JP2022147205A - Water heater, computer-implemented method for controlling water heater, and program for causing computer to execute the method - Google Patents

Abstract

To provide a water heater in which generation of scale is suppressed in a heat exchanger.SOLUTION: A process performed by a water heater comprises: a step (S720) of reading a hot water supply set temperature from a memory; steps (S730, S740, S750) of setting the maximum temperature of a can body for each combustion level (the number of combustion stages) according to a preset pattern according to the hot water supply set temperature; a step (S780) of continuing the combustion operation when it is desired to detect the end of the operation of the water heater 100 in a case where no change in the hot water supply set temperature has been detected (NO in step S770); and steps (S730, S740, S750) of setting the maximum temperature of the can body again for each combustion level (number of combustion stages) when a change in hot water supply set temperature has been detected (YES in step S760).SELECTED DRAWING: Figure 7

Description

TECHNICAL FIELD The present disclosure relates to control of a water heater, and more particularly to control for suppressing deposition of scale.

Conventionally, when hard water containing a large amount of calcium and the like is used as tap water supplied to a hot water heater, calcium (scale) precipitates and sometimes adheres and accumulates in the water heater. . As a result, heat exchange between the can body and the water in the can body is impeded, excessive thermal stress is applied to the can body, and eventually thermal fatigue failure may occur.

As a countermeasure against scale deposits on the can body, for example, Japanese Patent Application Laid-Open No. 2014-88976 (Patent Document 1) discloses “a water heater capable of suppressing deposition of scale in a heat exchanger”. This water heater comprises a combustion burner (5), a blower fan (51), a heat exchanger (31) heated by combustion exhaust gas generated by combustion of the combustion burner (5), and a heat exchanger (31). A water supply pipe (1) for supplying water to the pipe (3), a hot water discharge pipe (2) for discharging hot water after heat-exchanging the water in the pipe (3) with a heat exchanger (31), and hot water discharge. When the drain pipe (42) branched from the pipe (2), the on-off valve (43) provided in the drain pipe (42), and the hot water supply operation are stopped to stop the combustion of the combustion burner (5), a control unit (14) that performs a heat exchanger cooling operation by opening the on-off valve (43) to allow water to flow from the water supply pipe (1) through the pipe (3) to the drain pipe (42); have” (see [Abstract]). According to this hot water supply apparatus, "after the hot water supply operation, the temperature of the heat exchanger is quickly lowered by executing a heat exchanger cooling operation in which water is passed through the conduit of the heat exchanger from the water supply pipe. Therefore, it is possible to prevent problems such as high-temperature hot water remaining in the pipes and post-boiling phenomenon, thereby suppressing the deposition of scale in the pipes of the heat exchanger. You can do it." (see paragraph [0018]).

Japanese Patent Application Laid-Open No. 2001-50589 (Patent Document 2) discloses a technique for "preventing boiling of hot water on the heat exchanger outlet side of a water heater and generation of drainage in the heat exchanger at low cost". . According to this technique, when the set temperature Ts of the water heater is higher than the high-temperature set temperature THS, and the outlet heated water temperature To is higher than the set temperature Ts, the inner cylinder control temperature TNDS is obtained according to the outlet heated water temperature To and the set temperature Ts. When the outlet heated water temperature To is lower than the set temperature Ts, the inner cylinder control temperature TNDS is increased by the high temperature adjustment temperature ΔTh and the hot water is not boiled by the heating of the heat exchanger 30. and control the combustion of the burner so that the inner shell temperature becomes equal to the set inner shell control temperature” (see [Summary]).

JP 2014-88976 A JP-A-2001-50589

According to the technique disclosed in Patent Document 1, the suppression of scale deposits is performed after the hot water supply is stopped, so there is a possibility that the effect of suppressing scale deposits during use of the hot water supply apparatus is low. In addition, since the heat exchanger (can body) is cooled by a cooling action such as the passage of water, the temperature of the can body may be lowered more than necessary. Furthermore, water cooling may cause rapid cooling of the pipe, resulting in reduced durability due to heat shock.

The present disclosure has been made in view of the background as described above, and according to a certain aspect, a technique for suppressing the deposition of scale during use of a hot water supply apparatus is disclosed.

According to one embodiment, a water heater is provided. This water heater includes a burner, a can body including a heat exchanger heated by the burner, a water supply path for supplying water to an inlet of the can body, a hot water outlet path for supplying hot water from an outlet of the can body, a can a bypass passage that bypasses the body and is connected to the water supply passage and the hot water discharge passage; a temperature sensor that detects the temperature of the water supplied to the boiler; a temperature sensor that detects the temperature of the hot water at the outlet of the boiler; A temperature sensor for detecting the temperature of hot water supplied from the hot water supply apparatus after the bypass path and the hot water supply path are joined, and a control device for controlling the operation of the hot water supply apparatus. The control device receives an input of a set value for the temperature of hot water supplied from the water heater, determines the combustion level of the burner based on the set value and the amount of hot water supplied from the water heater, and determines the combustion level according to the combustion level. Combustion operation by the burner is controlled according to a predefined maximum can body temperature.

In a water heater according to another aspect, the burner fires at multiple combustion levels. A maximum temperature is set for each combustion level.

In the water heater according to another aspect, the maximum temperature of the can body when the burner combustion level is minimum is lower than the maximum temperature of the can body when the burner combustion level is maximum.

In the water heater according to another aspect, when the combustion level is equal to or lower than a preset combustion level, the maximum temperature of the boiler when the set value is lower than the preset temperature is set to the preset value. lower than the maximum temperature of the can body above the specified temperature.

In the water heater according to another aspect, the control device further detects that scale adheres to the inside of the heat exchanger based on the temperature of the outlet of the boiler body, and the scale adheres to the inside of the heat exchanger. The hot water supply apparatus is made to perform a predetermined operation based on the detection of adhesion.

In the hot water supply device according to still another aspect, the maximum temperature of the boiler includes the temperature of water supplied to the boiler, the temperature of hot water delivered from the boiler, the temperature of hot water supplied from the water heater, the set value, and the temperature of hot water supplied from the boiler. It can be changed based on either the hot water supply capacity required for the device.

According to another embodiment, a computer implemented method for controlling a water heater is provided. This method comprises the steps of: accepting an input of a set value for the temperature of hot water supplied from a hot water supply apparatus comprising a burner and a boiler body including a heat exchanger heated by the burner; determining a combustion level of the burner based on the quantity of hot water supplied; and controlling combustion operation by the burner in accordance with a predetermined maximum can body temperature corresponding to the combustion level.

In a method according to another aspect, the burner fires at multiple firing levels and a maximum temperature is set for each firing level.

In a method according to another aspect, the maximum can body temperature at minimum burner firing level is less than the maximum can body temperature at maximum burner firing level.

In the method according to another aspect, when the combustion level is equal to or lower than the preset combustion level, the maximum temperature of the can body when the set value is lower than the predetermined temperature is Lower than the maximum temperature of the can body above the temperature.

A method according to another aspect comprises the steps of: detecting scale deposits inside a heat exchanger based on the temperature at the outlet of the boiler body; and causing the water heater to perform a predefined action based on the detection of .

In the method according to still another aspect, the maximum temperature of the can includes the temperature of water supplied to the can, the temperature of hot water delivered from the can, the temperature of hot water supplied from the water heater, the set value, the water heater It can be changed based on either the hot water supply capacity and the required hot water supply capacity.

According to yet another embodiment, a program is provided for causing a computer to execute a method for controlling a water heater. The program receives, in the computer, a set value for the temperature of hot water supplied from a hot water supply device comprising a burner and a boiler body including a heat exchanger heated by the burner; determining a combustion level of the burner based on the amount of hot water supplied; and controlling combustion operation by the burner according to a predetermined maximum can body temperature corresponding to the combustion level.

In programs according to other aspects, the burner fires at multiple firing levels. A maximum temperature is set for each combustion level.

In a program according to another aspect, the maximum can body temperature at minimum burner firing level is less than the maximum can body temperature at maximum burner firing level.

In the program according to another aspect, when the combustion level is equal to or lower than the preset combustion level, the maximum temperature of the can body when the set value is lower than the preset temperature is Lower than the maximum temperature of the can body above the temperature.

According to another aspect, the program instructs the computer to detect scale deposits inside the heat exchanger based on the temperature at the outlet of the boiler; and causing the hot water supply apparatus to perform a predetermined operation based on the fact that it is detected that the hot water supply device is running.

In the program according to still another aspect, the maximum temperature of the can body is the temperature of water supplied to the can body, the temperature of hot water delivered from the can body, the temperature of hot water supplied from the water heater, the set value, the water heater It can be changed based on either the hot water supply capacity and the required hot water supply capacity.

The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the invention taken in conjunction with the accompanying drawings.

1 is a diagram showing a schematic configuration of a water heater according to an embodiment; FIG. 2 is a block diagram showing an example of the hardware configuration of control device 110. FIG. 4 is a graph showing the relationship between the number (hot water supply capacity) of water heater 100 and the temperature of can body 102. FIG. FIG. 3 is a diagram showing an example of information set through operation panel 112 according to an embodiment; FIG. 4 is a diagram showing one mode of data storage in memory 220 of hot water supply apparatus 100 according to an embodiment. FIG. FIG. 10 is a diagram illustrating one mode of data storage in memory 220 according to another aspect; 4 is a flowchart showing part of a process executed by CPU 210 of hot water supply apparatus 100 according to an embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are given the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

The configuration of hot water supply apparatus 100 will be described with reference to FIG. FIG. 1 is a diagram showing a schematic configuration of a water heater according to an embodiment.

Water heater 100 includes case 101, can body 102, heat exchanger 103, burner 104, fan 105, gas valve 106, spark plug 107, motor 109, controller 110, and display unit. 111, an operation panel 112, a flow rate sensor 113, a flow rate adjustment valve 114, temperature sensors 141, 142, 143, pipes 180a, 180b, 180c, and a gas pipe 190. In addition, the arrow in FIG. 1 indicates the direction in which the fluid flows. The fluid may include hot water, water, and cleaning liquid used in a cleaning mode in which water heater 100 operates to remove scale adhering to the interior of heat exchanger 103 .

Can body 102 , control device 110 , display unit 111 , flow sensor 113 , flow control valve 114 , and pipes 180 a , 180 b , 180 c are arranged in case 101 . The heat exchanger 103 , the burner 104 and the blower fan 105 are arranged in the can body 102 . The can body 102 is provided with an exhaust port 102a and an intake port (not shown).

The heat exchanger 103 heats the fluid containing hot water with the heat from the burner 104 . Specifically, heat exchanger 103 is configured to exchange heat with combustion gas generated by burner 104 . In the example of FIG. 1, the heat exchanger 103 has a fin-and-tube structure having a plurality of plate-like fins and heat transfer tubes passing through the plurality of fins. Note that the heat exchanger 103 is not limited to the fin-and-tube type. In FIG. 1, each part including heat exchanger 103 and pipes 180a, 180b, and 180c constitutes a "hot water supply circuit." Burner 104 corresponds to an example of a "heating section" that heats the hot water supply circuit.

The burner 104 produces combustion gases by combusting the fuel gas. In one aspect, burner 104 is comprised of multiple combustion devices. A plurality of combustion devices are ignited according to preset combustion levels, depending on the temperature and quantity of hot water required. It can be said that the combustion level corresponds to the so-called “number of combustion stages” required for water heater 100 . For example, combustion levels may be defined from 1 to 6 and the burner 104 may consist of 20 combustors. As an example of this case, burn level "1" has three combustors operating, burn level "2" has five combustors operating, burn level "3" has ten combustors operating, and burn level "1" has five combustors operating. At "4", 13 combustors are activated, at burn level "5", 15 combustors are activated, and at burn level "6", 20 combustors are activated. The number of combustion levels is not limited to six, and may be less than six or more than six.

Burner 104 is connected to gas pipe 190 . Gas valve 106 is provided in gas pipe 190 . The ignition plug 107 is arranged above the burner 104 . When the ignition plug 107 generates an ignition spark between the targets provided on the burner 104 , flame is produced in the mixture of fuel and air ejected from the burner 104 .

Blower fan 105 supplies air necessary for combustion to burner 104 . Blower fan 105 is rotatably driven by motor 109 . The blower fan 105 introduces air into the can body 102 from the air intake port, and discharges the air used for combustion to the outside of the can body 102 from the exhaust port 102a.

Temperature sensor 141 is arranged in pipe 180 a and detects the temperature of water supplied to hot water supply apparatus 100 . The temperature sensor 142 is arranged at the outlet of the heat exchanger 103 and detects the outlet temperature (hereinafter also referred to as “bottle body temperature”) which is the temperature of the hot water immediately after being discharged from the outlet of the heat exchanger 103 . The temperature sensor 143 detects the temperature of hot water in which the hot water delivered from the pipe 180b and the water delivered from the pipe 180c are mixed. In one aspect, the temperature sensors 141, 142, and 143 are composed of so-called NTC (Negative Temperature Coefficient) thermistors, which have the characteristic that the electrical resistance value decreases as the temperature rises.

In one aspect, control device 110 can detect the occurrence of scale clogging in heat exchanger 103 using the body temperature detected by temperature sensor 142 . As an example, when scale adheres to the inside of the piping of the heat exchanger 103, the normal heat transfer of the heat exchanger 103 is impaired and the heat transfer efficiency is lowered. As a result, the amount of heat retained in the heat exchanger 103 increases, and the post-boiling temperature rises when the hot water supply operation is stopped. Therefore, it can be estimated that the higher the can body temperature detected by the temperature sensor 142, the larger the amount of deposit of scale. Therefore, in one embodiment, the control device 110 compares the temperature detected by the temperature sensor 142 with a predetermined threshold, and if the detected temperature exceeds the threshold, , the degree of scale clogging (amount of scale adhesion) can be determined.

When the control device 110 detects scale clogging, the control device 110 notifies that the scale is attached to the heat exchanger 103 . For example, control device 110 displays a message to that effect on display unit 111 . As an example, when the display unit 111 includes a red light emitting device, the control device 110 turns on the red light emitting device. In another aspect, if operation panel 112 has a monitor, control device 110 displays a message on the monitor indicating that scale is adhering to heat exchanger 103 .

When control device 110 detects the adhesion of scale, controller 110 switches the operation mode of water heater 100 to the cleaning mode of heat exchanger 103 automatically or based on the operation of the user of water heater 100, and cleans the cleaning liquid prepared in advance. is sent to the heat exchanger 103 to wash the heat exchanger 103 and remove the scale. After completing the cleaning of heat exchanger 103 , control device 110 can switch the operation mode of hot water supply apparatus 100 to the normal mode and restart the operation of hot water supply apparatus 100 .

In one aspect, the temperature sensor 142 may be attached to the hot water outlet pipe 180 b downstream of the heat exchanger 103 or may be attached to a heat transfer tube within the heat exchanger 103 . As another method for detecting the occurrence of clogging with scale, other than the temperature sensor 142 that detects the body temperature, for example, a decrease in the flow rate of hot water due to clogging with scale downstream of the heat exchanger 103 can be detected. A configuration for detection may be employed.

Piping 180 a , 180 b , 180 c is configured to flow the above fluids through heat exchanger 103 . Specifically, the pipe 180a is a water supply pipe, the pipe 180b is a hot water supply pipe, and the pipe 180c is a bypass pipe.

The pipe 180a is connected to the water supply side of the heat exchanger 103, and supplies fluid (such as water) from the pipe inlet 122A to the heat exchanger 103 (more specifically, heat transfer pipes).

The pipe 180b is connected to the hot water outlet side of the heat exchanger 103, and delivers the fluid from the heat exchanger 103 to the outside through the pipe outlet 123A.

The pipe 180c forms a bypass channel between the pipes 180a and 180b. More specifically, the pipe 180c is connected to each of the pipes 180a and 180b so as to bypass the fluid supplied from the pipe inlet 122A to the pipe 180a and guide the fluid to the pipe 180b. A bypass flow control valve 115 is connected to the pipe 180c. The bypass flow control valve 115 adjusts the flow rate of the fluid in the pipe 180c.

The flow control valve 114 is provided downstream of the confluence of the pipes 180b and 180c, that is, between the confluence and the pipe outlet 123A. The flow control valve 114 adjusts the amount of fluid (for example, hot water) delivered from the piping outlet 123A. The flow rate control valve 114 and the bypass flow rate control valve 115 also function as cutoff valves by being completely closed. The opening degrees of flow rate control valve 114 and bypass flow rate control valve 115 are adjusted, for example, by a stepping motor.

The display unit 111 is controlled by the control device 110 to display information. The displayed information includes the set temperature, the current temperature (for example, hot water temperature), an error when the occurrence of clogging with scale is detected, and information regarding the scale cleaning mode. In the example of FIG. 1 , display unit 111 is configured separately from operation panel 112 , but in another aspect, operation panel 112 capable of remotely controlling water heater 100 may have display unit 111 . . In yet another aspect, a speaker may be provided for audibly outputting information or warnings.

Control device 110 outputs electric power supplied to hot water supply apparatus 100 via a power plug (not shown) to each part. Control device 110 also controls the operation of the components of hot water supply apparatus 100 by executing a program stored in the memory. For example, controller 110 controls the operation (combustion)/stop of burner 104 and the amount of gas supplied to burner 104, and also controls the operation/stop of blower fan 105 and the fan speed during operation.

In another aspect, control device 110 may output an error to display unit 111 upon detecting the occurrence of clogging with scale. In this case, the control device 110 controls each unit to prohibit the combustion operation of the burner 104 after outputting the error. Furthermore, when control device 110 receives a start operation for starting the cleaning mode for water heater 100, control device 110 controls each unit to start the cleaning mode for cleaning inside of heat exchanger 103 with the cleaning liquid. do. Note that when the cleaning mode ends, the control device 110 can delete the error notification history and cancel the prohibition of the combustion operation of the burner 104 . The configuration of the control device 110 will be described later.

[Hardware configuration of control device]
The configuration of the control device 110 will be described with reference to FIG. FIG. 2 is a block diagram showing an example of the hardware configuration of control device 110. As shown in FIG. Control device 110 is typically configured by a microcomputer. Control device 110 includes a CPU (Central Processing Unit) 210 , a memory 220 , an input/output circuit 230 and an electronic circuit 240 . The CPU 210 , the memory 220 and the input/output circuit 230 can exchange signals with each other via the bus 250 . The electronic circuit 240 is configured to execute predetermined arithmetic processing using dedicated hardware. The electronic circuit 240 can exchange signals with the CPU 210 and the input/output circuit 230 .

Control device 110 is electrically connected to spark plug 107 , motor 109 , temperature sensor 142 , flow rate sensor 113 , display section 111 and operation panel 112 .

CPU 210 receives input of output signals (detected values) from sensors including temperature sensor 142 through input/output circuit 230 . Further, CPU 210 receives input of a signal indicating an operation instruction given to operation panel 112 through input/output circuit 230 . The operation instruction includes, for example, an on/off operation of the operation switch of hot water supply apparatus 100, hot water supply temperature setting, and various time reservation settings (also referred to as "timer setting"). CPU 210 controls the operation of each component including spark plug 107 and motor 109 so that hot water supply apparatus 100 operates according to the operation instruction.

CPU 210 can output information indicating the state of hot water supply apparatus 100 via display unit 111 . The display unit 111 includes a liquid crystal monitor, an organic EL (Electro Luminescence) monitor, a lamp, and the like. In another aspect, CPU 210 can notify the state of hot water supply apparatus using a speaker (not shown) using voice, melody, or the like.

[Relationship between hot water supply capacity and boiler body temperature]
With reference to FIG. 3, the relationship between the hot water supply capacity and the boiler body temperature will be described. FIG. 3 is a graph showing the relationship between the number (hot water supply capacity) of water heater 100 and the temperature of can body 102 . In one aspect, the maximum temperature of the can body 102 can have a linear relationship with the hot water supply capacity. For example, if the number (hot water supply capacity) required for water heater 100 is No. 40, the maximum temperature of can body 102 is about 80° C. (=176° F.). On the other hand, if the number (hot water supply capacity) is No. 70, the maximum temperature of the can body 102 is about 70° C. (=158° F.).

However, the hot water supply set temperature indicated to hot water supply apparatus 100 does not always require the maximum scale (hot water supply capacity). have a nature.

Therefore, according to an embodiment, the maximum temperature of can body 102 can be controlled according to the hot water supply set temperature of water heater 100 and the combustion level (the so-called number of combustion stages). For example, in one aspect, temperature control of can body 102 is performed as follows.

If the set temperature≦120 degrees Fahrenheit (=approximately 49 degrees C.), the maximum temperature of the can body 102 can be set at 140 degrees Fahrenheit (=60 degrees C.) at burn levels 1-4. At burn levels 5 and 6, the maximum temperature may be set at 176 degrees Fahrenheit (=80 degrees Celsius).

When 120 degrees Fahrenheit (=approximately 49 degrees Celsius)<set temperature≦140 degrees Fahrenheit (=60 degrees Celsius), the maximum temperature of the can body 102 can be set to 158 degrees Fahrenheit (=70 degrees Celsius) at combustion levels 1 to 4. . At burn levels 5 and 6, the maximum temperature may be set at 176 degrees Fahrenheit (=80 degrees Celsius).

If the set temperature>140 degrees Fahrenheit (=60 degrees C.), at burn levels 1-6, the maximum temperature of the can body 102 is set to 176 degrees Fahrenheit (=80 degrees C.).

[Temperature setting]
The temperature setting of water heater 100 will be described with reference to FIG. FIG. 4 is a diagram showing an example of information set through operation panel 112 according to an embodiment. Operation panel 112 includes, for example, a touch panel. Touch panel displays setting information of hot water supply apparatus 100 and accepts operation input by the user of operation panel 112 .

For example, as shown in state A, in a certain situation, operation panel 112 indicates 60° C. (that is, 140° F.) as the set temperature of water heater 100 . When the user presses the “Confirm” button after setting the temperature to 60° C., information indicating that the set temperature is 60° C. (=140° F.) is written in the memory 220 . Thereafter, CPU 210 adjusts combustion by burner 104 based on the set temperature.

Thereafter, when the user presses the "down" button, operation panel 112 may display 45 degrees Celsius (ie, 113 degrees Fahrenheit), as shown as state B. When the user presses the “confirm” button, information indicating that the set temperature is 45° C. is written into the memory 220 . After that, the CPU 210 supplies hot water of 45° C. by suppressing combustion by the burner 104 based on the set temperature and adjusting the amount of water flowing through the pipe 180c as necessary.

[data structure]
A data structure in hot water supply apparatus 100 will be described with reference to FIGS. 5 and 6. FIG. FIG. 5 is a diagram showing one mode of data storage in memory 220 of hot water supply apparatus 100 according to an embodiment. FIG. 6 is a diagram illustrating one aspect of data storage in memory 220 according to another aspect.

As shown in FIG. 5, in one aspect memory 220 maintains table 510 . Table 510 defines a predetermined maximum temperature of the can body for each combustion level of water heater 100 . In table 510, the maximum temperature of can body 102 is set to a constant value.

On the other hand, according to an embodiment, water heater 100 can use data as defined in table 520 instead of data defined in table 510 . For example, when the set temperature of hot water supply apparatus 100 is set to be higher than 120 degrees Fahrenheit (=49 degrees Celsius) and not higher than 140 degrees Fahrenheit (=60 degrees Celsius), CPU 210 controls combustion by burner 104 based on the data in table 520. Control.

That is, the table 520 defines two stages of maximum temperature according to the combustion level. More specifically, the maximum temperature of the can body 102 is switched between combustion levels 4 and 5. Therefore, when the required amount of hot water can be supplied to hot water supply apparatus 100 at combustion level "4", the maximum temperature of can body 102 is controlled at 70° C. (=158° C.). After that, when the user further opens the faucet (not shown) and the amount of hot water used increases, and as a result, combustion level "6" is required for supplying hot water, the maximum temperature of the can body 102 is 80°C (= 176 degrees Celsius). That is, the upper temperature limit used to control the can body 102 is raised.

In a certain aspect, the heat load on the fin pipes (not shown) and fins (not shown) increases in a range where the combustion level (the number of combustion stages) is low (eg, combustion level "1" to combustion level "4"). In some cases, scale formation is likely to occur. However, according to the settings shown in table 520, the maximum can body 102 temperature in that range is higher than the maximum can body 102 temperature in the higher burn level ranges (eg, burn levels "5" and "6"). is also lowered, the generation of scale can be suppressed.

Referring to FIG. 6, the user of hot water supply apparatus 100 may lower the set temperature to 49.degree. In this case, CPU 210 can use data defined in table 610 instead of data in table 520 . That is, the table 610 sets the maximum temperature of the can body 102 to 60 degrees Celsius (=140 degrees Fahrenheit) for combustion level "1" to combustion level "4". For burn levels "5" and "6", the maximum temperature of the can body 102 remains at 80°C (=176°F).

Therefore, if the amount of hot water used by the user of hot water supply apparatus 100 can be supplied within the range of combustion levels "1" to "4", the maximum temperature of can body 102 is 60° C. (=140° F.). In one aspect, hot water supply apparatus 100 can perform so-called bypass mixing control by mixing hot water flowing through pipe 180a and water flowing through pipe 180c. (=120 degrees Fahrenheit) or lower), the hot water supply apparatus can control the temperature of the hot water delivered by bypass mixing control without maintaining the temperature of the boiler body 102 at a high temperature. can. Subsequently, when the required amount of hot water increases and the combustion level rises to 5 or 6, the maximum temperature of the can body 102 can be set to 80°C (=176°F).

Thus, by changing the maximum temperature of can body 102 according to the set value (hot water supply set temperature) for hot water supply apparatus 100, the maximum temperature of can body 102 is also lowered when the hot water supply set temperature is low. , unnecessary combustion is suppressed. As a result, the thermal stress generated in the can body 102 is reduced, so that deterioration in the durability of the can body 102 can be suppressed.

[Control structure]
Referring to FIG. 7, the control structure of hot water supply apparatus 100 will be described. FIG. 7 is a flowchart showing part of the process executed by CPU 210 of hot water supply apparatus 100 according to an embodiment.

In step S710, CPU 210 detects that water heater 100 is powered on.

In step S<b>720 , CPU 210 reads a set temperature for hot water supply (for example, table 510 , table 520 or table 610 ) from memory 220 based on an operation signal from operation panel 112 .

At step S730, CPU 210 sets the maximum temperature of can body 102 according to the first pattern. More specifically, the CPU 210 sets the maximum temperature of the can body 102 to 60° C. (=140 degrees Fahrenheit) for the combustion levels “1” to “4”, and for the combustion levels “5” and “6”, The maximum temperature of the can body 102 is set at 80° C. (=176° F.).

In step S740, CPU 210 sets the maximum temperature of can body 102 according to the second pattern. More specifically, the CPU 210 sets the maximum temperature of the can body 102 to 70° C. (=158 degrees Fahrenheit) for the combustion levels “1” to “4”, and for the combustion levels “5” and “6”, The maximum temperature of the can body 102 is set at 80° C. (=176° F.).

In step S750, CPU 210 sets the maximum temperature of can body 102 according to the third pattern. More specifically, the CPU 210 sets the maximum temperature of the can body 102 to 80° C. (=176 degrees Fahrenheit) for the combustion levels “1” to “4”, and also sets the maximum temperature for the combustion levels “5” and “6”. Similarly, the maximum temperature of the can body 102 is set to 80° C. (=176° F.).

In step S760, CPU 210 determines whether or not a change in hot water supply temperature setting has been detected. For example, the user may operate operation panel 112 to change the set temperature of hot water supply while using hot water supply apparatus 100 . When CPU 210 receives a new temperature setting signal from operation panel 112, CPU 210 can determine that the hot water supply temperature setting has been changed. When CPU 210 determines that a change in the set hot water supply temperature has been detected (YES in step S760), CPU 210 returns the control to step S720. Otherwise (NO in step S760), CPU 210 switches control to step S770.

In step S770, CPU 210 determines whether or not an instruction to end the operation of hot water supply apparatus 100 has been given. For example, when the user presses a stop button (not shown) on operation panel 112, CPU 210 determines that an instruction to end the operation of hot water supply apparatus 100 has been given. When CPU 210 determines that an instruction to end the operation of water heating apparatus 100 has been given (YES in step S770), the operation of water heating apparatus 100 ends. Otherwise (NO in step S770), CPU 210 switches control to step S780.

In step S780, CPU 210 continues the combustion operation of water heater 100. FIG. In one aspect, when CPU 210 detects that scale has adhered to the inside of heat exchanger 103 , CPU 210 switches the operation mode of hot water supply apparatus 100 to the cleaning mode to start cleaning heat exchanger 103 . After completing the cleaning of the heat exchanger 103, the CPU 210 switches the operation mode to the normal mode. Thereafter, CPU 210 returns control to step S760.

Some of the technical features disclosed above can be summarized as follows.
(1) In one aspect, CPU 210 accepts input of a set value for the temperature of hot water supplied from hot water supply apparatus 100 . CPU 210 determines the combustion level of burner 104 based on the set value and the amount of hot water supplied from water heater 100 . The amount of hot water can also correspond to the so-called demand number. The CPU 210 controls the combustion operation by the burner 104 according to the maximum temperature of the can body 102 which is predetermined according to the combustion level.

(2) In some aspects, the burner 104 may fire at multiple firing levels. A maximum temperature is set for each combustion level. CPU 210 controls the combustion operation of burner 104 according to the maximum temperature set for each combustion level.

(3) In one aspect, the maximum temperature of the can body 102 at the minimum combustion level of the burner 104 is less than the maximum temperature of the can body 102 at the maximum combustion level of the burner 104 .

(4) In one aspect, when the combustion level is equal to or lower than the preset combustion level, the maximum temperature of the can body 102 when the set value is lower than the preset temperature is lower than the maximum temperature of the can body 102 above the temperature specified.

(5) In a certain aspect, CPU 210 further detects that scale adheres to the inside of heat exchanger 103 based on the temperature at the outlet of can body 102 . CPU 210 causes hot water supply apparatus 100 to perform a predetermined operation based on detection that scale adheres to the inside of heat exchanger 103 .

(6) In a certain aspect, the maximum temperature of can body 102 is the temperature of water supplied to can body 102, the temperature of hot water delivered from can body 102, the temperature of hot water supplied from hot water supply apparatus 100, and the set value. , and the hot water supply capacity required of the hot water supply apparatus 100 .

As described above, according to the disclosure in this specification, hot water supply apparatus 100 sets the upper limit value (maximum temperature) can be changed. By doing so, the set temperature of the can body 102 is not set higher than necessary. As a result, adhesion of scale can be suppressed at hot water supply capacity and combustion level at which the can body 102 is frequently used. In addition, since the maximum temperature is set according to the hot water supply capacity and the combustion level, the adhesion of scale to the heat exchanger during use of hot water heater 100 is suppressed without lowering the maximum supply amount of hot water heater 100. obtain.

In addition, there is a case where the mode of use of water heater 100 is set independently, but water heater 100 may not always be used with the highest hot water supply capacity. According to hot water supply apparatus 100 according to the present embodiment, the maximum temperature of can body 102 is not lowered over the entire supply capacity, but is lowered at the combustion level (the number of combustion stages) at which the maximum flow rate of water does not decrease. As a result, adhesion of scale can be suppressed while maintaining the specifications of hot water supply apparatus 100 .

Further, since the can body 102 is not heated more than necessary, the thermal stress generated in the can body 102 is reduced. As a result, the durability of the can body 102 can be improved. For example, if the maximum temperature of the can body 102 is lowered by about 10 degrees, the durability of the can body 102 can be two or three times the durability of the can body 102 if the maximum temperature is not lowered.

Further, the water heater 100 according to the above embodiment is exemplified as a water heater capable of switching the hot water supply capacity or the combustion level, but in another aspect, the disclosed technical features can be applied to a water heater that cannot be switched. Applicable. In this case, the hot water supply device according to another aspect can be configured to be able to increase or decrease its hot water supply capacity itself.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and range of equivalents of the scope of the claims.

The disclosed technical features are applicable to commercial or domestic water heaters, combi-boilers, and the like.

100 hot water supply device 101 case 102 can body 102a exhaust port 103 heat exchanger 104 burner 105 blower fan 106 gas valve 107 spark plug 109 motor 110 control device 111 display unit 112 operation panel 113 flow sensor, 114 flow control valve, 115 bypass flow control valve, 122A pipe inlet, 123A pipe outlet, 141, 142, 143 temperature sensor, 180a, 180b, 180c pipe, 190 gas pipe, 220 memory, 230 input/output circuit, 240 electronics, 250 buses, 510, 520, 610 tables.

Claims (18)

A water heater,
burner and
a can body including a heat exchanger heated by the burner;
a water supply channel for supplying water to the inlet of the can;
a hot water outlet through which hot water is supplied from the outlet of the can;
a bypass passage that bypasses the boiler body and is connected to the water supply passage and the hot water discharge passage;
a temperature sensor that detects the temperature of water supplied to the can;
a temperature sensor for detecting the temperature of the hot water at the outlet of the can;
a temperature sensor for detecting the temperature of hot water supplied from the hot water supply apparatus after the bypass passage and the hot water outlet merge;
a control device that controls the operation of the water heater,
The control device is
receiving an input of a set value for the temperature of hot water supplied from the hot water supply device;
determining the combustion level of the burner based on the set value and the amount of hot water supplied from the hot water supply device;
A water heater that controls combustion operation by the burner in accordance with a maximum temperature of the can body that is predetermined in accordance with the combustion level. the burner fires at a plurality of combustion levels;
The water heater according to claim 1, wherein said maximum temperature is set for each said combustion level. 3. The hot water supply apparatus according to claim 1, wherein a maximum temperature of said can body when said burner has a minimum combustion level is lower than a maximum temperature of said can body when said burner has a maximum combustion level. When the combustion level is equal to or lower than the preset combustion level, the maximum temperature of the can body when the set value is lower than the predetermined temperature is higher than the preset temperature. 4. The water heater according to any one of claims 1 to 3, wherein the temperature is lower than the maximum temperature of said boiler body at a time. The control device further detects that scales have adhered to the inside of the heat exchanger based on the temperature of the outlet of the boiler body, and detects whether the scales have adhered to the inside of the heat exchanger. 5. The hot water supply apparatus according to claim 4, wherein said hot water supply apparatus is caused to perform a predetermined operation based on detection of presence. The maximum temperature of the can body includes the temperature of water supplied to the can body, the temperature of hot water delivered from the can body, the temperature of hot water supplied from the hot water supply device, the set value, and the temperature requested to the hot water supply device. The hot water supply apparatus according to any one of claims 1 to 5, which can be changed based on either the hot water supply capacity to be supplied. A computer implemented method for controlling a water heater comprising:
a step of receiving an input of a set value for the temperature of hot water supplied from a hot water supply apparatus comprising a burner and a boiler body including a heat exchanger heated by the burner;
determining a combustion level of the burner based on the set value and the amount of hot water supplied from the water heater;
and controlling combustion operation by said burner according to a predetermined maximum temperature of said can according to said combustion level. the burner fires at a plurality of combustion levels;
8. The method of claim 7, wherein said maximum temperature is set for each said combustion level. 9. A method according to claim 7 or 8, wherein the maximum temperature of the can body at a minimum firing level of the burner is less than the maximum temperature of the can body at a maximum firing level of the burner. When the combustion level is equal to or lower than the preset combustion level, the maximum temperature of the can body when the set value is lower than the predetermined temperature is higher than the preset temperature. 10. The method according to any one of claims 7 to 9, wherein the temperature is lower than the maximum temperature of the can body at that time. a step of detecting that scale adheres to the inside of the heat exchanger based on the temperature of the outlet of the can body;
11. The method of claim 10, further comprising causing the water heater to perform a predefined action based on detecting that the scale adheres to the interior of the heat exchanger. . The maximum temperature of the can body includes the temperature of water supplied to the can body, the temperature of hot water delivered from the can body, the temperature of hot water supplied from the hot water supply device, the set value, and the temperature requested to the hot water supply device. The method according to any one of claims 7 to 11, which can be changed based on either the hot water supply capacity to be supplied. A program for causing a computer to execute a method for controlling a water heater, the program comprising:
a step of receiving an input of a set value for the temperature of hot water supplied from a hot water supply apparatus comprising a burner and a boiler body including a heat exchanger heated by the burner;
determining the combustion level of the burner based on the set value and the amount of hot water supplied from the water heater;
and controlling the combustion operation of the burner in accordance with the maximum temperature of the can that is predetermined in accordance with the combustion level. the burner fires at a plurality of combustion levels;
14. The program according to claim 13, wherein said maximum temperature is set for each said combustion level. 15. The program according to claim 13 or 14, wherein the maximum temperature of the can body when the combustion level of the burner is minimum is lower than the maximum temperature of the can body when the combustion level of the burner is maximum. When the combustion level is equal to or lower than the preset combustion level, the maximum temperature of the can body when the set value is lower than the predetermined temperature is higher than the preset temperature. 16. The program according to any one of claims 13 to 15, wherein the temperature is lower than the maximum temperature of said can body at that time. The program causes the computer to:
a step of detecting that scale adheres to the inside of the heat exchanger based on the temperature of the outlet of the can body;
and causing the water heater to perform a predetermined operation based on the detection that the scale adheres to the inside of the heat exchanger. Program as described in any. The maximum temperature of the can body includes the temperature of water supplied to the can body, the temperature of hot water delivered from the can body, the temperature of hot water supplied from the hot water supply device, the set value, and the temperature requested to the hot water supply device. 18. The program according to any one of claims 13 to 17, which can be changed based on the hot water supply capacity to be supplied.

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