JP2011252678A - Forced supply and exhaust type heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology of preventing the situation in which dew condensation water gathers on the downstream side of an air supply and exhaust fan, in a forced supply and exhaust type heater of negative pressure type.SOLUTION: This invention is embodied as a heater. The heater includes: a combustion chamber for burning fuel to generate a combustion gas; a heat exchanger for heat exchanging the combustion gas from the combustion chamber between itself and surrounding air; an air supply and exhaust flow path for supplying the combustion chamber with the air from outdoors and discharging an exhaust gas from the heat exchanger to outdoors; the air supply and exhaust fan provided on the downstream side of the heat exchanger of the air supply and exhaust flow path; and a convection fan for taking in indoor air, passing the air through the heat exchanger, and sending the air to indoors. The heater is provided with a dew condensation water discharge mechanism for discharging the dew condensation water generated from the exhaust gas on the downstream side of the air supply and exhaust fan of the air supply and exhaust flow path.

Description

  The present invention relates to a forced air supply / exhaust heater.

  In general, in a heater, indoor air is heated by heating air taken in from indoors through heat exchange with combustion gas obtained by burning fuel gas, and sending the heated air again indoors. Among these, in the forced air supply / exhaust heater, the air required for the combustion of the fuel gas is forcibly taken in from the outside by the air supply / exhaust fan, and the exhaust gas after the combustion is forcibly discharged outside. In a forced air supply / exhaust heater, a path through which air taken from indoors flows and a path through which combustion gas flows are separated, and heating can be performed without polluting indoor air.

  Among forced air supply / exhaust heaters, the air supply / exhaust fan is located downstream of the heat exchange section that exchanges heat between indoor air and combustion gas in a series of paths through which air, combustion gas, and exhaust gas flow from outside. What is being called is called a negative pressure type forced air supply and exhaust type heater. In the negative pressure type forced air supply / exhaust heater, when the air supply / exhaust fan is driven to rotate, the heat exchanging portion located upstream of the air supply / exhaust fan is maintained at a negative pressure. In a negative pressure type forced air supply / exhaust heater, even if the piping through which the combustion gas flows is damaged in the heat exchange section, the combustion gas leaks to the outside because the inside of the piping is maintained at a negative pressure. The combustion gas can be prevented from leaking into the air from inside.

  As a negative-pressure type forced air supply / exhaust heater, for example, those described in Patent Documents 1-4 are known.

Australian Utility Model No. 2009100240 Specification US Pat. No. 4,974,579 US Pat. No. 5,347,980 Japanese Utility Model Publication No. 58-5892

  In the negative pressure type forced air supply / exhaust heater, the air supply / exhaust fan is disposed downstream of the heat exchanging section, so that the combustion gas cooled by exchanging heat with the air from the inside (that is, exhaust gas) After being further cooled by contact with the air supply / exhaust fan, it is discharged outside. That is, the supply / exhaust fan also plays a role of recovering residual heat from the exhaust gas. Therefore, the negative pressure type forced air supply / exhaust heater has high overall thermal efficiency and low environmental load. However, since the exhaust gas is further cooled by contact with the supply / exhaust fan, a problem arises in that a drain is generated from the exhaust gas that has passed through the supply / exhaust fan.

  In the forced air supply / exhaust heater of the prior art, the drain discharge mechanism is provided upstream of the air supply / exhaust fan, and the drain generated when the combustion gas passes through the heat exchange section can be discharged. However, when a drain is generated downstream of the supply / exhaust fan, the forced supply / exhaust heater of the prior art cannot discharge the drain. The drain accumulates inside the flow path for exhausting the exhaust gas to the outside, causing problems such as corrosion of the member.

  Even in the conventional forced air supply / exhaust heater, if the temperature of the exhaust gas is raised to some extent by raising the input of the fuel gas to be burned, it is possible to prevent the drain from being generated downstream of the supply / exhaust fan. I can. However, in this case, since the input of the fuel gas cannot be reduced, it is difficult to finely adjust the indoor air temperature when heating.

  The present invention solves the above problems. The present invention provides a technique capable of preventing a situation in which a drain is accumulated on the downstream side of an air supply / exhaust fan in a negative pressure type forced air supply / exhaust heater.

  The present invention is embodied as a heater. The heater includes a combustor that burns fuel to generate combustion gas, a heat exchanger that exchanges heat between the combustion gas from the combustor and the surrounding air, and air from outside to the combustor. Supply and exhaust flow path for supplying and exhausting exhaust gas from the heat exchanger to the outside, a supply and exhaust fan provided downstream of the heat exchanger in the supply and exhaust flow path, and indoor air And a convection fan that passes around the heat exchanger and feeds it indoors. In the heater, a drain discharge mechanism for discharging a drain generated from the exhaust gas is provided on the downstream side of the supply / exhaust fan in the supply / exhaust flow path.

  In the above heater, even when the exhaust gas from the heat exchanger is cooled by contact with the supply / exhaust fan and a drain is generated, the drain can be discharged by the drain discharge mechanism. The drain does not accumulate on the downstream side of the supply / exhaust fan. Further, in the above-described heater, since the generation of the drain on the downstream side of the supply / exhaust fan can be allowed, the fuel input can be reduced. When heating is performed, it is possible to perform delicate temperature adjustment of indoor air.

  In the heater, the heat exchanger is preferably composed of a plurality of pipes through which combustion gas passes.

  When the heat exchanger is composed of a plurality of pipes, it is possible to secure a wide heat transfer area in the heat exchange between the combustion gas from the combustor and the surrounding air, so that the efficiency of heat exchange can be increased. .

  In the heater, it is preferable that a fan motor for rotating the supply / exhaust fan is exposed in a flow path through which air taken in from the room by the convection fan flows.

  When the supply / exhaust fan is provided on the downstream side of the heat exchanger, the supply / exhaust fan collects residual heat from the exhaust gas and becomes high temperature, and the fan motor mechanically connected to the supply / exhaust fan also becomes high temperature. If the fan motor becomes too hot, there is a risk of causing a motor failure due to grease breakage. In the above heater, since the fan motor is exposed in the flow path through which the air taken in from the inside flows, the air supply / exhaust fan is exchanged by heat exchange with the air when the air is taken in from the room by the rotation of the convection fan. The fan motor is cooled. It is possible to prevent the fan motor from becoming excessively hot. Moreover, since the air heated by heat exchange with a fan motor is utilized for heating after that, the thermal efficiency of a heater can be improved.

  In the heater, the drain discharge mechanism includes a drain discharge port and a drain tray that collects a drain from the drain discharge port, and the drain tray detects a water level of the drain inside. It is preferable to provide.

  According to said heater, it becomes possible to control operation | movement of a heater according to the water level of the drain collected in the drain tray. For example, when the water level inside the drain pan reaches a predetermined water level, it is possible to notify the user that the user is prompted to discard the drain accumulated in the drain pan. Alternatively, when the water level inside the drain pan reaches a predetermined water level, the user performs control to prohibit operation of the heater until the drain accumulated in the drain pan is discarded, and the drain overflows from the drain pan. Can be prevented.

  ADVANTAGE OF THE INVENTION According to this invention, the situation where a drain accumulates in the downstream rather than an air supply / exhaust fan can be prevented in a negative pressure type forced air supply / exhaust heater.

It is a front view which shows typically the structure inside the heater 10 of an Example. It is a longitudinal cross-sectional view about the II-II cross section of FIG. It is a perspective view which shows the external appearance of the heat exchange unit 16 of the heater 10 of an Example. It is a perspective view which shows the external appearance of the exhaust unit 20 of the heater 10 of an Example. It is a partial longitudinal cross-sectional view which shows typically the attachment state of the exhaust unit 20 of the heater 10 of an Example.

The main features of the embodiments described below are listed below.
(Characteristic 1) The supply / exhaust fan is accommodated inside, and the supply / exhaust fan casing through which the exhaust gas passes is exposed in the flow path through which the air taken in by the convection fan flows.
(Characteristic 2) Another drain discharge mechanism for discharging the drain generated from the combustion gas is provided upstream of the supply / exhaust fan in the supply / exhaust flow path.

  Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 schematically shows an internal configuration when the heater 10 according to the present embodiment is viewed from the front, and FIG. 2 is a longitudinal sectional view of the heater 10. As shown in FIG. 2, the heater 10 is installed close to the wall surface W of the house. The heater 10 includes an inner case 15 and an outer case 14 that covers the inner case 15 from above. The outer case 14 is disposed so as to cover the upper surface and both side surfaces of the space sandwiched between the back surface of the inner case 15 and the wall surface W of the house. The outer case 14 is provided with a plurality of slits 22 through which indoor air can pass.

  A blower unit 12 is provided on the upper side of the inner case 15. As shown in FIG. 1, the blower unit 12 includes a pair of convection fans 26 a and 26 b and a convection fan motor 28 that rotationally drives the convection fans 26 a and 26 b. The convection fans 26a and 26b are sirocco fans, which take in air from the side (left-right direction in FIG. 1) and send out air downward. When the convection fans 26a and 26b rotate, the indoor air flows into the outer case 14 through the slit 22 in FIG. 2, flows upward in the space between the inner case 15 and the wall surface W, and the convection in FIG. It flows into the fans 26a and 26b from the side. The air flowing into the convection fans 26 a and 26 b is sent downward from the convection fans 26 a and 26 b and flows into the inner case 15. Below, the surface orthogonal to the flow of air sent out from the convection fans 26a, 26b is referred to as the air blowing surface of the convection fans 26a, 26b. The air sent downward from the convection fans 26 a and 26 b is heated by heat exchange with the heat exchange unit 16 and the exhaust unit 20, and then indoors from an air outlet 30 formed in the lower front portion of the inner case 15. Sent out. The operation of the convection fan motor 28 is controlled by the control unit 24.

  Combustion gas is supplied from the combustion unit 18 to the heat exchange unit 16. The combustion unit 18 is disposed in the vicinity of one side end of the lower portion of the heater 10 (in the vicinity of the right side end in FIG. 1). The combustion unit 18 includes a burner (not shown) inside. A fuel gas supply pipe (not shown) for supplying fuel gas and a combustion air supply pipe 19 (see FIG. 2) for supplying air for burning the fuel gas are connected to the combustion unit 18. As the fuel gas, city gas, natural gas, or the like can be used. As shown in FIG. 2, the combustion air supply pipe 19 communicates with the outdoors via an indoor side adapter 70, a double pipe 72, and an outdoor side adapter 74 provided on the wall surface W of the house. In the combustion unit 18, the fuel gas supplied via the fuel gas supply pipe and the air supplied via the combustion air supply pipe 19 are mixed to burn the mixed gas. The combustion gas generated by the combustion unit 18 is sent to the heat exchange unit 16 via the plate 38. The operation of the combustion unit 18 is controlled by the control unit 24.

  As shown in FIGS. 1, 2 and 3, the heat exchange unit 16 includes large diameter tubes 32a, 32b, 32c, 32d, small diameter tubes 34a, 34b, 34c, 34d, 34e, 34f, 34g, 34h, A merge chamber 36 is provided. One ends of the large-diameter tubes 32a, 32b, 32c, and 32d are caulked and joined to a plurality of holes provided in the plate 38, respectively. The large-diameter tubes 32a, 32b, 32c, and 32d extend along the left and right directions in FIG. 1 at the lower part inside the inner case 15, and near the side end of the inner case 15 (near the left side end in FIG. 1). It is formed in a substantially L shape that bends upward. Skirt portions 42a, 42b, 42c, and 42d are formed at the other ends of the large-diameter tubes 32a, 32b, 32c, and 32d, respectively. The skirt portions 42a, 42b, 42c, and 42d are formed so as to widen toward the end surfaces 44a, 44b, 44c, and 44d, respectively. As shown in FIG. 3, two holes are formed in each of the end faces 44a, 44b, 44c, and 44d. One end of each of the small diameter tubes 34a and 34b is caulked and joined to the two holes formed in the end face 44a. Similarly, one end of the small diameter tubes 34c and 34d is caulked and joined to the two holes formed in the end face 44b, and one end of the small diameter tubes 34e and 34f is caulked to the two holes formed in the end face 44c. One end of each of the small-diameter tubes 34g and 34h is caulked and joined to the two holes formed in the end face 44d. As shown in FIGS. 1 and 2, the end faces 44a, 44b, 44c, and 44d are all disposed so as to face the air blowing surfaces of the convection fans 26a and 26b in parallel. In other words, the end faces 44a, 44b, 44c, 44d are all arranged so as to be orthogonal to the flow of air sent out from the convection fans 26a, 26b. According to this configuration, the air sent from the convection fans 26a and 26b collides with the end faces 44a, 44b, 44c and 44d substantially perpendicularly, so that heat exchange with the air is sufficiently performed and the end faces 44a, 44b and 44c. 44d are sufficiently cooled. As a result, the occurrence of cracks due to thermal strain, loosening of caulking, etc. at the caulking joints of the end faces 44a, 44b, 44c, 44d and the small diameter tubes 34a, 34b, 34c, 34d, 34e, 34f, 34g, 34h. Can be prevented. The durability of the heat exchange unit 16 can be increased.

  Note that the large-diameter tubes 32a and 32b arranged on the inner side of the inner case 15 and the large-diameter tubes 32c and 32d arranged on the outer side have a pipe length of approximately the same in order to make the pressure loss comparable. It is formed to be equal. As a result, the skirt portions 42a and 42b of the inner large-diameter tubes 32a and 32b and the skirt portions 42c and 42d of the outer large-diameter tubes 32c and 32d are different in height disposed inside the inner case 15. Accordingly, the skirt portions 42a and 42b of the inner large-diameter tubes 32a and 32b and the skirt portions 42c and 42d of the outer large-diameter tubes 32c and 32d do not physically interfere with each other, and the large-diameter tubes 32a, 32b, and 32c. , 32d can be arranged close to each other. The efficiency of heat exchange with the air flowing around the large-diameter tubes 32a, 32b, 32c, 32d can be increased.

  As shown in FIG. 1, the small-diameter tubes 34a, 34b, 34c, 34d, 34e, 34f, 34g, 34h extend upward from the end faces 44a, 44b, 44c, 44d, and are bent just below the convection fans 26a, 26b. Thereafter, the space above the large-diameter tubes 32a, 32b, 32c, and 32d is formed to meander in a substantially Z-shape. By adopting such a shape, the small diameter tubes 34a, 34b, 34c, 34d arranged on the inner side and the small diameter tubes 34e, 34f, 34g, 34h arranged on the outer side are brought close to each other without interfering with each other. Can be arranged. The efficiency of heat exchange with the air flowing around the small diameter tubes 34a, 34b, 34c, 34d, 34e, 34f, 34g, 34h can be increased. The other ends of the small diameter tubes 34 a, 34 b, 34 c, 34 d, 34 e, 34 f, 34 g, 34 h are caulked and joined to a plurality of holes formed in the connection surface of the merge chamber 36. The small diameter tubes 34a, 34b, 34c, and 34d arranged on the inner side and the small diameter tubes 34e, 34f, 34g, and 34h arranged on the outer side have pipe lengths in order to make pressure loss the same level. It is formed so as to be substantially equal.

  When the combustion gas supplied from the combustion unit 18 to the heat exchange unit 16 passes through the large diameter tubes 32a, 32b, 32c, 32d and the small diameter tubes 34a, 34b, 34c, 34d, 34e, 34f, 34g, 34h, Cooled by heat exchange with surrounding air. The drain generated when the combustion gas is cooled in the heat exchange unit 16 drops from the first drain outlet 50 (see FIG. 1) provided in the junction chamber 36 to the drain tray 52. The combustion gas flowing into the merge chamber 36 is sent to the exhaust unit 20 through the bellows tube 46 as exhaust gas. Since the junction chamber 36 is fixed to the plate 38 by the holding metal 48, the bending vibration in the large diameter tubes 32a, 32b, 32c, 32d and the small diameter tubes 34a, 34b, 34c, 34d, 34e, 34f, 34g, 34h. Can be suppressed.

  As shown in FIGS. 4 and 5, the exhaust unit 20 includes an exhaust fan 54 (see FIG. 5), an exhaust fan casing 56 that accommodates the exhaust fan 54, and an exhaust fan motor disposed outside the exhaust fan casing 56. 58 and an exhaust duct 60 communicating with the exhaust fan casing 56. When the exhaust fan motor 58 rotates the exhaust fan 54, the exhaust gas is sucked from the heat exchange unit 16 via the bellows tube 46 and flows into the exhaust fan casing 56. The exhaust gas flowing into the exhaust fan casing 56 flows from the exhaust fan casing 56 to the exhaust duct 60 and is sent to the exhaust gas discharge pipe 62 via the exhaust duct 60. As shown in FIG. 2, the exhaust gas discharge pipe 62 communicates with the outdoors via an indoor side adapter 70, a double pipe 72, and an outdoor side adapter 74 provided on the wall surface W of the house. The operation of the exhaust fan motor 58 is controlled by the control unit 24.

  In the heater 10 of the present embodiment, when the exhaust fan motor 58 rotates and drives the exhaust fan 54, outdoor air is taken in from the outdoor side adapter 74 of FIG. 2, and the double pipe 72, the indoor side adapter 70, and the combustion air It is supplied to the combustion unit 18 of FIG. The combustion gas generated in the combustion unit 18 sequentially passes through the large diameter tubes 32a, 32b, 32c, 32d and the small diameter tubes 34a, 34b, 34c, 34d, 34e, 34f, 34g, 34h, the merging chamber 36, and the bellows tube 46. Then, it flows into the exhaust unit 20 as exhaust gas. The exhaust gas flowing into the exhaust unit 20 is exhausted to the outdoors from the outdoor side adapter 74 through the exhaust gas exhaust pipe 62, the indoor side adapter 70, and the double pipe 72 of FIG. That is, the heater 10 is a forced supply / exhaust heater that supplies air from the outside to the combustion unit 18 through the series of supply / exhaust passages described above, and exhausts the exhaust gas from the heat exchange unit 16 to the outdoors. Further, in the heater 10 of the present embodiment, the exhaust fan 54 is disposed on the downstream side of the heat exchange unit 16, and when the exhaust fan 54 is driven to rotate, the bellows tube located on the upstream side of the exhaust fan 54. 46, the inside of the merge chamber 36, the small diameter tubes 34a, 34b, 34c, 34d, 34e, 34f, 34g, 34h and the large diameter tubes 32a, 32b, 32c, 32d are maintained at a negative pressure. That is, the heater 10 is a negative pressure type forced air supply / exhaust heater.

  When the exhaust gas passes through the exhaust unit 20 of FIG. 4, the exhaust gas is cooled by heat exchange with the exhaust fan 54, the exhaust fan casing 56, and the exhaust duct 60 and then sent out to the exhaust gas discharge pipe 62. Conversely, the exhaust fan 54, the exhaust fan casing 56, the exhaust duct 60, and the exhaust fan motor 58 that is mechanically connected to the exhaust fan 54 recovers residual heat from the exhaust gas and becomes high temperature. If the exhaust fan 54 becomes excessively high in temperature, the exhaust fan 54 must be manufactured with a material having high heat resistance, and the manufacturing cost of the heater 10 increases. Further, if the exhaust fan motor 58 becomes excessively high in temperature, there is a risk of causing a motor failure due to grease breakage. Therefore, as shown in FIG. 5, in the heater 10 of the present embodiment, the exhaust unit 20 is disposed so as to penetrate the plate surface on the rear side (side facing the wall surface W of the house) of the inner case 15, and indoors The exhaust unit 20 is cooled by heat exchange with the air taken in from.

  As shown in FIG. 5, in the heater 10 of the present embodiment, the exhaust duct 60 is disposed so as to be exposed inside the inner case 15, and the exhaust fan motor 58 is disposed between the inner case 15 and the wall surface W of the house. The exhaust fan casing 56 is exposed to the space, and the front surface (the surface connected to the exhaust duct 60) of the exhaust fan casing 56 is exposed inside the inner case 15, and the rear surface (the side where the exhaust fan motor 58 is provided). Surface) is exposed to the outside of the inner case 15. With such a configuration, when the convection fans 26a and 26b are rotationally driven, the exhaust fan motor 58 and the rear surface of the exhaust fan casing 56 exchange heat with air flowing upward between the inner case 15 and the wall surface W. Cooled by. Further, the exhaust duct 60 and the front surface of the exhaust fan casing 56 are cooled by heat exchange with the air flowing downward in the inner case 15. With such a configuration, it is possible to prevent the exhaust fan 54, the exhaust fan casing 56, the exhaust duct 60, and the exhaust fan motor 58 that have recovered the residual heat from the exhaust gas from becoming excessively hot. Moreover, since the air heated by heat exchange with the exhaust unit 20 is used for subsequent heating, the thermal efficiency of the heater 10 can be increased.

  As shown in FIGS. 1 and 4, a second drain discharge port 64 is provided in the lower portion of the exhaust duct 60. As shown in FIG. 4, the exhaust fan casing 56 is formed in a shape that guides the drain generated inside the exhaust fan casing 56 to the exhaust duct 60. Further, the second drain discharge port 64 is disposed immediately below the connection portion with the exhaust fan casing 56. Accordingly, the drain generated from the exhaust gas cooled by heat exchange with the exhaust fan 54 and the exhaust fan casing 56 when passing through the exhaust fan casing 56 drops from the second drain outlet 64 to the drain tray 52. The lower portion of the exhaust duct 60 is formed so as to have a downward slope toward the second drain discharge port 64, and from the exhaust gas cooled by heat exchange with the exhaust duct 60 when passing through the exhaust duct 60. The generated drain also drops from the second drain outlet 64 to the drain pan 52.

  As shown in FIGS. 1 and 2, the drain pan 52 is provided at the lowermost part inside the inner case 15. The drain tray 52 stores the drain dripping from the first drain outlet 50 and the second drain outlet 64. The drain stored in the drain tray 52 remains in the drain tray 52 until the user discards it. When the indoor air is dry, the drain tray 52 also serves to humidify the dry air by evaporating moisture from the accumulated drain.

  In the drain pan 52, a first water level sensor 66 that detects whether or not the water level of the drain pan 52 has reached a first predetermined water level, and whether or not a second predetermined water level that is higher than the first predetermined water level has been reached. A second water level sensor 68 for detection is provided. When it is detected by the first water level sensor 66 that the water level of the drain pan 52 has reached the first predetermined water level, the control unit 24 notifies the user that the drain collected in the drain pan 52 is to be discarded. Against. In this state, the heater 10 can be used continuously. When the water level of the drain pan 52 further rises and the second water level sensor 68 detects that the water level of the drain pan 52 has reached the second predetermined water level, the control unit 24 stops the operation of the heater 10. . Once this state is reached, the control unit 24 will continue until the drain accumulated in the drain pan 52 is discarded by the user and the first water level sensor 66 detects that the water level in the drain pan 52 is below the first predetermined water level. The operation of the heater 10 is prohibited. By adopting such a configuration, it is possible to reliably prevent a situation in which the water level of the drain tray 52 rises excessively and water overflows to the bottom of the inner case 15.

  In the heater 10 of the present embodiment, the exhaust fan 54 is provided on the downstream side of the heat exchange unit 16. Therefore, when the exhaust fan 54 is driven to rotate, the inside of the heat exchange unit 16 on the upstream side becomes negative pressure. Thus, for example, even when a part of the heat exchange unit 16 is damaged, the combustion gas does not leak to the outside.

  In the heater 10 of the present embodiment, the exhaust gas from the heat exchange unit 16 is cooled in the exhaust unit 20 by contact with the exhaust fan 54, the exhaust fan casing 56, and the exhaust duct 60. If the second drain discharge port 64 is not provided on the downstream side of the exhaust fan 54 and the drain is generated in the exhaust unit 20, the drain is accumulated in the exhaust fan casing 56 and the exhaust duct 60, and the member It will cause the situation of corrosion. In order to avoid such a situation, if the temperature of the exhaust gas is raised by raising the input of the fuel gas in the combustion unit 18, the generation of the drain in the exhaust unit 20 can be prevented. However, in this case, the input of the fuel gas cannot be reduced, and delicate temperature adjustment of indoor air becomes difficult. With respect to the above problem, in the heater 10 of the present embodiment, the second drain outlet 64 is provided on the downstream side of the exhaust fan 54. As a result, even when a drain is generated from the exhaust gas cooled by the contact with the exhaust fan 54, the drain is dropped from the second drain discharge port 64 to the drain tray 52, so that the drain inside the exhaust unit 20 is discharged. The trouble which originates can be avoided. Further, the fuel gas input can be lowered without worrying about the generation of the drain in the exhaust unit 20.

  As mentioned above, although the Example of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

DESCRIPTION OF SYMBOLS 10 Heater 12 Air blower unit 14 Outer case 15 Inner case 16 Heat exchange unit 18 Combustion unit 19 Combustion air supply pipe 20 Exhaust unit 22 Slit 24 Control unit 26a, 26b Convection fan 28 Convection fan motor 30 Blower 32a, 32b, 32c , 32d Large diameter tube 34a, 34b, 34c, 34d, 34e, 34f, 34g, 34h Small diameter tube 36 Merge chamber 38 Plates 42a, 42b, 42c, 42d Skirt portions 44a, 44b, 44c, 44d End face 46 Bellows tube 48 Holding bracket 50 First drain outlet 52 Drain tray 54 Exhaust fan 56 Exhaust fan casing 58 Exhaust fan motor 60 Exhaust duct 62 Exhaust gas exhaust pipe 64 Second drain outlet 66 First water level sensor 68 Second water level sensor 70 Indoor side adapt 72 double pipe 74 outdoor-side adapter

Claims (4)

A combustor that burns fuel to produce combustion gas;
A heat exchanger that exchanges heat between the combustion gas from the combustor and the surrounding air;
An air supply / exhaust flow path for supplying air from outside to the combustor and exhausting exhaust gas from the heat exchanger to the outside;
An air supply / exhaust fan provided downstream of the heat exchanger in the air supply / exhaust flow path;
A heater with a convection fan that takes in indoor air, passes around the heat exchanger, and sends it out indoors,
A heater having a drain discharge mechanism for discharging a drain generated from the exhaust gas downstream of the supply / exhaust fan in the supply / exhaust flow path.   The heater according to claim 1, wherein the heat exchanger is composed of a plurality of pipes through which combustion gas passes.   The heater according to claim 1 or 2, wherein a fan motor that rotates the supply / exhaust fan is exposed in a flow path through which air taken in from the indoor by the convection fan flows. The drain discharge mechanism includes a drain discharge port and a drain pan that stores the drain from the drain discharge port inside.
The heater according to any one of claims 1 to 3, wherein the drain tray is provided with a water level detecting means for detecting a water level of an internal drain.

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