JP2001021225A - Combustion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure low noise of a combustion apparatus without bringing the entire of an apparatus into a large size and further without providing particularly a large exhaust chamber by effectively absorbing the noise from combustion waste gas in the exhaust chamber. SOLUTION: The present apparatus includes a heat exchanger heated with combustion of a burner, and an exhaust recovery box for recovering combustion waste gas heat exchanged in the heat exchanger, and further includes an exhaust chamber 9 communicated with the exhaust recovery box for exhausting the combustion wastew gas from the exhaust recovery box and an exhaust passage 11 communicated with the exhaust chamber 9 for discharging the combustion waste gas to the outside. An exhaust passage 11 is disposed in the state where an inlet thereof is protruded into the exhaust chamber 9. Further, there is provided an inflow hole 9b at a position facing a lateral side of the inlet 11a of the exhaust passage 11 for flowing the combustion waste gas from the exhaust recovery box into the exhaust chanber 9 such that the combustion waste gas is caused to flow toward a psition where the inlet 11a of the exhaust passage 11 is not provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger heated by combustion of a burner and a combustion apparatus provided with an exhaust gas recovery box for recovering combustion exhaust gas heat-exchanged in the heat exchanger.

[0002]

2. Description of the Related Art In such a combustion apparatus, in recent years, low noise has been required. Conventionally, an exhaust chamber provided with a sound absorbing member such as glass wool has been provided on the inner surface, and the combustion exhaust gas from the exhaust gas recovery box has been used. Let it flow into the exhaust chamber and let it absorb sound,
After that, there has been known a configuration in which combustion exhaust gas is discharged to the outside from an exhaust passage opened and communicated with a wall surface of an exhaust chamber.

[0003]

In the above-mentioned conventional apparatus, the noise of the combustion exhaust gas is absorbed by a sound absorbing member such as glass wool provided on the inner surface of the exhaust chamber, so that the noise can be reduced to some extent. However, there was a limit to the noise reduction. In other words, since such a combustion device needs to be as compact as possible as a whole, it is not possible to provide a very large exhaust chamber or the like, and therefore, the sound absorbing effect of the sound absorbing member is limited. There was room for improvement.

The present invention focuses on such a conventional problem. It is an object of the present invention to eliminate the need for providing a particularly large exhaust chamber and to effectively absorb the noise of the combustion exhaust gas in the exhaust chamber. Accordingly, it is an object of the present invention to provide a combustion device capable of reducing the noise of the combustion device without increasing the size of the entire combustion device.

[0005]

According to the first aspect of the present invention, there is provided a heat exchanger which is heated by combustion of a burner and a flue gas which has been heat-exchanged in the heat exchanger. A combustion device having an exhaust gas recovery box for recovery, wherein the combustion device is communicated with the exhaust gas recovery box, communicates with an exhaust chamber for discharging combustion exhaust gas from the exhaust gas to the outside, and the exhaust chamber, and discharges the combustion exhaust gas to the outside. An exhaust passage for discharging the exhaust gas, wherein the exhaust passage is disposed in a state where an inlet portion of the exhaust passage protrudes into the exhaust chamber, and an inflow port through which combustion exhaust gas from the exhaust recovery box flows into the exhaust chamber. But,
The exhaust passage is provided at a position facing the lateral side of the inlet portion so that the combustion exhaust gas flows toward a portion where the inlet portion of the exhaust passage does not exist.

In other words, an exhaust passage for discharging the combustion exhaust gas from the exhaust chamber to the outside is provided with its inlet portion protruding into the exhaust chamber, and furthermore, the exhaust gas from the exhaust recovery box is discharged into the exhaust chamber. An inlet for inflow is provided at a location facing the lateral side of the inlet portion of the exhaust passage so as to flow the combustion exhaust gas toward a portion where the inlet portion does not exist. The flow direction of the combustion exhaust gas flowing into the chamber is complicatedly bent before flowing into the exhaust path from the inlet of the exhaust path. Therefore, the sound energy is attenuated by the bending in the flow direction, and the absorption action by interference and reflection of various sounds due to the complicated bending in the flow direction in the exhaust chamber can be expected. Without increasing the size of the device, it is possible to effectively absorb the combustion exhaust gas in the exhaust chamber, and to reduce the noise of the device.

According to the second aspect of the present invention, the inflow port causes the combustion exhaust gas to flow toward a portion where the exhaust path does not exist closer to the outlet section of the exhaust path than the inlet section of the exhaust path. It is provided as follows.

Therefore, the flue gas flowing into the exhaust chamber from the inlet port is rapidly bent and flows, so that a more effective sound absorbing effect can be expected, and the exhaust passage becomes longer, so that the exhaust chamber becomes longer. Can be expected to have a further sound absorbing effect, and effective sound absorption can be achieved despite a relatively simple configuration.

According to the third aspect of the present invention, a plurality of exhaust paths are provided, and the plurality of exhaust paths are provided side by side in a parallel or substantially parallel posture.

That is, the combustion exhaust gas that has flowed into the exhaust chamber is bent and flows as described above, and at the same time, is split and flows into a plurality of parts, so that the energy attenuation due to the bending and the energy attenuation due to the branch flow are synergistic. The function enables more reliable sound absorption, and is also advantageous in respect of the branch flow of the flue gas, since the pressure loss of the flue gas is relatively small.

According to the fourth aspect of the present invention, there is provided an auxiliary exhaust chamber communicating with an outlet portion of the exhaust path, and an auxiliary exhaust path communicating with the auxiliary exhaust chamber.

Therefore, the combustion exhaust gas that has flowed into the exhaust passage while being absorbed as described above is rapidly expanded in volume when flowing into the auxiliary exhaust chamber from the outlet portion of the exhaust passage, and When the air flows into the auxiliary exhaust passage from the auxiliary exhaust chamber, the volume is contracted again. This rapid expansion and contraction of the volume also enables effective sound absorption, thereby further reducing noise. Becomes possible.

According to the fifth aspect of the present invention, the exhaust chamber and the auxiliary exhaust chamber are provided with a sound absorbing member which functions to absorb the flowing combustion exhaust gas.

Therefore, in addition to the sound absorbing function due to the bending of the combustion exhaust gas as described above, the sound absorbing function provided by the sound absorbing members provided in the exhaust chamber and the auxiliary exhaust chamber becomes possible, so that more effective and reliable sound absorbing is possible. Becomes

According to the sixth aspect of the present invention, the tubular body having the inflow port through which the combustion exhaust gas from the exhaust gas recovery box flows into the exhaust chamber has a longitudinal direction that is exhausted from the heat exchanger. It is provided so as to be directed in a direction intersecting with the inflow direction of the combustion exhaust gas flowing into the recovery box, and with its inlet located inside the exhaust recovery box.

That is, since the inlet of the cylindrical body provided in a direction intersecting with the direction of inflow of the combustion exhaust gas is located inside the exhaust gas recovery box, it flows from the heat exchanger into the exhaust gas recovery box. The flue gas is bent in a direction intersecting with the inflow direction and flows, and the energy of sound is attenuated by the bending of the flow. Since the tubular body becomes longer by the position of the inside of the collection box, the sound absorbing effect by the internal reflection of the tubular body is also improved. As a result, even in the exhaust gas recovery box, a sound absorbing effect on combustion exhaust gas can be expected, and effective noise reduction can be achieved as a whole of the apparatus.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which a combustion device according to the present invention is used for a hot water supply device will be described with reference to the drawings. As shown in FIGS. 1 to 3, this hot water supply apparatus heats water supplied from a water supply channel 1 and supplies hot water to a hot water tap 2 a provided in the hot water supply channel 2, and the operation of the hot water supply unit K. Control section H for controlling
And a remote control operation unit R for instructing the control unit H of operation information.

The hot water supply unit K includes a gas-fired burner 3.
A heat exchanger 4 for water heating heated by the burner 3, a fan 5 for supplying a mixture of combustion air and fuel gas to the burner 3, and the like. Are configured so that the direction of generation of the flame is downward. Then, a heat exchanger 4 is provided below the burner 3.
Is disposed below the heat exchanger 4, and an exhaust gas collection box 6 for collecting combustion exhaust gas after heat exchange in the heat exchanger 4 is provided.
Are arranged, and the burner 3, the heat exchanger 4, the fan 5, the exhaust recovery box 6, and the like are housed and arranged in the casing C.

The exhaust recovery box 6 is provided with three cylindrical tubular bodies 8 for introducing the combustion exhaust gas from the exhaust recovery box 6 into the sound absorbing unit 7. Body 8
Is directed in the front-rear direction of the hot water supply device, that is, in a direction in which the longitudinal direction thereof intersects in a state substantially orthogonal to the inflow direction of the combustion exhaust gas flowing into the exhaust recovery box 6 from the heat exchanger 4. Are arranged side by side in a direction parallel or substantially parallel to each other. Each tubular body 8 is placed inside the exhaust collection box 6 such that the inlet 8 a of the tubular body 8 is located inside the exhaust collection box 6 about 3/4 of the width of the exhaust collection box 6. It is provided so as to protrude.

The sound absorbing portion 7 is formed in a rectangular box shape that is long in the vertical direction and thin in the front and rear direction, and is disposed along the inner surface of the rear wall of the casing C. Glass wool G as a sound absorbing member that absorbs sound is affixed thereto, and is divided by the glass wool G into an exhaust chamber 9 located below and an auxiliary exhaust chamber 10 located above. As shown in detail in FIGS. 4 and 5, the exhaust chamber 9 and the auxiliary exhaust chamber 10 vertically penetrate through the glass wool G that divides the two exhaust chambers 9 and 10, and have a large number of holes around them. The two exhaust pipes 11 are connected to each other by two rectangular tubular exhaust pipes 11c as exhaust paths having exhaust ports 11c. An outlet 8b as an inflow port through which the combustion exhaust gas flows into the exhaust chamber 9 is opened.

The flue gas flowing into the exhaust chamber 9 from the outlet portion 8b flows into the exhaust tube 11 from the inlet portions 11a of the two exhaust tubes 11, and the flue gas flowing into the exhaust tube 11 In the transverse direction of the two exhaust pipes 1
1 is configured such that the total of the cross-sectional areas is smaller than the cross-sectional area of the exhaust chamber 9. The two exhaust stacks 11
Are arranged side by side in the vertical direction and in a posture parallel or substantially parallel to each other in the horizontal direction, and the inlet portion 11a of each exhaust pipe 11 is located below the half of the vertical width of the exhaust chamber 9, that is, The exhaust chamber 9 is disposed in a protruding position in a state where the exhaust chamber 9 projects downward to a greater extent than half the width of the exhaust tube 11 along the longitudinal direction.

In contrast to the two exhaust cylinders 11 described above, the outlet portions 8b of the three cylindrical bodies 8 are provided at the inlet portions 11 of the exhaust cylinder 11.
a, that is, closer to the auxiliary exhaust chamber 10 and
It is provided at a position deviated in the transverse direction with respect to each exhaust pipe 11. In other words, the outlet portion 8b of each tubular body 8
However, it is configured such that the combustion exhaust gas flows toward a portion where the respective exhaust tubes 11 do not exist, that is, a portion facing the lateral side above the inlet portion 11a of each of the exhaust tubes 11.

Specifically, as shown in FIG. 4, the outlet portion 8b of the cylindrical body 8 located on the right side is further deviated to the right side than the exhaust pipe 11 on the right side, and the cylindrical body 8 located on the left side. 8 is further deviated to the left than the left exhaust pipe 11, and the outlet 8 b of the tubular body 8 located at the center is connected to the left and right exhaust pipes 1.
1, and all the outlets 8b of the three tubular members 8 are provided above the inlet portions 11a of the two exhaust cylinders 11, so that The combustion exhaust gas is configured to flow in a direction orthogonal to the longitudinal direction of the cylinder 11.

The flue gas from the exhaust chamber 9 flows into the auxiliary exhaust chamber 10 from the outlet portion 11b of the exhaust stack 11, and two flue gas flow in the transverse direction of the flue gas flowing into the auxiliary exhaust chamber 10. The total cross-sectional area of the exhaust pipe 11 is smaller than the cross-sectional area of the auxiliary exhaust chamber 10. In the upper part of the auxiliary exhaust chamber 10,
A cylindrical auxiliary exhaust pipe 12 as a single auxiliary exhaust path having glass wool G as a sound absorbing member adhered to the inner surface thereof communicates with the auxiliary exhaust pipe 12. The auxiliary exhaust pipe 12 is configured to be smaller than the cross-sectional area of the auxiliary exhaust chamber 10 in the cross direction of the combustion exhaust gas flowing from the casing C, and the auxiliary exhaust pipe 12 extends to the front side of the casing C, The combustion exhaust gas is discharged from the front surface of the casing C to the outside from the exhaust top 13 provided in the outlet portion 12b of the casing C.

Next, the flow of the combustion exhaust gas from the heat exchanger 4 will be described. First, the combustion exhaust gas flowing into the exhaust recovery box 6 is bent in the exhaust recovery box 6 in a direction intersecting the flow direction. At the same time, the flow is split into three flows and flows into the cylindrical body 8, and the energy of the sound is attenuated by the bending and splitting of the flow, so that the sound of the combustion exhaust gas can be absorbed. Furthermore, a sound absorbing effect can be expected due to internal reflection even within the three cylindrical bodies 8, and since the cylindrical bodies 8 are relatively long and protrude into the exhaust collection box 6, the length is effective. To use
An effective sound absorbing effect can be expected.

The combustion exhaust gas flowing into the three cylindrical bodies 8 is
Although it flows into the exhaust chamber 9 from the outlet portion 8b of the cylindrical body 8, it suddenly flows into the exhaust chamber 9 having a large cross-sectional area from the cylindrical body 8 having a small cross-sectional area. The volume expansion attenuates the sound energy and allows sound absorption. Further, in the exhaust chamber 9, the combustion exhaust gas flowing from each outlet portion 8b is bent downward perpendicular to the inflow direction, then bent transversely perpendicularly, and further vertically perpendicularly. Exhaust pipe 11
Flows into the exhaust pipe 11 from the inlet portion 11a, an effective sound absorbing action can be expected due to the attenuation of the sound energy due to the bending a plurality of times and the sound absorbing action by the glass wool G therebetween.

During the flow through the exhaust pipe 11, the sound is absorbed by coming into contact with the glass wool G via the many holes 11c, and flows into the auxiliary exhaust chamber 10 from the outlet portion 11b of the exhaust pipe 11. Also at this time, since the gas suddenly flows from the exhaust pipe 11 having a small cross-sectional area into the auxiliary exhaust chamber 10 having a large cross-sectional area, the sound energy is attenuated by the volume expansion and the sound can be absorbed. Thereafter, the sound is absorbed by the glass wool G in the auxiliary exhaust chamber 11 and is discharged from the exhaust top 13 to the outside of the casing C through the auxiliary exhaust pipe 12.

The bottom of the exhaust recovery box 6 is
The condensed water that falls from, that is, the drain collecting unit 14 that receives and collects the drain, the collected drain is neutralized by the neutralizer 16,
It is configured to be discharged outside through the drainage channel 15. Glass wool G as a sound absorbing member that absorbs sound from flowing combustion exhaust gas is also attached to the inner periphery of the exhaust gas collection box 6.

A fuel supply passage 17 for supplying fuel gas is connected to the fan 5. The greater the air flow of the fan 5 by the suction action of the fan 5, the more the fuel gas is sucked and the more fuel gas is drawn. It is configured to mix with air and supply the mixture to the burner 3. The fuel supply passage 17 is provided with an electromagnetically operated safety valve 18 for intermittently supplying the fuel gas from the upstream side in the fuel gas supply direction.
In addition, an igniter 21 for executing an ignition operation for the burner 3 and a frame rod 22 for detecting whether or not the burner 3 is ignited are provided near the burner 3. .

The above-described water supply channel 1 and the hot water supply channel 2 are connected to the heat exchanger 2. The water supply channel 1 has a water flow rate sensor 23 for detecting the flow rate of water to the heat exchanger 4, and a water supply path. Feed water temperature thermistor 24 for detecting the temperature of water supplied through 1
The hot water supply path 2 is provided with a hot water supply temperature thermistor 25 for detecting the temperature of hot water after being heated by the heat exchanger 4. The remote control operation unit R includes an operation switch 26 for instructing start and stop of operation of the hot water supply unit K, an operation lamp 27 for displaying an operation state, and a burner 3.
Are provided with a combustion lamp 28 for displaying that the fuel is burning, a temperature setting switch 29 for setting a target temperature for hot water supply, a display unit 30 for displaying the target temperature and the like.

The control section H is provided with a microcomputer, and the temperature of hot water supplied from the hot water tap 2a is set by a temperature setting switch 29 based on an operation command of the remote control operation section R. The configuration is such that the hot water supply unit K is controlled to reach the temperature. That is,
If the water flow detected by the water flow sensor 23 in response to the opening operation of the hot-water tap 2a exceeds the set water flow in a state where the operation state is set in accordance with the ON operation of the operation switch 26, the ventilation operation by the fan 5 is performed. Is started, the safety valve 18 and the fuel regulating valve 19 are opened, the igniter 21 ignites the burner 3, and the flame rod 22 confirms the ignition of the burner 3.

Thereafter, based on the detection information from the feed water temperature thermistor 24, the hot water temperature thermistor 25, the flow rate sensor 23, and the information of the tapping target temperature set by the temperature setting switch 29, the hot water tap 2a is turned on. The amount of gas required to bring the temperature of the supplied hot water to the target temperature for tapping is calculated, and the fuel adjustment valve 19 is adjusted so that the calculated gas amount is reached, and the ventilation amount of the fan 5 is also adjusted. Execute feedforward control. In addition to the feedforward control, feedback control for finely adjusting the fuel regulating valve 19 and the fan 5 is also performed based on a deviation between the temperature detected by the hot water temperature thermistor 25 and the hot water target temperature, and the hot water tap 2a Is controlled so that the temperature of the hot water supplied from the hot water reaches the target temperature for hot water supply.

[Another Embodiment] (1) Next, another embodiment will be described with reference to FIG. 6. However, in order to avoid redundant description, the same components and components having the same functions as those of the previous embodiment will be described. The description is omitted by attaching the same reference numerals, and the points that are different from the previous embodiment will be mainly described. In another embodiment shown in FIG. 6, the cylindrical body 8 is not provided as in the previous embodiment, and two inflow ports 8 b through which the combustion exhaust gas from the exhaust recovery box 6 flows into the exhaust chamber 9. Are provided directly on the front plate 7a of the casing constituting the sound absorbing portion 7. In this alternative embodiment as well, the two inlets 8b are connected to the inlet portion 1 of the exhaust stack 11.
1 a, that is, closer to the auxiliary exhaust chamber 10 and at a position deviated in the transverse direction with respect to each exhaust pipe 11, and each inflow port 8 b is provided at an inlet portion of each exhaust pipe 11. The combustion exhaust gas is configured to flow toward a portion where the respective exhaust pipes 11 do not exist, that is, a portion facing the lateral side above the portion 11a.

Therefore, in this alternative embodiment, the combustion exhaust gas from the heat exchanger 4 is bent in the exhaust recovery box 6 in a direction intersecting the inflow direction, and is simultaneously split into two flows. The energy of the sound is attenuated by the bending and splitting of the flow, and flows into the exhaust chamber 9 from the inlet 8b. Since it flows into the chamber 9, sound energy is attenuated by volume expansion at that time, and sound absorption becomes possible. Further, in the exhaust chamber 9, the combustion exhaust gas flowing from each of the inlets 8b is bent downward perpendicular to the inflow direction, then bent laterally perpendicularly, and further perpendicularly upward. Is bent into the exhaust pipe 11 from the inlet portion 11a of the exhaust pipe 11, so that the sound energy is attenuated due to the bending a plurality of times, and the sound absorbing action by the glass wool G therebetween is expected to provide an effective sound absorbing action. it can.

(2) In the above embodiments, the exhaust chamber 9
Two exhaust pipes 11 using the exhaust pipe and the auxiliary exhaust chamber 10 as exhaust paths
However, the number of exhaust pipes 11 is not limited to two, and may be one or three or more according to the amount of flowing combustion exhaust gas. In addition, the inlet portion 11a of the exhaust pipe 11 does not necessarily need to protrude below a half of the vertical width of the exhaust chamber 9, but may protrude to a position less than half of the vertical width of the exhaust chamber 9. It can also be implemented.
Further, the exhaust gas may be directly discharged to the outside from the outlet portion 11b of the exhaust pipe 11 without providing the auxiliary exhaust chamber 10 and the auxiliary exhaust pipe 12 as in the embodiments described above.

(3) In the above embodiments, the sound absorbing portion 7
The glass wool G which is an example of the sound absorbing member is disposed on the inner surfaces of the exhaust chamber 9 and the auxiliary exhaust chamber 10 constituting
The present invention can be implemented without disposing the glass wool G in the exhaust chamber 9 and the auxiliary exhaust chamber 10, and when disposing a sound absorbing member, ceramic wool or the like can be used instead of the glass wool. In addition, as for the arrangement of the sound absorbing portions 7, in addition to being arranged vertically along the inner surface of the rear wall of the casing C as in the previous embodiments, along with the inner surface of the front wall and the lateral wall of the casing C. It can be arranged in various forms.

(4) The combustion device according to the present invention can be used not only for a hot water supply device but also for various devices such as a heating device as in the previous embodiments. The burner 3 is also configured to generate its flame upward, the heat exchanger 4 for water heating is arranged above the burner 3, and the exhaust recovery box 6 is arranged above the heat exchanger 4.
Can also be implemented.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of a water heater.

FIG. 2 is an exploded perspective view of the water heater.

FIG. 3 is a vertical side view of the hot water supply device.

FIG. 4 is a longitudinal sectional front view of the sound absorbing section.

FIG. 5 is an exploded perspective view of the sound absorbing unit.

FIG. 6 is an exploded perspective view of a sound absorbing unit according to another embodiment.

[Explanation of symbols]

 Reference Signs List 3 Burner 4 Heat exchanger 6 Exhaust recovery box 8 Cylindrical body 8a Inlet portion of cylindrical body 8b Inflow port 9 Exhaust chamber 10 Auxiliary exhaust chamber 11 Exhaust path 11a Inlet section of exhaust path 11b Outlet section of exhaust path 12 Auxiliary exhaust path G sound absorbing member

Continuing from the front page (72) Yoshikazu Ishikawa, 1-15-1 Oka, Minami-shi, Minato-ku, Osaka-shi, Osaka Prefecture Herman Co., Ltd. (72) Keiji Yokoyama 1-1-52, Oka, Minami-shi, Minato-ku, Osaka, Osaka Stock 3K070 AB03 AB04 AB05 DA73 3L036 AA04 AA21 AA43 AA46 AE23 3L037 AA02 AC05 AC18 BB03 BB06

Claims (6)

[Claims] 1. A combustion device comprising a heat exchanger heated by combustion of a burner and an exhaust gas recovery box for recovering combustion exhaust gas heat-exchanged in the heat exchanger, wherein the combustion device is connected to the exhaust gas recovery box. An exhaust chamber for discharging the combustion exhaust gas from the exhaust chamber to the outside, and an exhaust passage communicating with the exhaust chamber to exhaust the combustion exhaust gas to the outside are provided. The exhaust port is disposed in a state of being protruded into the inside, and an inflow port through which the combustion exhaust gas from the exhaust gas collection box flows into the exhaust chamber is located at a position opposed to the side of the entrance portion of the exhaust path. A combustion device provided to flow the combustion exhaust gas toward a portion where the inlet portion does not exist. 2. The exhaust gas inlet according to claim 1, wherein the inflow port is provided so as to allow the combustion exhaust gas to flow toward a portion where the exhaust path does not exist closer to an outlet section of the exhaust path than an inlet section of the exhaust path. The combustion device according to claim 1. 3. The combustion apparatus according to claim 1, wherein a plurality of the exhaust passages are provided, and the plurality of exhaust passages are arranged side by side in a parallel or substantially parallel posture. 4. The combustion according to claim 1, wherein an auxiliary exhaust chamber communicated with an outlet of the exhaust path and an auxiliary exhaust path communicated with the auxiliary exhaust chamber are provided. apparatus. 5. The combustion apparatus according to claim 4, wherein the exhaust chamber and the auxiliary exhaust chamber are provided with a sound absorbing member that absorbs sound from the flowing combustion exhaust gas. 6. A tubular body provided with the inlet for allowing flue gas from the exhaust gas recovery box to flow into the exhaust chamber, wherein a longitudinal direction of the tubular body flows from the heat exchanger into the exhaust gas recovery box. The combustion device according to any one of claims 1 to 5, wherein the combustion device is provided so as to be directed in a direction intersecting with the direction and to have an inlet portion thereof positioned inside the exhaust gas collection box.