JP3042067B2 - Water heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water supply apparatus for dissolving combustion gas containing carbon dioxide gas to obtain hot water containing carbon dioxide gas.

[0002]

2. Description of the Related Art Conventionally, this type of hot water supply apparatus is as shown in FIG. The solid line arrows in the figure indicate the flow direction of hot water, and the wavy lines indicate the flow direction of combustion gas.

[0003] A combustion chamber 1 whose upper end in the vertical direction is open to the atmosphere, a combustion means 2 provided on a side surface of the combustion chamber 1 for forming a flame f in a horizontal direction, and a combustion chamber 1 below the combustion means 2 are connected. A hot water storage chamber 3 for storing hot water, a water supply passage 4 for supplying water downward from above in the combustion chamber 1, and a hot water storage chamber 3 for supplying hot water stored in the hot water storage chamber 3 to a predetermined location. A hot water supply path 5 is provided, and a transport device 6 provided in the middle of the hot water supply path 5. And the water passes through the water supply channel 4 and the combustion chamber 1
It is discharged into the inside, and is brought into direct contact with the flame f formed by the combustion means 2 to exchange heat and become hot water in which carbon dioxide in the combustion gas is dissolved. The hot water falls vertically downward and is stored in the hot water storage chamber 3, and then supplied to a predetermined location by the transport device 6 via the hot water supply path 5.

[0004]

However, in the above configuration, since the hot water storage chamber 3 is provided, the equipment becomes very large, and the transport device 6 for transporting the hot water stored in the hot water storage chamber 3 is required. Become. The inside of the combustion chamber 1 where the combustion gas and water come into contact is at atmospheric pressure, the solubility of carbon dioxide is low, and the concentration of carbon dioxide in the hot water is low.

If the pressure of the supplied water is different, the amount of heat recovered from the combustion gas is different because the amount of water supplied from the water supply passage 4 is different, and the tapping temperature is changed. If the supplied fuel is different, the temperature of the combustion gas is different and the concentration of carbon dioxide in the combustion gas is different. Therefore, the amount of heat recovered from the combustion gas is different and the concentration of carbon dioxide contained in the supplied hot water is also different. .

Another problem is that the concentration of carbon dioxide contained in hot water cannot be changed according to personal preference, even if it is desired.

The present invention has been made to solve the above-mentioned conventional problems. By changing the amount of combustion gas introduced into the hot water, even if the temperature of the hot water changes, the hot water at a temperature desired by the user is always supplied stably. The first purpose is to do so.

A second object of the present invention is to stably supply hot water having a carbon dioxide gas concentration desired by a user by detecting the concentration of carbon dioxide gas contained in the hot water.

[0009]

In order to achieve the first object, a first hot water supply apparatus according to the present invention comprises a combustion means using a fuel for producing a combustion gas containing carbon dioxide, and an exhaust gas from the combustion means. An exhaust path through which the combustion gas passes, a heat exchanger that exchanges heat between the combustion gas and water, a water supply path that supplies water to the heat exchanger, and a hot water supply path that supplies hot water from the heat exchanger to a predetermined location. An exhaust introduction means for introducing combustion gas into the hot water supply path, an exhaust introduction path for supplying combustion gas from the exhaust path to the exhaust introduction means, and an exhaust introduction path for adjusting the amount of combustion gas introduced into the hot water supply path. Introducing amount adjusting means provided, gas-liquid separating means for separating hot gas and combustion gas provided on the downstream side of the hot water supply path of exhaust introducing means, and an exhaust discharger for discharging only the combustion gas separated by the gas-liquid separating means, Exhaust return that returns combustion gas separated from the exhaust discharger to the exhaust path A water path adjusting means provided in the middle of the water supply path or the hot water supply path for adjusting the amount of water; a hot water temperature detecting means provided downstream of the hot water supply path of the gas-liquid separation means for detecting a hot water temperature; and setting the hot water temperature. The apparatus includes a tapping temperature setting unit, and a control unit that controls the combustion unit, the water amount adjusting unit, and the introduction amount adjusting unit based on signals from the temperature setting unit and the tapping temperature detecting unit.

In order to achieve the second object, a second hot water supply apparatus according to the present invention includes a combustion unit that uses a fuel that generates a combustion gas containing carbon dioxide, and a combustion gas that is discharged from the combustion unit. An exhaust passage, a heat exchanger for exchanging heat between combustion gas and water, a water supply passage for supplying water to the heat exchanger, a hot water supply passage for supplying hot water from the heat exchanger to a predetermined location, and a combustion in the hot water supply passage. Exhaust introducing means for introducing gas, an exhaust introducing path for supplying combustion gas from the exhaust path to the exhaust introducing means, and an introduction amount adjusting means provided in the exhaust introducing path for adjusting the amount of combustion gas introduced to the hot water supply path. Gas-liquid separating means for separating hot gas and combustion gas provided on the downstream side of the hot water supply path of the exhaust introducing means, and an exhaust discharger for discharging only the combustion gas separated by the gas-liquid separating means,
An exhaust return path for returning the combustion gas separated from the exhaust discharger to the exhaust path, a water amount adjusting means provided in the middle of the water supply path or the hot water supply path, and a hot water supply provided downstream of the gas-liquid separation means on the hot water supply path. Carbon dioxide concentration detecting means for detecting the concentration of carbon dioxide contained in the hot water flowing through the road, carbon dioxide concentration setting means for setting the carbon dioxide concentration contained in the hot water to be discharged, and signals from the carbon dioxide concentration setting means and the carbon dioxide concentration detecting means. It is provided with control means for controlling the combustion means, the water amount adjusting means and the introduction amount adjusting means based on the combustion means.

[0011]

According to the present invention, the first means produces a combustion gas containing carbon dioxide by the combustion means. The combustion gas is heat-exchanged in the heat exchanger and becomes low temperature and is discharged through the exhaust passage. Part of the combustion gas whose flow rate has been adjusted by the introduction amount adjusting means on the way is guided to the exhaust introduction means via the exhaust introduction path.

On the other hand, the water whose flow rate has been adjusted by the water amount adjusting means is supplied to the heat exchanger through the water supply passage, exchanges heat with the combustion gas and becomes hot water and enters the hot water supply passage. The heat-exchanged hot water is mixed with the combustion gas introduced by the exhaust gas introduction means provided in the middle of the hot water supply path, and further heat-exchanges with the combustion gas. Becomes Thereafter, the undissolved combustion gas and hot water are separated by the gas-liquid separation means, and the combustion gas is discharged from the exhaust discharger and returned to the exhaust path via the exhaust return path. Hot water containing carbon dioxide gas is supplied to a predetermined place such as a shower or a bath via a hot water supply path.

The temperature of the hot water to be supplied is detected by a tapping temperature detecting means provided on the downstream side of the supply path of the gas-liquid separating means.
The control means controls the combustion means, the water amount adjusting means, and the introduction amount adjusting means such that the hot water temperature detected by the hot water temperature detecting means becomes the hot water temperature set by the temperature setting means.

In the second means of the present invention, the concentration of carbon dioxide contained in the supplied hot water is detected by a carbon dioxide concentration detecting means provided on the downstream side of the hot water supply path of the gas-liquid separation means. The control unit controls the combustion unit, the water amount adjusting unit, and the introduction amount adjusting unit such that the concentration detected by the carbon dioxide concentration detecting unit becomes the concentration set by the concentration setting unit.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawing, solid arrows indicate the flow direction of hot water, dashed arrows indicate the flow direction of exhaust gas, and dashed lines indicate signal lines. The same components are denoted by the same reference numerals.

FIG. 1 is a schematic configuration diagram of one embodiment of the hot water supply apparatus of the present invention. Reference numeral 7 denotes combustion means for mixing and supplying air supplied by a combustion fan 8 for supplying air for combustion and fuel supplied by a fuel transfer pipe 9.
A combustion chamber 10, a heat exchanger 11, and an exhaust passage 12 are provided in order from the combustion means 7 in order. The heat exchanger 11 is connected to a water supply path 13 for supplying water and a hot water supply path 14 for supplying hot water heat-exchanged by the heat exchanger 11 to a predetermined location. In the middle of the water supply passage 13, a water amount adjusting means 15 for adjusting the flow rate of the water flowing through the water supply passage 13 is provided. Further, an exhaust introduction path 16 is provided branching from the middle of the exhaust path 12 so that a part of the combustion gas flows. In the middle of the hot water supply path 14, a direct pressure type edging device 17 that can prevent the backflow to the water supply channel 13 and use the supply pressure of the water supply channel 13 is provided, and an exhaust introduction path 16 is provided downstream of the direct pressure type edging device 17. Exhaust gas introducing means 18 for introducing the combustion gas from the exhaust passage 12 through the exhaust passage 12 and mixing into the hot water is provided. Further, a gas-liquid separating means 19 for separating the combustion gas and the hot water is provided downstream of the exhaust gas introducing means 18. ing. The gas-liquid separation means 19 is provided with an exhaust discharger 20 for discharging only residual combustion gas, and the exhaust discharger 20 and the exhaust path 12 are connected by an exhaust return path 21. On the downstream side of the hot water supply path 14 of the gas-liquid separation means 19, there is provided a tapping temperature detecting means 22 for detecting the temperature of hot water flowing through the hot water supply path 14. In the middle of the exhaust gas introduction path 16, an introduction amount adjusting means 2 for adjusting the flow rate of the combustion gas guided to the exhaust introduction means 18.
3 are provided. Reference numeral 24 denotes tapping temperature setting means for setting tapping temperature by a user. 25 is tap water temperature setting means 2
4 so that the temperature obtained by the tapping water temperature detecting means 22 becomes the temperature set in 4.
5 and control means for controlling the introduction amount adjusting means 23.

FIG. 2 shows details of the exhaust introducing means 18. Reference numeral 26 denotes a hot water supply inlet, which is connected to the direct pressure type edger 17. 27 is a hot water supply outlet, which is connected to the gas-liquid separation means 19. Reference numeral 28 denotes a nozzle, 29 denotes a venturi, and 30 denotes an exhaust inlet connected to the exhaust introduction path 16.

FIG. 3 shows the details of the gas-liquid separating means 19 and the exhaust / discharge device 20. 31 is a float, 32 is an exhaust outlet, which is connected to the exhaust return path 21. Reference numeral 33 denotes an inlet connected to the hot water supply outlet 27 of the exhaust gas introducing means 18, and reference numeral 34 denotes an outlet connected to the hot water supply passage 14.

In the above configuration, the air supplied by the combustion fan 8 and the fuel supplied by the fuel transfer pipe 9 are mixed by the combustion means 7 to form a flame f in the combustion chamber 10. The combustion gas generated by the flame f exchanges heat with the water supplied from the water supply passage 13 in the heat exchanger 11, and the combustion gas is cooled to a low temperature and exhausted from the exhaust passage 12. On the other hand, the water supplied from the water supply channel 13 becomes hot water and enters the hot water supply channel 14. The hot water is sent to the exhaust introducing means 18 provided in the middle of the hot water supply path 14 while the backflow is prevented by the direct pressure type edger 17 on the way. As shown in FIG. 2, the exhaust gas introducing means 18 comprises a nozzle 28 connected to a hot water supply inlet 26 and a venturi 29 connected to a hot water supply outlet 27 for reducing hot water supply pressure. A part of the combustion gas adjusted by the amount adjusting means 23 is supplied to the exhaust passage 1
2 through the exhaust introduction passage 16 and venturi 2
In the hot water supply passage 9 and the hot water supply passage 14, the carbon dioxide in the combustion gas is dissolved directly and heat exchange is performed with the combustion gas. Thereafter, the hot water enters the gas-liquid separation means 19 shown in FIG. 3 and is separated into hot water and residual combustion gas. When residual combustion gas exists, the float 31 in the exhaust discharger 20 descends, and the residual combustion gas is exhausted. The water is returned from the outlet 32 to the exhaust path 12 via the exhaust return path 21, and when hot water exists, the float 31 rises and closes the exhaust outlet 32. Hot water whose temperature has risen due to the dissolution of carbon dioxide is supplied to a shower or bathtub through a hot water supply path 14 after the final temperature is confirmed by a tapping temperature detecting means 22 provided downstream of the gas-liquid separating means 19. Is done.

The temperature of the hot water to be discharged is determined by a hot water temperature setting means 2
4, the combustion means 7, the combustion fan 8, the water amount adjusting means 15, the introduction amount adjustment so that the temperature detected by the tapping temperature detecting means 22 is set by the user at the tapping temperature setting means 24. The control means 25 controls the means 23.

With such a configuration, a conventional hot water storage room is not required, so that the equipment is compact and hot water can be supplied by tap water without a transporter. Further, since the combustion gas is directly dissolved under high water pressure, carbon dioxide can be dissolved more efficiently than under atmospheric pressure. The obtained hot water in which the carbon dioxide gas is dissolved is supplied to a bath or shower, and exerts a heat retaining effect, a fatigue recovery effect, a blood pressure stabilizing effect, and a wound healing effect on the human body. Furthermore, since the combustion gas and hot water come into direct contact,
The latent heat of water vapor in the combustion gas is also recovered, resulting in high efficiency. Further, since carbon dioxide and NOx in the combustion gas are dissolved, emission of carbon dioxide and harmful NOx, which cause global warming, can be suppressed. Furthermore, since the temperature of the hot water downstream of the gas-liquid separation means is detected and controlled so as to be the temperature set by the user, even if the amount of hot water discharged, the amount of combustion, and the amount of introduced combustion gas change, a stable temperature can be obtained. Hot water can be supplied and safety in use can be ensured.

FIG. 4 shows another embodiment of the present invention. Reference numeral 7 denotes a mixture of air supplied by a combustion fan 8 for supplying combustion air and fuel supplied by a fuel transfer pipe 9 for combustion. It is a combustion means. A combustion chamber 10, a heat exchanger 11, and an exhaust passage 12 are provided in order from the combustion means 7 in order. Water supply channel 1 for supplying water to heat exchanger 11
A hot water supply path 14 for supplying hot water heat-exchanged by the heat exchanger 3 and the heat exchanger 11 to a predetermined place is connected. In the middle of the water supply channel 13, a water amount adjusting means 1 for adjusting the flow rate of water flowing through the water supply channel 13.
5 are provided. Further, an exhaust introduction path 16 is provided branching from the middle of the exhaust path 12 so that a part of the combustion gas flows. In the middle of the hot water supply path 14, a direct pressure type edging device 17 that can prevent the backflow to the water supply channel 13 and use the supply pressure of the water supply channel 13 is provided, and an exhaust introduction path 16 is provided downstream of the direct pressure type edging device 17. Exhaust introducing means 18 is provided for introducing the combustion gas from the exhaust passage 12 through the exhaust passage 12 and mixing it into the hot water. Further, a gas-liquid separating means 19 is provided downstream of the exhaust introducing means 18. The gas-liquid separation means 19 is provided with an exhaust discharger 20 for discharging only residual combustion gas, and the exhaust discharger 20 and the exhaust path 12 are connected by an exhaust return path 21. On the downstream side of the hot water supply path 14 of the gas-liquid separation means 19, a carbon dioxide concentration detecting means 35 for detecting the concentration of carbon dioxide contained in the hot water flowing through the hot water supply path 14 is provided. Further, an introduction amount adjusting means 23 for adjusting the flow rate of the combustion gas guided to the exhaust introduction means 18 is provided in the exhaust introduction path 16.
Reference numeral 36 denotes a carbon dioxide concentration setting means for setting the concentration of carbon dioxide contained in the hot water to be supplied by the user. Reference numeral 25 denotes control means for controlling the combustion means 7, the water amount adjusting means 15, and the introduction amount adjusting means 23 so that the concentration obtained by the carbonic acid concentration detecting means 35 becomes the concentration set by the carbonic acid concentration setting means 36.

FIG. 2 shows the details of the exhaust introducing means 18. Reference numeral 26 denotes a hot water supply inlet, which is connected to the direct pressure type edger 17. 27 is a hot water supply outlet connected to the gas-liquid separation means 19. Reference numeral 28 denotes a nozzle, 29 denotes a venturi, and 30 denotes an exhaust inlet connected to the exhaust introduction path 16.

FIG. 3 shows details of the gas-liquid separation means 19 and the exhaust / discharge device 20. 31 is a float, and 32 is an exhaust outlet which is connected to the exhaust return path 21. Reference numeral 33 denotes an inlet connected to the hot water supply outlet 27 of the exhaust gas introducing means 18, and reference numeral 34 denotes an outlet connected to the hot water supply passage 14.

In the above configuration, the air supplied by the combustion fan 8 and the fuel supplied by the fuel transfer pipe 9 are mixed by the combustion means 7 to form a flame f in the combustion chamber 10. The combustion gas generated by the flame f exchanges heat with the water supplied from the water supply passage 13 in the heat exchanger 11, and the combustion gas is cooled to a low temperature and exhausted from the exhaust passage 12. On the other hand, the water supplied from the water supply channel 13 becomes hot water and enters the hot water supply channel 14. The hot water is sent to the exhaust introducing means 18 provided in the middle of the hot water supply path 14 while the backflow is prevented by the direct pressure type edger 17 on the way. As shown in FIG. 2, the exhaust gas introducing means 18 comprises a nozzle 28 connected to a hot water supply inlet 26 and a venturi 29 connected to a hot water supply outlet 27 for reducing hot water supply pressure. A part of the combustion gas adjusted by the amount adjusting means 23 is introduced from the exhaust path 12 through the exhaust introduction path 16, and comes into direct contact with hot water in the venturi 29 and the hot water supply path 14, and carbon dioxide in the combustion gas is removed. Dissolution and heat exchange with the combustion gas take place. Thereafter, the hot water is supplied to the gas-liquid separation means 19 shown in FIG.
The hot water and the residual combustion gas are separated into each other, and when the residual combustion gas exists, the float 31 in the exhaust discharger 20 descends, and the residual combustion gas is discharged from the exhaust outlet 32 through the exhaust return passage 21 through the exhaust passage 12. When there is hot water, the float 31 rises and closes the exhaust outlet 32. The temperature of the hot water in which the carbon dioxide is dissolved is raised after the concentration of carbon dioxide contained in the hot water is confirmed by the carbon dioxide concentration detecting means 35 provided downstream of the gas-liquid separation means 19, and then showered through the hot water supply path 14. And supplied to the bathtub.

The concentration of carbon dioxide contained in the hot water is set by the user in the carbonic acid concentration setting means 36, and the concentration detected by the carbonic acid concentration detecting means 35 is adjusted to the concentration set by the carbonic acid concentration setting means 36. The control means 25 controls the combustion means 7, the combustion fan 8, the water amount adjustment means 15, and the introduction amount adjustment means 23 so as to be as follows.

With such a configuration, a conventional hot water storage room is not required, so that the equipment is compact and hot water can be supplied without a transporter by tap water pressure. Further, since the combustion gas is directly dissolved under high water pressure, carbon dioxide can be dissolved more efficiently than under atmospheric pressure. The obtained hot water in which the carbon dioxide gas is dissolved is supplied to a bath or shower, and exerts a heat retaining effect, a fatigue recovery effect, a blood pressure stabilizing effect, and a wound healing effect on the human body. Furthermore, since the combustion gas and hot water come into direct contact,
The latent heat of water vapor in the combustion gas is also recovered, resulting in high efficiency. Further, since carbon dioxide and NOx in the combustion gas are dissolved, emission of carbon dioxide and harmful NOx, which cause global warming, can be suppressed. Furthermore, since the concentration of carbon dioxide contained in the hot water downstream of the gas-liquid separation means is detected and controlled so as to be the concentration set by the user, the amount of hot water discharged, the amount of combustion, and the amount of combustion gas introduced change. Can supply hot water with a stable concentration, and can secure safety in use.

[0028]

As described above, the hot water supply apparatus of the present invention has the following effects. (1) According to the first aspect of the present invention, since the combustion gas is introduced directly into the hot water flowing through the hot water supply path to dissolve the carbon dioxide, the equipment is very compact without the need for a hot water storage device according to the prior art. It can be. In addition, since it can be transported using tap water pressure, it can be transported to the second floor or the like without a transporter. Since carbon dioxide can be dissolved under high water pressure, high efficiency dissolution can be achieved. Hot water is supplied to baths and showers and exerts a heat retaining effect, a fatigue recovery effect, a blood pressure stabilizing effect, and a wound healing effect on the human body. Since carbon dioxide and NOx in the combustion gas are dissolved, emissions of carbon dioxide and harmful NOx, which cause global warming, can be reduced. The concentration of dissolved carbon dioxide can be changed by the introduction amount adjusting means. Since the hot water and the combustion gas are in direct contact, the latent heat of water vapor in the combustion gas can also be recovered, and high efficiency can be achieved. Furthermore, since the tap water temperature detection means is provided in the downstream hot water supply path of the gas-liquid separation means, the amount of combustion gas introduced is changed by the introduction amount adjustment means, so that even if the latent heat recovery amount changes, the temperature desired by the user is always maintained. Hot water can be provided. (2) According to the second aspect of the present invention, since the combustion gas is introduced directly into the hot water flowing through the hot water supply path to dissolve the carbon dioxide, the equipment is very compact without the need for a hot water storage device according to the prior art. It can be. In addition, since it can be transported using tap water pressure, it can be transported to the second floor or the like without a transporter. Since carbon dioxide can be dissolved under high water pressure, high efficiency dissolution can be achieved. Hot water is supplied to baths and showers and exerts a heat retaining effect, a fatigue recovery effect, a blood pressure stabilizing effect, and a wound healing effect on the human body. Since carbon dioxide and NOx in the combustion gas are dissolved, emissions of carbon dioxide and harmful NOx, which cause global warming, can be reduced. The concentration of dissolved carbon dioxide can be changed by the introduction amount adjusting means. Since the hot water and the combustion gas are in direct contact, the latent heat of water vapor in the combustion gas can also be recovered, and high efficiency can be achieved. Furthermore, since the carbon dioxide concentration detection means is provided in the hot water supply path downstream of the gas-liquid separation means, it is always used even if the flow rate of water changes the introduction amount of combustion gas and the carbon dioxide concentration in the hot water changes. Can provide hot water of the concentration desired by the person.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of a hot water supply device according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view of the exhaust gas introducing means in the embodiment.

FIG. 3 is a cross-sectional view of a gas-liquid separation unit and an exhaust discharger in the same embodiment.

FIG. 4 is a schematic configuration diagram of a main part of a hot water supply device according to another embodiment of the present invention, which is omitted

FIG. 5 is a schematic configuration diagram of a main part of a hot water supply device in a conventional example, which is not mounted.

[Explanation of symbols]

 Reference Signs List 7 Combustion means 11 Heat exchanger 12 Exhaust path 13 Water supply path 14 Hot water supply path 15 Water volume adjustment means 16 Exhaust introduction path 18 Exhaust introduction means 19 Gas-liquid separation means 20 Exhaust discharger 21 Exhaust return path 22 Outlet hot water temperature detection means 23 Introduction amount adjustment Means 24 Hot water temperature setting means 25 Control means 35 Carbon dioxide concentration detecting means 36 Carbon dioxide concentration setting means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F24H 1/10 301 F24H 1/14

Claims (2)

(57) [Claims] A combustion unit that uses a fuel that generates a combustion gas containing carbon dioxide; an exhaust passage through which the combustion gas discharged from the combustion unit passes; a heat exchanger that exchanges heat between the combustion gas and water; A water supply path for supplying water to the heat exchanger; a water supply path for supplying hot water from the heat exchanger to a predetermined location; exhaust introduction means for introducing combustion gas into the hot water supply path; An exhaust gas introduction path for supplying combustion gas to the introduction means, an introduction amount adjustment means provided in the middle of the exhaust gas introduction path for adjusting the amount of combustion gas introduced to the hot water supply path, and the hot water supply path downstream of the exhaust gas introduction means. A gas-liquid separating means for separating hot water and combustion gas, an exhaust discharger for discharging only the combustion gas separated by the gas-liquid separation means, and a combustion gas separated from the exhaust discharger to the exhaust passage. Return exhaust return path,
A water amount adjusting means for adjusting an amount of water provided in the middle of the water supply path or the hot water supply path; a tapping temperature detecting means for detecting a tapping temperature provided on the downstream side of the hot water path of the gas-liquid separation means; and setting a tapping temperature. A hot water supply apparatus comprising: a hot water temperature setting means for controlling the combustion means, the water amount adjusting means and the introduction amount adjusting means based on signals from the hot water temperature setting means and the hot water temperature detecting means. 2. A combustion means using a fuel for producing a combustion gas containing carbon dioxide, an exhaust passage through which the combustion gas discharged from the combustion means passes, a heat exchanger for exchanging heat between the combustion gas and water, A water supply path for supplying water to the heat exchanger; a water supply path for supplying hot water from the heat exchanger to a predetermined location; exhaust introduction means for introducing combustion gas into the hot water supply path; An exhaust gas introduction path for supplying combustion gas to the introduction means, an introduction amount adjustment means provided in the middle of the exhaust gas introduction path for adjusting the amount of combustion gas introduced to the hot water supply path, and the hot water supply path downstream of the exhaust gas introduction means. A gas-liquid separating means for separating hot water and combustion gas, an exhaust discharger for discharging only the combustion gas separated by the gas-liquid separation means, and a combustion gas separated from the exhaust discharger to the exhaust passage. Return exhaust return path,
A water amount adjusting means for adjusting an amount of water provided in the water supply path or the hot water supply path; and detecting a concentration of carbon dioxide contained in hot water flowing through the hot water supply path provided on the downstream side of the hot water supply path of the gas-liquid separation means. Carbonic acid concentration detecting means, carbonic acid concentration setting means for setting the concentration of carbon dioxide contained in hot water to be discharged, the burning means and the water amount adjusting means based on signals from the carbonic acid concentration setting means and the carbonic acid concentration detecting means. A hot water supply apparatus comprising control means for controlling the introduction amount adjusting means.