Exhaust case and combustion apparatus provided with the same

An exhaust case comprising:

• an exhaust case body provided to cover an upper opening of a heat exchanger and formed with an exhaust vent on a front part;
• a water-shielding plate extending from a forward area to a rear area in the exhaust case body;
• a dropping plate part downward from a front end of the water-shielding plate;
• a lower board having an upright plate part and a horizontal plate part which are provided under the water-shielding plate,
• the upright plate part rising in vertical height direction so as to extend without winding from a lower face of the water-shielding plate to an upper end of a forward part of the heat exchanger,
• the horizontal plate part extending in a horizontal manner from a lower end of the upright plate part toward a front of the lower end, the lower end of the upright plate part being positioned on the upper end of the heat exchanger, the anteroposterior length of the horizontal plate part being larger than the vertical height of the upright plate part, a front end of the horizontal plate part being close to the dropping plate part;
• a first exhaust gas flow path guiding a part of combustion exhaust gas passing the heat exchanger behind and onto the water-shielding plate;
• and
• a second exhaust gas flow path guiding a part of combustion exhaust gas passing the heat exchanger under the water-shielding plate;
• wherein
• the second exhaust gas flow path includes a space of which front, rear, up and down parts are surrounded with the dropping plate part, the upright plate part, the water-shielding plate and the horizontal plate part,
• the upright plate part has a plurality of ventilation holes opening in horizontal direction for flowing combustion exhaust gas into the space,
• a gap is formed between the front end of the horizontal plate part and the dropping plate part so as to flow combustion exhaust gas in the space to the exhaust vent, a flow path of the gap being less than that of the space in the area, and
• the combustion exhaust gas is compressed when flowing into the ventilation holes, expands when flowing into the space, is compressed again when flowing into the gap, and expands again after passing through the gap to thereby achieve a noise reduction effect.