0043]
Next, the operation will be described.
When the water heater 10 shifts to a standby mode in which the water in the heat exchanger 14 is preheated and kept warm, the minimum gas amount is obtained using all the first to third combustion surfaces 16a to 16c of the hot water burner 12. The initial combustion is performed for only a few seconds, for example, about 1 second to 2 seconds, for a time during which there is no problem even if there is no water in the heat exchanger 14 even if it is repeatedly heated for durability. Then, based on the temperature rise characteristic detected by the heat exchanger temperature sensor 15 that measures the temperature of the hot water coming out of the heat exchanger 14 at that time, it is determined whether or not water is present in the heat exchanger 14. It is to be determined.
[0044]
FIG. 3 shows the state of temperature change detected by the heat exchanger temperature sensor 15 during initial combustion for both cases where water is present in the heat exchanger 14 and when it is not present. . A lower rectangular wave 81 represents a period during which the hot water supply burner 12 is burning. The upper characteristic diagram shows the characteristic of the temperature change detected by the heat exchanger temperature sensor 15, where the solid line 82 indicates the case where water is present in the heat exchanger 14, and the dotted line 83 indicates that in the heat exchanger 14. Each case shows no water.
[0045]
When the hot water supply burner 12 is initially burned for several seconds from time t1 to time t2, if water is present, after a predetermined time (t3: time required for heat transfer, which is determined by the distance 88 shown in FIG. 4). A predetermined temperature range 86 is entered. This is due to the amount of heat applied and the heat capacity of the heat exchanger 14 (the sum of the water capacity of the internal water and the copper constituting the heat exchanger 14) and the air blown by the fan until the measurement time (t3). It depends on the amount of heat taken away.
[0046]
In contrast, when no water is present in the heat exchanger, the heat transfer medium to the heat exchange temperature sensor 15 that is the measurement point is air, so that the temperature rises relatively slowly as shown by the dotted line 83. To do.
[0047]
Furthermore, although not shown in the figure, when the amount of water in the heat exchanger 14 is less than when the water is full, the heat capacity of the water is reduced accordingly, so that at the time t3 than that indicated by the solid line 82 in FIG. The temperature rises. In addition, when only a small amount of water is present in the heat exchanger 14, the water is boiled by heating for several seconds, steam is generated, and the temperature rise is greater than when the water is full.
[0048]
Thus, in the vicinity of the time t3 when several seconds have passed since the hot water supply burner 12 is extinguished, there is a case where the water is almost full, a case where there is less water than the full water, and there is no water at all. There is a difference in the temperature rise characteristics between the cases where no operation is performed. Therefore, the presence or absence of water can be detected by measuring the temperature when a certain time has elapsed.
[0049]
Moreover, the case where the water temperature in the heat exchanger 14 is already high before a heating is also considered. Therefore, by determining the presence or absence of water based on the temperature difference (FIG. 3, 85) between the temperature detected by the heat exchanger temperature sensor 15 at the start time (t1) of the initial combustion and the temperature detected at the time t3. The presence or absence of residual water can be confirmed with high accuracy.
[0050]
FIG. 5 shows a flow of operations performed by the water heater 10 when shifting to the standby mode. When the operation button for setting the standby mode is pressed or when the time to shift to the reserved standby mode has arrived (step S101), the flow sensor 30 confirms the presence or absence of water flow (step S102). When there is water flow (step S102; Y), combustion for normal hot water supply is performed (step S103). In addition, when water flow is confirmed in each step, the operation | work of each step is stopped and normal hot water supply combustion is started immediately.
[0051]
When there is no water flow (step S102; N), it is checked whether or not the water temperature in the heat exchanger 14 is equal to or higher than the lower limit temperature of the heat retention temperature range (step S104). When the temperature is equal to or higher than the lower limit temperature (step S104; Y), it is only necessary to keep the temperature as it is, so normal backup combustion that is combustion for keeping temperature is performed (step S105).
[0052]
When the temperature is equal to or lower than the lower limit temperature (step S104; N), the remaining water confirmation unit 52 performs initial combustion by burning all the combustion surfaces 16a to 16c of the hot water supply burner 12 with a minimum gas amount for several seconds (step S106). .
[0053]
The CPU 71 of the control unit 50 measures the temperature rise near the heat exchanger 14 detected by the heat exchanger temperature sensor 15 (step S107), and determines whether the temperature rise is within a predetermined reference range (step S108). ).
[0054]
That is, the temperature at the time of starting the initial combustion is measured, and after the completion of the initial combustion, the difference from the temperature when a predetermined time required for heat conduction has elapsed is obtained, and the temperature difference is within the reference range. It is determined whether or not. The reference range is determined based on the measurement results obtained by measuring in advance the temperature rise characteristics when the heat exchanger 14 has no water and when there is water.
[0055]
When the temperature rise does not fall within the reference range (step S108; N), it is a case where there is no water in the heat exchanger 14, so an error message is displayed on the display unit 62 (step S109). Exit.
[0056]
On the other hand, when the temperature rise falls within the reference range (FIGS. 4 and 84) (step S108; Y), it indicates that water is present inside the heat exchanger 14, so the hot water supply burner 12 is again opened. The water temperature in the heat exchanger 14 is raised to a target temperature to be ignited and kept warm. At this time, all the combustion surfaces 16a to 16c of the hot water supply burner 12 are combusted until the primary target temperature slightly lower than the target temperature is reached, and rapid heating is performed (step S110).
[0057]
The time for heating is calculated by the CPU 71 based on the temperature difference between the water temperature in the heat exchanger 14 and the primary target temperature before the rapid heating is started. The specific heat of the heat exchanger 14 when water is present inside is measured in advance, and the unit time applied to the heat exchanger 14 when the specific heat and the previous temperature difference and the entire surface of the hot water supply burner 12 are burned. The required combustion time is determined from the amount of heat per unit.
[0058]
After the combustion for raising to the primary target temperature, the temperature in the heat exchanger 14 becomes uniform, and the temperature detected by the heat exchanger temperature sensor 15 is necessary to substantially match the water temperature in the heat exchanger 14. Wait until the time (referred to as heat conduction time) elapses (step S111). When the heat conduction time has elapsed (step S111; Y), the temperature information detected by the heat exchanger temperature sensor 15 is taken in and it is checked whether or not this temperature matches the final target temperature (step S112).
[0059]
When the final target temperature has not been reached (step S112; N), only the central second combustion surface 16b provided with the ignition device 25 among the combustion surfaces of the hot water supply burner 12 is burned for a short time (step S113). ) Again, after the heat conduction time has elapsed (step S111; Y), the hot water temperature in the heat exchanger 14 is measured. At this time, it may be a time different from the previous heat conduction time according to the distance (88) shown in FIG.
[0060]
Combusting only the second combustion surface 16b for a short time (about 2 seconds) will be referred to as short ignition. Repeat the ignition and temperature measurement until the hot water temperature almost matches the target temperature. When the hot water temperature in the heat exchanger 14 reaches the target temperature (step S112; Y), the hot water temperature in the heat exchanger 14 is shifted to a heat retention mode for maintaining the target temperature (step S114), and the plug is opened. Keeping the temperature until the standby mode is turned off so that the temperature is within the allowable temperature range set by the remote controller so that hot water at an appropriate temperature can be immediately discharged.
[0061]
In the heat retention mode, when the hot water temperature in the heat exchanger 14 falls below the lower limit of the allowable temperature range, a slight ignition is performed.
[0062]
When shifting to the standby mode, it is desirable to raise the water temperature in the heat exchanger 14 to the target temperature in as short a time as possible after receiving an instruction to shift to the mode. For this reason, it is conceivable to burn the hot water supply burner 12 over the entire surface and reach the target temperature all at once.
[0063]
However, normally, the water temperature inside the heat exchanger 14 when shifting to the standby mode is substantially equal to the outside air temperature, for example, about 15 ° C. If the target temperature is 50 ° C., it is necessary to increase the water temperature by 35 ° C. . When the heating time necessary for this is obtained by calculation and the entire surface of the hot water supply burner 12 is burned and rapidly heated, a part with a high temperature is generated, and the heat exchanger 14 is not durable.
[0064]
Therefore, the rapid heating is performed up to the primary target temperature lower than the target temperature, and thereafter, the heating is gradually performed by slight ignition. Therefore, in this rapid heating, combustion is performed on the entire surface so as not to generate a place where the temperature is partially high, and heating is performed with a minimum amount of gas so that a temperature equilibrium time by heat transfer can be gained, and then gradually heated. Thus, the hot water temperature in the heat exchanger 14 is accurately matched with the target temperature without applying excessive stress to the heat exchanger 14.
[0065]
FIG. 6 shows the combustion state of the hot water supply burner 12 when shifting to the standby mode and the rise characteristic of the water temperature in the heat exchanger 14. Initial combustion is performed from time T1 to time T2. Then, at time T3 when the heat conduction time has elapsed, it is determined whether water is present in the heat exchanger 14 based on the temperature rise at that time. When it is confirmed that water is present, rapid heating for burning the hot water supply burner 12 over the entire surface is performed until time T4, and the temperature is measured again at time T5 when the heat conduction time has elapsed.
[0066]
At the time T5, the target temperature indicated by the broken line 91 has not yet been reached, so that a slight ignition is performed from the time T5 to the time T6. Since the temperature measured at the time T7 when the heat conduction time has elapsed is within the allowable error range (92) of the target temperature, the temperature is shifted to the heat retention mode from this point.
[0067]
In the heat retention mode, the hot water temperature in the heat exchanger 14 is constantly monitored, and the ignition is performed again at time T8 when the temperature falls below the lower limit of the allowable range (92).
[0068]
The heat exchanger temperature sensor 15 for detecting the temperature of the hot water inside the heat exchanger 14 is arranged at a location that is not directly heated by the hot water supply burner 12 and detects a temperature rise due to heat conduction, so it is directly applied from the hot water supply burner 12. The influence of heat is small, and the difference in heat capacity (temperature increase rate) due to the presence or absence of water can be detected appropriately.
[0069]
Further, the heating when detecting the temperature rise characteristic is performed by burning the entire surface of the hot water supply burner 12, whereby the heat exchanger 14 is heated over a wide range, and the heat exchanger temperature sensor 15 is arranged by heat conduction. The time during which heat is transmitted to a location is shortened, and it is possible to determine whether or not water is present in a short time.
[0070]
As the amount of heat applied increases, the temperature difference caused by the difference in heat capacity increases, so that the entire surface of the hot water supply burner 12 is burned and a large amount of heat is applied, so that the determination can be made with high accuracy. Furthermore, since the heat exchanger is heated over a wide area by the entire surface combustion, the heat exchanger 14 is not partially overheated even when there is no water, which improves safety and improves the heat exchanger. There is also less fatigue of 14.
[0071]
Further, since residual water is checked using the heat exchanger temperature sensor 15 necessary for keeping the temperature of the hot water in the heat exchanger 14, it is directly detected whether or not water is present in the heat exchanger 14. There is no need to provide a separate sensor, and an increase in the price of the apparatus can be reduced.
[0072]
In the embodiment described above, the temperature inside the heat exchanger is kept at the set temperature of the hot water, but the temperature inside the heat exchanger is raised to a high temperature so that it does not boil, and is mixed with the water supply by the mixing valve. Thus, the tapping water may be adjusted to the set temperature. Moreover, although it heated rapidly to the primary target temperature, you may make it raise to target temperature only by a small ignition.
[0073]
Furthermore, although residual water confirmation was performed by the temperature difference, you may make it perform residual water confirmation by another sensor or a detection means. For example, a water level sensor may be provided.
[0074]
【The invention's effect】
According to the water heater according to the present invention, when the heat exchanger is heated without being opened, whether or not water is present is confirmed before the temperature inside the heat exchanger rises to the target temperature. Since it did in this way, even if it is a case where water does not exist in the inside of a heat exchanger, emptying can be prevented and safety can be improved.
[0075]
Also, the hot water burner was burned without being opened, and it was determined whether water was present inside the heat exchanger based on the temperature rise rate inside the heat exchanger at that time. In addition to the necessary temperature sensor, there is no need to provide a separate sensor for directly detecting the presence or absence of water, and the increase in price can be suppressed to a minimum.
[0076]
Furthermore, the temperature detection means is placed in a place where it is not directly heated by the hot water burner, and the temperature rise transmitted by convection is detected, so there is little influence of the heat directly applied from the hot water burner, and the difference in heat capacity and heat conduction due to the presence or absence of water Can be detected appropriately.
[0077]
In addition, since the heating for detecting the temperature rise characteristic is performed by burning the entire surface of the hot water supply burner, the time for transferring heat to the place where the temperature detecting means is arranged by heat conduction is shortened, and the remaining time is left. Water confirmation can be performed in a short time. Furthermore, by burning the entire surface of the hot water supply burner, it is possible to accurately check the remaining water due to the temperature difference, and even when there is no water, the heat exchanger does not partially overheat and is safe. In addition, durability can be improved.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a water heater according to an embodiment of the present invention.
FIG. 2 is a block diagram showing an outline of a circuit configuration of a water heater according to an embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a state in which the temperature of the heat exchanger rises when checking residual water.
FIG. 4 is an explanatory diagram showing an outline of a mounting position of a heat exchanger temperature sensor.
FIG. 5 is a flowchart showing a flow of operations performed when the water heater according to the embodiment of the present invention shifts to a standby mode.
FIG. 6 is an explanatory diagram showing how the water temperature in the heat exchanger changes when the water heater according to the embodiment of the present invention shifts to the standby mode.
[Explanation of symbols]
10 ... Water heater
12 ... Hot water burner
14 ... Heat exchanger
15. Heat exchange temperature sensor
16a ... 1st combustion surface
16b ... 2nd combustion surface
16c ... 3rd combustion surface
18 ... Gas piping
20 ... Gas valve
22 ... Gas detection sensor
24a ... First gas amount control valve
24b ... Second gas amount control valve
24c ... Third gas amount control valve
25 ... Ignition device
26 ... Combustion fan
26a ... rotational speed sensor
28 ... Water supply pipe
30 ... Flow sensor
32 ... Water supply temperature sensor
34 ... Water supply valve
36 ... Hot water supply pipe
38 ... Bypass route
40 ... Mixing valve
42 ... Water control valve
44 ... Hot water temperature sensor
50. Control unit
52 ... Combustion control unit
54. Residual water confirmation section
56 ... Heating control unit
60 ... operation unit
62 ... Display section
71 ... CPU
72 ... Bus
73 ... ROM
74 ... RAM
75 ... Timer section
76 ... Input port
77 ... Output port

Claims (4)

In a water heater having a hot water supply burner and a heat exchanger for transferring heat from the hot water supply burner to the water supply,
Temperature detecting means for detecting the temperature inside the heat exchanger;
Combustion control means for burning the hot water supply burner for a predetermined time in a state where it is not opened;
When a certain amount of time has elapsed after the combustion control means burns the hot water supply burner for a predetermined time, when the temperature rise inside the heat exchanger is within a predetermined range, the heat exchanger has a certain amount or more. Residual water confirmation means for determining that there is water,
A water heater characterized by providing a.   The temperature detecting means is disposed at a location where heat from the hot water burner is not directly applied but is conducted by convection of a medium existing inside the heat exchanger. 1. The water heater according to 1.   When it is determined by the remaining water confirmation means that water is present in the heat exchanger, the hot water burner is burned and heated until the water in the heat exchanger reaches a predetermined target temperature, and the remaining water is heated. The hot water supply according to claim 1 or 2, further comprising a heating control means for stopping the subsequent heating by the hot water supply burner when it is determined by the water confirmation means that no water is present inside the heat exchanger. vessel.   The hot water heater according to claim 1, 2 or 3, wherein the combustion control means burns a hot water supply burner for heating the heat exchanger over the entire surface thereof.

Images