JP5571611B2 - Latent heat recovery type water heater - Google Patents

Description

  The present invention relates to prevention of freezing of a latent heat recovery type water heater.

  In the conventional water heater, in order to improve the heat exchange efficiency, a primary heat exchanger that recovers sensible heat from the combustion gas generated by combustion of the burner, and a latent heat from the combustion gas that has passed through the primary heat exchanger are recovered. A latent heat recovery type water heater having a secondary heat exchanger and a neutralizer that neutralizes the drain generated in the secondary heat exchanger has become widespread, and in such a water heater, the drain in the neutralizer In order to prevent freezing, a freezing prevention heater is added to the neutralizer (for example, see Patent Document 1), and the freezing prevention heater is used to prevent freezing in a low temperature environment. .

JP-A-9-26291

  By the way, with this latent heat recovery type water heater, freezing inside the neutralizer can be prevented when the outside air temperature is low, but the problem is that power consumption is increased and the cost is increased by adding the antifreezing heater. It was what had.

  Therefore, the present invention has an object to provide a latent heat recovery type water heater that can reduce power consumption and cost by eliminating a freeze prevention heater while preventing the freezing of the drain in the neutralizer when the outside air temperature is low. It is what.

  In order to solve the above-described problems, the present invention is particularly configured in the first aspect of the invention in that water that collects sensible heat from combustion gas generated by combustion of a water supply pipe and a burner that burns fuel and circulates through the primary heat receiving pipe is used. A primary heat exchanger, a secondary heat exchanger that recovers latent heat from the combustion gas after passing through the primary heat exchanger and heats water flowing through the secondary heat receiving pipe, a hot water supply pipe, and the A hot water supply circuit composed of a water supply pipe, the primary heat receiving pipe, the secondary heat receiving pipe, and the hot water supply pipe, and a drain that drains the drain generated in the secondary heat exchanger as the water is heated in the hot water supply circuit In the latent heat recovery type water heater provided with a drainage path and a neutralizer provided in the middle of the drainage drainage path, the drainage drainage path on the upstream side of the neutralizer or the neutralizer And a communication path connecting the hot water supply circuit and the communication path An opening / closing means for opening and closing and a temperature detection means for detecting a freezing prevention temperature are provided, and when the heating of the water in the hot water supply circuit is stopped and the temperature detection means detects the freezing prevention temperature, The opening / closing means was opened to allow water to flow.

  Further, in claim 2, a primary heat exchanger that recovers sensible heat from combustion gas generated by combustion of a burner that burns fuel and heats water flowing through the primary heat receiving pipe, and the primary heat exchanger A secondary heat exchanger that recovers latent heat from the combustion gas after passing through and heats water flowing through the secondary heat receiving pipe, a hot water supply pipe, the water supply pipe, the primary heat receiving pipe, and the secondary heat receiving pipe, A hot water supply circuit constituted by the hot water supply pipe, a drain drainage passage for draining drain generated in the secondary heat exchanger as the water is heated in the hot water supply circuit, and the drain provided in the middle of the drain drainage route A latent heat recovery type water heater provided with a neutralizer that neutralizes the neutralizer, a communication passage that connects the drain drain passage upstream of the neutralizer or the neutralizer and the hot water pipe, and the communication Opening and closing means for opening and closing the passage, and temperature for detecting the freeze prevention temperature The detecting means is provided, with the heating of the water in the hot water supply circuit is stopped, when the temperature detecting means detects the antifreeze temperature was assumed to be passed through by opening the switching means.

  According to a third aspect of the present invention, the water flow rate of the communication passage is set to be smaller than the minimum operating flow rate at which the burner starts to burn.

  According to a fourth aspect of the present invention, when heating of the water by the hot water supply circuit is started while the opening / closing means is open, the opening / closing means is closed.

  According to the first aspect of the present invention, when the temperature detecting means detects the antifreezing temperature in the state where the heating of the water in the hot water supply circuit is stopped, the neutralizer or the upstream side of the neutralizer. By opening and closing the open / close means that opens and closes the communication path connecting the drain drainage path and the hot water supply circuit, water can be passed through at least the neutralizer to prevent freezing in the neutralizer. A heater for preventing freezing of the neutralizer is not required, parts can be simplified, and power consumption and cost can be reduced.

  According to claim 2, when the temperature detection means detects the antifreezing temperature in the state where the heating of the water in the hot water supply circuit is stopped, the drain on the upstream side of the neutralizer or the neutralizer Opening and closing means that opens and closes the communication path connecting the drainage channel and the hot water supply pipe is made to pass water, so that water is supplied to the water supply pipe, primary heat receiving pipe, secondary heat receiving pipe, and hot water supply pipe constituting the hot water supply circuit. In addition, it is possible to prevent freezing of the portion where the water stays by passing the water through the neutralizer, eliminating the need for the whole hot water supply circuit and the antifreeze heater of the neutralizer, simplifying the parts, power consumption and Cost can be reduced.

  According to the third aspect of the present invention, the flow rate of the communication passage is set to be smaller than the minimum operation flow rate at which the burner starts to burn, so that the burner can be opened even when the open / close means is open. Without burning, it is possible to prevent the freezing of the hot water supply circuit and the neutralizer by passing the amount of water necessary for preventing freezing, so that useless energy is not consumed.

  According to the fourth aspect of the present invention, when heating of the water by the hot water supply circuit is started when the opening / closing means is opened, water flows through the hot water supply circuit and drainage is generated in the secondary heat exchanger. Since warm drain flows into the neutralizer and there is no need to prevent freezing, by closing the opening and closing means, water flow related to freezing can be stopped and wasteful discharge of water can be prevented. Is.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram which shows the latent-heat-recovery type water heater of one Embodiment of this invention. The flowchart which showed the freezing prevention operation | movement of the latent heat recovery type hot water heater of the same embodiment.

Next, a water heater according to an embodiment of the present invention will be described with reference to FIG.
Reference numeral 1 denotes a latent heat recovery type water heater according to the present embodiment, 2 a kerosene or the like as a fuel, a burner that burns the fuel and generates a downward flame, 3 a blower that supplies combustion air to the burner 2, 4 It is a combustion chamber provided below the burner 2.

  5 is a heat exchanger housed in the combustion chamber 4, and this heat exchanger 5 collects sensible heat from the combustion gas generated by the combustion of the burner 2 and heats the water flowing through the primary heat receiving pipe 6. It comprises a primary heat exchanger 7 and a secondary heat exchanger 9 that recovers latent heat from the combustion gas after passing through the primary heat exchanger 7 and heats water flowing through the secondary heat receiving pipe 8 It is. An exhaust unit 10 communicates with the combustion chamber 4. The exhaust unit 10 has a sound absorbing material (not shown) inside, reduces noise of the combustion gas, and supplies the combustion gas that has passed through the combustion chamber 4 with hot water. This is the part that exhausts outside the machine 1.

  11 is a drain drainage path for draining the drain generated in the secondary heat exchanger 9, and this drain drain path 11 includes a drain inflow pipe 12 into which drain generated in the secondary heat exchanger 9 flows, A neutralizer 13 that is filled with a neutralizing agent made of calcium carbonate and stores and neutralizes strongly acidic drain that flows in from the drain inflow pipe 12, and a drain that is neutralized in the neutralizer 13 1 is composed of a drain outlet pipe 14 that drains outside, and the drained water outside the water heater 1 is discharged into a general drainage passage such as a sewer.

  15 is a water supply pipe for distributing water supplied from a water supply source to the heat exchanger 5, 16 is a water supply pipe for distributing hot water heated by the heat exchanger 5, and 17 is a water supply bypass pipe branched from the water supply pipe 15. The primary heat receiving pipe 6, the secondary heat receiving pipe 8, the water supply pipe 15, the hot water supply pipe 16, and the water supply bypass pipe 17 constitute a hot water supply circuit 18.

  A mixing valve 19 is provided at a connecting portion between the hot water supply pipe 16 and the water supply bypass pipe 17, mixes hot water from the hot water supply pipe 16 and water from the water supply bypass pipe 17, and 20 can change the mixing ratio. 15 is a water supply temperature sensor as a temperature detection means for detecting a water supply temperature, 21 is a flow rate sensor as a flow rate detection means for detecting a flow rate provided in the water supply pipe 15, and 22 is a heat exchanger 5 provided in the hot water supply pipe 16. A heat exchange outlet temperature sensor as temperature detecting means for detecting the temperature of the hot water heated in step 23, and a hot water supply temperature sensor 23 as temperature detecting means for detecting the temperature of hot water mixed in the mixing valve 19 provided in the hot water supply pipe 16. It is.

  Reference numeral 24 denotes a communication passage that branches off from the hot water supply pipe 16 and is connected to the drain inflow pipe 12, and connects the hot water supply pipe 16 and the drain inflow pipe 12 as the drain drainage path 11 upstream of the neutralizer 13. Is provided with an opening / closing valve 25 as an opening / closing means that opens and closes the communication passage 24 and is normally closed. The water flow rate of the communication passage 24 is set to be smaller than the minimum operating flow rate at which combustion of the burner 2 is started by adjusting the pipe diameter of the communication passage 24 or the like.

  26 is built in the hot water heater 1 and receives signals from various sensors such as the water temperature sensor 20 and the flow rate sensor 21 of the hot water heater 1 as a main body, and controls the driving of the actuators such as the burner 2 and the blower 3. Control means.

Next, the operation of the water heater 1 of this embodiment will be described.
Now, when a hot water tap (not shown) installed at an appropriate location is opened and hot water supply is started, the flow rate sensor 21 detects this flow of water, and the flow rate sensor 21 starts combustion of the burner 2. When a flow rate equal to or higher than the minimum operating flow rate is detected, the control means 26 determines that there is a combustion request, and starts burning of the burner 2.

  The combustion gas generated by this combustion flows through the primary heat exchanger 7, passes through the primary heat exchanger 7, then flows through the secondary heat exchanger 9, passes through the secondary heat exchanger 9, and then exhausts It is discharged out of the water heater 1 from the section 10. Further, the water supplied from the water supply source is introduced from the water supply pipe 15 to the secondary heat receiving pipe 8 and circulates in order from the secondary heat receiving pipe 8 to the primary heat receiving pipe 6 where it is heated by heat exchange with the combustion gas. Then, the hot water guided from the primary heat receiving pipe 6 to the hot water supply pipe 16 and adjusted to the hot water supply set temperature by adjusting the opening of the mixing valve 19 is finally supplied from the hot water tap.

  At this time, in the secondary heat exchanger 9, the water flowing through the secondary heat receiving pipe 8 and the combustion gas are subjected to heat exchange, and the drain generated by cooling the combustion gas below the dew point passes through the drain inflow pipe 12. The water is stored in the neutralizer 13, neutralized by the neutralizer filled in the neutralizer 13, and then discharged out of the water heater 1 through the drain outlet pipe 14.

  Next, the situation of the water heater 1 in a low temperature environment will be described. When the outside air temperature is as low as below freezing point in winter or the like, and the heating of the water in the hot water supply circuit 18 by combustion of the burner 2 has been stopped for a long time The temperature in the water heater 1 approximates the outside air temperature outside the water heater 1, and when the heating of the water in the hot water supply circuit 18 is stopped, there is no water circulation in the hot water supply circuit 18, and the water supply pipe 15. The water staying in the secondary heat receiving pipe 8, the primary heat receiving pipe 6, and the hot water supply pipe 16 and the drain staying in the neutralizer 13 may be frozen.

Here, the freeze prevention operation executed in the above case will be described with reference to the flowchart shown in FIG.
Based on the flow rate detected by the flow rate sensor 21, the control means 26 determines whether or not the detected flow rate of the flow rate sensor 21 is less than the minimum operating flow rate, that is, whether or not heating of water in the hot water supply circuit 18 is stopped. When the determination is made (step S1) and it is determined that the heating of the water in the hot water supply circuit 18 is stopped, the temperature detected by the heat exchange outlet temperature sensor 22 is set in advance to prevent freezing. It is determined whether the temperature is equal to or lower than the temperature, for example, 1 ° C. or lower (step S2). If it is determined that the temperature detected by the heat exchange outlet temperature sensor 22 is equal to or lower than the freeze prevention temperature, the normally closed on-off valve 25 is opened to start the freeze prevention operation (step S3). At this time, when the opening degree of the mixing valve 19 is the water side full open, the opening degree of the mixing valve 19 is set to an opening degree other than the water side full opening so that water flows to the heat exchanger 5 side, for example, the water side half open, The hot water side is half open.

  When the on-off valve 25 is opened in the step S3 and the freeze prevention operation is started, water passes through the water supply pipe 15, the secondary heat receiving pipe 8, the primary heat receiving pipe 6, and the hot water supply pipe 16 by the water supply pressure. A drain inflow pipe 12, a neutralizer 13, and a drain outflow pipe 14, which are the drain drainage path 11, are passed from 16 through a communication path 24 and discharged to the outside of the water heater 1. Since the water flow rate of the communication passage 24 is smaller than the minimum operation flow rate and is set to the minimum water flow rate necessary for preventing freezing, the hot water supply circuit 18 has a flow rate higher than the minimum operation flow rate even if the on-off valve 25 is opened. Water is not passed and combustion by the burner 2 is not started.

  After the opening / closing valve 25 is opened in step S3, the control means 26 determines whether or not the flow rate detected by the flow rate sensor 21 is equal to or higher than the minimum operating flow rate based on the flow rate detected by the flow rate sensor 21, that is, due to combustion of the burner 2. It is determined whether or not heating of water in the hot water supply circuit 18 has been started (step S4). If it is determined that heating of water in the hot water supply circuit 18 has been started, the on-off valve 25 is closed (step S5) to prevent freezing. Water flow related to the operation is stopped, and the process returns to the process of step S1.

  On the other hand, if the control means 26 determines in step S4 that heating of the water in the hot water supply circuit 18 has not started, the temperature detected by the heat exchange outlet temperature sensor 22 is set in advance so that there is no risk of freezing. It is determined whether the temperature is higher than the release temperature, for example, 4 ° C. or higher (step S6). If it is determined that the temperature detected by the heat exchange outlet temperature sensor 22 is higher than the release temperature, the on-off valve 25 is closed (step S5). Water flow related to the freeze prevention operation is stopped, and the process returns to the process of step S1. When it is determined in step S6 that the temperature detected by the heat exchange outlet temperature sensor 22 is lower than the release temperature, the process returns to step S4. is there.

  In the anti-freezing operation described above, the control means 26 detects that the temperature detected by the heat exchange outlet temperature sensor 22 is equal to or lower than the preset anti-freezing temperature in a state where the heating of the water in the hot water supply circuit 18 is stopped. If it is determined that the water has passed, the on-off valve 25 is opened to allow water to flow, so that the hot water supply circuit 18 including the water supply pipe 15, the secondary heat receiving pipe 8, the primary heat receiving pipe 6, the hot water supply pipe 16, and the neutralizer 13 Freezing of the portion where the water stays when water heating in the hot water supply circuit 18 is stopped can be prevented by passing water, and further, the drain in the neutralizer 13 is diluted with the supplied water and has an acidity. Since the water is lowered and drained, there is no concern about water pollution even if the water is drained out of the hot water heater 1. Further, the freezing prevention heater attached to the entire hot water supply circuit 18 and the neutralizer 13 is not required, the parts can be simplified, and power consumption and cost can be reduced.

  Further, since the water flow rate of the communication passage 24 is set to be smaller than the minimum operation flow rate, the burner 2 is not combusted even when the on-off valve 25 is open and water is passed, and at least for preventing freezing. The required amount of water can be passed to prevent the hot water supply circuit 18 and the neutralizer 13 from freezing, and useless energy is not consumed.

  Further, when the hot water tap is opened and heating of the water in the hot water supply circuit 18 is started while the on-off valve 25 is open, water flows through the hot water supply circuit 18 and drainage is generated in the secondary heat exchanger 9. Since the generated and warm drain flows into the neutralizer 13, it is not necessary to prevent freezing. Therefore, the control means 26 determines that heating of the water in the hot water supply circuit 18 is started when the on-off valve 25 is open. Then, by closing the on-off valve 25, water flow related to freeze prevention can be stopped, and wasteful discharge of water can be prevented.

  The present invention is not limited to the embodiment described above. In this embodiment, the communication path 24 is a drain drainage path upstream of the hot water supply pipe 16 and the neutralizer 13 constituting the hot water supply circuit 18. 11, the communication passage 24 may connect the water supply pipe 15 and the drain inflow pipe 12 in the hot water supply circuit 18, or the primary heat receiving pipe 6 and the drain. The inflow pipe 12 may be connected, or the secondary heat receiving pipe 8 and the drain inflow pipe 12 may be connected, and the communication path 24 is connected to the hot water supply circuit 18 and the drain inflow pipe. 12 is connected to at least the neutralizer 13 during the freeze prevention operation so that the drain in the neutralizer 13 can be prevented from freezing, and the antifreeze heater of the neutralizer 13 is unnecessary. Power consumption and cost In which it can be reduced.

  In the present embodiment, the temperature detection means for detecting the freeze prevention temperature is the heat exchange outlet sensor 22, but the temperature detection means has a low outside air temperature in winter and the like, and heating of water in the hot water supply circuit 18 is stopped. It is possible to detect the temperature for judging whether or not the water in the water heater 1 (the water in the hot water supply circuit 18 and the drain in the neutralizer 13) may be frozen in the state where it is being used. Instead of the heat exchanger outlet temperature sensor 22, the hot water supply temperature sensor 23 and the water supply temperature sensor 20 in the water heater 1 may be used as temperature detection means for detecting the antifreezing temperature, and the ambient temperature in the water heater 1. It is possible to provide a dedicated temperature sensor for detecting the freezing temperature and to detect it as a temperature detecting means for detecting the freezing prevention temperature. Furthermore, an outside air temperature sensor for detecting the outside air temperature outside the water heater 1 is provided and this is used as the freezing prevention temperature. Detect temperature It is also what may as detection means.

  In the present embodiment, in step S2, the control unit 26 determines the start of the freeze prevention operation based on the temperature detected by the heat exchange outlet temperature sensor 22, but the detection by the heat exchange outlet temperature sensor 22 is performed. The start of the anti-freezing operation may be determined based not only on the temperature but also on the detected temperatures of the plurality of temperature sensors. Similarly, the stop of the anti-freezing operation in the step S6 is stopped by the plurality of temperature sensors. The determination may be made based on the detected temperature.

  In the present embodiment, the communication path 24 branches from the hot water supply pipe 16 and is connected to the drain inflow pipe 12 as the drain drainage path 11 upstream of the neutralizer 13, but the communication path 24 is connected to the hot water supply pipe 16. The hot water pipe 16 and the neutralizer 13 may be communicated with each other by branching off from the neutralizer 13, and similar to the case where the communication path 24 is connected to the drain inflow pipe 12. An anti-freezing effect can be obtained.

  In the present embodiment, the water flow rate of the communication passage 24 is set to be smaller than the minimum operation flow rate by adjusting the pipe diameter of the communication passage 24, but the flow rate is set as an opening / closing means instead of the opening / closing valve 25. Instead of adjusting the pipe diameter of the communication path 24 by providing an adjustment valve, the flow rate of the communication path 24 is made smaller than the minimum operating flow rate by changing the flow rate by adjusting the opening of the flow rate adjustment valve during anti-freezing operation. It may be set so as to be.

  Further, in the present embodiment, the flow rate sensor 21 is provided in the water supply pipe 15 upstream of the water supply bypass pipe 17, but may be provided in the water supply pipe 15 downstream of the water supply bypass pipe 17, It may be provided in the hot water supply pipe 16 on the downstream side of the mixing valve 19 and may be provided in any location of the hot water supply circuit 18 capable of detecting the flow rate of the water flowing through the hot water supply circuit 18.

2 Burner 5 Heat exchanger 6 Primary heat receiving pipe 7 Primary heat exchanger 8 Secondary heat receiving pipe 9 Secondary heat exchanger 11 Drain drainage path 13 Neutralizer 15 Water supply pipe 16 Hot water supply pipe 18 Hot water supply circuit 22 Heat exchange outlet temperature sensor 24 Communication passage 25 Open / close valve

Claims (4)

  A primary heat exchanger that recovers sensible heat from combustion gas generated by combustion of a burner that burns fuel and heats water flowing through the primary heat receiving pipe, and the combustion after passing through the primary heat exchanger It consists of a secondary heat exchanger that recovers latent heat from the gas and heats water flowing through the secondary heat receiving pipe, a hot water supply pipe, the water supply pipe, the primary heat receiving pipe, the secondary heat receiving pipe, and the hot water supply pipe. Hot water supply circuit, drain drainage passage for draining drain generated in the secondary heat exchanger as the water is heated in the hot water supply circuit, and neutralizer for neutralizing the drain provided in the drain drainage route In the latent heat recovery type hot water supply apparatus, the neutralizer or a communication passage connecting the drain drainage channel upstream of the neutralizer and the hot water supply circuit, and an opening / closing means for opening and closing the communication passage; Provide temperature detection means to detect anti-freezing temperature, A latent heat recovery type characterized in that when the temperature detection means detects the anti-freezing temperature in a state where heating of water in the hot water supply circuit is stopped, the opening / closing means is opened to allow water to flow. Water heater.   A primary heat exchanger that recovers sensible heat from combustion gas generated by combustion of a burner that burns fuel and heats water flowing through the primary heat receiving pipe, and the combustion after passing through the primary heat exchanger It consists of a secondary heat exchanger that recovers latent heat from the gas and heats water flowing through the secondary heat receiving pipe, a hot water supply pipe, the water supply pipe, the primary heat receiving pipe, the secondary heat receiving pipe, and the hot water supply pipe. Hot water supply circuit, drain drainage passage for draining drain generated in the secondary heat exchanger as the water is heated in the hot water supply circuit, and neutralizer for neutralizing the drain provided in the drain drainage route In the latent heat recovery type hot water heater provided with the above, the neutralizer or the communication passage connecting the drain drainage channel upstream of the neutralizer and the hot water supply pipe, and the opening and closing means for opening and closing the communication passage; Providing a temperature detecting means for detecting the anti-freezing temperature, A latent heat recovery type characterized in that, when heating of water in the hot water circuit is stopped, when the temperature detection means detects the anti-freezing temperature, the opening / closing means is opened to allow water to flow. Water heater.   The latent heat recovery type hot water heater according to claim 2, wherein the amount of water passing through the communication passage is set to be smaller than a minimum operating flow rate at which combustion of the burner is started.   The latent heat according to any one of claims 1 to 3, wherein when the heating means starts heating water when the opening / closing means is open, the opening / closing means is closed. Recovery type water heater.

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