JP6281357B2 - Water heater - Google Patents

Description

  The present invention relates to a hot water supply apparatus, and more particularly to a technique for preventing dew condensation intended for a hot water supply apparatus having a plurality of combustion regions and capable of switching the combustion capacity in a plurality of stages from small to large.

In Patent Document 1, as an anti-condensation measure in the exhaust pipe of a latent heat recovery type heat source unit, the combustion area of the burner is usually fixed in a wide range and the output of the combustion amount is variably controlled, while the burner is intermittently controlled to be turned on / off. It has been proposed that when the operation is continued for a certain time, the operation is switched to the condensation drying mode operation in which the combustion region is narrowed and the combustion amount is the maximum output.
Further, in Patent Document 2, as a countermeasure for preventing adhesion of condensed water (drain) between adjacent fins of a heat exchanger for latent heat recovery, which is composed of a fin-and-tube type of a latent heat recovery type combustion apparatus, a predetermined exhaust gas is used. It has been proposed to increase the blowing amount or blowing pressure of the blowing means for supplying combustion air to the burner if the blocking occurrence condition is detected.
Furthermore, in patent document 3, as a dew condensation prevention measure in the said heat exchanger of the hot water circulation boiler which circulates the hot water heat-exchange-heated with the combustion apparatus from a heat exchanger to the radiator, the return temperature of the warm water after heat radiation with a radiator Has been proposed to increase the amount of combustion of the combustion device if a state of a predetermined temperature or lower is continuously detected for a certain period of time.

JP 2010-117100 A JP 2004-44912 A JP 2001-201063 A

  By the way, the combustion apparatus for heat exchange heating the fluid passed through the heat exchanger has a plurality of combustion regions that can be selectively switched, and the combustion capacity is reduced from small to large depending on which combustion region is burned. In the hot water supply apparatus that can be switched to a plurality of stages, dew condensation is likely to occur particularly in a portion of the heat exchanger corresponding to the vicinity of the boundary between the combustion region and the non-combustion region. If condensation occurs, it is likely to cause precipitation and accumulation of copper sulfate, and eventually the heat exchanger may be clogged between adjacent fins especially when the heat exchanger is composed of a large number of fins. There is. If an avoidance measure such as removing some fins is used to avoid the blockage, the combustion efficiency may be deteriorated. Further, if the amount of combustion is increased in order to prevent condensation, the hot water temperature is likely to fluctuate, which impairs user convenience.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide hot water supply capable of preventing dew condensation while maintaining the hot water supply temperature without causing deterioration in combustion efficiency. To provide an apparatus.

  In order to achieve the above object, the present invention is configured to supply hot water after water exchanged into the heat exchanger is heat-exchanged and heated by combustion of the combustion heating unit, and the combustion heating unit includes a plurality of independent heating units. Combustion-combustible combustion areas are provided, and each combustion area is selectively burned independently or in combination so that the combustion capacity can be changed and switched over a plurality of stages. Switching control of the combustion capacity stage number and each combustion capacity stage number The following specific items are provided for a hot water supply apparatus that is configured to perform a hot water supply operation at a predetermined hot water supply temperature by the combustion capacity switching control that executes the combustion capacity change adjustment control. In other words, in order to prevent the occurrence of condensation, a condensation prevention control means for changing the combustion state by the combustion capacity switching control for the combustion heating section is provided. Then, as the dew condensation prevention control means, when the determination condition for preventing the occurrence of dew condensation including that the combustion state at the specific combustion capacity stage number continues for a certain time is satisfied, the specific combustion capacity stage number is set to the low combustion capacity stage number. The number of stages is controlled to be switched to the side (claim 1).

  In the case of the present invention, when the determination condition for preventing the occurrence of condensation is satisfied, the specific combustion capacity stage number that is currently burned is switched to the combustion capacity stage number on the low combustion capacity stage side. Occurrence prevention is achieved.

  As the specific combustion capacity stage number in the present invention, the combustion region corresponding to the upstream range of the heat exchanger is stopped, and the combustion region corresponding to the downstream range adjacent to the upstream range of the heat exchanger is burned. And the combustion capacity stage number corresponding to the upstream range of the heat exchanger can be set as the combustion capacity stage number on the low combustion capacity stage number side (claim 2). . By doing so, the technical significance of preventing the occurrence of dew condensation becomes clearer. That is, in the combustion state at a specific number of combustion capacity stages, the combustion region corresponding to the upstream range of the heat exchanger is in a non-combustion state, so that cold water flows in this upstream range, while the heat adjacent to this region flows. Since the combustion region in the downstream range of the exchanger is in a combustion state, the water flowing in the downstream range is heated. For this reason, a large temperature difference will arise in the heat exchanger of both boundary part, As a result, it will become easy to produce dew condensation in this boundary part. If this is continued for a certain time and the determination condition is satisfied, the stage number switching to the low combustion capacity stage number side is executed, and the combustion region corresponding to the upstream range of the heat exchanger is switched to the combustion state. The water in the heat exchangers in the range is also heated, so that there is no portion where a large temperature difference occurs in the heat exchanger. Thereby, the possibility of the occurrence of condensation can be surely prevented.

  Further, as the dew condensation prevention control means of the present invention, when switching the stage number to the low combustion capacity stage number side, the stage number switching control is performed so as to maintain the combustion capacity at the specific combustion capacity stage before and after the stage number switching. It can be set as a structure (Claim 3). By doing so, it is possible to perform stage number switching control for preventing condensation while maintaining the hot water supply temperature reliably. For example, when the combustion number is used as the combustion capacity, the combustion number may be controlled to be kept the same before and after switching the number of stages.

  Furthermore, in that case, a hot water supply flow rate changing means for changing the hot water supply flow rate supplied from the heat exchanger is provided, and as the dew condensation prevention control means, the number of stages is controlled when switching the number of stages to the low combustion capacity stage number side. When the combustion capacity of the specific combustion capacity stage before switching is larger than the combustion capacity range set for the combustion capacity stage on the low combustion capacity stage after switching the stage, the hot water flow rate change means is used to change the hot water flow rate to the throttle side. Thus, the stage number switching control can be executed. In this way, even if the switching from the specific combustion capacity stage number to the low combustion capacity stage number is larger than the combustion capacity range of the low combustion capacity stage so far, Since the required combustion capacity can be reduced by reducing the flow rate, the stage number can be appropriately switched from the specific combustion capacity stage number to the low combustion capacity stage number. As a result, even if the combustion capacity range that may cause condensation at the specific combustion capacity stage number is expanded more widely on the large side, the stage number switching to the low combustion capacity stage number is properly performed while maintaining the hot water supply temperature until then. Therefore, it is possible to more widely and reliably prevent the occurrence of condensation.

  As described above, according to the hot water supply apparatus of the present invention, if the determination condition for preventing the occurrence of condensation is satisfied, the specific combustion capacity stage number currently burned is changed to the combustion capacity stage number on the low combustion capacity stage side. By performing the switching control, it is possible to prevent the occurrence of condensation.

  In particular, according to the hot water supply apparatus of claim 2, as a specific combustion capacity stage number, the combustion region corresponding to the upstream range of the heat exchanger is stopped and corresponds to the downstream range adjacent to the upstream range of the heat exchanger. The combustion capacity stage number in which the combustion area is to be burned, and the combustion capacity stage number on the low combustion capacity stage number side are the combustion capacity stage number in which the combustion area corresponding to the upstream range of the heat exchanger is burned. This makes it possible to clarify the technical significance of preventing condensation. That is, in the combustion state with a specific number of combustion capacity stages, the boundary portion between the water flowing in the upstream range of the heat exchanger that is in the non-combustion state and the hot water flowing in the heat exchanger in the downstream range that is in the combustion state As a result of the large temperature difference in the heat exchanger, condensation tends to occur at the boundary part. By switching the number of stages to the low combustion capacity stage number, the water in the heat exchanger in the upstream range is also heated. It is possible to eliminate the presence of a portion in which a large temperature difference occurs. As a result, the possibility of the occurrence of condensation can be reliably prevented.

  According to the third aspect of the present invention, when the number of stages is switched to the low combustion capacity stage side as the dew condensation prevention control means, the combustion capacity at the specific combustion capacity stage until then is changed before and after the stage number switching. By adopting a configuration in which the stage number switching control is performed so as to be maintained, the stage number switching control for preventing dew condensation can be performed while the hot water supply temperature is reliably maintained.

  In addition, according to the hot water supply apparatus of claim 4, the hot water supply flow rate changing means for changing the hot water supply flow rate of hot water supplied from the heat exchanger is further provided. When performing the switching control, if the combustion capacity of the specific combustion capacity stage before switching the stage number is larger than the combustion capacity range set for the combustion capacity stage number on the low combustion capacity stage side after the stage number switching, the hot water flow rate change means is used. By switching to the throttle side and performing the stage number switching control, switching from the specific combustion capacity stage number to the low combustion capacity stage number, the previous combustion capacity is less than the combustion capacity range of the low combustion capacity stage number. Even on the large side, it is possible to reduce the required combustion capacity by reducing the hot water flow rate with the hot water flow rate changing means, so it is appropriate to switch the stage number from the specific combustion capacity stage number to the low combustion capacity stage number. It will be able to be performed. As a result, even if the combustion capacity range that may cause condensation at the specific combustion capacity stage number is expanded more widely on the large side, the stage number switching to the low combustion capacity stage number is properly performed while maintaining the hot water supply temperature until then. Therefore, it is possible to prevent the occurrence of dew condensation more widely and reliably.

It is a schematic diagram of the hot water supply apparatus which concerns on embodiment of this invention. FIG. 2 (a) shows an example of the combustion capacity of one stage, FIG. 2 (b) shows an example of the combustion capacity of two stages, and FIG. 2 (c) shows the combustion. This is an example of a three-stage ability. It is a table | surface which shows the example of setting of the number of the combustion pipe | tube for every combustion capacity stage number, the switching condition of a capacity switching valve, a required capacity, etc. in the combination example of change switching of a combustion capacity. Similar to FIG. 2, FIG. 4 (a) is an example of a four-stage combustion capacity, and FIG. 4 (b) is an example of a five-stage combustion capacity. It is a related figure of the combustion number in each combustion stage of 1st stage-5th stage, and supply gas pressure. It is a flowchart of the dew condensation prevention control in 1st Embodiment. It is explanatory drawing which shows the relationship between the 4-stage combustion state and the heat exchanger which may generate | occur | produce dew condensation. It is explanatory drawing which shows the relationship with the heat exchanger when it switches to a three-stage combustion state in order to prevent dew condensation generation | occurrence | production. It is a flowchart of the condensation prevention control in 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram of a hot water supply apparatus according to an embodiment of the present invention. This hot water supply apparatus includes a hot water supply circuit 2 that realizes a hot water supply function, a remedy circuit 3 that realizes a reheating function, and water or water injection that supplies hot water or water from the hot water supply circuit 2 to the remedy circuit 3 for hot water filling or the like. A circuit 4 and a controller 5 for controlling these operations are provided. In addition, although the thing of the figure has shown the thing of 1 can 2 water type, not only this but 2 can 2 water type thing can implement this invention. Further, the present invention can be carried out even with a single-function hot water supply apparatus having only a hot water supply function, without realizing a plurality of functions such as hot water supply and chasing. Furthermore, the example shown in the figure is configured as a latent heat recovery type that combines a primary heat exchanger that absorbs sensible heat of combustion gas and a secondary heat exchanger that recovers latent heat from combustion exhaust gas as a heat exchanger. Although the present invention is illustrated, the present invention is not limited to this, and the present invention can be carried out even without a secondary heat exchanger, and it is not essential to be a latent heat recovery type. In the following description, the primary heat exchanger and the secondary heat exchanger may be combined and simply referred to as a hot water supply heat exchanger or a reheating heat exchanger.

  The hot water supply device 2 receives tap water such as tap water in the water supply passage 21 and causes the hot water supply heat exchanger 22 to discharge hot water heated to a predetermined temperature by heat exchange heating with the combustion heat of the combustion heating unit 23 to the hot water supply passage 24. The hot water is supplied to the hot water taps 25 in various places such as the kitchen and the washroom. Between the water supply passage 21 and the hot water supply passage 24, a bypass passage 26 is provided to bypass the hot water supply heat exchanger 22 and allow the water supply from the water supply passage 21 to flow into the hot water supply passage 24, and the bypass valve 26a is opened. Communicate with each other. A flow rate sensor 27 and a feed water temperature sensor 28 for detecting the feed water temperature are interposed in the feed water passage 21, and a can outlet temperature for detecting the temperature of the hot water immediately after being heated by the hot water supply heat exchanger 22 in the hot water supply passage 24. A sensor 29 is interposed, and a water amount adjusting valve 24 a configured by a servo valve is interposed downstream of the junction with the bypass path 26. As heat exchange heating in the hot water supply heat exchanger 22, the water supplied through the water supply passage 21 is first passed through the secondary heat exchanger 22 b and preheated, and then through the connection passage 20 to the primary heat exchanger 22 a. And heated to be discharged into the hot water supply passage 24. Here, the relationship between the water amount adjusting valve 24a and the combustion heating unit 23 will be described. For example, when the water amount adjusting valve 24a is throttled to reduce the hot water supply flow rate to the hot water tap 25, the hot water supply heat exchanger 22 When heat exchange heating is performed with the same amount of combustion, the temperature of the hot water discharged becomes high. Therefore, in order to maintain the same hot water supply temperature, the amount of combustion may be reduced. This water amount adjusting valve 24a constitutes a hot water supply flow rate changing means. The primary heat exchanger 22a is constituted by a fin-and-tube type, and the secondary heat exchange 22b is constituted by a multi-tube type. The combustion heating section 23 includes a plurality (three in the illustrated example) of independently and selectively combustible combustion regions, and each combustion region is selectively burned individually or alternatively Combustion capacity can be switched over a plurality of stages (in this embodiment, five stages) by burning in combination. Details of the combustion heating unit 23 will be described later.

  The memorial circuit 3 includes a memorial circuit 30 including a return path 30a and an outgoing path 30b piped between the bathtub 6 and the circulation adapter 61 in order to realize a chasing function. The stretched bath water can be reheated to a predetermined temperature and heated. That is, by the operation of the circulation pump 31, heat is exchanged by the heat of combustion of the combustion heating section 33 in the reheating heat exchanger 32 from the bathtub 6 through the return path 30a, and the hot water from the reheating is reheated. It is circulated so as to be supplied to the bathtub 6 through, and is driven up to a predetermined boiling temperature. The circulation pump 31 is interposed in one of the return path 30a and the forward path 30b (return path 30a in the illustrated example). The return path 30a is provided with a water flow switch 34 that detects the flow and outputs it to the controller 5 described later, and a return temperature sensor 35 that detects the temperature of the bathtub hot water in the bathtub 6 returned by the return path 30a. A forward temperature sensor 36 for detecting the temperature of the bath water after reheating is interposed in the path 30b. Reference numeral 37 in FIG. 1 denotes a gas supply system for supplying fuel gas to the hot water supply combustion burner 23 and the combustion combustion burner 33. Similarly to the example of the hot water supply heat exchanger 22, the remedy heat exchanger 32 also has a primary heat exchanger 32a that absorbs sensible heat of the combustion gas, and secondary heat for recovering latent heat from the combustion exhaust gas. It is comprised with the exchanger 32b. Similarly to the combustion heating unit 23 on the hot water supply circuit 2 side, the combustion heating unit 33 includes a plurality of (two in the illustrated example) combustion regions, and the combustion capacity can be switched over two stages.

  The water pouring / pouring circuit 4 includes a pouring passage 41 branched from the middle of the hot water supply passage 24 and connected to the return passage 30 a of the recirculation circuit 30. Hot water (or water) flows into the return path 30a, and is divided into both sides to be poured into the bathtub 6 in a double-conveyance system that passes through the return path 30a and the outgoing path 30b. It can be stretched. The pouring channel 41 has a flow rate sensor 42, a pouring electromagnetic valve 43, a pair of check valves 44 for preventing backflow, and a backflow when negative pressure is generated on the upstream side in order from the upstream side that is the hot water supply channel 24 side. An edge cut-off valve 45 for preventing the generation is provided, and in addition, a pressure-type water level sensor 46 for detecting the water level in the bathtub 6 is provided in the vicinity of the junction with the tracking circuit 30.

  1 is an outside air temperature sensor, and this outside air temperature sensor 7 detects the outside air temperature by detecting the ambient temperature in the case. Reference numeral 8 denotes a drain processing circuit. This drain processing circuit 8 is a secondary heat exchanger included in the hot water supply heat exchanger 22 or the reheating heat exchanger 32, and the combustion exhaust gas generates heat for recovering latent heat. It is installed to collect drainage generated by cooling and condensing in exchange and draining it after, for example, neutralizing. That is, the drain treatment circuit 8 shown in the figure collects drain from the neutralization tank 81 and the secondary heat exchangers 22b and 32b included in the hot water supply heat exchanger 22 and the additional heat exchanger 32. A water collecting channel 82 that leads to the neutralization tank 81 and a drainage channel 83 for draining the neutralized drain from the neutralization tank 81 to the outside of the system are configured.

  Next, the combustion heating unit 23 will be described in detail. The combustion heating unit 23 includes a plurality of combustion regions having different scales, and a wide range of combustion capacity can be adjusted by selective combustion operation in the combustion regions. That is, the combustion heating unit 23 includes a plurality of (for example, a total of 10 in the example of FIG. 2A) combustion tubes 231 arranged from one side to the other side in the left-right direction at the lower position of the can body 1. Are divided into groups according to a predetermined number, and a fuel gas is supplied to each of the predetermined number of combustion tubes 231, 231,. As a result, a plurality of combustion regions having different scales are formed. For example, the first combustion region F1 is formed by the two combustion pipes 231 and 231 in the central portion in the left-right direction, and the second combustion region F2 is formed by the three combustion tubes 231 231,. A third combustion region F3 is formed by the five combustion tubes 231, 231,. Each combustion pipe 231 is connected to a gas manifold 371 partitioned for each combustion region F1, F2, F3, and the gas supply system 37 is opened by opening the original gas solenoid valve SV0 (see FIG. 1) and the gas proportional valve SVL. Is selectively supplied to the corresponding sections of the gas manifold 371 via the first to third capacity switching valves SV1, SV2, SV3. For example, if the capacity switching valve SV1 is opened (see FIG. 2A), the first combustion region F1 formed by the two combustion pipes 231 and 231 is burned, and if the capacity switching valve SV2 is opened (FIG. 2 ( See b)) The second combustion region F2 formed by the three combustion pipes 231, 231, 231 is combusted, so that the combustion region can be switched. The “combustion tube” is synonymous with a combustion burner.

  The original gas solenoid valve SV0 and each capacity switching valve SV1, SV2, SV3 are selectively selected by the combustion capacity switching control unit of the controller 5 according to the combustion number (combustion quantity) corresponding to the required heat quantity (requested heat quantity). Open / close switching control is executed, whereby the corresponding combustion regions F1, F2, F3 are selectively burned, and the combustion capacity is changed and switched stepwise and continuously. In this embodiment, the gas proportional valve SVL is separately provided. However, the capacity switching valves SV1 to SV3 themselves may be used as a flow control valve or a pressure control valve.

  As an example of the selective opening / closing switching control, for example, as shown in FIG. 3, the combustion regions F1 to F3 are individually or selectively combined to perform combustion operation, thereby increasing the number of combustion capacity stages of five stages (five stages). Switching is possible. That is, only the capacity switching valve SV1 is opened and the first combustion region F1 (see also FIG. 2 (a)) is combusted so that the number of combustion capacity stages corresponding to the two combustion pipes 231 and 231 is one stage. It becomes possible to operate, and only the capacity switching valve SV2 is opened and the second combustion region F2 (see also FIG. 2B) is combusted so that the number of combustion capacity stages corresponding to the three combustion tubes 231, 231, 231 is reached. Is capable of two-stage combustion operation and opens the capacity switching valves SV1 and SV2 to burn the first and second combustion regions F1 and F2 (see also FIG. 2 (c)), thereby five combustions. The combustion operation with the number of combustion capacity stages corresponding to the pipes 231, 231,... Is enabled, the capacity switching valves SV 1 and SV 3 are opened, and the first and third combustion regions F 1 and F 3 (FIG. 4A are also combined). 7) and the seven combustion tubes 231 ,... Can be operated with four combustion capacity stages, and all the capacity switching valves SV1, SV2, SV3 are opened and the first to third combustion regions F1, F2, F3 (FIG. 4 (b) ) Is also burned, and a combustion operation with five combustion capacity stages corresponding to the ten combustion pipes 231, 231,.

  The combustion heating unit 23 can change and adjust the number of combustion at each combustion stage number (the number of combustion capacity stages) when the gas proportional valve SVL is controlled by the opening control by the combustion capacity switching control section. ing. For example, as shown in FIGS. 3 and 5, the number of combustion capacity stages can be changed and adjusted within the combustion range of No. 2.5 to 5.0 when the number of combustion capacity stages is 1, and similarly, the number of combustion capacity stages is 2 when the number of combustion capacity stages is 2. Combustion range of No. 5 to 7.5, combustion range of 6.1 to 11.0 when the number of combustion capacity stages is 3, combustion of No. 8.5 to 15.3 when the number of combustion capacity stages is 4 When the range and the number of combustion capacity stages are 5, the change can be adjusted in the combustion ranges of 13.2 to 24.0.

  The hot water supply circuit 2, the reheating circuit 3, and the water / water pouring circuit 4, etc. are provided with an MPU, a memory, etc., and a controller 5 in which various control programs are stored. Based on the output from the remote controller 51 and the outputs from the various sensors described above, various operation controls such as hot water filling operation, automatic bathing operation that automatically controls hot water filling, memorialization, and heat retention, or pipe cleaning control, etc. It is supposed to be done. That is, the controller 5 includes a hot water supply operation control unit, a bath automatic operation control unit, and the like. When the hot water supply operation control is performed by the hot water supply operation control unit, the combustion capacity switching control unit controls the switching of the number of combustion stages of the combustion heating unit 23 and the combustion at each combustion stage number in order to realize hot water supply at the set hot water supply temperature. Quantity adjustment control is executed.

  Hot water supply operation control by the hot water supply operation control unit and automatic bathing control by the bath automatic operation control unit will be briefly described. The hot water supply operation control is started when the user opens the hot water tap 25 and the flow sensor 27 detects a flow exceeding the minimum operating flow rate. First, the hot water supply combustion system including the hot water combustion heating unit 23 and the gas supply system 37 is controlled. By supplying a predetermined amount of combustion in a predetermined combustion stage, the water supplied through the heat exchanger 22 for hot water supply is subjected to heat exchange heating by receiving the combustion heat, and the hot water heated to the set hot water temperature is adjusted to a hot water supply path. The hot water is supplied to the hot water tap 25 through 24. The automatic bath control is started when the user turns on the automatic bath switch of the remote controller 51. First, hot water from the hot water supply device 2 flows into the bathtub 6 through the pouring / hot pouring circuit 4 and the additional circulation circuit 30. It is stretched. The amount of hot water filling at this time is grasped and specified by integration of the water level sensor 46 or the pouring flow rate sensor 42, and the hot water is filled in the bathtub 6 to a predetermined water level. Next, the remedy combustion system including the remedy combustion heating unit 33 and the gas supply system 37 and the circulation pump 31 of the remedy circuit 3 are operated and controlled. The hot and cold water in the bathtub 6 passing through the heat exchanger 32 is heat-exchanged and heated to a predetermined boiling temperature. When the remedy heating is completed, the warming operation in which the remedy control is intermittently performed to maintain the hot water temperature in the bathtub 6 constant is continued until the set time elapses or the bath is automatically operated by the user. Continue until the switch is turned off.

  In the hot water supply operation control, the FF number (number for feed forward control) of the required combustion number (required number) is determined according to the set hot water supply temperature, and based on the FF number The number of combustion stages is determined (see FIGS. 3 and 5), and then hot water supply at the set hot water supply temperature is performed by changing the number of combustion stages and adjusting the amount of combustion according to the change in the required number. become. In this case, the temperature adjustment by the mixed water with the water from the bypass passage 26 or the water amount adjustment valve according to the detected temperature or flow rate of the water entering the heat exchanger 22 for hot water supply from the water supply passage 21. By adjusting the opening degree of 24a, the hot water supply to the hot water tap 25 is controlled so as to become the set hot water supply temperature.

<First Embodiment>
Next, with respect to the dew condensation prevention control, which is a characteristic part, for the combustion heating unit 23, the occurrence of blockage between the fins of the primary heat exchanger 22 a configured as a fin-and-tube type of the heat exchanger 22 for hot water supply is avoided. The target first embodiment will be described with reference to FIGS. The controller 5 is provided with the condensation prevention control unit (condensation prevention control means) of the first embodiment, and the condensation prevention control by the condensation prevention control unit is the switching control of the number of combustion stages by the combustion capacity switching control unit. This is executed in parallel with the change adjustment of the combustion amount as described below. Of course, the same control can be performed on the combustion heating section 33 on the side of the remedy circuit 3.

  First, it is determined whether or not the number of stages of the current combustion capacity set by the combustion stage switching control by the combustion capacity switching control unit is four (step S11). If combustion is performed in four stages (YES in step S11), it is determined whether or not the combustion number is within a predetermined combustion number range G1 for preventing the occurrence of condensation (step S12), and the combustion number is determined. If the combustion is within the range G1, the time during which the combustion is continued is integrated (step S13). If the combustion stage is not 4 in step S11 or the combustion number is not in the predetermined combustion number range G1, the process returns and repeats step S11 and subsequent steps. The combustion number range G1 (see FIG. 5) in the first embodiment is determined as follows. That is, the number of combustion numbers within the range of the number of combustion numbers that can be achieved by combustion in four stages (8.5 to 15.3), and the number of combustion numbers that can be achieved by combustion in three stages Combustion number range (8.5 to 11.0) overlapping with the range (6.1 to 11.0), that is, the minimum combustion number in four stages (8.5) to three stages Based on the range of the maximum combustion number (11.0), the range (8.5 to 10.2) obtained by subtracting the maximum side of this range by a predetermined value α (for example, 0.8) is the combustion number. It is defined as a number range G1.

  This is based on the fact that the combustion state in the four-stage combustion region and the combustion state in the small range of the four-stage combustion number are considered to be most likely to cause dew condensation. Therefore, when switching to the three-stage combustion region on the low-stage number side, the combustion number range that can be switched while maintaining the tapping temperature (the overlapping range with the three-stage combustion number range) is switched. This is determined as a control determination range G1. In addition, if the maximum side of the combustion number range G1 is reduced by the predetermined value α, the change is controlled from the 4th stage to the 3rd stage by the dew condensation prevention control when the boundary on the maximum side is too small. First, due to the occurrence of minor fluctuations (for example, deviation fluctuation due to hunting of the gas supply pressure), the switching control is again performed from the third stage to the fourth stage by the execution of the original combustion capacity switching control, and further condensation prevention control is performed. In order to avoid inconveniences such as switching the number of stages from 4 stages to 3 stages, a margin for α is set. Thereby, condensation prevention can be realized under stable control.

  If the accumulated time accumulated in step S13 exceeds a predetermined set time (YES in step S14), it is determined that the number of stages needs to be switched to 3 to prevent the occurrence of condensation. While maintaining the above, the four combustion stages so far are switched to three stages (step S15). For example, if the combustion stage has four combustion stages and the combustion number is indicated by a (see FIG. 5), the number of combustion stages indicated by b (see FIG. 5) is the same as the combustion number a. Switch to combustion. Thereby, even if the number of stages is switched, it becomes possible to prevent the occurrence of condensation while maintaining the same hot water supply temperature. In the above, the determination conditions for preventing the occurrence of condensation are that the number of combustion capacity stages is four, the combustion number is within a predetermined small range of the four stages, and the accumulated time during which the combustion state continues. It is set to be longer than a certain time.

  FIG. 7 shows the state of hot water moving in the heat exchanger 22a (planar sectional view state) when the combustion heating section 23 (front sectional view state) is combusting in four stages of combustion. In addition, in FIG. 7, the combustion heating part 23 is represented in the front sectional view state, and the heat exchanger 22a is represented in the planar sectional view state. As shown in FIG. 7, in the four combustion stages, the combustion regions F1 and F3 in the downstream range of the heat exchanger 22a are operated for combustion, and the combustion region F2 in the upstream region of the heat exchanger 22a is in a combustion stopped state. . For this reason, the cold water that enters the heat exchanger 22a through the connection path 20 (water supply path 21) and flows into the heat exchanger 22a above the combustion area F2 in the combustion stopped state, and the combustion area F1, in the combustion state Condensation is likely to occur at the boundary portion K with hot water heated in the heat exchanger 22a in the upper range of F3. By switching the number of stages to three by the condensation prevention control, the possibility of the occurrence of condensation can be eliminated as shown in FIG. That is, in the three combustion stages, the combustion regions F1 and F2 in the upstream range of the heat exchanger 22a are operated for combustion, and the combustion region F3 in the downstream region of the heat exchanger 22a is in a combustion stopped state. For this reason, the cold water that has entered through the connection channel 20 (the water supply channel 21) is heated as soon as it enters the heat exchanger 22a, and is further heated while moving to the downstream side. The hot water is discharged to the road 24. That is, since hot water heated from the upstream side to the downstream side flows in the heat exchanger 22a, there is no risk of condensation. And the boundary between the cold water and the heated hot water on the water entering side becomes an inlet part that enters the can body 1 from the outside, and there is no possibility of causing clogging between the fins of the heat exchanger 22a even if condensation occurs. It can be. Moreover, even if the control is switched to three stages, the combustion continues with the combustion number equivalent to the number of combustion in the four stages before switching the number of stages, so that the hot water can be discharged while maintaining the same temperature as before, There is no inconvenience for users who are using hot water.

Second Embodiment
FIG. 9 is a flowchart of condensation prevention control according to the second embodiment. In the second embodiment, the combustion number range G2 for determining the number of stages is expanded to the maximum side from the combustion number range G1 of the first embodiment. In order to prevent condensation, the number of stages is switched to three stages. The difference is that the water amount adjusting valve 24a is controlled to be changed to the throttle side.

  In the condensation prevention control by the condensation prevention control unit (condensation prevention control means) of the second embodiment, first, it is determined whether or not the current number of stages of combustion capacity is 4 (step S21), and combustion is performed in 4 stages. If so (YES in step S21), it is determined whether or not the combustion number is within a predetermined combustion number range G2 for preventing the occurrence of condensation (step S22). If it is combustion, the time during which combustion is continued is integrated (step S23). If the combustion stage is not 4 in step S21 or the combustion number is not in the predetermined combustion number range G2, the process returns and repeats step S21 and subsequent steps. The combustion number range G2 (see FIG. 5) in the second embodiment is determined as follows. That is, a small side combustion number range (for example, 8.0 to 12.3) considered to be likely to cause dew condensation within a combustion number range (8.5 to 15.3) that can be achieved by combustion in four stages. No. 0) is defined as the combustion number range G2. That is, the combustion number range G1 of the first embodiment is limited to an overlapping range with a range in which the number of stages can be switched to combustion in three stages, whereas the combustion number range G2 of the second embodiment is 4 A small combustion number range, which is considered to easily cause dew condensation in the stage combustion state, is set. Thereby, in 2nd Embodiment, the stage number switching to the low stage number side by condensation prevention control can be performed in the combustion number range wider than 1st Embodiment, and more reliable condensation prevention control is implement | achieved. become able to.

  If the accumulated time accumulated in step S23 exceeds a predetermined set time (YES in step S24), it is determined that the number of stages needs to be switched to three stages to prevent the occurrence of condensation, and the same tapping temperature is maintained. In order to check whether or not the number of stages can be switched to three stages, whether the current combustion number is in the number range G1 (8.5 to 10.2) in which the number of stages can be switched to three stages. It is determined whether or not (step S25). If it is larger than the number range G1 (NO in step S25), the water amount adjusting valve 24a is controlled to change the opening to the throttle side (step S26). By changing the opening of the water amount adjusting valve 24a to the throttle side, the hot water flow rate flowing through the hot water supply passage 24 decreases, and the hot water temperature becomes higher than before when the combustion number (combustion amount) is the same. For this reason, in order to maintain the same hot water temperature, proportional control is automatically performed by hot water supply control so that the combustion number of the combustion heating unit 23 becomes smaller by the amount of flow reduction. Then, again, it is determined whether or not the current combustion amount (combustion number) is in a number range G1 (8.5 to 10.2) in which the number of steps can be switched to three, and this number range G1. If it is within (YES in step S25), the previous four combustion stages are switched and controlled to three stages while maintaining the same combustion number (step S27). For example, when the number of combustion until that time is the combustion number indicated by c (see FIG. 5), the number of stages cannot be switched to three stages while maintaining this number of combustion c. If the necessary combustion number is lowered to d (for example, d ≦ 10.2; see FIG. 5) by restricting the regulating valve 24a, three stages with the same combustion number e as the combustion number d (see FIG. 5) The number of stages can be switched to In the initial check in step S25, if the combustion amount (combustion number) at that time is within the number range G1 (8.5 to 10.2) in which the number of stages can be switched to three stages (step 10.2) In S25, the combustion stage is switched to three stages while maintaining the same combustion number without passing through the adjustment to change the water amount adjusting valve 24a to the throttle side (Step S26) (Step S27).

  In the case of this second embodiment, it is possible to reliably prevent the combustion in the number of combustion stages (combustion region) / combustion number range where condensation is expected to occur for a long time, and to reliably prevent the occurrence of condensation. become able to. Specifically, the current combustion is not combustion in a combustion number range in which the number of stages can be immediately switched to a low number of conditions within the predetermined conditions for preventing the occurrence of condensation in the case of the first embodiment. Therefore, even if the combustion is in a wider combustion number range, processing control (change adjustment to the throttle side of the water amount adjustment valve 24a) to enable switching of the number of stages to a lower number of stages is added. As a result, the number of stages can be switched to the same number of stages as in the first embodiment.

<Other embodiments>
The present invention is not limited to the first and second embodiments described above, but includes other various embodiments. That is, the number of combustion regions in the embodiment (three), the number of combustion tubes 231 in each combustion region, the number of combustion capacity stages (five stages), etc. are examples, and other than these can be set.

  In the above embodiment, the latent heat recovery type hot water supply device is shown, but not limited to this, as long as the hot water supply device is configured to be able to change and change the combustion capacity of a plurality of stages by selective combustion in a plurality of combustion regions, The present invention can be applied.

5 Controller (Condensation prevention control means)
22a Primary heat exchanger (heat exchanger)
23 Combustion heating unit 24a Water amount adjustment valve (hot water flow rate changing means)
F1, F2, F3 combustion area

Claims (4)

The water passed through the heat exchanger is configured to supply hot water after heat exchange heating is performed by combustion of the combustion heating unit, and the combustion heating unit includes a plurality of independently combustible combustion regions, each combustion region Combustion in which the combustion capacity can be changed over a plurality of stages by being selectively burned independently or in combination, and the combustion capacity stage switching control and the combustion capacity change adjustment control in each combustion capacity stage number are executed. In a hot water supply apparatus configured to perform a hot water supply operation at a predetermined hot water supply temperature by capability switching control,
Condensation prevention control means for changing the combustion state by the combustion capacity switching control for the combustion heating unit to prevent the occurrence of condensation,
The dew condensation prevention control means sets the specific combustion capacity stage number to the low combustion capacity stage number side by establishing a determination condition for preventing the occurrence of dew condensation including that the combustion state at the specific combustion capacity stage number continues for a certain period of time. It is configured to control the number of stages.
A water heater characterized by that. The hot water supply device according to claim 1,
In the specific combustion capacity stage number, the combustion region corresponding to the upstream range of the heat exchanger is stopped in combustion, and the combustion region corresponding to the downstream range adjacent to the upstream range of the heat exchanger is burned. Is the number of combustion capacity stages
The hot water supply apparatus, wherein the combustion capacity stage number on the low combustion capacity stage number side is a combustion capacity stage number in which a combustion region corresponding to an upstream range of the heat exchanger is burned. The hot water supply device according to claim 1 or 2,
The dew condensation prevention control means, when performing the switching control of the number of stages to the low combustion capacity stage number side, controls the switching of the number of stages so as to maintain the combustion capacity at the specific combustion capacity stage number before and after the switching of the number of stages. Constructed hot water supply device. The hot water supply device according to claim 3,
Hot water supply flow rate changing means for changing the hot water supply flow rate of hot water supplied from the heat exchanger,
The dew condensation prevention control means sets the combustion capacity of the specific combustion capacity stage number before the stage number switching to the combustion capacity stage number on the low combustion capacity stage side after the stage number switching when performing the stage switching control to the low combustion capacity stage number side. A hot water supply apparatus configured to execute the stage number switching control after changing the hot water supply flow rate to the throttle side by the hot water supply flow rate changing means when the combustion capacity range is larger.

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