COMBUSTION APPARATUS

Abstract

An exhaust portion is connected to a lower peripheral edge of a secondary heat exchanger case, has an exhaust vent configured to exhaust combustion gas which has passed through the secondary heat exchanger case, and has a bottom surface including a first face parallel to the lower peripheral edge. A drainage water discharge port is configured to discharge drainage water from the first face of the bottom surface. The drainage water discharge port is provided, to avoid a region overlapping with the secondary heat exchanger case from a point of view as seen in an up-down direction, in an exhaust path from the secondary heat exchanger case toward the exhaust vent.

Claims

1. A combustion apparatus comprising: a combustion portion configured to generate combustion gas; a heat exchanger of latent heat recovery type configured to exchange heat with combustion gas generated by the combustion portion; a heat exchanger case having an internal space and configured to accommodate the heat exchanger in the internal space; an exhaust portion connected to a peripheral edge which is one of an upper peripheral edge and a lower peripheral edge of the heat exchanger case, having an exhaust vent configured to exhaust combustion gas which has passed through the heat exchanger case, and having a bottom surface including a first face parallel to the peripheral edge; and a drainage water discharge port configured to discharge drainage water from the first face of the bottom surface, the drainage water discharge port being provided, to avoid a region overlapping with the heat exchanger case from a point of view as seen in an up-down direction, in an exhaust path from the heat exchanger case toward the exhaust vent.

2. The combustion apparatus according to claim 1, wherein the exhaust portion has a rising portion rising from the bottom surface, and the drainage water discharge port is arranged at a corner formed by the bottom surface and the rising portion.

3. The combustion apparatus according to claim 2, wherein the rising portion is composed of an outer wall of the exhaust portion.

4. The combustion apparatus according to claim 2, wherein the rising portion is a plate member arranged in the exhaust path.

5. The combustion apparatus according to claim 1, wherein the bottom surface of the exhaust portion includes a second face inclined relative to the peripheral edge of the heat exchanger case to have a down grade toward the first face.

6. The combustion apparatus according to claim 1, wherein the drainage water discharge port is provided in a sidewall of the exhaust portion and opens laterally.

7. The combustion apparatus according to claim 6, wherein the first face is provided with a guiding inclined face having a down grade toward the drainage water discharge port.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 schematically shows a construction of a combustion apparatus in one embodiment.

[0026] FIG. 2 is an exploded perspective view showing a construction of part of an exhaust portion of the combustion apparatus shown in FIG. 1 and a heat exchanger case.

[0027] FIG. 3 is a partial breakaway perspective view showing a construction of an exhaust collection and guide member in the combustion apparatus shown in FIG. 1.

[0028] FIG. 4 is a plan view of the exhaust collection and guide member shown in FIG. 3.

[0029] FIG. 5 is a schematic cross-sectional view taken along the line V-V in FIG. 4.

[0030] FIG. 6 is a schematic cross-sectional view taken along the line VI-VI in FIG. 4.

[0031] FIG. 7 is a schematic cross-sectional view taken along the line VII-VII in FIG. 4.

[0032] FIG. 8 is cross-sectional view showing a construction of an exhaust collection and guide member in a comparative example.

[0033] FIG. 9 is a plan view showing a construction of a first variation of the exhaust collection and guide member.

[0034] FIG. 10 is a schematic cross-sectional view taken along the line X-X in FIG. 9.

[0035] FIG. 11 is a plan view showing a construction of a second variation of the exhaust collection and guide member.

[0036] FIG. 12 schematically shows a construction of a combustion apparatus in another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] An embodiment of the present invention will be described below in detail with reference to the drawings.

[0038] It should be noted that the same or corresponding components are denoted by the same characters in the specification and drawings, and redundant description thereof is not repeated. In addition, constructions may be omitted or simplified in the drawings for the sake of illustration. Further, the embodiment and each variation may be at least partially combined together in an arbitrary manner.

[0039] <Construction of Combustion Apparatus 10>

[0040] As shown in FIG. 1, a combustion apparatus 10 in the present embodiment is a combustion apparatus of inverse combustion type. Combustion apparatus 10 includes an exhaust portion 1, a secondary heat exchanger 11, a secondary heat exchanger case 12, a primary heat exchanger 13, a primary heat exchanger case 14, a combustion portion 15, a fan 16, a drainage water tank 17, and a housing 20.

[0041] Exhaust portion 1, secondary heat exchanger 11, secondary heat exchanger case 12, primary heat exchanger 13, primary heat exchanger case 14, combustion portion 15, fan 16 and drainage water tank 17 are accommodated in housing 20.

[0042] Fan 16 serves to supply mixed gas of fuel gas and fuel air to combustion portion 15. An air supply pipe 16a is connected to fan 16. Air supply pipe 16a extends to the outside of housing 20 in combustion apparatus 10.

[0043] Combustion portion 15 serves to burn the mixed gas to generate combustion gas serving as gas for heating. Combustion portion 15 is a combustion device of inverse combustion type which supplies combustion gas downward. The combustion gas exchanges heat with water in each of primary heat exchanger 13 and secondary heat exchanger 11.

[0044] Primary heat exchanger case 14 and secondary heat exchanger case 12 are connected to combustion portion 15 so that the combustion gas sequentially passes through primary heat exchanger 13 and secondary heat exchanger 11. Primary heat exchanger case 14 is attached below combustion portion 15, and secondary heat exchanger case 12 is attached below primary heat exchanger case 14.

[0045] Secondary heat exchanger case 12 has an upper peripheral edge 12b and a lower peripheral edge 12a. Upper peripheral edge 12b of secondary heat exchanger case 12 is connected to a lower peripheral edge of primary heat exchanger case 14. Secondary heat exchanger case 12 and primary heat exchanger case 14 form a can body. Secondary heat exchanger case 12 and primary heat exchanger case 14 are made of a metal material including copper or aluminum, for example.

[0046] Primary heat exchanger case 14 and secondary heat exchanger case 12 each have an internal space. Primary heat exchanger 13 of sensible heat recovery type is accommodated in the internal space of primary heat exchanger case 14. Primary heat exchanger 13 is a fin-and-tube type heat exchanger, for example. Secondary heat exchanger 11 of latent heat recovery type is accommodated in the internal space of secondary heat exchanger case 12. Secondary heat exchanger 11 is a fin-and-tube type heat exchanger, for example. Secondary heat exchanger 11 may be a plate type heat exchanger.

[0047] Exhaust portion 1 is connected to lower peripheral edge 12a of secondary heat exchanger case 12. Exhaust portion 1 includes an exhaust collection and guide member 2, an exhaust duct 3, and an exhaust vent 4. Exhaust portion 1 serves to exhaust combustion gas which has passed through secondary heat exchanger case 12 to the outside of housing 20 in combustion apparatus 10.

[0048] Exhaust portion 1 is made of a material different from that for secondary heat exchanger case 12 and primary heat exchanger case 14. Exhaust portion 1 is made of resin, for example.

[0049] Drainage water tank 17 serves to store drainage water generated at secondary heat exchanger 11 or primary heat exchanger 13. Drainage water tank 17 is connected to exhaust portion 1. Specifically, drainage water tank 17 is connected through a pipe 18 to a drainage water discharge port 2aa in exhaust collection and guide member 2.

[0050] In combustion apparatus 10 shown in FIG. 1, when a temperature of hot water introduced to primary heat exchanger 13 of sensible heat recovery type is low, or when an amount of heating by combustion portion 15 is small, water vapors of the combustion gas condense in primary heat exchanger 13, generating condensed water (drainage water). Drainage water is generated also in secondary heat exchanger 11 of latent heat recovery type. Such drainage water flows through exhaust collection and guide member 2 of exhaust portion 1 to be drained to drainage water tank 17.

[0051] <Construction of Exhaust Portion 1>

[0052] As shown in FIG. 1, exhaust collection and guide member 2 is connected to lower peripheral edge 12a of secondary heat exchanger case 12 by a bolt, for example. Exhaust duct 3 is connected to exhaust collection and guide member 2. Exhaust duct 3 extends upward, for example, from exhaust collection and guide member 2. Exhaust vent 4 is connected to exhaust duct 3. Exhaust vent 4 extends upward, for example, from exhaust duct 3. The combustion gas which has passed through secondary heat exchanger case 12 is exhausted through exhaust collection and guide member 2, exhaust duct 3 and exhaust vent 4 to the outside of housing 20.

[0053] Exhaust portion 1 has a bottom surface 2b. Bottom surface 2b is a bottom surface of exhaust collection and guide member 2, and is a bottom surface in an exhaust path. Bottom surface 2b is located below secondary heat exchanger case 12. Bottom surface 2b has a first face 2ba and a second face 2bb.

[0054] First face 2ba has a face parallel to lower peripheral edge 12a of secondary heat exchanger case 12. First face 2ba is a substantially horizontal face when combustion apparatus 10 is properly installed.

[0055] Second face 2bb has a face inclined relative to lower peripheral edge 12a of secondary heat exchanger case 12. Second face 2bb is inclined by an angle , for example, relative to lower peripheral edge 12a of secondary heat exchanger case 12.

[0056] As shown in FIGS. 2 and 3, bottom surface 2b may have a third face 2bc in addition to first face 2ba and second face 2bb. Third face 2bc has, similarly to second face 2bb, a face inclined relative to lower peripheral edge 12a of secondary heat exchanger case 12.

[0057] Second face 2bb and third face 2bc are each connected to first face 2ba. Second face 2bb and third face 2bc are also connected to each other.

[0058] As shown in FIG. 2, secondary heat exchanger case 12 and exhaust duct 3 are connected to an upper end portion of exhaust collection and guide member 2.

[0059] As shown in FIG. 4, first face 2ba, second face 2bb and third face 2bc are each located in a region RA overlapping with secondary heat exchanger case 12 from a point of view as seen in an up-down direction (in plan view). The up-down direction as used herein refers to a direction in which exhaust collection and guide member 2 and secondary heat exchanger case 12 are stacked on each other, which is a point of view shown in FIG. 4.

[0060] Second face 2bb is located only in region RA overlapping with secondary heat exchanger case 12, and is not located in a region RB overlapping with exhaust duct 3, from the point of view as seen in the up-down direction. In contrast, first face 2ba and third face 2bc are each located both in region RA overlapping with secondary heat exchanger case 12 and in region RB overlapping with exhaust duct 3, from the point of view as seen in the up-down direction. Region RB is a region where exhaust collection and guide member 2 and exhaust duct 3 are joined to each other.

[0061] Exhaust collection and guide member 2 has a sidewall 2d and drainage water discharge port 2aa. Sidewall 2d of exhaust collection and guide member 2 surrounds bottom surface 2b, and rises upward from bottom surface 2b. Sidewall 2d forms an outer wall of exhaust portion 1.

[0062] Drainage water discharge port 2aa opens at sidewall 2d and extends laterally. Drainage water discharge port 2aa serves to discharge drainage water which has fallen to bottom surface 2b of exhaust collection and guide member 2 to drainage water tank 17 (FIG. 1) from exhaust collection and guide member 2.

[0063] Drainage water discharge port 2aa is provided, to avoid region RA overlapping with secondary heat exchanger case 12 from the point of view as seen in the up-down direction, in the exhaust path from region RA toward exhaust vent 4 (FIG. 1).

[0064] Drainage water discharge port 2aa is provided in sidewall 2d in region RB overlapping with exhaust duct 3 from the point of view as seen in the up-down direction. Drainage water discharge port 2aa is also provided to be able to discharge drainage water from first face 2ba of bottom surface 2b.

[0065] Bottom surface 2b further has a guiding inclined face 2c. Guiding inclined face 2c is provided in region RB overlapping with exhaust duct 3 from the point of view as seen in the up-down direction. Guiding inclined face 2c is provided on first face 2ba and third face 2bc so as to reach drainage water discharge port 2aa. Guiding inclined face 2c extends linearly toward drainage water discharge port 2aa.

[0066] As shown in FIG. 3, exhaust collection and guide member 2 has a bolt attachment portion 2e and support portions 2f. Bolt attachment portion 2e and support portions 2f each rise from bottom surface 2b into the exhaust path. Bolt attachment portion 2e is a portion into which a bolt (not shown) for fixing exhaust collection and guide member 2 to secondary heat exchanger case 12 is to be inserted. Support portions 2f are portions for supporting an upper end portion 2m (FIG. 2) with respect to bottom surface 2b of exhaust collection and guide member 2.

[0067] As shown in FIG. 5, first face 2ba is parallel to upper end portion 2m of exhaust collection and guide member 2. Second face 2bb is inclined to have a down grade toward a joining portion of first face 2ba and second face 2bb.

[0068] Guiding inclined face 2c is recessed relative to first face 2ba. Although not shown, guiding inclined face 2c is also recessed relative to third face 2bc. Guiding inclined face 2c has an arc shape, for example, in cross section.

[0069] Drainage water discharge port 2aa is provided at a corner formed by first face 2ba and a rising portion rising from first face 2ba. In the present embodiment, the rising portion rising from first face 2ba is sidewall 2d. Thus, drainage water discharge port 2aa is provided at a corner formed by first face 2ba and sidewall 2d.

[0070] That drainage water discharge port 2aa is provided at the corner includes not only the case in which drainage water discharge port 2aa is provided in contact with the corner, but also the case in which drainage water discharge port 2aa is provided while being laterally spaced apart from the corner by a predetermined dimension. This predetermined dimension refers to a dimension required based on constraints on integral formation of drainage water discharge port 2aa and sidewall 2d, which is several mm (not more than 1 cm), for example.

[0071] As shown in FIG. 6, third face 2bc is inclined to have a down grade toward a joining portion of first face 2ba and third face 2bc.

[0072] As shown in FIG. 7, guiding inclined face 2c is provided in region RB where exhaust collection and guide member 2 overlaps with exhaust duct 3 from the point of view as seen in the up-down direction. Guiding inclined face 2c is provided across both first face 2ba and third face 2bc. Guiding inclined face 2c is inclined to have a down grade until reaching drainage water discharge port 2aa.

Effects of Present Embodiment

[0073] Effects of the present embodiment will now be described in comparison with a comparative example shown in FIG. 8.

[0074] In the comparative example shown in FIG. 8, drainage water discharge port 2aa is located in region RA where exhaust collection and guide member 2 overlaps with secondary heat exchanger case 12 from the point of view as seen in the up-down direction. In this comparative example, combustion gas flows from a side of region RA where exhaust collection and guide member 2 overlaps with secondary heat exchanger case 12 to a side of region RB where exhaust collection and guide member 2 overlaps with exhaust duct 3, as indicated by an arrow in the figure.

[0075] Accordingly, drainage water DR1 which has fallen to bottom surface 2b of exhaust collection and guide member 2 on a side opposite to the side of region RB with respect to drainage water discharge port 2aa is pushed by a flow of the combustion gas to reach the drainage water discharge port. In contrast, drainage water DR2 which has fallen to bottom surface 2b of exhaust collection and guide member 2 on the side of region RB with respect to drainage water discharge port 2aa has difficulty in being pushed by the flow of the combustion gas to reach drainage water discharge port 2aa.

[0076] In particular, when the quantity of airflow exhausted by fan 16 increases, or when the exhaust path in exhaust collection and guide member 2 decreases in area due to size reduction, a flow velocity of the combustion gas exhausted in the exhaust path above increases, making the problem above more pronounced.

[0077] In contrast, according to the present embodiment, as shown in FIG. 5, drainage water discharge port 2aa is provided, to avoid region RA where exhaust collection and guide member 2 overlaps with secondary heat exchanger case 12 from the point of view as seen in the up-down direction, in the exhaust path from region RA toward exhaust vent 4 (FIG. 1). Thus, drainage water which has fallen to bottom surface 2b of exhaust collection and guide member 2 from the inside of secondary heat exchanger case 12 can be pushed by the flow of the combustion gas to readily reach drainage water discharge port 2aa. Accordingly, the drainage water can be efficiently discharged through drainage water discharge port 2aa.

[0078] According to the present embodiment, as shown in FIG. 1, bottom surface 2b of exhaust portion 1 has first face 2ba parallel to lower peripheral edge 12a of secondary heat exchanger case 12. Thus, the thickness of exhaust portion 1 in the up-down direction can be reduced as compared to an example where bottom surface 2b of exhaust portion 1 includes only an inclined face relative to lower peripheral edge 12a. The size reduction of combustion apparatus 10 in the up-down direction is thus facilitated.

[0079] According to the present embodiment, as shown in FIG. 1, exhaust portion 1 is provided separately from secondary heat exchanger case 12 which accommodates secondary heat exchanger 11. Exhaust portion 1 is connected to lower peripheral edge 12a of secondary heat exchanger case 12, and is configured to exhaust the combustion gas which has passed through secondary heat exchanger case 12. Thus, most of the combustion gas is able to pass through secondary heat exchanger 11 of latent heat recovery type. The efficiency of heat exchange at secondary heat exchanger 11 of latent heat recovery type is thus improved.

[0080] According to the present embodiment, as shown in FIG. 5, drainage water discharge port 2aa is arranged at the corner formed by bottom surface 2b and the rising portion (sidewall 2d) rising from bottom surface 2b. At the corner formed by bottom surface 2b and the rising portion (sidewall 2d), a flow velocity of the combustion gas decreases. The drainage water thus stays at the corner. By providing drainage water discharge port 2aa at this corner, therefore, the drainage water staying at the corner can be effectively discharged through drainage water discharge port 2aa.

[0081] According to the present embodiment, as shown in FIG. 5, the rising portion (sidewall 2d) is composed of the outer wall of exhaust portion 1. Accordingly, the drainage water staying at a corner between the outer wall and bottom surface 2b of exhaust portion 1 can be discharged through drainage water discharge port 2aa.

[0082] According to the present embodiment, as shown in FIG. 5, bottom surface 2b of exhaust portion 1 includes second face 2bb inclined relative to lower peripheral edge 12a of secondary heat exchanger case 12 to have a down grade toward first face 2ba. This facilitates guiding of the drainage water which has fallen to second face 2bb from the inside of secondary heat exchanger case 12 to first face 2ba by the inclination of second face 2bb. Discharge of the drainage water from first face 2ba through drainage water discharge port 2aa is thus further facilitated.

[0083] If drainage water discharge port 2aa opens downward, pipe 18 connecting drainage water tank 17 and drainage water discharge port 2aa shown in FIG. 1 needs to be extended downward. Thus, a space for such downward extension of pipe 18 is needed between drainage water tank 17 and exhaust portion 1, resulting in a corresponding increase in the dimension of combustion apparatus 10 in the up-down direction.

[0084] In contrast, according to the present embodiment, as shown in FIG. 1, drainage water discharge port 2aa is provided in the sidewall of exhaust portion 1 and opens laterally. Thus, pipe 18 connecting drainage water tank 17 and drainage water discharge port 2aa can be laterally extended for connection to drainage water tank 17. Accordingly, there is no need to provide a space for downward extension of pipe 18 from bottom surface 2b of exhaust portion 1, allowing for a further corresponding reduction in the dimension of the combustion apparatus in the up-down direction.

[0085] According to the present embodiment, as shown in FIGS. 4 and 7, first face 2ba is provided with guiding inclined face 2c having a down grade toward drainage water discharge port 2aa. Discharge of the drainage water on first face 2ba through drainage water discharge port 2aa via guiding inclined face 2c is thus further facilitated.

[0086] <Variations>

[0087] The embodiment above has described a construction in which drainage water discharge port 2aa is arranged at the corner formed by bottom surface 2b and sidewall 2d, as shown in FIG. 5. The present invention is not limited thereto, however. As shown in FIGS. 9 and 10, drainage water discharge port 2aa may be arranged at a corner formed by bottom surface 2b and a plate member 2g.

[0088] Plate member 2g is a rising portion rising from bottom surface 2b. Plate member 2g is arranged in the exhaust path, and does not form the outer wall of exhaust portion 1 (wall facing the outer side of the exhaust path).

[0089] Plate member 2g may be formed integrally with exhaust portion 1 (exhaust collection and guide member 2), or may be prepared separately from exhaust portion 1 (exhaust collection and guide member 2) and then attached to exhaust portion 1 (exhaust collection and guide member 2).

[0090] As shown in FIG. 10, plate member 2g is arranged in region RB where exhaust collection and guide member 2 overlaps with exhaust duct 3 from the point of view as seen in the up-down direction. Drainage water discharge port 2aa is also arranged in region RB where exhaust collection and guide member 2 overlaps with exhaust duct 3 from the point of view as seen in the up-down direction. Drainage water discharge port 2aa may be provided in sidewall 2d and open laterally. Drainage water discharge port 2aa may open downward at bottom surface 2b as indicated by a broken line in FIG. 9.

[0091] That drainage water discharge port 2aa is arranged at the corner formed by bottom surface 2b and a plate member 2g includes, similarly to the above, not only the case in which drainage water discharge port 2aa is provided in contact with the corner, but also the case in which drainage water discharge port 2aa is provided while being laterally spaced apart from the corner by a predetermined dimension. This predetermined dimension refers to a dimension required based on constraints on integral formation of drainage water discharge port 2aa and plate member 2g, which is several mm (not more than 1 cm), for example.

[0092] At such corner formed by plate member 2g and bottom surface 2b, too, a flow velocity of the combustion gas decreases, causing the drainage water to stay. By providing drainage water discharge port 2aa at this corner, therefore, the drainage water staying at the corner formed by plate member 2g and bottom surface 2b can be effectively discharged through drainage water discharge port 2aa.

[0093] As shown in FIG. 11, shielding portions 2e may rise from bottom surface 2b into the exhaust path, and drainage water discharge port 2aa may be arranged in a region

[0094] RC opposite to region RA with respect to shielding portions 2e from the point of view as seen in the up-down direction. Shielding portions 2e may be attachment portions for bolts, for example, for fixing exhaust collection and guide member 2 to secondary heat exchanger case 12.

[0095] In region RC, the flow of the combustion gas is inhibited by shielding portions 2e, causing a flow velocity of the combustion gas to decrease and the drainage water to stay. That is, in region RC, the flow of the exhausted combustion gas creates a stagnation region of the drainage water, and this causes the drainage water to stay. By providing drainage water discharge port 2aa in region RC, therefore, the staying drainage water can be efficiently discharged through drainage water discharge port 2aa.

[0096] With drainage water discharge port 2aa provided in a portion where a flow velocity of the combustion gas decreases and the drainage water stagnation region is created as described above, discharge of the drainage water through drainage water discharge port 2aa is facilitated.

[0097] Drainage water discharge port 2aa may be provided in sidewall 2d in region RC and open laterally. In this case, drainage water discharge port 2aa is provided in sidewall 2d located opposite to region RA with respect to region RB from the point of view as seen in the up-down direction. Drainage water discharge port 2aa extends laterally along a direction in which region RA and region RB are aligned with each other. Drainage water discharge port 2aa may be provided downward in bottom surface 2b in region RC as indicated by a broken line in FIG. 11.

[0098] In the construction shown in FIG. 4, drainage water discharge port 2aa is provided in sidewall 2d located in a direction intersecting (for example, orthogonal to) the direction in which region RA and region RB are aligned with each other with respect to region RB. Drainage water discharge port 2aa shown in FIG. 4 may be provided, similarly to drainage water discharge port 2aa shown in FIG. 10, in sidewall 2d located opposite to region RA with respect to region RB. In this case, drainage water discharge port 2aa extends laterally along the direction in which region RA and region RB are aligned with each other.

[0099] While the embodiment above has described combustion apparatus 10 of inverse combustion type as shown in FIG. 1, the present invention may be applied to combustion apparatus 10 of normal combustion type shown in FIG. 12.

[0100] As shown in FIG. 12, combustion apparatus 10 of normal combustion type includes, in order from the bottom, fan 16, combustion portion 15, primary heat exchanger 13, secondary heat exchanger 11, and exhaust portion 1.

[0101] Combustion portion 15 is a combustion device of normal combustion type which supplies combustion gas upward. Primary heat exchanger 13 is accommodated in primary heat exchanger case 14. Secondary heat exchanger 11 is accommodated in secondary heat exchanger case 12.

[0102] Secondary heat exchanger case 12 has lower peripheral edge 12a and upper peripheral edge 12b. Exhaust portion 1 is connected to upper peripheral edge 12b of secondary heat exchanger case 12. Exhaust portion 1 includes exhaust collection and guide member 2, exhaust duct 3, and exhaust vent 4. Exhaust collection and guide member 2 is connected to upper peripheral edge 12b of secondary heat exchanger case 12. Exhaust vent 4 exhausts combustion gas which has passed through secondary heat exchanger case 12.

[0103] Exhaust collection and guide member 2 of exhaust portion 1 has bottom surface 2b. Bottom surface 2b has a portion which is located, to avoid the region overlapping with secondary heat exchanger case 12 from the point of view as seen in the up-down direction, in the exhaust path toward exhaust vent 4.

[0104] Bottom surface 2b has first face 2ba and second face 2bb. First face 2ba is parallel to upper peripheral edge 12b of secondary heat exchanger case 12. Second face 2bb is inclined relative to upper peripheral edge 12b of secondary heat exchanger case 12.

[0105] Drainage water discharge port 2aa is provided, to avoid the region overlapping with secondary heat exchanger case 12 from the point of view as seen in the up-down direction, in the exhaust path toward exhaust vent 4. Sidewall 2d rises from bottom surface 2b toward exhaust vent 4. Drainage water discharge port 2aa is provided at a corner formed by bottom surface 2b and sidewall 2d.

[0106] In combustion apparatus 10 of normal combustion type as described above, too, drainage water can be efficiently discharged through drainage water discharge port 2aa.

[0107] Although the embodiment of the present invention has been described, it should be understood that the embodiment disclosed herein is illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the meaning and scope equivalent to the terms of the claims.