Patent Publication Number: US-2021190329-A1

Title: Hot water heating system

Description:
BACKGROUND 
     Technical Field 
     The disclosure relates to a hot water heating system which performs heating using heat of a heat medium heated by a hot water heating device. 
     Description of Related Art 
     Conventionally, a hot water heating system has been widely used to perform heating by supplying hot water heated by a hot water heating device as a heat medium to a heating terminal. For example, as in Patent Document 1, such a hot water heating system is configured so that, during a heating operation, the heat medium heated by a heating part of the hot water heating device is supplied to the heating terminal, and the heat medium returning from the heating terminal is heated again by the heating part. The hot water heating device is connected to the heating terminal via a heat circulation circuit, and includes a pump which circulates the heat medium to the heat circulation circuit and an expansion tank for absorbing a volumetric expansion of the heat medium due to an increase in temperature. In addition, the hot water heating device has a hot water supply function which supplies a hot water supply heated by the heating part. 
     Moreover, in the case where there are a plurality of heating terminals or in the case where the distance between the hot water heating device and the heating terminal is large, the passage length of the heat circulation circuit increases. In such a case, since the load on the pump of the hot water heating device increases, an external pump capable of circulating the heat medium in conjunction with the pump of the hot water heating device is provided outside the hot water heating device. 
     In addition, as the passage length of the heat circulation circuit increases, the amount of the heat medium to be circulated increases, so that the amount of the volumetric expansion of the heat medium also increases. Therefore, in the case where the capacity of the expansion tank of the hot water heating device is insufficient, the expansion tank may be provided outside the hot water heating device. Further, on the assumption that the expansion tank is provided outside, it is also possible that the hot water heating device does not include an expansion tank in the first place. 
     RELATED ART 
     Patent Document(s) 
     Patent Document 1: Japanese Laid-open No. 2015-222137 
     SUMMARY 
     Problems to be Solved 
     In the case where the hot water heating system is configured by providing the expansion tank and the external pump outside the hot water heating device, the expansion tank and the external pump are arranged in the heat circulation circuit which connects the hot water heating device and the heating terminal. In that case, if the positional relationship between the expansion tank and the external pump is inappropriate, an internal pressure of the flow passage of the heat medium in the hot water heating device at the time driving of the external pump starts will be lower than that before the driving. As a result, the hot water heating device determines that the heat medium decreases, and automatically supplies the heat medium or issues a notification which prompts the supply. 
     However, since the cause of the decrease in the internal pressure is not the decrease in the heat medium, the decrease in the internal pressure is not eliminated even if the heat medium is supplied. For this reason, there is a risk that the hot water heating device would make an erroneous determination of a leak of the heat medium and thus notify occurrence of the leak and stop the heating operation. 
     An objective of the disclosure is to provide a hot water heating system capable of determining that a positional relationship between a circulation means and an expansion-absorbing means is inappropriate. 
     Means for Solving the Problems 
     In the disclosure of claim  1 , a hot water heating system includes a hot water heating device, a heating terminal, a heat circulation circuit connecting the hot water heating device and the heating terminal, a circulation means provided in the heat circulation circuit, and an expansion-absorbing means provided in the heat circulation circuit to absorb a volumetric expansion of a heat medium due to an increase in temperature. The hot water heating device includes a heating passage connected to the heat circulation circuit, a heating means which heats the heat medium in the heating passage, a pressure detection means which detects an internal pressure of the heating passage, a supply passage connected to the heating passage, an opening/closing means for opening and closing the supply passage, and a control means which opens the opening/closing means to supply the heat medium when the pressure detection means detects that the internal pressure of the heating passage is less than a preset reference value. The control means determines that a positional relationship between the circulation means and the expansion-absorbing means is inappropriate in a case where a detection pressure of the pressure detection means at the time driving of the circulation means starts is lower than a detection pressure before the driving of the circulation means. 
     According to the above configuration, during a heating operation, the hot water heating system circulates the heat medium heated by the hot water heating device to the heat circulation circuit through the circulation means. The expansion-absorbing means provided in the heat circulation circuit absorbs the volumetric expansion of the heat medium due to the increase in temperature to prevent damage or leak resulting from an increase in the internal pressure of the heat circulation circuit and the heating passage. The internal pressure of the heating passage is detected by the pressure detection means of the hot water heating device, and when the amount of the heat medium decreases and the internal pressure of the heating passage becomes less than the reference value, the control means supplies the heat medium. In the case where the internal pressure of the heating passage at the time the driving of the circulation means starts is lower than the internal pressure before the driving, the control means determines that the positional relationship between the circulation means and the expansion-absorbing means is inappropriate. Therefore, in a test operation performed at the time of construction of the hot water heating system, since it is possible to determine that the circulation means and the expansion-absorbing means have been connected in an inappropriate positional relationship at the time the driving of the circulation means starts, they can be reconnected in an appropriate positional relationship. 
     In the disclosure of claim  2  according to claim  1 , the hot water heating device includes a bypass passage which branches off from the heating passage downstream of the heating means and connects to the heating passage upstream of the heating means so as to bypass the heat circulation circuit. The bypass passage includes a heat exchanger for performing heat exchange between the heat medium and a hot water supply. 
     According to the above configuration, the hot water supply can be heated using the heat medium, so that it is possible to configure a hot water heating system having a hot water supply function. 
     The disclosure of claim  3  according to claim  2  further includes a distribution valve capable of adjusting a distribution ratio of the heat medium at a branching part of the heating passage and the bypass passage. 
     According to the above configuration, since the heated heat medium can be distributed for heating and for hot water supply, it is possible to configure a hot water heating system which can simultaneously perform heating and hot water supply. 
     Effects 
     According to the hot water heating system of the disclosure, it is possible to determine that a positional relationship between the circulation means and the expansion-absorbing means is inappropriate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing an overall configuration of a hot water heating system according to an embodiment. 
         FIG. 2  is a view showing a configuration of a hot water heating device according to the embodiment. 
         FIG. 3  is a view showing a hot water supply system in which a circulation pump and an expansion tank are arranged in an inappropriate positional relationship. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, the configuration for implementing the disclosure will be described based on the embodiments. 
     Embodiments 
     First, the overall configuration of a hot water heating system  1  will be described based on  FIG. 1 . The hot water heating system  1  is configured to perform a heating operation in which heating is performed by supplying a heat medium heated by a hot water heating device  2  to a heating terminal  3 . The hot water heating system  1  includes a hot water heating device  2 , a heating terminal  3 , a heat circulation circuit  4  connecting the hot water heating device  2  and the heating terminal  3 , an external pump  5  (circulation means) provided in the heat circulation circuit  4 , and a closed expansion tank  6  (expansion-absorbing means) provided in the heat circulation circuit  4  to absorb a volumetric expansion of the heat medium due to an increase in temperature, and the passage through which the heat medium flows is configured as a closed type. For example, the heating terminal  3  may be a hot air heating device which blows air heated by the heat of the heat medium, a panel heater or a floor heating device which performs heating by using the radiant heat of the heat medium and natural convection of air, and the like, and a plurality of these devices may also be connected. 
     The heat circulation circuit  4  includes a terminal circulation circuit part  4   a  which circulates and supplies the heat medium to the heating terminal  3  through driving of the external pump  5 , and a heating circulation circuit part  4   b  which supplies the heat medium from the terminal circulation circuit part  4   a  to the hot water heating device  2  and supplies the heat medium heated by the hot water heating device  2  to the terminal circulation circuit part  4   a . To have an appropriate positional relationship with respect to the external pump  5 , the expansion tank  6  is provided upstream of the external pump  5  of the terminal circulation circuit part  4   a . The heating circulation circuit part  4   b  is connected to the upstream of the expansion tank  6  of the terminal circulation circuit part  4   a . During the heating operation, even if the supply of the heat medium from the hot water heating device  2  is temporarily interrupted for a hot water supply operation as described below, heating can be continued with the heat medium which circulates through the terminal circulation circuit part  4   a.    
     Next, the hot water heating device  2  will be described based on  FIG. 2 . During the heating operation, the hot water heating device  2  heats the heat medium and supplies the heat medium to the heat circulation circuit  4 . In addition, it has a hot water supply function which supplies hot water by adjusting the tap water heated using the heat of the heat medium to a hot water supply setting temperature. The hot water heating device  2  is configured so that the hot water supply function can be used even during the heating operation. 
     The hot water heating device  2  includes a heating passage  10  connected to the heat circulation circuit  4 , a heating part  11  (heating means) which heats the heat medium in the heating passage  10 , a built-in pump  13  provided in the heating passage  10 , a pressure sensor  14  (pressure detection means) which detects an internal pressure of the heating passage  10 , a supply passage  15  connected to the heating passage  10 , an opening/closing valve  16  (opening/closing means) for opening and closing the supply passage  15 , and a control part  17  (control means) which controls the heating operation and the like. During the heating operation, the built-in pump  13  can circulate the heat medium in conjunction with the external pump  5 . The heating part  11  heats the heat medium by using, for example, the heat of combustion when a fuel gas indicated by an arrow F and air indicated by an arrow AS are mixed and burned. 
     The hot water heating device  2  includes a first bypass passage  18  (bypass passage), a hot water supply heat exchanger  19  (heat exchanger) provided in the first bypass passage  18 , a water supply passage  20 , a hot water passage  21 , etc. To bypass the heat circulation circuit  4 , the first bypass passage  18  is branched off from the heating passage  10  downstream of the heating part  11 , and joins the heating passage  10  upstream of the built-in pump  13 . The water supply passage  20  supplies tap water indicated by an arrow CW to the hot water supply heat exchanger  19 . The hot water supply passage  21  supplies a hot water supply heated by the hot water supply heat exchanger  19  to a hot water tap or the like, as indicated by an arrow HW. 
     Next, the heating passage  10  will be described. The heating passage  10  includes a first temperature sensor  22  between the heating part  11  and the built-in pump  13 , and includes a second temperature sensor  23  downstream of the heating part  11 . The first temperature sensor  22  detects the temperature of the heat medium flowing to the heating part  11 . The second temperature sensor  23  detects the temperature of the heat medium heated by the heating part  11 . Based on the detection temperatures of these sensors, the heating part  11 , the built-in pump  13 , etc. are controlled by the control part  17  so that the temperature of the heated heat medium can become a predetermined temperature. 
     A first distribution valve  24  (distribution valve) is provided at a branching part of the heating passage  10  and the first bypass passage  18 . The first distribution valve  24  can adjust a distribution ratio to be adaptable to the heating operation, the hot water supply operation, and the simultaneous operation of heating and hot water supply, and distributes the heat medium heated by the heating part  11  to the heating passage  10  and the first bypass passage  18 . The distribution ratio of the first distribution valve  24  is adjusted so that the heat medium is supplied only to the heating passage  10  during the heating operation and is adjusted so that the heat medium is supplied only to the first bypass passage  18  during the hot water supply operation. In addition, during the simultaneous operation of heating and hot water supply, with the distribution ratio of the first distribution valve  24  adjusted so that hot water supply is prioritized, the heat medium is distributed to the heating passage  10  and the first bypass passage  18 . The heat medium distributed by the first distribution valve  24  to the heating passage  10  is supplied to the heat circulation circuit  4  as indicated by an arrow HS. 
     A pressure release valve  25  capable of releasing the pressure in the heating passage  10  is provided between the heating part  11  and the first distribution valve  24 . A heat return temperature sensor  26  which detects the temperature of the heat medium returning from the heat circulation circuit  4 , as indicated by an arrow HR, is provided upstream of the built-in pump  13 . A supply passage  15  for supplying the heat medium, as indicated by an arrow AF, is connected between the built-in pump  13  and the heat return temperature sensor  26 . The supply passage  15  is provided with an opening/closing valve  16 , and a pressure sensor  14  is provided in the supply passage  15  downstream of the opening/closing valve  16 . 
     Next, the water supply passage  20  and the hot water supply passage  21  will be described. The water supply passage  20  includes a second distribution valve  27 , a flow adjustment valve  28 , a flow sensor  29 , and an incoming water temperature sensor  30 . A second bypass passage  31  is branched off from the water supply passage  20 , and the second distribution valve  27 , which is provided at the branching part and can adjust the distribution ratio, distributes tap water to the water supply passage  20  and the second bypass passage  31 . The flow adjustment valve  28  adjusts the flow rate of the tap water entering the second distribution valve  27 . The flow sensor  29  detects the flow rate of the tap water entering the second distribution valve  27 . The incoming water temperature sensor  30  detects the temperature of the tap water entering the second distribution valve  27 . 
     The second bypass passage  31  joins the hot water supply passage  21  at a junction part C. A hot water delivery temperature sensor  32  is provided between the junction part C of the hot water supply passage  21  and the hot water supply heat exchanger  19 . The hot water delivery temperature sensor  32  detects the temperature of the hot water delivered from the hot water supply heat exchanger  19 . 
     A hot water supply temperature sensor  33  is provided at the downstream end of the hot water supply passage  21 . The hot water supply temperature sensor  33  detects a hot water supply temperature of the hot water supply which is mixed from the hot water heated by the hot water supply heat exchanger  19  and the tap water flowing through the second bypass passage  31 . During the hot water supply operation, the distribution ratio of the second distribution valve  27  is adjusted so that the hot water supply temperature can become a set temperature. 
     Next, the control part  17  will be described based on  FIG. 1  and  FIG. 2 . Based on detection signals of sensors provided in the hot water heating device  2 , the control part  17  controls the heating part  11 , the built-in pump  13 , the external pump  5 , the first distribution valve  24 , etc. to control each of the heating operation, the hot water supply operation, and the simultaneous operation of heating and hot water supply. For the control of the heating operation, the control part  17  is communicably connected to the heating terminal  3  and the external pump  5 , respectively. The control part  17  is connected to an operation terminal  34  for performing a setting operation and the like on the hot water heating device  2 . The operation terminal  34  includes, for example, a display part  35  capable of displaying information such as temperature, and a switch part  36  for performing a setting operation and the like. 
     When the pressure sensor  14  detects that the internal pressure of the heating passage  10  is less than a preset reference value, the control part  17  opens the opening/closing valve  16  to supply the heat medium. In the case where any abnormality is detected in the hot water heating device  2 , the abnormality is notified through the operation terminal  34 , and an operation stop or the like is performed for safety. The reference value of the internal pressure of the heating passage  10  is preset based on an internal pressure or the like obtained, for example, through an experiment in which the heat medium is heated and circulated, and it may be adjusted through the operation of the operation terminal  34 . 
     At the time of construction of the hot water heating system  1 , after connecting each device, the installer introduces the heat medium into the hot water heating system  1 , performs a test operation of the heating operation and the like, and checks whether there is any abnormality such as a leak of the heat medium. In the test operation, if a detection pressure of the pressure sensor  14  at the time driving of the external pump  5  starts is lower than the detection pressure before driving, the controller  17  determines that the positional relationship between the external pump  5  and the expansion tank  6  is inappropriate. Then, the determination of the inappropriateness is, for example, displayed on the display part  35  of the operation terminal  34  to notify the installer. 
     The determination of the positional relationship between the external pump  5  and the expansion tank  6  will be described. When driving of the external pump  5  starts, the heat medium is pushed out to downstream of the external pump  5 , and the heat medium upstream of the external pump  5  equivalent to the pushed amount is drawn into the external pump  5 . 
     As shown in  FIG. 1 , if the expansion tank  6  is provided upstream of the external pump  5  (which is an appropriate position with respect to the external pump  5 ), the heat medium equivalent to the amount pushed out from the external pump  5  is pushed out from the heating terminal  3 , a part thereof flows into the hot water heating device  2 , and the remaining part flows through the terminal circulation circuit part  4   a . As heated heat medium equivalent to the amount of the heat medium which has flowed into the hot water heating device  2  is supplied from the hot water heating device  2  to the terminal circulation circuit part  4   a , the amount pushed out from the external pump  5  is in line with the amount drawn into the external pump  5 . Therefore, the internal pressure of the heating passage  10  detected by the pressure sensor  14  of the hot water heating device  2  does not change before and after the driving of the external pump  5  starts. 
     On the other hand, as shown in  FIG. 3 , if the expansion tank  6  is provided downstream of the external pump  5  (which is an inappropriate position with respect to the external pump  5 ), a part of the heat medium pushed out from the external pump  5  flows into the expansion tank  6 , the heat medium flowing into the hot water heating device  2  decreases, and the heat medium pushed out from the hot water heating device  2  decreases. Then, a part thereof flows into the hot water heating device  2  and the remaining part flows through the terminal circulation circuit part  4   a . Heated heat medium more than the amount of the heat medium flowing into the hot water heating device  2  is drawn into the external pump  5  from the hot water heating device  2  so that the amount pushed out from the external pump  5  is in line with the amount drawn into the external pump  5 . For this reason, the internal pressure of the heating passage  10  detected by the pressure sensor  14  of the hot water heating device  2  is lower than that before the driving of the external pump  5  starts. Therefore, the inappropriateness of the positional relationship between the external pump  5  and the expansion tank  6  can be determined based on the detection pressure of the pressure sensor  14  when the external pump  5  is driven. In the case where the amount of the heat medium is insufficient, the detection pressure of the pressure sensor  14  becomes less than the reference value regardless of whether the external pump  5  is driven, and thus distinction can be easily made. 
     The operation and effect of the disclosure will be described. At the time of construction of the hot water heating system  1 , after connecting each device, the installer introduces the heat medium into the hot water heating system  1  and performs a test operation of the heating operation and the like. When driving of the external pump  5  starts, in the case where the internal pressure of the heating passage  10  is lower than that before the driving of the external pump  5 , since it is possible to determine that the positional relationship between the external pump  5  and the expansion tank  6  is inappropriate, the installer can immediately reconnect them in an appropriate positional relationship. Therefore, it is possible to prevent the use of the hot water heating system  1  in which the external pump  5  and the expansion tank  6  are connected in an inappropriate positional relationship, and prevent a situation in which the heating operation is stopped due to the erroneous determination of a heat medium leak. 
     Moreover, the hot water heating device  2  includes the hot water supply heat exchanger  19  for performing heat exchange between the heat medium and the hot water supply at the first bypass passage  18  branched off from the heating passage  10 , and the hot water supply can be heated using the heat medium. Therefore, it is possible to configure a hot water heating system  1  having a hot water supply function. In addition, since the first distribution valve  24  which can adjust the distribution ratio of the heat medium is provided at the branching part of the heating passage  10  and the first bypass passage  18 , it is possible to configure a hot water heating system  1  which can simultaneously perform heating and hot water supply by distributing the heated heat medium for heating and for hot water supply. 
     A person skilled in the art can implement various modifications to the above-described embodiments without departing from the spirit of the disclosure, and the disclosure includes such modifications. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
         
           
               1 : Hot water heating system 
               2 : Hot water heating device 
               3 : Heating terminal 
               4 : Heat circulation circuit 
               5 : External pump (circulation means) 
               6 : Expansion tank (expansion-absorbing means) 
               10 : Heating passage 
               11 : Heating part (heating means) 
               14 : Pressure sensor (pressure detection means) 
               15 : Supply passage 
               16 : Opening/closing valve (opening/closing means) 
               17 : Control part (control means) 
               18 : First bypass passage (bypass passage) 
               19 : Hot water supply heat exchanger (heat exchanger) 
               20 : Water supply passage 
               21 : Hot water supply passage 
               24 : First distribution valve (distribution valve) 
               34 : Operation terminal