JP6128649B2 - Heating device - Google Patents

Description

  The present invention relates to a heating apparatus that heats a liquid by exchanging heat with combustion gas generated by combustion in a burner, and in particular, has a secondary heat exchanger for recovering latent heat and has a one-can / two-channel heat exchange as a primary heat exchanger. The present invention relates to a heating device using a vessel.

  2. Description of the Related Art Conventionally, in the field of hot water supply apparatuses, a heating apparatus that includes a secondary heat exchanger for recovering latent heat and uses a single can / two-channel heat exchanger as a primary heat exchanger is known (for example, Patent Document 1). 1 and FIG. 6 of Patent Document 2). FIG. 7 is a configuration diagram of the single can / two water channel hot water supply system described in Patent Document 1. The single can / two water channel hot water supply system includes a hot water supply pipe 101, a follow-up pipe 102, a burner 104, a primary heat exchanger 105, and a secondary heat exchanger 106. The hot water supply pipe 101 is a pipe that supplies heated water supplied from city water to a hot water tap. The follow-up pipe 102 is a pipe for circulating and heating the water in the bathtub 103. The burner 104 is a heating means that performs hot water supply combustion and follow-up combustion. The primary heat exchanger 105 is a one-can two-water channel heat exchanger in which a hot water supply heat exchanger and a follow-up heat exchanger are integrated by being heated by combustion gas generated by combustion of the burner 104. The secondary heat exchanger 106 is a heat exchanger for recovering latent heat that is disposed on the combustion gas flow path farther than the primary heat exchanger 105 with respect to the burner 104. The hot water supply pipe 101 is connected to the hot water tap through the secondary heat exchanger 106 and the primary heat exchanger 105 in this order from the side connected to the water pipe. The chasing pipe 102 is connected to the bathtub 103 at both ends, and passes through the primary heat exchanger 105 in the middle thereof.

  In such a can / two-channel hot-water supply system, when hot water is supplied, the hot-water tap 107 is opened and water is supplied to the hot-water supply pipe 101, and the burner 104 is started to activate the secondary heat exchanger 106 and the primary heat exchanger. The water passing through the hot water supply pipe 101 is heated by 105. On the other hand, when the bathtub water in the bathtub 103 is driven, the circulation pump 108 is started to circulate the bathtub water in the discharge pipe 102, and the burner 104 is started and the hot water supply pipe 101 is started by the primary heat exchanger 105. Heat the water passing through.

  In the hot water supply system as described above, when hot water supply or chasing is not performed for a long time, water is drained to prevent freezing in the piping. When draining water, if water remains in the primary heat exchanger and the secondary heat exchanger, it may cause pipe rupture due to freezing, so water is placed at the lowest point in the hot water supply piping around the heat exchanger. It is set as the structure which discharges the water in a primary heat exchanger and a secondary heat exchanger by connecting a extraction pipe. As a configuration of such a drain pipe, a configuration described in Patent Document 3 is known.

  FIG. 8 is a piping configuration diagram of the heating device described in Patent Document 3 (see FIGS. 1 and 2 of Patent Document 3). The heating device of FIG. 8 includes a primary heat exchanger 105 and a secondary heat exchanger 106 in the hot water supply pipe 101 as in the case of FIG. There is no follow-up piping 102. In the heating device of FIG. 8, a trap structure 110, a bypass pipe 111 and a drain pipe 112 are provided in the middle of the hot water supply pipe 101 from the secondary heat exchanger 106 to the primary heat exchanger 105. The trap structure 110 is configured to rise from the secondary heat exchanger 106 side to a position below the primary heat exchanger 105 and then to the water inlet 105 a of the primary heat exchanger 105. The bypass pipe 111 is a flow path that bypasses the trap structure section 110, and when the flow of water is blocked due to freezing in the trap structure section 110 or the like, the trap structure section 110 can be bypassed to pass water, It is provided to prevent the primary heat exchanger 105 from being blown. The drainage pipe 112 is a drainage channel connected to the lowest position of the trap structure unit 110, and the drain valve 113 provided in the middle is opened so that the water inside the trap structure unit 110 can be drained. It is provided for. The drainage pipe 112 extends from the trap structure 110 to the outside of the heating device. As a result, when water in the primary heat exchanger 105 and the secondary heat exchanger 106 is drained to prevent freezing, the water in the primary heat exchanger 105 and the secondary heat exchanger 106 can be opened by opening the discharge valve 113. All flow down to the trap structure 110 and are discharged to the outside through the drain pipe 112.

JP 2007-120865 A JP-A-10-132388 JP 2007-32935 A

  However, the trap structure described in Patent Document 3 is applied to a heating device including the primary heat exchanger and the secondary heat exchanger of the single can / two-channel heat exchanger described in Patent Documents 1 and 2 above. In such a case, there is a problem that the thermal efficiency is lowered when only chasing is performed without hot water supply.

  FIG. 9 is a piping configuration diagram in which the trap structure of the heating device described in Patent Document 3 is applied to the single can / two water channel hot water supply system described in Patent Document 1. In the 1-can 2-water-channel heat exchanger, when only hot water is not supplied, the hot-water tap 107 is closed so that water does not flow through the hot-water supply pipe 101, and the circulation pump 108 is activated to add the heat. The operation of circulating the bathtub water through the hot water supply pipe 101 by starting the burner 104 and circulating the bathtub water through the inlet pipe 102 is performed. At this time, in the primary heat exchanger 105, the bath water in the follow-up pipe 102 is heated, and at the same time, the water accumulated in the hot water supply pipe 101 is also heated. Therefore, since the specific gravity of the water staying in the hot water supply pipe 101 of the primary heat exchanger 105 is reduced by heating, the secondary heat exchanger passes through the bypass pipe 111 as shown in FIG. 9B. On the other hand, the water in the hot water supply pipe 101 of the secondary heat exchanger 106 is lowered because the temperature is lower and the specific gravity is larger than that of the primary heat exchanger 105, and the water falls in the secondary heat exchanger 106 through the trap structure 110. Heat convection (flow as indicated by a dotted line in FIG. 9B) is generated in the hot water supply pipe 101 so as to move to the heater 106. Therefore, a heat dissipation circuit is formed in which the heat of the secondary heat exchanger 106 is transferred to the secondary heat exchanger 106 through the water in the hot water supply pipe 101 and is radiated, which causes a decrease in thermal efficiency.

  Therefore, it is conceivable to eliminate the bypass pipe 111, but in order to prevent the hot water supply pipe 101 from being aired in the primary heat exchanger 105 when the trap structure 110 is frozen as described above. The bypass pipe 111 is necessary. Therefore, in this configuration, it is difficult to eliminate the bypass pipe 111 for safety.

  In addition, also in the 1 can 2 water channel hot-water supply system of patent document 1 which does not have a trap structure, the heat radiation by the same convection arises and the problem that thermal efficiency falls is held.

  Further, in the heating device of Patent Document 3, the drainage pipe 112 connected to the trap structure 110 is extended to the outside of the heating device for drainage, and thus becomes a relatively long pipe. Therefore, the surface area of the pipe is large, and a heat dissipation circuit is also formed by heat transfer through the drain pipe 112, which also causes a decrease in thermal efficiency.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a primary heat exchanger and a secondary heat exchanger in a heating apparatus including a secondary heat exchanger for recovering latent heat and a one-can / two-channel heat exchanger as a primary heat exchanger. It is an object of the present invention to provide a heating device that can drain the water in the interior and can suppress a decrease in thermal efficiency compared to the conventional case even when only chasing without hot water supply.

A first configuration of the heating device according to the present invention includes a heating unit that generates a heating gas,
A heated gas flow path through which the heated gas flows;
A primary heat exchanger that is a one-can two-water channel heat exchanger disposed in the heated gas flow path;
A secondary heat exchanger disposed downstream of the primary heat exchanger in the heated gas flow path;
A flow path through which heated water passes, wherein the first heating flow path passes through the primary heat exchanger after passing through the secondary heat exchanger;
In a heating apparatus comprising a flow path through which heated water passes, and a second heating flow path that passes only through the primary heat exchanger,
The first heating flow path from the secondary heat exchanger to the primary heat exchanger has one lowest point, and the height of the ceiling in the pipe at the lowest point is the first heating flow path. At least one trap structure provided with a convex bent pipe that is lower than the height of the inner floor of the pipe at the inlet to the primary heat exchanger is provided,
The lowest point of the trap structure and a position lower than the lowest point on the first heating channel on the downstream side of the water outlet from the primary heat exchanger of the first heating channel, the lowest point And a bypass flow path connected to the nearest position.

  According to this configuration, when water is drained from the first heating channel, if the water is drained from the downstream side of the first heating channel, the water in the primary heat exchanger and the secondary heat exchanger is It flows down to the lowest point of the trap structure and drains from the downstream side of the first heating channel through the bypass channel. Since the bypass flow path is always connected to the downstream side of the water outlet to the primary heat exchanger of the first heating flow path, water does not stay in the trap structure. It is not necessary to provide the drain pipe 112 and the discharge valve 113 connected to the trap structure section 110, and it is not necessary to provide a flow path (bypass pipe 111) for bypassing the trap structure section 110.

  Further, in a state where water flow through the first heating channel is stopped and water is passed through the second heating channel (hereinafter referred to as “second channel water heating state”), the primary heat exchanger is moved by the heating means. When heating and heating the water in the second heating channel, the water accumulated in the first heating channel of the primary heat exchanger is simultaneously heated to reduce the specific gravity, but the lowest point is the first heating Since there is a trap structure having a convex bent pipe below the water inlet to the primary heat exchanger in the flow path, the water in the first heating flow path having a reduced specific gravity is converted into secondary heat. The phenomenon of moving to the exchanger is suppressed, and convection is less likely to occur in the first heating flow path between the primary heat exchanger and the secondary heat exchanger. Therefore, it is difficult to form a heat dissipation circuit by convection of water in the first heating flow path, so that high thermal efficiency can be achieved.

  Further, the bypass flow path for draining the water in the trap structure includes the lowest point of the trap structure and the lowest flow path on the first heating flow path downstream from the water outlet from the primary heat exchanger of the first heating flow path. Is connected to the position closest to the lowest point, and the length of the bypass flow path is shortened, and both ends of the bypass flow path are connected to the first heat exchanger near the primary heat exchanger. Since it is connected to one heating channel, it is possible to almost eliminate heat radiation due to heat transfer through the bypass channel. Therefore, high thermal efficiency can be achieved.

  Here, in the present invention, a plurality of trap structures may be provided, but it is preferable to use one trap structure in order to simplify the piping. Moreover, the shape of the trap structure has one lowest point, and if the lowest point is a downwardly convex bent pipe that is lower than the water inlet to the primary heat exchanger of the first heating channel, what kind of shape is used? For example, a U-shaped tube shape, a V-shaped tube shape, a one-turn loop tube shape, or the like is conceivable.

  The second configuration of the heating device according to the present invention is that, in the first configuration, the trap structure is configured such that the height of the ceiling portion of the pipe at the lowest point is within the pipe at the water inlet to the primary heat exchanger. It is characterized by being at least 3 cm lower than the height of the floor.

  By making the height of the ceiling part in the pipe at the lowest point of the trap structure at least 3 cm lower than the height of the floor part in the pipe at the inlet of the primary heat exchanger, in the second channel water heating state, Convection in the first heating flow path with the secondary heat exchanger can be substantially suppressed, and high thermal efficiency can be achieved.

  A third configuration of the heating device according to the present invention is the first or second configuration, wherein the trap is provided in the first heating flow path from the secondary heat exchanger to the primary heat exchanger. A plurality of structures are provided, and the bypass flow path is connected to the lowest point of each trap structure.

  Thus, by using a plurality of trap structures, it is possible to more reliably prevent water in the hot water supply pipe in the primary heat exchanger from moving to the secondary heat exchanger due to heat convection.

  As described above, according to the present invention, by providing the trap structure and the bypass flow path described above, in the heating apparatus provided with a single can two-water channel heat exchanger as the primary heat exchanger, the primary heat exchanger and the two It is possible to provide a heating apparatus capable of completely draining water in the secondary heat exchanger and capable of suppressing a decrease in thermal efficiency as compared with the prior art even in the second channel water heating state.

It is a figure showing the piping structure of the heating apparatus which concerns on Example 1 of this invention. It is a figure showing the specific piping structure of the trap structure 30 periphery. 3 is a diagram schematically showing a peripheral structure of a trap structure 30. FIG. It is a figure showing the relationship between the effective height h1 of the trap structure 30, and the thermal efficiency of the primary heat exchanger 6 when only chasing is performed without hot water supply. It is the figure which showed typically the surrounding structure of the trap structure 30 of the heating apparatus which concerns on Example 2 of this invention. It is the figure which showed typically the surrounding structure of the trap structure 30 of the heating apparatus which concerns on Example 3 of this invention. 1 is a configuration diagram of a single can / two water channel hot water supply system described in Patent Document 1. FIG. It is a piping lineblock diagram of a heating device given in patent documents 3. 2 is a piping configuration diagram in which a trap structure of a heating device described in Patent Document 3 is applied to a single can / two water channel hot water supply system described in Patent Document 1. FIG. (A) Overall view, (b) Enlarged view around the primary heat exchanger and the secondary heat exchanger.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a piping configuration of a heating device according to Embodiment 1 of the present invention. In this embodiment, an example in which the heating device 1 is applied to a water heater having a function of performing hot water supply and bathing is shown. The heating device 1 includes a hot water supply pipe 2, a follow-up pipe 3, a burner 4, a heating gas flow path 5, a primary heat exchanger 6, and a secondary heat exchanger 7 as a basic configuration.

  The hot water supply pipe 2 (first heating channel) is a pipe that is supplied with water from the city water to the water supply connection port 2a and supplies heated water from the hot water connection port 2b to a hot water tap (not shown). The follow-up pipe 3 (second heating flow path) is a pipe for circulating and heating the water in the bathtub 8. The burner 4 is a heating means for generating heated gas, and in this embodiment, a gas burner is shown as an example of the burner 4. The heated gas channel 5 is a channel through which the heated gas generated in the burner 4 flows. The primary heat exchanger 6 is a one-can two-water channel heat exchanger disposed in the heated gas flow path 5. The secondary heat exchanger 7 is a heat exchanger disposed on the downstream side of the primary heat exchanger 6 in the heating gas flow path 5.

  The hot water supply pipe 2 passes through the secondary heat exchanger 7 from the water supply connection port 2a and then passes through the primary heat exchanger 6 to reach the hot water connection port 2b. In a section between the water supply connection port 2a of the hot water supply pipe 2 and the secondary heat exchanger 7, a water supply thermistor 14 for detecting the water supply temperature and a water supply amount sensor 15 for detecting the water supply flow rate are arranged from the water supply connection port 2a side. It is installed. A heat exchange thermistor 16 for detecting the water temperature in the hot water supply pipe 2 in the primary heat exchanger 6 is disposed in the middle of the primary heat exchanger 6 in the hot water supply pipe 2, and the primary heat exchanger 6 in the hot water supply pipe 2. A heat exchange outlet thermistor 17 for detecting the water temperature in the hot water supply pipe 2 at the outlet of the primary heat exchanger 6 is disposed in the vicinity of the water outlet 6b. Between the primary heat exchanger 6 and the outlet port 2b of the hot water supply pipe 2, a mixing proportional valve 18 that mixes water and hot water at a desired ratio is adjusted from the primary heat exchanger 6 side, and the amount of water after mixing is adjusted. A water amount control valve 19 and a hot water thermistor 20 for detecting the hot water temperature are provided. Further, a bypass pipe 21 is branched and provided between the feed water amount sensor 15 of the hot water supply pipe 2 and the water inlet 7 a of the secondary heat exchanger 7. The downstream side of the bypass pipe 21 is connected to the mixing proportional valve 18. The mixing proportional valve 18 mixes the water supplied from the bypass pipe 21 and the hot water supplied from the outlet 6b side of the primary heat exchanger 6 and sends the mixed hot water to the outlet port 2b side. Has the function of adjusting the temperature.

  The follow-up piping 3 passes through the primary heat exchanger 6 through the bath water flow switch built-in unit 9 and the bath circulation pump 10 from the bathtub 8, and returns to the bathtub 8 again. The bath circulation pump 10 is a normal water pump, and is provided for feeding the bathtub water in the bathtub 8 to the primary heat exchanger 6. The water flow switch built-in unit 9 has three ports, two of the three ports are connected to the follower pipe 3, and the remaining one port is connected to the portion of the hot water supply pipe 2 in front of the hot water outlet 2b. Connected to the pouring pipe 11. The pouring pipe 11 is a pipe for supplying hot water to the bathtub 8, and a pouring electromagnetic valve 12 and a check valve 13 are provided on the way.

  The heating device 1 of the present embodiment has one minimum point 30a in the section between the water outlet 7b of the secondary heat exchanger 7 of the hot water supply pipe 2 and the water inlet 6a of the primary heat exchanger 6, and the lowest point. A trap structure 30 is provided that includes a bent pipe that protrudes downward in the pipe 30a so that the height of the pipe ceiling 30b is lower than the height of the pipe floor 6a 'at the water inlet 6a. In the present embodiment, a specific shape of the trap structure 30 employs a downwardly convex U-shaped tube. Further, the upstream side of the trap structure 30 is piped so that there is no upwardly protruding portion in the section to the water outlet 7 b of the secondary heat exchanger 7. That is, the piping from the outlet 7b of the secondary heat exchanger 7 to the lowest point 30a of the trap structure 30 is always downward. Further, the downstream side of the trap structure 30 is piped so that there is no upward convex portion in the section to the water outlet 6 b of the primary heat exchanger 6. That is, piping from the water outlet 6b of the primary heat exchanger 6 to the lowest point 30a of the trap structure 30 is always downward piping. Furthermore, the lowest point 30a of the trap structure 30 and a position lower than the lowest point 30a on the hot water supply pipe 2 on the downstream side of the outlet 6b from the primary heat exchanger 6 of the hot water supply pipe 2, and the lowest point 30a. A bypass channel 31 connected to the nearest connection position 31a is provided.

  By providing the bypass flow path 31, a constant flow rate of water always flows in the hot water supply pipe 2 bypassing the primary heat exchanger 6, but the pipe diameter Rb of the bypass flow path 31 is set to the pipe diameter of the hot water supply pipe 2. By setting it smaller than R0, there is no actual problem in use. The tube diameter ratio Rb / R0 is appropriately set according to the specific design. For example, the pipe diameter ratio Rb / R0 is determined so that 7 to 15% of the total flow rate passes through the bypass flow path 31.

  With this structure, when draining the hot water supply pipe 2, if the water supply connection port 2 a and the hot water connection port 2 b are opened, all the water in the hot water supply pipe 2 in the primary heat exchanger 6 goes to the lowest point 30 a of the trap structure 30. The water flows down, passes through the bypass flow path 31, and is drained from the hot water connection port 2b side of the hot water supply pipe 2. The water in the hot water supply pipe 2 in the secondary heat exchanger 7 is drained from the water supply connection port 2a, but the water in the section from the water outlet 7b of the secondary heat exchanger 7 in the hot water supply pipe 2 to the trap structure 30 is It flows down to the lowest point 30 a of the trap structure 30, passes through the bypass channel 31, and is drained from the hot water outlet 2 b side of the hot water supply pipe 2. Thereby, the water in the hot water supply pipe 2 can be drained completely.

  FIG. 2 is a diagram illustrating a specific piping configuration around the trap structure 30. In FIG. 2, the same reference numerals are given to the components corresponding to the components in FIG. In the present embodiment, as shown in FIG. 2, the secondary heat exchanger 7 is arranged continuously with the upper portion of the primary heat exchanger 6. In the present invention, the secondary heat exchanger 7 does not necessarily have to be positioned above the primary heat exchanger 6. For example, the secondary heat exchanger 7 is arranged side by side on the primary heat exchanger 6. It can also be set as the structure to do.

  The trap structure 30 is configured in a U-tube shape that protrudes downward. The upstream side of the trap structure 30 extends straight upward and then bends at a right angle with a constant bending radius and is connected horizontally to the outlet 7b of the secondary heat exchanger 7. The downstream side of the trap structure 30 is bent at a right angle with a constant bending radius and is connected horizontally to the water inlet 6 a of the primary heat exchanger 6. The lowest point 30a of the trap structure 30 is the lowest bottom portion of the bent portion of the U-shaped tube. The upstream end of the bypass channel 31 is connected to the lowest point 30a. The bypass channel 31 is a vertical pipe on the upstream side, and is bent at a right angle with a constant bending radius, and is a horizontal pipe having a minimum length on the downstream side (a horizontal pipe having a minimum dimension that can be designed). The downstream end portion of the bypass channel 31 is connected to a connection position 31 a lower than the lowest point 30 a of the hot water supply pipe 2 on the downstream side of the outlet 6 b from the primary heat exchanger 6 of the hot water supply pipe 2. In order to make the length of the bypass flow path 31 as short as possible and make the connection position 31a as close to the primary heat exchanger 6 as possible, the connection position 31a is the position closest to the lowest point 30a. The “nearest neighbor” here does not mean the exact nearest neighbor, but the mechanical structure of the pipe of the bypass passage 31 (a necessary constant bending radius, a gap necessary for pipe welding, etc.) ) Also means that it is as close as possible.

  The height h1 from the ceiling 30b in the pipe at the lowest point 30a of the trap structure 30 to the floor 6a 'in the pipe at the inlet 6a of the primary heat exchanger 6 is 4.4 cm, which is 3 cm or more. The height h2 from the ceiling part 30b in the pipe 30a to the floor part in the pipe at the outlet 7b of the secondary heat exchanger 7 is 14.6 cm.

  Next, in the heating apparatus 1 of the present embodiment configured as described above, the operation of the present invention in the case where only chase is performed without hot water supply will be described. FIG. 3 is a diagram schematically showing the peripheral structure of the trap structure 30.

  When only chasing is performed without hot water supply, water is not passed through the hot water supply pipe 2, so that the water in the hot water supply pipe 2 is basically stationary. In this state, first, when the burner 4 is activated, the primary heat exchanger 6 is heated and the secondary heat exchanger 7 is also heated, but the secondary heat exchanger 7 is the primary in the heated gas flow path 5. Since it is disposed downstream of the heat exchanger 6, the temperature of the secondary heat exchanger 7 is lower than the temperature of the primary heat exchanger 6. Therefore, if the water temperature in the hot water supply pipe 2 near the water inlet 6a of the primary heat exchanger 6 is T1, and the water temperature in the hot water pipe 2 near the water outlet 7b of the secondary heat exchanger 7 is T2, T1> T2. .

  Moreover, since the trap structure 30 is between the water inlet 6a of the primary heat exchanger 6 and the water outlet 7b of the secondary heat exchanger 7, if the water temperature near the lowest point 30a of the trap structure 30 is T3, T1> T3> T2. Accordingly, in the pipe in the section between the lowest point 30a of the trap structure 30 and the outlet 7b of the secondary heat exchanger 7, the water temperature at the low position is high and the water temperature at the high position is low. Thermal convection (Benard convection) occurs. However, in the pipe in the section between the lowest point 30a of the trap structure 30 and the inlet 6a of the primary heat exchanger 6, the water temperature at the high position is high and the water temperature at the bottom position is low. A high temperature water layer and a low temperature water layer in the lower part, and the water in both layers is not mixed and is stable), and almost no heat convection occurs in the pipe. Therefore, the water in the hot water supply pipe 2 in the primary heat exchanger 6 is prevented from moving to the secondary heat exchanger 7 by heat convection. As a result, the thermal efficiency of the primary heat exchanger 6 can be improved when only chasing is performed without hot water supply.

  In order not to cause thermal convection in the pipe in the section between the lowest point 30a of the trap structure 30 and the water inlet 6a of the primary heat exchanger 6, the primary heat from the ceiling 30b in the pipe at the lowest point 30a of the trap structure 30. There is a need for a certain level difference to the inner floor 6a 'of the water inlet 6a of the exchanger 6. Specifically, h1 is 3 cm or more (h1 is the height of the section from the ceiling 30b in the pipe at the lowest point 30a to the floor 6a 'in the inlet 6a of the primary heat exchanger 6 (hereinafter referred to as "effective height"). )), More preferably, by h1 being 4 cm or more, it has been experimentally confirmed that a decrease in thermal efficiency due to thermal convection can be suppressed.

  On the other hand, the heat conduction through the hot water supply pipe 2 from the primary heat exchanger 6 also reduces the thermal efficiency of the primary heat exchanger 6. This heat loss due to heat conduction cannot be avoided because it is necessary to connect the hot water supply pipe 2 to the outside. However, in the present embodiment, the bypass flow path 31 for draining the primary heat exchanger 6 is connected to the hot water supply pipe 2 (the lowest point 30a and the connection position 31a) in the vicinity of the primary heat exchanger 6, Heat is prevented from diffusing to the outside through heat transfer through the bypass channel 31. Thereby, in the case where only chasing is performed without hot water supply, the thermal efficiency of the primary heat exchanger 6 can be improved as compared with the conventional case.

(Test example)
FIG. 4 shows measured data on the relationship between the effective height h1 of the trap structure 30 and the thermal efficiency of the primary heat exchanger 6 when only the chase is performed without hot water supply. The test was performed using a heating apparatus having the configuration shown in FIG. The inner diameter of the tube in the trap structure 30 was 13 mm. In FIG. 4, h1 = −D = −13 mm ([1] in FIG. 4) represents a case where the trap structure 30 is not provided. h1 = 0 mm ([2] in FIG. 4) represents a state in which the height of the pipe ceiling 30b at the lowest point 30a is the same as the height of the pipe floor 6a 'at the water inlet 6a. Basically, as the effective height h1 is increased, the temperature difference / layer thickness between the upper and lower layers of the stratified hot water storage state increases, and the thermal diffusion due to the mixing of water between the upper and lower layers decreases. Can be seen to improve. However, when the effective height h1 is small, the temperature difference and the layer thickness between the upper layer and the lower layer are not sufficiently large, so that convection and mixing inside the tube cannot be sufficiently suppressed, and improvement in thermal efficiency is seen. Absent. From FIG. 4, it can be seen that the thermal efficiency is improved from the vicinity of the effective height h1 of 20 mm, and that the thermal efficiency can be improved by about 1.5% or more if the effective height h1 is set to 30 mm or more. Since the heat efficiency of the primary heat exchanger 6 is originally about 80%, which is a high level, the fact that the heat efficiency is further improved by 1.5% or more can be said to be a considerably effective means for improving the heat efficiency. Furthermore, it can be seen that if the effective height h1 is 40 mm or more, the thermal efficiency can be improved by about 2% or more.

  FIG. 5 is a view schematically showing a peripheral structure of the trap structure 30 of the heating apparatus according to the second embodiment of the present invention. In the present embodiment, the shape of the trap structure 30 is not a U-shaped tube but a loop tube. Even with such a structure, as in the first embodiment, the thermal efficiency of the primary heat exchanger 6 can be improved in the case where only the chasing is performed without hot water supply.

  FIG. 6 is a diagram schematically showing a peripheral structure of the trap structure 30 of the heating apparatus according to the third embodiment of the present invention. In this embodiment, the shape of the trap structure 30 is a two-turn loop tube. Even with such a structure, as in the first embodiment, the thermal efficiency of the primary heat exchanger 6 can be improved in the case where only the chasing is performed without hot water supply. In the case of a loop tube having a plurality of windings, since the lowest points 30a and 30a ′ exist in each loop, the bypass channel 31 needs to be connected to each lowest point 30a and 30a ′ as shown in FIG. is there.

  As shown in FIG. 6, the effective height of the loop on the proximal side of the outlet 6a of the primary heat exchanger 6 (the entrance of the primary heat exchanger from the inner ceiling 30b ′ at the lowest point 30a ′ of the proximal loop). The height of the water inlet 6a up to the inner floor 6a 'is h1', and the effective height of the loop on the distal side of the water inlet 6a (from the inner ceiling 30b at the lowest point 30a of the distal loop to the distal loop). When h1 is the height from the highest point 30d to the pipe floor 30c, h1> h1 ′. The water temperature near the lowest point 30a ′ of the loop on the proximal side of the inlet 6a of the primary heat exchanger 6 is T3 ′, and the distal side of the inlet 6a (proximal to the outlet 7b of the secondary heat exchanger 7). The water temperature near the lowest point 30a of the side loop is T3, and the temperature near the highest point 30d of the distal loop is T1 '. When only chasing is performed without hot water supply, T1> T3 '> T1'> T3. Since T1 ′> T3, the section between the lowest point 30a and the highest point 30d of the loop on the distal side of the inlet 6a of the primary heat exchanger 6 is in a stratified hot water storage state, and heat convection (Benard) Convection is unlikely to occur. Further, since the height difference of the section between the lowest point 30a and the highest point 30d is increased as h1> h1 ′, the layer thickness of the water layer in the stratified hot water storage state in this section is larger than those in the first and second embodiments. Can be made thicker, and heat convection and mixing are less likely to occur.

  Further, when the trap structure 30 has a plurality of winding loop tubes, the stratified hot water storage state as described in the first embodiment occurs on the water inlet 7a side of the secondary heat exchanger 7 of each loop. Therefore, it is possible to prevent the water in the hot water supply pipe 2 in the primary heat exchanger 6 from moving to the secondary heat exchanger 7 by heat convection more reliably.

  In this embodiment, an example in which the trap structure 30 is a two-turn loop pipe is shown. However, in the present invention, the loop pipe need not be a loop pipe. It is good also as a structure provided in series. Further, the number of windings of the loop tube (the number of U-tube structures) may be two or more.

DESCRIPTION OF SYMBOLS 1 Heating device 2 Hot water supply piping 2a Water supply connection port 2b Hot water connection port 3 Follow-up piping 4 Burner 5 Heating gas flow path 6 Primary heat exchanger 6a Inlet 6a 'In-pipe floor 6b Outlet 7 Secondary heat exchanger 7a Inlet 7b Outlet 8 Bath 9 Built-in bath water flow switch unit 10 Bath circulation pump 11 Pouring pipe 12 Pouring solenoid valve 13 Check valve 14 Water supply thermistor 15 Water supply amount sensor 16 Heat exchange thermistor 17 Heat exchange outlet thermistor 18 Mixing proportion Valve 19 Water volume control valve 20 Hot water thermistor 21 Bypass piping 30 Trap structure 30a, 30a 'Minimum point 30b, 30b' In-pipe ceiling 30c at the lowest point In-pipe floor 30d at the highest point Maximum point 31 Bypass passage 31a Connection position

Claims (3)

Heating means for generating heated gas;
A heated gas flow path through which the heated gas flows;
A primary heat exchanger that is a one-can two-water channel heat exchanger disposed in the heated gas flow path;
A secondary heat exchanger disposed downstream of the primary heat exchanger in the heated gas flow path;
A flow path through which heated water passes, wherein the first heating flow path passes through the primary heat exchanger after passing through the secondary heat exchanger;
A heating apparatus comprising: a flow path through which heated water passes, and a second heating flow path that passes only through the primary heat exchanger;
The first heating flow path from the secondary heat exchanger to the primary heat exchanger has one lowest point, and the height of the ceiling in the pipe at the lowest point is the first heating flow path. At least one trap structure provided with a convex bent pipe that is lower than the height of the inner floor of the pipe at the inlet to the primary heat exchanger is provided,
The lowest point of the trap structure and a position lower than the lowest point on the first heating channel on the downstream side of the water outlet from the primary heat exchanger of the first heating channel, the lowest point And a bypass channel connected to the nearest position of the heating device.   The height of the ceiling part in the pipe at the lowest point of the trap structure is at least 3 cm lower than the height of the floor part in the pipe at the water inlet to the primary heat exchanger. Heating device.   A plurality of the trap structures are provided in the first heating flow path from the secondary heat exchanger to the primary heat exchanger, and the bypass flow path is connected to the lowest point of each trap structure. The heating apparatus according to claim 1 or 2, wherein