JP2002333212A - Water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water heater that does not require neutralizing treatment on drains and is high in thermal efficiency. SOLUTION: Since the drain generated from the auxiliary heat exchanger 8 of this water heater is evaporated by means of a drain evaporator 9, this water heater does not discharge the drain to the outside and, accordingly, does not require neutralizing treatment on the drain. In addition, since almost all of the sensible heat in combustion gas is recovered by means of a main heat exchanger 7, the auxiliary heat exchanger 8, and a wound pipe 20, the thermal efficiency of this water heater is improved greatly. Moreover, since the combustion gas can also be introduced smoothly to the upper part of an auxiliary heat transfer pipe 8a in which the flow of the combustion gas is disturbed by the drain evaporator 9, the heat exchange in the upper part is activated and the thermal efficiency of this water heater can be improved further.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater provided with a heat exchanger for heating water flow with combustion gas.

[0002]

2. Description of the Related Art Conventionally, an instantaneous water heater mainly used in a kitchen or the like includes a heat exchanger to which a water supply pipe and a tapping pipe are connected, and a burner for heating the heat exchanger. It is generally known that water is heated by a heat exchanger by the combustion of water and is discharged from a tapping pipe. In such a water heater, in order to prevent generation of drain (condensed water) in the heat exchanger, a considerably high temperature combustion gas is discharged from the heat exchanger, and high heat efficiency is not obtained. Drain is generated when the combustion gas falls below the dew point (approximately 50 to 60 ° C.). Therefore, in principle, the heat exchanger exchanges heat to the dew point without generating drain to generate heat in the combustion gas. It is possible to recover sensible heat. However, in the heat exchanger, there is a local low-temperature part such as a heat transfer tube that is a water passage part.In practice, in order to prevent partial drainage in the low-temperature part, the combustion gas is heated to a considerably high temperature. And sufficient sensible heat has not been recovered.

Meanwhile, in a high-power water heater for supplying hot water to a bathtub or supplying a large amount of hot water to a shower or the like, a main heat exchanger mainly for recovering sensible heat is provided upstream in a combustion gas flow path. In general, a latent heat recovery type water heater that obtains high thermal efficiency by providing a sub heat exchanger mainly for the purpose of latent heat recovery on the downstream side is generally known. In such a latent heat recovery type water heater, in addition to the sensible heat that could not be recovered by the main heat exchanger in the sub heat exchanger, when the temperature of the combustion gas falls below the dew point, drain is generated, so that the latent heat can be recovered. For this reason, since most of the thermal energy (sensible heat + latent heat) in the combustion gas can be recovered, it is possible to achieve extremely high thermal efficiency.

[0004]

However, since the condensed drain reacts with sulfur (S) and nitrogen (N) in the combustion gas to become acidic at a pH of about 3, the above-described latent heat recovery type appliance is used. In addition, a neutralization process must be performed before the wastewater is discharged to a general drainage passage such as a sewage system, which complicates the structure of a device including a neutralizer and increases the manufacturing cost.
Therefore, an object of the present invention is to solve the above-described problem and to provide a water heater with high thermal efficiency that does not require a neutralization treatment of drain water.

[0005]

According to a first aspect of the present invention, there is provided a water heater, comprising: a burner for burning fuel in a combustion chamber; and a burner gas provided above the burner. And a main heat exchanger that recovers sensible heat from the main heat exchanger and heats water flowing in the heat transfer tube, and is provided above the main heat exchanger and is separated from the combustion gas passing through the main heat exchanger by the main heat exchanger. In addition to the sensible heat that could not be recovered, in the water heater with a sub heat exchanger that recovers latent heat and heats the water flow in the heat transfer tube,
A drain evaporator that is provided below the sub heat exchanger and above the main heat exchanger, receives the drain generated by latent heat recovery in the sub heat exchanger, and heats and evaporates the drain with a combustion gas. And a flow straightening plate for guiding the combustion gas passing through the main heat exchanger flowing beside the drain evaporator toward the heat transfer tube of the sub heat exchanger.

[0006] The water heater according to claim 2 of the present invention comprises:
2. The water heater according to claim 1, wherein the auxiliary heat exchanger has heat transfer tubes arranged in two rows in front and back, and the straightening plate extends between the heat transfer tubes in parallel with the heat transfer tubes, The gist is that the cross section is substantially V-shaped.

[0007] The water heater according to claim 3 of the present invention comprises:
3. The water heater according to claim 1 or 2, wherein the drain evaporator is made of a porous heat-resistant and nitric acid-resistant material, and receives a drain and permeates the entire drain; And a plurality of openings are provided on the mounting surface of the penetrating body mounting plate.

Further, the water heater according to claim 4 of the present invention,
In the water heater according to any one of claims 1 to 3, the gist is characterized in that the current plate is provided with a plurality of openings through which combustion gas passes.

Further, the water heater according to claim 5 of the present invention,
5. The water heater according to claim 3, wherein a step is formed on a side wall of the combustion chamber, and the drain penetrant is sandwiched between the step and the permeant placement plate. 6. The gist is to prevent the falling off.

[0010] In the water heater according to the first aspect of the present invention, the combustion gas of the burner heats the main heat exchanger and then heats the sub heat exchanger with residual heat. At this time, the combustion gas is
The drain evaporator also heats. Therefore, the combustion gas is first cooled by the main heat exchanger to recover most of the sensible heat, and then cooled to the temperature at which drain is generated by the sub heat exchanger to generate drain and recovered by the main heat exchanger. Latent heat is recovered in addition to sensible heat that could not be obtained. The drain generated in the sub heat exchanger is received by the drain evaporator, evaporated and returned to the combustion gas, so that the drain is not discharged to the outside of the water heater. As a result, in order to evaporate the drain, the same amount of heat as the recovered latent heat is taken, but in the sub heat exchanger, unlike the main heat exchanger, it is not necessary to keep drain from being generated. In addition, the exhaust temperature of the combustion gas discharged from the appliance can be sufficiently reduced, and sensible heat that cannot be recovered by the main heat exchanger can be recovered.
Therefore, the entire apparatus collects most of the sensible heat of the thermal energy of the combustion gas. In this way, the water is efficiently heated and discharged from the main heat exchanger and the sub heat exchanger without discharging the drain out of the apparatus. Also, since the drain evaporator is provided below the sub heat exchanger, the flow of the combustion gas to the heat transfer tubes of the sub heat exchanger is deteriorated. In order to smoothly guide the gas to the heat transfer tube, the combustion gas can be brought into good contact with the heat transfer tube, and heat exchange is promoted.

Further, the water heater according to claim 2 of the present invention,
By rectifying plates having a substantially V-shaped cross section extending in parallel with the heat transfer tubes between the heat transfer tubes of the sub heat exchangers arranged in the front and rear two rows, both the heat transfer tubes can be favorably burned. Gas can be introduced, and heat recovery in the sub heat exchanger can be sufficiently performed.

Further, the water heater according to claim 3 of the present invention is characterized in that:
The drain penetrating body placed on the penetrating body mounting plate receives the drain dripped from the sub heat exchanger, and the received drain penetrates into the entire drain penetrating body which is a porous body. Since the penetrating body mounting plate has a plurality of openings on the mounting surface, the drain that has penetrated the drain penetrating body to the contact surface with the penetrating body mounting plate is heated by coming into direct contact with the combustion gas. , And can be efficiently evaporated without wasting heat. In addition, since a wide range is evaporated by the drain penetrant, abnormal noise due to partial bumping does not occur.

Further, the water heater according to claim 4 of the present invention,
By providing a plurality of openings through which the combustion gas passes through the current plate provided in the combustion gas passage, the exhaust resistance of the combustion gas can be reduced.

Further, the water heater according to claim 5 of the present invention,
By sandwiching the drain penetrant between the step formed on the side wall of the combustion chamber and the penetrant mounting plate, the drain penetrant can be prevented from coming off. Furthermore, the drain generated around the side wall of the combustion chamber through which the heat transfer tube of the sub-heat exchanger penetrates and runs down along the side wall is surely drained by the drain penetrator in contact with the side wall at the step portion. The drain does not fall on the main heat exchanger or burner located below.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the structure and operation of the present invention described above, a preferred embodiment of a water heater according to the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic configuration diagram of a main stop type instantaneous water heater 1 as one embodiment, FIG. 2 is an external view of the water heater 1, and FIG. FIG. On the front of the appliance, there are provided an operation button 2 for performing a point fire extinguishing operation, water amount adjustment and hot water temperature adjustment, and a gas amount adjustment lever 3. The operation button 2 is a push-type button, but is rotatably provided. The point fire extinguishing operation is performed by a push operation, and the tapping water temperature adjustment by water flow adjustment is performed by a turning operation. A scale for temperature control is printed around the operation button 2 on the case of the appliance body 4.
By adjusting a, the tapping temperature and the amount of water are continuously adjusted. Further, by operating the gas amount adjusting lever 3 from the small capacity position on the left side to the large capacity position on the right side, the supply gas amount is continuously adjusted.

As shown in FIG. 1, a combustion chamber 5 is provided in the appliance body 4, and a burner 6 for burning fuel gas and a combustion gas from the burner 6 are arranged in the combustion chamber 5 in order from the bottom. Fin-tube type main heat exchanger 7 that recovers much of the sensible heat
A drain evaporator 9 for receiving and evaporating the drain, a flow straightening plate 10 for changing the direction of the flow of the combustion gas, and a sub heat exchange for recovering sensible heat and latent heat that could not be recovered by the main heat exchanger 7. Vessel 8 is provided. The sub heat exchanger 8, the drain evaporator 9, and the rectifier plate 10 are integrally formed as a sub heat exchange unit 11, and details thereof will be described later. On the upper surface of the combustion chamber 5, an exhaust port 12 for discharging the combustion gas after the heat exchange in the main heat exchanger 7 and the sub heat exchanger 8 to the outside of the body is formed. And faces the exhaust hole 13 opened on the upper surface of the device. Note that a substantially L-shaped exhaust hood (not shown) may be provided above the exhaust hole 13 to guide the combustion gas discharged to the outside of the appliance forward and to prevent dust from falling into the appliance. The lower surfaces of the appliance main body 4 and the combustion chamber 5 are opened to take in the combustion air of the burner 6, and an air supply port 30 is provided on the side surface of the appliance main body 4.

An operation button 2 is provided in the water supply path from the water inlet.
A water faucet 14 that opens and closes a flow path in conjunction with manual operation by the user is provided, and a water pressure responsive device 15 is provided downstream thereof.
In the flow path on the downstream side of the water pressure responsive device 15, a water amount adjusting shaft 16 for adjusting the amount of hot water in conjunction with the turning operation of the operation button 2 is provided. The water flow adjusting shaft 16 branches the flow path in two directions, one of which is a water supply pipe 17 to the sub heat exchanger 8 and the other is a bypass pipe connected to a tapping pipe 18 from the main heat exchanger 7. 19 are provided. Therefore, the hot water (inner body passing water) that has passed through the sub heat exchanger 8 and the main heat exchanger 7 and the bypass pipe 1
Hot water mixed with water (bypass water) that has passed through 9 flows out of the appliance.

As shown in FIG. 3, a water supply pipe 17 is provided as a sub heat exchanger 8 and is connected to an inlet of a sub heat transfer pipe 8a arranged in two rows in front and rear in parallel, and an outlet of the sub heat transfer pipe 8a is connected to a combustion chamber. 5 is connected to the inlet of a winding tube 20 that winds the outside 5 and the outlet of the winding tube 20 is connected to the inlet of a main heat transfer tube 7a provided in the main heat exchanger 7 and penetrating through the fins 7b a plurality of times. And
The outlet of the main heat transfer pipe 7a is connected to the tapping pipe 18. Also,
A branch pipe 21 for draining water in the water passage for the purpose of preventing freezing after using the water heater 1 is provided at the end of the water supply pipe 17.
The drain pipe 22 is provided at the tip of the branch pipe 21. Further, the water flow path of the water heater 1 is changed from the sub heat transfer pipe 8a located above to the wound pipe 20 located below and the main heat transfer pipe 7a located above, so that the water is passed only by the branch pipe 21. Even if it is attempted to drain all the water in the water channel, water accumulates in the winding tube 20. Therefore, a draining tube 23 is provided at the lowest position of the winding tube 20 to drain the water.

The gas supply path from the gas inlet to the burner 6 includes a magnet safety valve 24 that is opened and held by the thermoelectromotive force of a thermocouple (not shown) during combustion, and the above-described hydraulic pressure responsive device 15 relating to water flow. , A water pressure responsive valve 25 that opens the gas flow path only when water is supplied, an instrument plug 26 that opens and closes the gas flow path in conjunction with manual operation by the operation button 2, and a manual operation of the gas amount adjustment lever 3. A gas amount adjusting shaft 27 for adjusting the gas supply amount is provided.

Next, a sub heat exchange unit 11 composed of a sub heat exchanger 8, a drain evaporator 9, and a flow straightening plate 10 will be described with reference to FIG.
This will be described in detail with reference to FIG. FIG. 4 shows the auxiliary heat exchange unit 11
, FIG. 5 is a front view, and FIG. 6 is a cross-sectional view taken along dashed line AA in FIGS. 4 and 5. In FIG. 4, the drain evaporator 9 is omitted, and in FIG. 5, a front plate 31 and a rear plate 32 for forming the flow straightening plate 10 and the combustion chamber 5 are shown.
Has been omitted. The sub heat exchanger 8 includes a front sub heat transfer tube 8aA and a rear sub heat transfer tube 8aB which are arranged in parallel in two front and rear rows. In the following description, when it is not necessary to distinguish between the front auxiliary heat transfer tube 8aA and the rear auxiliary heat transfer tube 8aB,
called a. Both ends of the sub heat transfer tube 8a protrude through the side wall of the combustion chamber 5, and are joined at one end by a curved tube. The water supply pipe 1 is connected to another end of the rear auxiliary heat transfer pipe 8aB.
7 is connected to another end of the front auxiliary heat transfer tube 8aA.
0 is connected.

Immediately below the front auxiliary heat transfer tube 8aA and the rear auxiliary heat transfer tube 8aB, the drain generated by recovering the latent heat of the combustion gas in the auxiliary heat transfer tube 8a is received, and the received drain is heated by the combustion gas. A drain evaporator 9 for evaporating the fuel is provided. The drain evaporator 9 includes a drain penetrating body 9a that receives drain dripped from the sub heat transfer tube 8a, and a penetrating body mounting plate 9b that supports the drain penetrating body 9a. The drain penetrating body 9a is made of porous ceramics having excellent heat resistance and drain resistance, and the penetrating body mounting plate 9b is formed by bending a stainless steel plate into a V-shape and forming both ends thereof on the side wall of the combustion chamber 5. It is formed by joining. And the drain penetrant 9a
Are placed two by two on this penetrant placement plate 9b.
Further, a plurality of evaporating openings 9c are provided in the penetrating body mounting plate 9b.

A step portion 29 is formed on the side wall of the combustion chamber 5 below the auxiliary heat transfer tube 8a so as to increase its lateral width, and the step portion 29 and the permeation member mounting plate 9b form a drain permeation member. 9a is sandwiched and retained. The flow straightening plate 10 is formed by forming a hot-dip aluminum-plated steel plate into a substantially V shape, and is provided at an intermediate position between two rows of front and rear sub heat transfer tubes 8a in parallel with the sub heat transfer tubes 8a. It is the structure joined to. A plurality of ventilation holes 10a through which the combustion gas passes are opened in the current plate 10. Such a sub heat exchange unit 11 is a unit integrally assembled, mounted on the main heat exchanger 7 and fixed with screws.

In the water heater 1 configured as described above,
In conjunction with the manual operation of the operation button 2, the appliance plug 26 and the faucet 14 are opened to start water flow. The water flowing from the water inlet (broken arrow in the figure) passes through a water faucet 14 and a water pressure responsive device 15 and passes through a water amount adjusting shaft 16, one of which passes through a water supply pipe 17, a sub heat exchanger 8, a winding pipe 20, Hot water pipe 18 through exchanger 7
And the other is mixed with hot water from the tapping pipe 18 through the bypass pipe 19. When water is passed through the hydraulic pressure responsive device 15, the hydraulic pressure responsive valve 25 and the magnet safety valve 24 are opened, gas is supplied to the burner 6, and ignition is caused by continuous spark from an electrode (not shown). During the combustion of the burner 6, the open state of the magnet safety valve 24 is maintained by the thermoelectromotive force of a thermocouple (not shown), and the combustion is maintained.

With the combustion of the fuel gas by the burner 6, outside air is sucked into the instrument body 4 from an opening on the lower face of the instrument body 4 and an air supply port 30 provided on the side face, and the opening on the lower face of the combustion chamber 5 is closed. The fuel gas passes through the burner 6 and is burned as combustion air. The air-fuel mixture burns near the flame opening of the burner 6 to form a flame, and the combustion is completed (complete combustion) while reaching the vicinity of the upstream of the main heat exchanger 7. Since the main heat exchanger 7 is provided upstream of the combustion gas flow path and the sub heat exchanger 8 is provided downstream of the combustion gas flow path, the high-temperature combustion gas from the burner 6 is supplied to the main heat exchanger 7 by natural draft force. The fins 7b flow through the fins 7b and exchange heat satisfactorily. As a result, the combustion gas whose temperature has decreased is also exchanged in the auxiliary heat exchanger 8 and discharged from the exhaust port 12 to the outside of the appliance. Further, before entering the main heat exchanger 7, the combustion gas also exchanges heat with the winding tube 20 wound around the outside of the combustion chamber 5 to heat the water flow.

In the main heat exchanger 7 and the winding tube 20, only sensible heat is recovered from the combustion gas without generating drain. In order to prevent partial drainage in such a low temperature area, heat exchange cannot be performed until the exhaust gas temperature of the combustion gas drops sufficiently, and not only latent heat but also some sensible heat Cannot be recovered. On the other hand, the sub heat exchanger tube 8a of the sub heat exchanger 8
Then, the combustion gas that has passed through the main heat exchanger 7 is further cooled to generate drain and recover latent heat, but at this time, the latent heat cannot be recovered by the main heat exchanger 7 and the winding tube 20. Also recovers sensible heat. The generated drain is received by a drain evaporator 9 provided immediately below the sub heat transfer tube 8a, and is heated and evaporated by the combustion gas passing through the main heat exchanger 7. At this time, the same amount of heat as the recovered latent heat is released into the combustion gas. However, in the sub heat exchanger 8, unlike the main heat exchanger 7 and the winding tube 20, no drain is generated. Since there is no necessity, the heat exchange is performed until the exhaust gas temperature of the combustion gas discharged from the appliance is sufficiently lowered, and the main heat exchanger 7
In addition, since the sensible heat that could not be recovered by the winding tube 20 can be recovered, the entire apparatus recovers most of the sensible heat in the combustion gas. Therefore, without draining,
High thermal efficiency can be achieved.

Further, since the drain evaporator 9 is provided immediately below the sub heat transfer tube 8a, the flow of the combustion gas to the sub heat transfer tube 8a is deteriorated. The direction is changed, and the combustion gas flows smoothly to the sub heat transfer tube 8a. For this reason, the combustion gas satisfactorily comes into contact with the auxiliary heat transfer tube 8a, thereby promoting heat exchange. In addition, in such a natural combustion type appliance in which the combustion air of the burner 6 is taken in only by the natural draft force, a rectifying plate 10 is provided in the combustion gas flow path as compared with a forced combustion type appliance in which a fan is forcibly taken in. An increase in the exhaust resistance of the combustion gas due to the provision of such foreign matter is a serious problem. However, by providing a plurality of ventilation holes 10a through which the combustion gas passes through the current plate 10, such an increase in the exhaust resistance can be suppressed. Burner 6
Can maintain a good combustion state.

The drain dropped into the porous drain penetrant 9a permeates the entire drain permeant 9a. The drain that has penetrated the inside of the drain permeant 9a to the contact surface with the permeant mounting plate 9b comes into direct contact with the combustion gas because a plurality of evaporation openings 9c are provided in the permeant mounting plate 9b. And evaporates well without wasting heat. Further, since the vapor is evaporated in a wide range by the drain penetrating body 9a, generation of abnormal noise due to partial bumping can be prevented.

Further, the drain permeator 9a is sandwiched between the stepped portion 29 formed on the side wall of the combustion chamber 5 and the permeant mount plate 9b, so that the heat transfer tube of the sub heat exchanger 8 is penetrated. The drain generated around the side wall 5 and drips down along the side wall can be reliably received by the drain penetrating body 9a in contact with the side wall at the step 29 of the side wall.
The drain does not drop on the main heat exchanger 7 or the burner 6 located below.

Further, by passing the coldest water in the water supply passage to the sub heat transfer pipe 8a, the latent heat and sensible heat in the combustion gas can be efficiently recovered within a large temperature difference. further,
Since the cold water is preheated by the heating in the sub heat transfer tube 8a, the generation of drain on the inner wall of the combustion chamber 5 covered with the winding tube 20 can be suppressed. Finally, since the hottest water can be passed through the main heat transfer pipe 7a in the water supply flow path, drainage there can be effectively suppressed.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention. is there.

[0031]

As described in detail above, claim 1 of the present invention
According to the described water heater, since the drain generated in the sub heat exchanger is evaporated by the drain evaporator, the drain is not discharged to the outside of the apparatus, the drain does not need to be neutralized, and most of the combustion gas Sensible heat can be recovered, so that the thermal efficiency becomes very high.
And, since the combustion gas can be smoothly guided to the heat transfer tube of the sub heat exchanger where the flow of the combustion gas is obstructed by the drain evaporator, heat exchange there is promoted, and the heat efficiency can be further improved. it can.

Further, according to the water heater according to the second aspect of the present invention, since the auxiliary heat exchanger and the current plate can be implemented with a simple structure, the cost for manufacturing the water heater can be suppressed. .

Further, according to the water heater of the third aspect of the present invention, since the drain can be directly heated by the combustion gas, the drain can be satisfactorily evaporated.

Further, according to the water heater of the fourth aspect of the present invention, the exhaust resistance of the combustion gas can be reduced and the combustion of the burner can be favorably maintained.

Further, according to the water heater of the fifth aspect of the present invention, the drain flowing down the side wall of the combustion chamber can be reliably received by the drain penetrant, so that the main heat exchanger and the burner Can be prevented from being corroded by the drain.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a water heater of the present embodiment.

FIG. 2 is an external view of a water heater of the present embodiment.

FIG. 3 is a diagram showing a water flow path of the water heater of the present embodiment.

FIG. 4 is a top view of the sub heat exchange unit of the present embodiment.

FIG. 5 is a front view of the sub heat exchange unit of the embodiment.

FIG. 6 is a cross-sectional view of the sub heat exchange unit of the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Boiler, 5 ... Combustion chamber, 6 ... Burner, 7 ... Main heat exchanger, 7a ... Main heat exchanger tube, 8 ... Sub heat exchanger, 8a ... Sub heat exchanger tube, 8aA ... Pre-sub heat exchanger tube, 8aB ... Rear auxiliary heat transfer tube, 9: drain evaporator, 9a: drain penetrant, 9b: penetrant mounting plate, 9c: evaporation opening, 10: rectifying plate, 10a: vent hole,
29 ... Stepped part.

Claims (5)

[Claims] A burner that burns fuel in a combustion chamber; a main heat exchanger that is provided above the burner and recovers sensible heat from combustion gas of the burner to heat water flowing in a heat transfer tube; It is provided above the main heat exchanger and collects latent heat in addition to the sensible heat that could not be recovered by the main heat exchanger from the combustion gas that passed through the main heat exchanger, and passed water through the heat transfer tube. A water heater provided with a sub heat exchanger for heating the main heat exchanger, below the sub heat exchanger, and receiving the drain generated by latent heat recovery in the sub heat exchanger. A drain evaporator that heats and evaporates the drain with the combustion gas, and guides the combustion gas passing through the main heat exchanger flowing beside the drain evaporator toward a heat transfer tube of the sub heat exchanger. A water heater comprising: a current plate. 2. The sub-heat exchanger has heat transfer tubes arranged in two rows in front and back, and the rectifying plate extends between the heat transfer tubes in parallel with the heat transfer tubes, and has a substantially V-shaped cross section. The water heater according to claim 1, wherein the water heater is in a shape. 3. The drain evaporator according to claim 1, wherein the drain evaporator is made of a porous heat- and nitrate-resistant material, and receives a drain and permeates the entirety of the drain evaporator; The mounting surface of the penetrant mounting plate is provided with a plurality of openings.
The described water heater. 4. The current plate is provided with a plurality of openings through which combustion gas passes.
4. The water heater according to any one of the above items 3. 5. A step is formed in a side wall of the combustion chamber, and the drain penetrant is sandwiched between the step and the permeant placement plate to prevent the drain penetrant from coming off. The water heater according to claim 3 or 4.