I AUSTRALIA F B RICE & CO Patent and Trade Mark Attorneys Patents Act 1990 RINNAI CORPORATION COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Forced draft direct vent type room heater The following statement is a full description of this invention including the best method of performing it known to us:- 2 FORCED DRAFT DIRECT VENT TYPE ROOM HEATER BACKGROUND OF THE INVENTION 5 Field of the Invention The present invention relates to a forced draft direct vent type room heater which forcibly supplies air for combustion and exhausts a combusted gas. Description of the Related Art Conventionally, such a room heater is known as is described in Japanese Patent 10 No. 4050744. This room heater has a burner housed in a combustion housing provided in an outer case. In the combustion housing, air for combustion is supplied and a combusted gas is exhausted by a combustion fan. In an exhaust path for exhausting the combusted gas therethrough, a main heat exchanger is provided in the upstream side, and a supplementary heat exchanger is provided in the downstream side. In the outer 15 case, an air intake and a vent hole are provided. In the outer case, a warm air fan is provided, and this warm air fan takes in room air from the air intake and sends the air to the inside of the room from the vent hole through the main heat exchanger and the supplementary heat exchanger. The room heater also has the vent hole opened in the lower part of the front 20 panel of the outer case, and leads the room air (warm air) having passed through the section in which the main heat exchanger is arranged to the vent hole through a space in the lower part of the combustion housing. In addition, in such a room heater, the one is also known that has a drain dish arranged in the lower space of the combustion housing, and makes a drain 25 (condensation water) formed in an exhaust extension tube (tube for exhausting exhaust gas to outside) which is connected to a downstream end of the exhaust path, to flow into the drain dish. In the above one, the drain which flowed into the drain dish is heated by a warm air flowing in the lower space of the combustion housing to be evaporated. 30 Here, in a weak combustion period, the temperature of the combusted gas flowing in the exhaust extension tube is lowered, and the amount of a formed drain increases, but the temperature of the warm air is lowered, so that an amount of an evaporated drain from the drain dish decreases. Accordingly, when the weak combustion is continued, the drain overflows from the drain dish. In order to prevent 35 the overflow of the drain from the drain dish, it is necessary to shorten the length of the 3 exhaust extension tube and to reduce the amount of the formed drain. As a result, a position where the room heater can be set becomes limited. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that 5 any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application. Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated 10 element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. SUMMARY OF THE INVENTION The present invention is designed to address the above described points, and its 15 aim is to provide a forced draft direct vent type room heater which may preferably prevent the drain from overflowing from the drain dish even without shortening the length of the exhaust extension tube. The present invention provides a forced draft direct vent type room heater comprising: an outer case, a combustion housing which is provided in the outer case 20 and houses a burner therein, a combustion fan for forced draft direct ventilation, which is provided on the way of any one of an air supply path that supplies air for combustion to the combustion housing and an exhaust path that exhausts a combusted gas from the combustion housing, a main heat exchanger which is provided in the outer case so as to be positioned rearward of the combustion housing and is provided on the way of the 25 exhaust path, an air intake and a vent hole which are opened in the outer case, a warm air fan in the outer case for taking in room air from the air intake and sending the air to the inside of the room from the vent hole through a section in which the main heat exchanger is arranged, and a drain dish which is provided in the outer case and makes a drain formed in an exhaust extension tube that is connected to a downstream end of the 30 exhaust path to flow into the drain dish itself, wherein the vent hole is opened in the upper part of a front panel of the outer case, thereby the room air having passed through the section in which the main heat exchanger is arranged is led to the vent hole through a space between an upper plate of the outer case and an upper wall of the combustion housing, and the drain dish is arranged on an upper face of the upper wall of the 35 combustion housing.
3A The room heater according to the present invention comprises the drain dish arranged on the upper wall of the combustion housing, so that a drain in the drain dish is heated by a heat transferred from the upper wall of the combustion housing, in addition to the room air (warm air) led to the vent hole through a space between the 5 upper plate of the outer case and the upper wall of the combustion housing. Here, the temperature of the upper wall of the combustion housing considerably rises even in the weak combustion period, and the evaporation of the drain from the drain dish is promoted. Accordingly, the drain can be prevented from overflowing from the drain dish while continuing the weak combustion even without shortening the length of the 10 exhaust extension tube.
4 The room heater according to the present invention also can inhibit the temperature of the upper wall of the combustion housing from excessively rising by the evaporation of the drain in a strong combustion period, and shows enhanced durability. A user often warms herself or himself while sitting on a sofa or the like placed 5 in front of a room heater. The room heater according to the present invention has the vent hole opened in the upper part of the front panel of the outer case, but can prevent the warm air from hitting the face of the user by setting a louver provided on the vent hole so as to face obliquely downward. On the other hand, when the vent hole is opened in the lower part of the front panel of the outer case as in a conventional 10 example, and when the louver is set so as to face obliquely downward or horizontally, the warm air hits the floor surface and causes the overheat of the floor surface. For that reason, there is no other choice but to provide the louver so as to face obliquely upward, in order to prevent the floor surface from being overheated, and the warm air results in hitting the face of the user. Accordingly, the room heater according to the 15 present invention, which has the vent hole opened in the upper part of the front panel of the outer case, is more advantageous for conducting comfortable heating while controlling the warm air so as not to hit the face. In the present invention, it is desirable that a partitioning plate is provided which partitions a space between the upper plate of the outer case and the upper wall of the 20 combustion housing into two of an upper room and a lower room, thereby, the room air having passed through the section in which the main heat exchanger is arranged is led to the vent hole through the lower room, a supplementary heat exchanger is arranged in the upper room, which is provided on the way of the exhaust path in a downstream side of the main heat exchanger, and thereby, one part of the room air taken in from the air 25 intake is led to the vent hole through the upper room, without passing through the section in which the main heat exchanger is arranged. Here, when the drain dish is arranged in the lower space of the combustion housing as in a conventional example, the drain dish is positioned in the lower part of the main heat exchanger, so that a drain formed in the inside of the main heat 30 exchanger can be drained to the drain dish. On the other hand, in the present invention, the drain dish is arranged on the upper wall of the combustion housing, so that the drain formed from the main heat exchanger cannot be drained to the drain dish. Accordingly, it is necessary to set the heat exchange efficiency of the main heat exchanger at a low value, and to prevent the drain from being formed in the main heat exchanger. 35 Otherwise, in this situation, the room heater results in showing poor heating efficiency. In this case, according to the above described structure, one part of the room air does 5 not pass through the section in which the main heat exchanger is arranged but is passed to the upper room and is efficiently heated by the supplementary heat exchanger, so that even though the heat exchange efficiency of the main heat exchanger is set at the low value, heating efficiency is not lowered. 5 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a room heater according to an embodiment of the present invention, which is viewed from an upper side in a diagonally front right direction; 10 FIG. 2 is a perspective view of a room heater according to the embodiment, which is viewed from an upper side in a diagonally backside left direction; FIG. 3 is a front view illustrating a state in which a front panel and a front door of a combustion housing in the room heater according to the embodiment are removed; and 15 FIG. 4 is a sectional view taken along the line IV-IV of FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiment in which the present invention is applied to a fireplace type room heater will now be described below. This room heater comprises an outer case 1 20 and a combustion housing 2 which is provided in the outer case 1, as is illustrated in FIG. 1 to FIG. 4. The outer case I is constituted by a bottom plate I a, right-and-left side plates Ib, a back plate Ic, an upper plate ld, a front panel le, a first extension case 1 f which is installed in a portion closer to one side of the back face of the back plate I c, and a second extension case Ig which is installed from the other half side of the back 25 face of the back plate Ic to the upper part of the first extension case lf. A burner 3 and a pilot burner 3a for igniting the burner 3 are arranged in the lower part of the inside of the combustion housing 2. In addition, a burner supporting plate 2a in which an opening for fitting the upper end part of the burner 3 is formed is arranged in the combustion housing 2, and a false firewood 4 which is formed from a 30 refractory material such as ceramics is arranged on the burner supporting plate 2a. A glass plate 2b is fitted in a front face of the combustion housing 2, and a window lh through which the glass plate 2b is overlooked is opened in the front panel le of the outer case 1. Thus, the inside of the combustion housing 2 can be viewed from the front of the front panel le, and when the burner 3 is burned, such an impression as if 35 the false firewood 4 is really burning can be visually given.
6 The front panel le can also be formed so that the peripheral portion of the window 1h closely contacts the peripheral portion of the front face of the combustion housing 2, but incidentally in the present embodiment, the front panel I e is arranged so that the window I h is slightly separated from the front face of the combustion housing 5 2, and a window glass Ii is fitted in the window 1 h. In addition, the above described glass plate 2b of the front face of the combustion housing 2 is fitted in the front door 2c which is provided on the front face of the main body of the combustion housing 2 so as to be freely opened and closed, and the burner 3 in the combustion housing 2 can be provided with maintenance in a state in which the front door 2c is opened. This front 10 door 2c is supported by the combustion housing 2 at the lower end part tiltably in a forward and backward direction, and is pushed backward by pushing means 2e arranged on the upper wall 2d of the combustion housing 2 to closely contact the front face of the main body of the combustion housing 2. A cover 2f for covering the pushing means 2e from above is provided on the upper wall 2d of the combustion 15 housing 2. An air supply duct 5 which constitutes an air supply path is connected to the bottom face of the combustion housing 2. Outdoor air is supplied to the air supply duct 5 through an air supply extension tube which is not shown. The outdoor air is forcibly supplied into the combustion housing 2 through the air supply duct 5 by a suction force 20 of a combustion fan 7 which will be described later. In the outer case 1, a main heat exchanger 6 is arranged which is positioned in the back side of the combustion housing 2 and is provided on the way of an exhaust path for exhausting a combusted gas sent from the combustion housing 2. The main heat exchanger 6 is connected to the combustion housing 2 through a communication 25 tube 6a. The combustion fan 7 for forced draft direct ventilation, which is arranged in the first extension case 1f, is provided on the way of the exhaust path. An exhaust duct 8 which is connected to the downstream side of the main heat exchanger 6 though the combustion fan 7 is inserted into the outer case I in a side space between the side plate lb in one side in a transverse direction of the outer case 1 and the combustion housing 30 2. In addition, a control substrate 9 is arranged in one side in a transverse direction of the lower part of the inside of the outer case 1, and a valve unit 10 for the burner 3 is arranged in a side space between the side plate lb in the other side in a transverse direction of the outer case 1 and the combustion housing 2. 35 An air intake 1 is opened in the lower part of the front panel I e of the outer case 1, and a vent hole 12 is opened in the upper part thereof. A warm air fan 13 that 7 takes in room air from the air intake 11, passes the air through a section in which the main heat exchanger 6 is arranged and sends the air to the inside of the room from the vent hole 12 is arranged in the outer case 1, and thereby a warm air heating function can be obtained. 5 The warm air fan 13 is arranged in a horizontally long fan box 14 which is installed in the lower space of the combustion housing 2. The fan box 14 has openings in both side parts of itself in a transverse direction. As is illustrated in FIG. 2, a wind introduction path 15 is provided which leads one part of air taken in from the air intake 11 to an aperture in one side in a transverse direction of the fan box 14 through a 10 section in which the control substrate 9 is arranged and a section in which a fan motor 7a for the combustion fan 7 is arranged. The wind introduction path 15 is constituted by: a first air guide plate 15a which surrounds the section in which the control substrate 9 is arranged from the inner side in the transverse direction to the upper side; a first air hole 15b which is formed in the back plate I c of the outer case 1 so as to face a part 15 surrounded by the first air guide plate 15a; a second air guide plate 15c placed in the first extension case If, which leads the air sent from the first air hole I5b to the section in which the fan motor 7a is arranged; and a second air hole 15d which is formed in the back plate I c of the outer case I so as to be positioned above the first air guide plate 15a. Then, the air which is returned to the inside of the outer case 1 from the second air 20 hole 15d is led to the aperture in one side in a transverse direction of the fan box 14 through a gap between the first air guide plate 15a and the side wall in one side in a transverse direction of the combustion housing 2. A pair of the warm air fans 13 are provided with space therebetween in a transverse direction. A common fan motor 13a which drives both of the warm air fans 25 13 and 13 is arranged between both of the warm air fans 13 and 13. The room air which is blown from the warm air fan 13 is led to the vent hole 12 through the section in which the main heat exchanger 6 is arranged, and a space between the upper plate 1 d of the outer case I and the upper wall 2d of the combustion housing 2. Then, the room air is heated by the main heat exchanger 6 due to the heat 30 exchange with the combusted gas, is heated to be a warm air, and is sent to the inside of the room from the vent hole 12. A louver 12a which is tilted obliquely downward is attached to the vent hole 12. Therefore, the warm air does not hit a face of a user who is warming oneself while sitting on a sofa or the like in front of a room heater. Here, the space between the upper plate 1 d of the outer case I and the upper 35 wall 2d of the combustion housing 2 is partitioned into two rooms of an upper room 16a and a lower room 16b by a partitioning plate 16. The room air having passed 8 through the section in which the main heat exchanger 6 is arranged is led to the vent hole 12 through the lower room 16b. In the upper room 16a, a supplementary heat exchanger 6' is provided on the way of the exhaust path so as to be positioned in a downstream side of the main heat 5 exchanger 6. The supplementary heat exchanger 6' is structured so as to meander in a U-shape the exhaust duct 8 in a transverse direction. The back plate Ic of the outer case I has a lower aperture lj which makes one part of the room air blown from the warm air fan 13 flow into a second extension case I g through a flow-dividing plate 17, and an upper aperture 1k which communicates a space in the second extension I g to the 10 upper room 16a. Thus, one part of the room air blown from the warm air fan 13 does not pass through the section in which the main heat exchanger 6 is arranged but is led to the vent hole 12 through the inside of the second extension case I g and the upper room 16a. In addition, a drain dish 18 is arranged on the upper face of the upper wall 2d of 15 the combustion housing 2. A drain pipe 18a which leads to the drain dish 18 is branched from and connected to a part of the exhaust duct 8 which is the bottommost part of the supplementary heat exchanger 6'. An exhaust extension tube 19 (see FIG. 2) for exhausting the combusted gas to the outdoors is connected to the downstream end (downstream end of exhaust path) of the exhaust duct 8. A drain formed in the exhaust 20 extension tube 19 flows down to the exhaust duct 8, and flows into the drain dish 18 through the drain pipe 18a. By the way, in the weak combustion period, the temperature of the combusted gas flowing in the exhaust extension tube 19 is lowered, and an amount of the formed drain increases. At this time, if the drain dish 18 is heated only by the warm air, an 25 amount of a drain vaporizing from the drain dish 18 decreases, because the temperature of the warm air is lowered in the weak combustion period. Accordingly, when the weak combustion is continued, the drain overflows from the drain dish 18. In order to prevent the overflow of the drain from the drain dish 18, it is necessary to shorten the length of the exhaust extension tube 19 and to reduce the amount of the formed drain. 30 As a result, a position where the room heater can be set becomes limited. In contrast to this, in the present embodiment, the drain dish 18 is arranged on the upper wall 2d of the combustion housing 2, so that the drain dish 18 is heated not only by the warm air but also by a heat transferred from the upper wall 2d of the combustion housing 2. The temperature of the upper wall 2d of the combustion 35 housing 2 becomes considerably high even in the weak combustion period, and the evaporation of the drain from the drain dish 18 is promoted. Accordingly, the drain can 9 be prevented from overflowing from the drain dish 18 by continuing the weak combustion even without shortening the length of the exhaust extension tube 19. The room heater also can inhibit the temperature of the upper wall 2d of the combustion housing 2 from excessively rising with the evaporation of the drain in a strong 5 combustion period, and shows enhanced durability. Incidentally, if the drain dish 18 is arranged on the upper wall 2d of the combustion housing 2, the drain formed from the main heat exchanger 6 cannot be drained to the drain dish 18. Accordingly, it is necessary to set the heat exchange efficiency of the main heat exchanger 6 at a low value, and to prevent the drain from 10 being formed in the main heat exchanger 6. Otherwise, in this situation, the room heater results in showing poor heating efficiency. However, in the present embodiment, the supplementary heat exchanger 6' is arranged in the upper room 16a as is described above, and one part of the room air does not pass through the main heat exchanger 6 but is led to the upper room 16a. Therefore, the air at a low temperature, 15 which is not heated by the main heat exchanger 6, results in flowing into the section in which the supplementary heat exchanger 6' is arranged, and is efficiently heated by the supplementary heat exchanger 6'. Accordingly, even when the heat exchange efficiency of the main heat exchanger 6 is set at a low value, the heating efficiency does not decrease. In addition, even when the drain is formed in the supplementary heat 20 exchanger 6', there is no problem because this drain flows into the drain dish 18 through the drain pipe I8a which is branched from and connected to the bottom part of the supplementary heat exchanger 6'. In the above, the embodiment of the present invention is described with reference to the drawings, but the present invention is not limited to the embodiment. 25 For instance, in the above described embodiment, the combustion fan 7 is provided on the way of the exhaust path, but the combustion fan can be provided on the way of the air supply path as well. In addition, in the above described embodiment, the air intake I I is opened in the lower part of the front panel I e of the outer case 1, but may be opened in each of the right and left side plates lb of the outer case I as well. In 30 addition, in the above described embodiment, the present invention is applied to a fireplace type of a forced draft direct vent type room heater, of which the inside of the combustion housing 2 can be viewed from the front of the front panel I e, but can be also applied to a forced draft direct vent type room heater of which the inside of the combustion housing 2 cannot be viewed.