JP4050735B2 - Combined heat source machine - Google Patents

Description

  The present invention relates to a composite heat source machine having a hot water supply function and a heating function.

  Conventionally, as this type of combined heat source machine, for hot water circulation, hot water is circulated between a first heat exchanger for hot water supply and a first combustion section having a first burner for heating the first heat exchanger and a heating terminal. And a second combustion section having a second burner for heating the second heat exchanger and the second heat exchanger are known. In this case, if separate proportional valves for the first burner and the second burner are provided, the combustion amounts of the first burner and the second burner can be individually controlled. However, this increases the cost. It is also known that a single proportional valve is provided in a common gas supply path for both the first and second burners so that the combustion area of the second burner can be switched to a plurality of stages by a capacity switching valve. For example, see Patent Document 1).

  Even when a single proportional valve is used as described above, only one of the first burner and the second burner burns during single operation of hot water supply or heating, so that the burner corresponding to the hot water supply load or heating load is used. The amount of combustion can be appropriately controlled by a proportional valve. That is, during the hot water supply single operation, the combustion amount of the first burner is controlled by the proportional valve so that the temperature of hot water sent from the first heat exchanger (hot water supply side hot water temperature) matches a predetermined set temperature, During the single operation, the combustion amount of the second burner can be controlled by the proportional valve so that the temperature of the hot water sent from the second heat exchanger (heating-side hot water temperature) matches the required hot water temperature of the heating terminal. However, during simultaneous operation of hot water supply and heating, either one of hot water supply or heating has priority, and the combustion amount must be controlled by the proportional valve.

  Here, it is the hot water supply side hot water temperature that requires more accurate temperature control between the hot water supply hot water temperature and the heating side hot water temperature, and the combustion of the first burner so that the hot water supply hot water temperature becomes the set temperature. It is desirable to control the amount with a proportional valve. In this case, it is necessary to switch the combustion area of the second burner by the capacity switching valve so that the heating side hot water temperature is as close as possible to the required hot water temperature of the heating terminal. For example, when the opening degree of the proportional valve is reduced while the second burner is burned at a medium combustion area, and the heating side hot water temperature falls below the required hot water temperature due to the decrease in the combustion amount of the second burner, When the combustion area of the 2 burner is widened and the combustion amount is increased, conversely, when the opening of the proportional valve is increased and the heating amount of the heating side becomes higher than the required hot water temperature due to the increase of the combustion amount of the second burner, It is necessary to reduce the combustion amount by narrowing the combustion area of the second burner.

Therefore, the capacity switching valve is controlled so that the combustion area of the second burner becomes narrower than before when the heating side hot water temperature becomes higher than a predetermined combustion down temperature set higher than the required hot water temperature of the heating terminal. When the heating side hot water temperature falls below a predetermined combustion up temperature set lower than the required hot water temperature of the heating terminal, the capacity switching valve is controlled so that the combustion area of the second burner becomes wider than before. It is possible to do. In this case, the temperature range between the combustion up temperature and the combustion down temperature becomes a dead zone in which the switching of the capacity switching valve is not performed. Here, if the dead zone is widened, the fluctuation range of the heating side hot water temperature increases, and conversely, if the dead zone is narrowed, the switching frequency of the capacity switching valve increases and the durability deteriorates, so the dead zone is set appropriately. It is very difficult.
JP 2000-291949 A

  In view of the above points, the present invention has as its object to provide a composite heat source machine that can suppress the fluctuation range of the heating side hot water temperature without adversely affecting the durability during simultaneous operation of hot water supply and heating. Yes.

  In order to solve the above-described problems, the present invention circulates hot water between a first heat exchanger for hot water supply and a first combustion unit having a first burner for heating the first heat exchanger and a heating terminal. A combined heat source apparatus comprising a second heat exchanger for heating and a second combustion section having a second burner for heating the second heat exchanger, and a common gas supply path for both the first and second burners And a capacity switching valve capable of switching the combustion area of the second burner between wide and narrow stages, and the temperature of the hot water sent from the first heat exchanger is the hot water supply side hot water temperature, (2) The temperature of the hot water sent from the heat exchanger is set as the heating side hot water temperature, and the combustion amount of the first burner is controlled by the proportional valve so that the hot water supply side hot water temperature becomes a predetermined set temperature during simultaneous operation of hot water supply and heating. At the same time, the heating side hot water temperature is set higher than the required hot water temperature of the heating terminal. The capacity switching valve is controlled so that the combustion area of the second burner becomes narrower than before when the predetermined combustion down temperature is reached, and the heating side hot water temperature is set lower than the required hot water temperature of the heating terminal. In the control of the capacity switching valve so that the combustion area of the second burner becomes wider than before when the temperature becomes equal to or lower than a predetermined combustion up temperature, the combustion down temperature and the combustion up temperature have a plurality of high and low temperatures, respectively. And a switching time is set for each of the plurality of combustion down temperatures and combustion up temperatures, and the switching time is set to be longer as the combustion down temperature and the combustion up temperature are close to the required hot water temperature, During simultaneous operation of hot water supply and heating, when the switching time set for the combustion down temperature has elapsed since the heating-side hot water temperature has exceeded one of the combustion down temperatures The capacity switching valve is controlled so that the combustion area of the second burner becomes narrower than before, and the switching time set for the combustion up temperature after the heating side hot water temperature falls below any combustion up temperature. And a control means for controlling the capacity switching valve so that the combustion area of the second burner becomes wider than before.

  According to the present invention, the temperature range between the minimum combustion down temperature closest to the required hot water temperature of the heating terminal and the maximum combustion up temperature closest to the required hot water temperature becomes a dead zone in which the switching of the capacity switching valve is not performed. . And even if the hot water supply operation is performed during the heating operation and the heating side hot water temperature becomes higher than the minimum combustion down temperature or lower than the maximum combustion up temperature by the control of the proportional valve according to the hot water supply load, a relatively long time is required. If it does not elapse, the switching control of the capacity switching valve is not performed, and during that time, the hot water supply operation is stopped, and the probability that the control of the proportional valve according to the heating load is resumed increases. Therefore, even if the dead zone is narrowed, the switching frequency of the capacity switching valve does not increase as much as the left, and deterioration of durability is prevented. When the heating side hot water temperature is higher than the combustion down temperature set higher than the minimum combustion down temperature or lower than the combustion up temperature set lower than the maximum combustion up temperature, the capacity is switched in a relatively short time. The switching control of the valve is performed, and in combination with the narrowing of the dead zone, the fluctuation range of the heating side hot water temperature is suppressed to be small.

  By the way, as a heating terminal, high temperature heating terminals, such as a warm air heater whose required hot water temperature is relatively high (for example, 80 ° C.), and low temperature, such as a floor heating panel, whose required hot water temperature is relatively low (for example, 60 ° C.). When a heating terminal is provided, it is required that the fluctuation range of the heating-side hot water temperature T is suppressed smaller during heating operation using the high-temperature heating terminal than during heating operation using the low-temperature heating terminal. Therefore, the respective combustion down temperatures used during the heating operation by the high temperature heating terminal and the temperature difference between each combustion up temperature and the required hot water temperature of the heating terminal are the combustion down temperatures used during the heating operation by the low temperature heating terminal and It is desirable to make it smaller than the temperature difference between each combustion up temperature and the required hot water temperature of the heating terminal.

  FIG. 1 shows a single can type combined heat source in which a first combustion section 2-1 for hot water supply and a second combustion section 2-2 for heating are arranged in parallel in a single can body 1 with a partition wall 1a therebetween. Showing the machine. The 1st combustion part 2-1 has the 1st heat exchanger 3-1 for hot-water supply, and the 1st burner 4-1 which heats this, and the 2nd combustion part 2-1 is the 2nd for heating. It has the heat exchanger 3-2 and the 2nd burner 4-2 which heats this. Combustion air is supplied from a common combustion fan 5 to both combustion sections 2-1 and 2-2. The combustion exhaust of each of the first and second burners 4-1 and 4-2 is led to the first and second heat exchangers 3-1 and 3-2, and the heat exchangers 3-1 and 3 are used. After the heat exchange at -2, the air flows to the common exhaust hood 6 on the upper side of both heat exchangers 3-1 and 3-2, and is discharged to the outside through an exhaust port 6a formed in the exhaust hood 6. The rotation speed of the combustion fan 5 is controlled by the controller 7 so that the amount of combustion air corresponding to the combustion amount of both the first and second burners 4-1, 4-2 is supplied.

  The first heat exchanger 3-1 is connected to an upstream water supply passage 8a and a downstream hot water supply passage 8b. The water supply path 8 a is provided with a flow rate sensor 81 and a flow rate adjustment valve 82 controlled by the controller 7, and further provided with a bypass passage 8 c that connects the water supply path 8 a and the hot water supply path 8 b downstream of the flow rate adjustment valve 82. The bypass flow rate adjusting valve 83 controlled by the controller 7 is interposed in the bypass passage 8c. In addition, an upstream hot water temperature sensor 84 and a hot water temperature sensor 85 on the downstream side of the joining portion of the bypass passage 8c are provided in the hot water outlet 8b.

  Detection signals from the flow sensor 81 and the hot water temperature sensors 84 and 85 are input to the controller 7. Then, when the hot water tap 86 at the downstream end of the hot water supply passage 8b is opened and water is passed through the first heat exchanger 3-1, when the flow rate detected by the flow rate sensor 81 becomes equal to or higher than a predetermined lower limit flow rate, the combustion fan 5 is turned on. While driving, the 1st burner 4-1 is ignited and a hot water supply operation is performed. During the hot water supply operation, the combustion amount of the first burner 4-1 is controlled so that the temperature detected by the hot water temperature sensor 84 (the hot water supply side hot water temperature) becomes a predetermined high temperature set temperature, and the first burner 4-1 When the hot water supply side hot water temperature does not reach the high temperature set temperature even when the combustion amount becomes maximum, the flow rate control valve 82 reduces the amount of water flow to the first heat exchanger 3-1. Then, the amount of water (bypass mixing amount) flowing through the bypass passage 8c via the bypass flow rate adjustment valve 83 is controlled so that the detected temperature of the hot water temperature sensor 85 becomes the set hot water supply temperature set by the remote controller.

  The second heat exchanger 3-2 is connected via a heating circuit 9 to a hot water hot air heater 10 which is a high temperature heating terminal having a relatively high required hot water temperature. In the illustrated example, there is one hot air heater 10, but a plurality of hot air heaters 10 may be connected to the heating circuit 10 in parallel. The heating circuit 9 includes a heating passage 9a for sending hot water heated by the second heat exchanger 3-2 to the hot air heater 10, and the hot water passing through the hot air heater 10 for the second heat exchanger 3-2. And a heating return passage 9b for returning to the interior. A systurn 91 and a heating pump 92 controlled by the controller 7 are interposed in the heating return passage 9b. When the operation switch of the hot air heater 10 is turned on, the water flow valve 10a of the hot air heater 10 is opened and the heating pump 92 is driven, and the hot air heater 10 and the second heat exchanger are opened. Hot water is circulated through the heating circuit 9 between 3-2.

  Moreover, in this embodiment, the floor heating panel 11 which is a low temperature heating terminal whose required hot water temperature is comparatively low is provided, and the low temperature heating going from the part of the heating return passage 9b on the downstream side of the heating pump 92 to the floor heating panel 11 is provided. The passage 9c is branched. The hot water that has passed through the floor heating panel 11 is returned to the system 91 together with the hot water that has passed through the hot air heater 10. Further, the heating circuit 9 is provided with a bypass passage 9 d having a relatively large pipe resistance in parallel with the hot air heater 10. When the operation switch for floor heating is turned on, the water flow valve 11a of the floor heating panel 11 is opened and the heating pump 92 is driven. As a result, hot water is circulated to the second heat exchanger 3-2 via the bypass passage 9d, and part of the hot water sent from the heating pump 92 flows to the floor heating panel 11, and the second heat exchanger 3 -2 is transferred to the floor heating panel 11 via the cistern 91.

  A hot water temperature sensor 93 that detects the temperature of the hot water sent from the second heat exchanger 3-2 (heating-side hot water temperature) is provided in the upstream portion of the heating going-out passage 9a. A signal is input to the controller 7. When the hot air heater 10 and the floor heating operation switch are turned on to perform the heating operation, the heating side hot water temperature detected by the hot water temperature sensor 93 is the required hot water temperature of the hot air heater 10 and the floor heating panel 11. The combustion amount of the second burner 4-2 is controlled so that The required hot water temperature of the hot air heater 10 is relatively high (for example, 80 ° C.), and the required hot water temperature of the floor heating panel 11 is relatively low (for example, 60 ° C.).

  Further, in the present embodiment, the second heat exchanger 3-2 can be used for bathing. That is, a bath pump 131 and a liquid heat exchanger 132 controlled by the controller 7 are interposed in the bath circuit 13 connected to the bathtub 12, and the liquid heat exchanger is connected to the heating circuit 9 from the heating forward passage 9a. A follow-up passage 9e that leads to the system turn 91 through 132 is provided, and a follow-up valve 133 that is controlled by the controller 7 is provided in the follow-up passage 9e. When the reheating operation switch is turned on, the bath pump 131 is driven to circulate hot water in the bathtub 12 to the bath circuit 13, and the reheating valve 133 is opened and the heating pump 92 is driven to Hot water is circulated to the 2 heat exchanger 3-2 through the liquid heat exchanger 132, and the hot water in the bathtub 12 circulated to the bath circuit 13 is heated by the liquid heat exchanger 132. The bath circuit 13 is provided with a hot water temperature sensor 134 for detecting the temperature of hot water sent out from the bathtub 12, and a detection signal of the hot water temperature sensor 134 is input to the controller 7, and the detected temperature of the hot water temperature sensor 134 is set. The above-described chasing operation is stopped when the set chasing water temperature rises.

  In addition, a pouring channel 135 branched from the hot water supply channel 8 b is connected to the bath circuit 13 via a check valve 136. A hot water filling valve 137 controlled by the controller 7 is interposed in the pouring passage 135, and when the hot water filling switch is turned on, the hot water filling valve 137 is opened, and the first heat exchanger 3-1 is opened. The hot water heated in is poured into the bathtub 12.

  Next, gas supply to both the first and second burners 4-1, 4-2 will be described. A main valve 41 and a proportional valve 42 are interposed in a common gas supply path 40 for both the first and second burners 4-1, 4-2. Then, gas is supplied from the common gas supply path 40 to the first burner 4-1 via the capacity switching valves 43S, 43M, 43L for the first burner 4-1, and the second burner is also supplied from the common gas supply path 40. Gas is supplied to the second burner 4-2 through the capacity switching valves 44S and 44L for 4-2. In detail, the first burner 4-1 is composed of a plurality of, for example, 16 unit burners 4a arranged in the horizontal direction, and these unit burners 4a are composed of three unit burners 4a. The first unit burner group 4-1S, the second unit burner group 4-1M composed of five unit burners 4a, and the third unit burner group 4-1L composed of eight unit burners 4a are grouped. Gas is supplied to each unit burner group 4-1S, 4-1M, 4-1L via each capability switching valve 43S, 43M, 43L. Thus, the combustion area of the first burner 4-1 is the minimum area when the gas is supplied only to the first burner group 4-1S and the gas to all the unit burner groups 4-1S, 4-1M, 4-1L. It is possible to switch to a plurality of stages between the maximum area when the is supplied.

  The second burner 4-2 is composed of five unit burners 4a arranged in the horizontal direction, and these unit burners 4a are divided into a first unit burner group 4-2S composed of two unit burners 4a and three unit burners 4a. Are divided into a second unit burner group 4-2L composed of the unit burners 4a, and gas is supplied to the unit burner groups 4-2S and 4-2L via the capacity switching valves 44S and 44L. Thus, the combustion area of the second burner 4-2 is the minimum area when only the first capacity switching valve 44S is opened and gas is supplied only to the first unit burner group 4-2S, and the second capacity switching valve. An intermediate area when only 44L is opened and gas is supplied only to the second unit burner group 4-2L, and both the first and second capacity switching valves 44S and 44L are opened, and the first and second These unit burner groups 4-2S and 4-2L can be switched in three stages with the maximum area when the gas is supplied.

  The main valve 41, the proportional valve 42, the capacity switching valves 43S, 43M, 43L for the first burner 4-1, and the capacity switching valves 44S, 44L for the second burner 4-2 are controlled by the controller 7. At the time of independent operation of hot water supply (including hot water filling), the proportional valve 42 and the capacity switching valves 43S, 43M, and 43L are set so that the hot water supply side hot water temperature detected by the first hot water temperature sensor 84 becomes a predetermined high temperature setting temperature. The amount of combustion of the first burner 4-1 is controlled by controlling the combination of the above. Further, even when heating (including bath reheating) is independently operated, the heating side hot water temperature detected by the hot water temperature sensor 93 is set to the required hot water temperature of the hot air heater 10 and the floor heating panel 11 that are the heating terminals. The combustion amount of the second burner 4-2 is controlled by controlling the combination of the proportional valve 42 and the capacity switching valves 44S and 44L.

  FIG. 3 shows a change in the combustion amount due to a change in the opening degree of the proportional valve 42 when the second burner 4-2 is burned in the large, medium, and small areas, and L and H on the horizontal axis indicate the proportional valve 42. The lower limit opening and the upper limit opening that can be proportionally controlled. When the second burner 4-2 is burned in the maximum area, the combustion amount changes as indicated by line a in FIG. 3, and the combustion amounts at the lower limit opening and the upper limit opening of the proportional valve 42 are 5265 kcal / h and 9545 kcal, respectively. / H. When the second burner 4-2 is burned at an intermediate area, the amount of combustion changes as shown by line b in FIG. 3, and the amount of combustion at the lower limit opening and the upper limit opening of the proportional valve 42 is 3120 kcal / h, respectively. 5925 kcal / h, and when the second burner 4-2 is burned in the minimum area, the amount of combustion changes as indicated by the line c in FIG. The combustion amounts are 2054 kcal / h and 3900 kcal / h, respectively. Therefore, the combustion amount of the second burner 4-2 can be varied over a wide range by combining the change in the opening degree of the proportional valve 42 and the switching of the combustion area of the second burner 4-2 by the capacity switching valves 44S and 44L. The same applies to the first burner 4-1. Note that the heating side hot water temperature is set higher than the required hot water temperature of the heating terminal even if the second burner 4-2 is burned with the minimum area and the proportional valve 42 set to the lower limit opening degree during the heating independent operation. When the temperature is equal to or higher than a predetermined combustion off temperature, the combustion on / off control of the second burner 4-2 is performed.

  By the way, at the time of simultaneous operation of hot water supply and heating, priority is given to hot water supply, and the proportional valve 42 and capacity switching valves 43S, 43M, The amount of combustion of the first burner 4-1 is controlled by 43L. For this reason, during simultaneous operation of hot water supply and heating, the combustion amount of the second burner 4-2 cannot be appropriately controlled, and the heating-side hot water temperature may deviate from the required hot water temperature of the heating terminal. For example, when the hot water supply operation is performed during the heating operation, the opening degree of the proportional valve 42 is decreased compared to that during the heating single operation, and the heating-side hot water temperature is lower than the required hot water temperature, or compared with the heating single operation. However, the opening degree of the proportional valve 42 may increase and the heating side hot water temperature may become higher than the required hot water temperature.

  Therefore, at the time of simultaneous operation of hot water supply and heating, when the heating side hot water temperature becomes equal to or higher than a predetermined combustion down temperature set higher than the required hot water temperature of the heating terminal, the combustion area of the second burner 4-2 until then is reached. When the capacity switching valves 44S and 44L are controlled so as to be narrower and the heating-side hot water temperature falls below a predetermined combustion up temperature set lower than the required hot water temperature of the heating terminal, the second burner 4-2 The capacity switching valves 44S and 44L are controlled so that the combustion area of the engine becomes wider than before.

  Furthermore, in the present embodiment, as the combustion down temperature, a first combustion down temperature Tdn1 (for example, Tdn1 = required hot water temperature + 3 ° C.) slightly higher than the required hot water temperature of the heating terminal, and a second higher than the first combustion down temperature Tdn1. The combustion down temperature Tdn2 (for example, Tdn2 = Tdn1 + 7 ° C.) is set, and the switching times tdn1 and tdn2 are set for the combustion down temperatures Tdn1 and Tdn2, respectively, and are set for the first combustion down temperature Tdn1. The first combustion down switching time tdn1 is set longer than the second combustion down switching time tdn2 set with respect to the second combustion down temperature Tdn2 (for example, tdn1 = 20 seconds, tdn2 = 2 seconds). Similarly, as the combustion up temperature, a first combustion up temperature Tup1 (for example, Tup1 = required hot water temperature −3 ° C.) slightly lower than the required hot water temperature of the heating terminal, and a second combustion up temperature lower than the first combustion up temperature Tup1. Tup2 (for example, Tup2 = Tup1-12 ° C.) is set, switching times tup1, tup2 are set for these combustion up temperatures Tup1, Tup2, and the first combustion up temperature Tup1 is set. The first combustion up switching time tup1 is longer than the second combustion up switching time tup2 set with respect to the second combustion up temperature Tup2 (for example, tup1 = 20 seconds, tup2 = 2 seconds). Further, a combustion on temperature Ton lower than the second combustion up temperature Tup2 is set, and a predetermined combustion on switching time ton is also set for the combustion on temperature Ton.

  FIG. 2 shows a combustion control program for the second burner 4-2 during simultaneous operation of hot water supply and heating. This will be described in detail. First, in a step S1, a determination process for the combustion area of the second burner 4-2 is performed. In this determination process, when the hot water supply operation is performed during the single heating operation and the operation shifts to the simultaneous operation, the combustion area of the second burner 4-2 immediately before the transfer to the simultaneous operation is determined, and the determination area is the maximum area. When the process proceeds to step S2, the combustion at the maximum area for opening both the first and second capacity switching valves 44S, 44L for the second burner 4-2 is continued, and the discriminating combustion area is an intermediate area. When there is, the routine proceeds to step S3, where the combustion is continued in the intermediate area where only the second capacity switching valve 44L is opened. When the discrimination area is the minimum area, the routine proceeds to step S4, where the first capacity switching is performed. The combustion in the minimum area that opens only the valve 44S is continued. In addition, when the heating operation is performed during the hot water supply operation and the operation is shifted to the simultaneous operation, the combustion area is determined according to the heating side hot water temperature detected by the hot water temperature sensor 93 in the combustion area determination process, and the heating side hot water is discharged. When the temperature is relatively low, the process proceeds to step S2 to start the combustion of the second burner 4-2 with the maximum area, and when the heating side tapping temperature is relatively high, the process proceeds to step S3 and the second burner 4-2. Starts burning in the middle area.

  At the time of combustion in the maximum area, first, it is determined whether or not the heating side tapping temperature T detected by the hot water temperature sensor 93 in step S5 is equal to or higher than the first combustion down temperature Tdn1, and if T ≧ Tdn1, In step S6, it is determined whether or not the heating-side tapping temperature T is equal to or higher than the second combustion down temperature Tdn2. If T <Tdn2, it is determined whether or not the first combustion down switching time tdn1 has elapsed since T ≧ Tdn1 in step S7. If T ≧ Tdn2, the process proceeds to step S8. It is determined whether or not the second combustion down switching time tdn2 has elapsed since T ≧ Tdn2, and when it is determined in step S7 that tdn1 has elapsed, or in step S8, it is determined that tdn2 has elapsed. In step S3, the combustion area of the second burner 4-2 is switched to the intermediate area.

  At the time of combustion in an intermediate area, first, it is determined in step S9 whether or not the heating side hot water temperature T is equal to or lower than the first combustion up temperature Tup1, and if T ≦ Tup1, the heating side hot water temperature is determined in step S10. It is determined whether T is equal to or lower than the second combustion up temperature Tup2. If T> Tup2, it is determined whether or not the first combustion up switching time tup1 has elapsed since T ≦ Tup1 in step S11. If T ≦ Tup2, the process proceeds to step S12. It is determined whether or not the second combustion up switching time tup2 has elapsed since T ≦ Tup2, and when it is determined that tup1 has elapsed in step S11, or when tup2 has elapsed in step S12 In step S2, the combustion area of the second burner 4-2 is switched to the maximum area.

  When it is determined in step S9 that T> Tup1, the process proceeds to step S13, where it is determined whether or not the heating-side hot water temperature T is equal to or higher than the first combustion down temperature Tdn1, and if T ≧ Tdn1, S14 In this step, it is determined whether or not the heating side tapping temperature T is equal to or higher than the second combustion down temperature Tdn2. If T <Tdn2, it is determined whether or not the first combustion down switching time tdn1 has elapsed since T ≧ Tdn1 in step S15. If T ≧ Tdn2, the process proceeds to step S16. It is determined whether or not the second combustion down switching time tdn2 has elapsed since T ≧ Tdn2, and when it is determined that tdn1 has elapsed in step S15 or when tdn2 has elapsed in step S16 In step S4, the combustion area of the second burner 4-2 is switched to the minimum area.

  At the time of combustion in the minimum area, first, in step S17, it is determined whether or not the heating side hot water temperature T is equal to or lower than the first combustion up temperature Tup1, and if T ≦ Tup1, the heating side hot water temperature is determined in step S18. It is determined whether T is equal to or lower than the second combustion up temperature Tup2. If T> Tup2, it is determined whether or not the first combustion up switching time tup1 has elapsed since T ≦ Tup1 in step S19. If T ≦ Tup2, the process proceeds to step S20. It is determined whether or not the second combustion up switching time tup2 has elapsed since T ≦ Tup2, and when it is determined at step S19 that tup1 has elapsed or when it is determined at step S20 that tup2 has elapsed In step S3, the combustion area of the second burner 4-2 is switched to the intermediate area.

  When it is determined in step S17 that T> Tup1, the process proceeds to step S21, in which it is determined whether or not the heating side hot water temperature T is equal to or higher than the first combustion down temperature Tdn1, and if T ≧ Tdn1, S22 is reached. In this step, it is determined whether or not the heating side tapping temperature T is equal to or higher than the second combustion down temperature Tdn2. If T <Tdn2, it is determined whether or not the first combustion down switching time tdn1 has elapsed since T ≧ Tdn1 in step S23. If T ≧ Tdn2, the process proceeds to step S24. It is determined whether or not the second combustion down switching time tdn2 has elapsed since T ≧ Tdn2, and when it is determined in step S23 that tdn1 has elapsed, or in step S24, it is determined that tdn2 has elapsed. In addition, the combustion of the second burner 4-2 is temporarily stopped in step S25. Thereafter, in step S26, it is determined whether or not the heating side hot water temperature T has become equal to or lower than the combustion on temperature Ton. If T ≦ Ton, the combustion on switching time ton is set after T ≦ Ton in step S27. It is determined whether or not it has elapsed, and when it is determined that ton has elapsed, the process proceeds to step S2 and the combustion of the second burner 4-2 is restarted with the maximum area.

  According to the above control, the temperature range between the first combustion down temperature Tdn1 closest to the required hot water temperature of the heating terminal and the first combustion up temperature Tup1 closest to the required hot water temperature is determined by the capacity switching valves 44S and 44L. This is a dead zone where the combustion area of the second burner 4-2 is not switched. In the simultaneous operation of hot water supply and heating, even if the heating side hot water temperature T becomes higher than the first combustion down temperature Tdn1 or lower than the first combustion up temperature Tup1 by the control of the proportional valve 42 according to the hot water supply load, the comparison is made. If the long time tdn1, tup1 has not elapsed, the switching control of the capacity switching valves 44S, 44L is not performed, and during that time, the hot water supply operation is stopped, and the probability that the control of the proportional valve 42 according to the heating load is resumed increases. . Therefore, even if the dead zone is narrowed, the switching frequency of the capacity switching valves 44S and 44L does not increase as much as the left, and deterioration of durability is prevented. Further, the heating side hot water temperature T becomes equal to or higher than the second combustion down temperature Tdn2 set higher than the first combustion down temperature Tdn1, or becomes equal to or lower than the second combustion up temperature Tup2 set lower than the first combustion up temperature Tup1. In this case, the switching control of the capacity switching valves 44S and 44L is performed in a relatively short time tdn2 and tup2, and the fluctuation range of the heating side tapping temperature T is suppressed to be small in combination with the narrowing of the dead zone.

  By the way, in the heating operation by the hot air heater 10 which is a high temperature heating terminal having a high required hot water temperature, the fluctuation range of the heating side hot water temperature T compared to the heating operation by the floor heating panel 11 which is a low temperature heating terminal having a relatively low required hot water temperature. Is required to be kept small. Therefore, the temperature differences between the combustion down temperatures Tdn1, Tdn2 and the combustion up temperatures Tup1, Tup2 used during the heating operation by the hot air heater 10 and the required hot water temperature of the heating terminal are used during the heating operation by the floor heating panel 11. It is desirable to make it smaller than the temperature difference between each combustion down temperature Tdn1, Tdn2 and each combustion up temperature Tup1, Tup2 and the required hot water temperature of the heating terminal.

  Moreover, in the said embodiment, although restart of the combustion after stopping the combustion of the 2nd burner 4-2 by the step of S25 is performed by the maximum area, restarting of combustion is performed by an intermediate area or the minimum area. Is also possible. However, in order to raise the heating side hot water temperature T, which has decreased during the combustion stop, to the required hot water temperature of the heating terminal at an early stage, it is desirable to restart the combustion in the maximum area.

  In the above embodiment, the combustion area of the second burner 4-2 can be switched in three stages, but it may be switched in two stages or four or more stages. In the above-described embodiment, the first and second temperatures Tdn1, Tdn2, Tup1, and Tup2 are set as the combustion down temperature and the combustion up temperature, respectively. It is also possible to set the temperature.

Explanatory drawing which shows the structure of embodiment of this invention heat source machine. The flowchart which shows the control program of the 2nd burner at the time of the simultaneous operation | movement of the hot water supply and heating of the heat-source machine of FIG. The graph which shows the relationship between the opening degree of a proportional valve and combustion amount when the combustion area of the 2nd burner of the heat source machine of FIG.

Explanation of symbols

  2-1 ... 1st combustion part, 2-2 ... 2nd combustion part, 3-1 ... 1st heat exchanger, 3-2 ... 2nd heat exchanger, 4-1 ... 1st burner, 4-2 ... 2nd burner, 42 ... proportional valve, 44S, 44L ... capacity switching valve, 7 ... controller (control means), 10 ... hot air heater (high temperature heating terminal), 11 ... floor heating panel (low temperature heating terminal).

Claims (2)

A second heat exchanger for heating and a second heat for circulating hot water between a first heat exchanger for hot water supply and a first combustion section having a first burner for heating the first heat exchanger and a heating terminal A combined heat source machine comprising a second combustion section having a second burner for heating the exchanger, a single proportional valve interposed in a common gas supply path for both the first and second burners; It is equipped with a capacity switching valve that can switch the combustion area of the two burners into a wide and narrow plurality of stages, and the temperature of the hot water sent from the first heat exchanger is set to the hot water supply hot water temperature, and the temperature of the hot water sent from the second heat exchanger is heated. As the side hot water temperature, during the simultaneous operation of hot water supply and heating, the combustion amount of the first burner is controlled by a proportional valve so that the hot water supply hot water temperature becomes a predetermined set temperature, and the heating hot water temperature is the required hot water of the heating terminal. When the specified combustion down temperature is set higher than the temperature When the capacity switching valve is controlled so that the combustion area of the second burner becomes narrower than before, the heating side hot water temperature becomes lower than the predetermined combustion up temperature set lower than the required hot water temperature of the heating terminal. In the control of the capacity switching valve so that the combustion area of the second burner is larger than before,
A plurality of temperatures are set as the combustion down temperature and the combustion up temperature, respectively, and a switching time is set for each of the plurality of combustion down temperatures and combustion up temperatures, and the switching time is a combustion close to the required hot water temperature. It is set to become longer as the down temperature and the combustion up temperature,
During simultaneous operation of hot water supply and heating, when the switching time set for the combustion down temperature has elapsed after the heating side hot water temperature has exceeded one of the combustion down temperatures, the combustion area of the second burner When the switching time set for the combustion up temperature has elapsed after the heating side hot water temperature has fallen below one of the combustion up temperatures, the capacity switching valve is controlled to be narrower than the second. A composite heat source machine comprising control means for controlling the capacity switching valve so that the burner has a larger combustion area than before.   2. The combined heat source machine according to claim 1, wherein the heating terminal includes a high temperature heating terminal and a low temperature heating terminal whose required hot water temperature is lower than that of the high temperature heating terminal. The temperature difference between the combustion up temperature and the required hot water temperature is smaller than the temperature difference between each combustion down temperature and each combustion up temperature and the required hot water temperature used during heating operation by a low-temperature heating terminal. Combined heat source machine.

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