JP2010133620A - Water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water heater for preventing degrading or damage of a heat exchanger by positively determining freezing of the heat exchanger and preventing heating operation during freezing even if there is freezing of only water in the heat exchanger while securing smooth heating operation of the water heater in regard to a water heater equipped with a bypass pipe bypassing the heat exchanger. <P>SOLUTION: In the water heater 1 having the bypass pipe 7 mixing one part of water supplied from a water supply pipe 5 into a tapping pipe 6 without going through the heat exchanger 25, a tapping temperature THa detected by a tapping temperature sensor 12 is monitored, and if the tapping temperature THa continuously indicates less than a freezing risk temperature TH in a predetermined time and a breadth of temperature rise of the tapping temperature THa in the predetermined time is less than a freezing evaluation temperature THs, even if a water amount detected by a flowing water sensor 8 is a minimum operation flow rate or more, the heating operation is stopped. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a so-called bypass mixing type hot water supply apparatus in which hot water heated by a heat exchanger is mixed with water from a bypass pipe that bypasses the heat exchanger to extract hot water at a hot water supply set temperature, and in particular, a function of detecting freezing. It is related with the hot water supply apparatus provided with.

  2. Description of the Related Art Conventionally, a bypass mixing type hot water supply apparatus including a bypass pipe that communicates a water supply pipe and a hot water discharge pipe without passing through a heat exchanger is known.

  In this type of hot water supply device, water supply to the heat exchanger is started by the user opening a curan connected to the tip of the hot water discharge pipe, and the amount of water flowing through the water supply pipe by the flow water sensor is equal to or greater than the minimum working water amount. When this is detected, the gas burner is activated in response to the detection of the flowing water, and a heating operation for heating the water passing through the heat exchanger is started. And hot water supply control which adjusts the combustion quantity of a gas burner and the amount of water mixed via a bypass pipe is performed so that the hot water temperature detected with a hot water temperature sensor may correspond with predetermined hot-water supply preset temperature. Further, when the user closes the currant and no running water is detected by the running water sensor, the operation of the gas burner is stopped.

  By the way, in the hot water supply apparatus as described above, a freeze prevention heater is provided in the hot water supply apparatus in order to prevent freezing in winter, and when the temperature detected by the external temperature sensor or the internal temperature sensor is equal to or lower than a predetermined temperature, Thermal insulation control for operating the anti-freezing heater is performed.

  However, for example, in a forced exhaust water heater with an exhaust pipe communicating with the outside, since the house has been highly airtight and highly insulated, the inside of the house becomes negative pressure due to ventilation, and the house is put indoors through the exhaust pipe. Outside air may enter. For this reason, the heat exchanger arranged in communication with the exhaust pipe is most cooled by the cold air that enters. Therefore, even if the temperature in the vicinity of the heat exchanger becomes lower than the temperature detected by the external temperature sensor or the internal temperature sensor as described above and the water in the heat exchanger freezes, the heat exchanger is placed below the heat exchanger. In many cases, the water in the installed water supply pipe is not frozen. As a result, even if the water in the heat exchanger freezes and solidifies in the winter, the water flows through the bypass pipe, so the running water provided upstream from the joint between the water supply pipe and the bypass pipe If the sensor detects this flowing water and the amount of water is greater than or equal to the minimum amount of working water required for the heating operation, the gas burner will be ignited. When only the water in the heat exchanger is frozen, a part of the water frozen in the heat exchanger is thawed by the heating operation, and the water pressure is increased as the temperature of the thawed water rises. , And excessive pressure may be applied to the heat exchanger, which may cause deterioration or breakage of the heat exchanger.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a hot water supply apparatus having a bypass pipe that bypasses the heat exchanger while ensuring a smooth heating operation of the hot water supply apparatus. Even if only water in the exchanger freezes, a hot water supply device that reliably determines whether the heat exchanger is frozen, prevents heating operation during freezing, and prevents deterioration and damage to the heat exchanger Is to provide.

The present invention comprises a water supply pipe,
A heat exchanger that heats water supplied by the water supply pipe, a gas burner that heats the heat exchanger, a combustion fan that supplies combustion air to the gas burner, and a heat exchanger that communicates with the gas burner; A heating unit having an exhaust pipe for discharging the combusted exhaust gas to the outside;
A tapping pipe from which the hot water heated by the heat exchanger is tapped,
A bypass pipe for mixing a part of water supplied from the water supply pipe into the hot water pipe without passing through the heat exchanger;
A water flow sensor that is provided in the water supply pipe and detects the amount of water disposed upstream of the joint between the water supply pipe and the bypass pipe;
A tapping temperature sensor that is provided in the tapping pipe and detects a tapping temperature disposed downstream of a junction between the tapping pipe and the bypass pipe;
A water amount determination unit that determines whether or not the amount of water detected by the flowing water sensor is equal to or greater than a minimum working water amount, a tapping temperature monitoring unit that monitors a tapping temperature THa detected by the tapping temperature sensor, and detected by the flowing water sensor. Combustion control for starting the heating operation of the heating unit when the amount of water is equal to or greater than the minimum working water amount and performing hot water supply control so that the hot water temperature THa monitored by the hot water temperature monitoring unit matches a predetermined hot water supply set temperature Even if the amount of water flowing through the water supply pipe detected by the flow sensor and the water flow sensor is equal to or higher than the minimum operating flow rate, the hot water temperature THa output from the hot water temperature monitoring unit continues below the freezing danger temperature THf within a predetermined time. And when the temperature rise width of the tapping temperature THa within the predetermined time is less than the freezing evaluation temperature THs, freezing for stopping the heating operation of the heating unit A hot water supply control means having a cross section, a hot water supply device comprising a.

  According to the hot water supply apparatus, even if the amount of water detected by the running water sensor is equal to or higher than the minimum operating flow rate, the hot water temperature THa detected by the hot water temperature sensor is lower than the freezing danger temperature THf, and the temperature rise of the hot water temperature THa is increased. When the width is less than the freezing evaluation temperature THs, the heating operation is stopped, so the water in the water supply pipe and the bypass pipe is not frozen, only the water in the heat exchanger is frozen by indoor ventilation, etc. Even when water flows through the water supply pipe via the bypass pipe, it is possible to reliably detect the blockage of the heat exchanger due to freezing. In addition, according to the hot water supply apparatus, since the heating operation is not stopped when either the tapping temperature THa or the temperature increase width thereof does not satisfy the conditions for freezing determination, it is possible to prevent unnecessary stopping of the heating operation. it can.

  As described above, according to the present invention, in a hot water supply apparatus provided with a bypass pipe that bypasses the heat exchanger, it is possible to reliably detect freezing of the heat exchanger while ensuring a smooth heating operation of the hot water supply apparatus. it can. For this reason, when only the water in the heat exchanger is frozen, it can be prevented from being heated and the deterioration and damage of the heat exchanger can be prevented.

  Hereinafter, as for the hot water supply apparatus of the present embodiment, a forced exhaust type hot water supply apparatus having a configuration in which indoor air is supplied by operation of a combustion fan and combustion exhaust gas burned by a gas burner is discharged from an exhaust pipe to the outside is taken as an example. Will be described. In the case of such a water supply / exhaust type hot water supply device, the indoor ventilation creates a negative pressure inside, the outside air enters the inside through the exhaust pipe, the heat exchanger is cooled, and only the water in the heat exchanger is likely to freeze. Therefore, the hot water supply apparatus of the present embodiment is particularly useful.

  FIG. 1 is a schematic configuration diagram illustrating an example of a hot water supply apparatus according to the present embodiment. This hot water supply device 1 is a heating unit 2, a gas burner 21 that burns the gas sent from the gas pipe G, a spark plug 23 that ignites the gas burner 21 by applying a high voltage via the igniter 22, and the combustion state of the gas burner 21 The flame rod 24 for detecting the gas, the heat exchanger 25 for recovering the combustion heat of the gas and heating the supplied water, the combustion air is blown to the gas burner 21, and the combustion exhaust of the gas burner 21 to the heat exchanger 25 A combustion fan 26 to be sent and an exhaust cylinder 27 for discharging combustion exhaust gas to the outside are provided. The gas burner 21 is connected to a gas pipe G through a gas supply pipe 28. The gas supply pipe 28 is provided with an original gas solenoid valve 29 and a proportional solenoid valve 30 in order from upstream to downstream. It is arranged. The proportional solenoid valve 30 is energized and controlled by the hot water supply control means 4, exhibits an opening according to the energization amount, and is a valve for continuously adjusting the amount of gas flowing through the gas supply line 28. The gas supply line 28 is branched downstream of the proportional solenoid valve 30 into a gas pipe 31 on one side and a gas pipe 32 on the other side in order to supply gas to the burner groups 211 and 212 of the double burner. Each branch pipe is provided with a switching electromagnetic valve 33 for switching the combustion state (ON or OFF) of each burner group.

  In addition, the hot water supply device 1 is connected to a water pipe (not shown) to supply water to the heat exchanger 25, a hot water pipe 6 from which hot water heated by the heat exchanger 25 is discharged, and a water supply pipe 5. And a bypass pipe 7 for mixing a part of the supplied water with the hot water pipe 6. Then, on the upstream side of the joint portion of the water supply pipe 5 with the bypass pipe 7, a flowing water sensor 8 that detects the presence or absence of flowing water passing through the heat exchanger 25 and outputs it to the hot water supply control means 4, and the hot water supply control means 4. A water amount servo 9 for limiting the opening degree of the water supply pipe 5 by a control signal from is provided. Further, on the upstream side of the junction of the outlet pipe 6 with the bypass pipe 7, a heat exchanger temperature sensor 11 that detects the temperature of the hot water near the outlet of the heat exchanger 25 and outputs it to the hot water supply control means 4, and the outgoing hot water The temperature of hot water in which hot water discharged from the heat exchanger 25 and water supplied from the bypass tube 7 are mixed to the downstream side of the joint between the pipe 6 and the bypass pipe 7 is detected and supplied to the hot water supply control means 4. An output hot water temperature sensor 12 is provided.

  The hot water supply control means 4 includes a flowing water sensor 8, a water amount servo 9, a heat exchange temperature sensor 11, a tapping temperature sensor 12, an igniter 22, a combustion fan 26, an original gas solenoid valve 29, a proportional solenoid valve 30, and a switching solenoid valve 33. Connected to the remote control device R via a communication cable.

  Further, the hot water supply control means 4 determines whether or not the amount of water detected by the combustion control unit 41, the hot water temperature monitor unit 42 for monitoring the hot water temperature detected by the hot water temperature sensor 12, and the running water sensor 8 is equal to or greater than the minimum working water amount. A water amount determination unit 43 to determine, a freezing determination unit 44 to determine whether or not to stop the heating operation based on the tapping temperature output from the tapping temperature monitoring unit 42, and a notification unit to notify the remote control device R of the risk of freezing. 45 and a timer 46, and is composed of a CPU, ROM, RAM, and the like.

  The remote control device R performs an operation switch 50 for instructing start and stop of the operation of the entire hot water supply device 1, a hot water supply temperature switch 51 for setting the hot water supply temperature, a display unit 52 for displaying the hot water supply temperature and time, and voice notification. A speaker 53 is provided.

  Next, a control configuration for detecting freezing in the hot water supply apparatus of the present embodiment will be described with reference to the flowchart of FIG.

  First, when the user operates the operation switch 50 of the remote control device R, the entire hot water supply device 1 enters an operation standby state, and the operation lamp 54 built in the operation switch 50 is lit. When the operation switch 50 is activated and the user opens a currant (not shown) connected to the tip of the hot water discharge pipe 6, water supply to the water supply pipe 5 is started, the flowing water sensor 8 detects the flowing water, and the amount of water is determined. The unit 43 confirms whether or not the amount of water detected by the running water sensor 8 is equal to or greater than a predetermined minimum working water amount (step S1). That is, when the amount of water detected by the flowing water sensor 8 is less than the predetermined minimum working water amount, it is considered that water does not flow through the water supply pipe 5 or the bypass pipe 7 below the hot water supply device 1. The water may be frozen. For this reason, unless the gas burner 21 is ignited until the amount of water detected by the flowing water sensor 8 becomes equal to or greater than the minimum amount of working water, deterioration or breakage of the heat exchanger 25 can be prevented.

  On the other hand, when it is determined from the output from the flowing water sensor 8 that the amount of water detected by the flowing water sensor 8 is equal to or greater than the minimum working water amount (YES in step S1), the water amount determination unit 43 sends an operation start signal to the combustion control unit 41. The combustion control unit 41 operates the combustion fan 26, opens the original gas solenoid valve 29, the proportional solenoid valve 30, and the switching solenoid valve 33, and applies a high voltage to the igniter 22 to apply the spark plug 23. A spark discharge is generated in the gas burner 21 to perform an ignition process (step S2). When ignition of the gas burner 21 is detected by the frame rod 24, a timer 46 is started to measure a predetermined time for determining whether the heat exchanger 25 is frozen or not, and initial detection detected by the tapping temperature sensor 12. The temperature THo is output to the tapping temperature monitoring unit 42, and the tapping temperature monitoring unit 42 starts monitoring the tapping temperature THa detected by the tapping temperature sensor 12 (step S3).

  When the heating operation is started, the tapping temperature monitoring unit 42 outputs the monitored tapping temperature THa to the freezing determination unit 44, and the freezing determination unit 44 has a tapping temperature THa that is lower than the freezing danger temperature THf (for example, 10 ° C.). Is continued for a predetermined time, and the temperature rise width (THa-THo) of the hot water temperature THa from the initial detected temperature THo at the start of monitoring continues below the freezing evaluation temperature THs (for example, 5 ° C.). (Step S4). The predetermined time for performing the freezing determination is, for example, a time during which the heat exchanger 25 is not damaged (for example, 5 to 10 seconds) even when the gas burner 21 is maximally burned with water in the heat exchanger 25 frozen. It can be determined in consideration.

  If the hot water temperature THa is lower than the freezing danger temperature THf for a predetermined time and the temperature rise width (THa-THo) of the hot water temperature THa is lower than the freezing evaluation temperature THs (YES in step S4), the freezing determination is performed. The unit 44 outputs a freezing signal to the combustion control unit 41, and the combustion control unit 41 stops the heating operation (step S5). That is, the hot water temperature THa detected by the hot water temperature sensor 12 that should rise in temperature by the heating operation continues for a predetermined time and is below the freezing danger temperature THf, and the hot water is discharged even if the predetermined time has elapsed since the heating operation was started. When the temperature THa does not rise above the initial detection temperature THo by a certain temperature or more, the water supplied from the water supply pipe 5 does not pass through the heat exchanger 25 but flows through the hot water pipe 6 through the bypass pipe 7 to exchange heat. It can be determined that water is not being heated in the vessel 25. Accordingly, if the hot water temperature THa within the predetermined time is less than the freezing danger temperature THf and the temperature rise (THa-THo) is less than the freezing evaluation temperature THs, the flowing water sensor 8 detects a water amount equal to or higher than the minimum working water amount. Even if it is determined that the heat exchanger 25 is closed due to freezing, the combustion control unit 41 stops the heating operation. Then, a signal is output from the notification unit 45 to the remote control device R to notify the possibility of freezing from the display unit 52 or the speaker 53 of the remote control device R (step S6). According to the hot water supply device having the above-described freezing detection function, the hot water is provided downstream of the hot water discharge pipe 6, the water is not easily frozen even by indoor ventilation or the like, and is not easily affected by the heat of the combustion exhaust gas when the gas burner 21 is burned. Since freezing is detected based on the temperature of the tapping water detected by the temperature sensor 12, water is not frozen in the water supply pipe 5 and the bypass pipe 7, and only water in the heat exchanger 25 is frozen by indoor ventilation or the like. Even when water of the minimum working water amount or more flows through the water supply pipe via the bypass pipe 7, it is possible to reliably detect the freezing of the heat exchanger 25. Thereby, since the gas burner 21 is not burned in the state where the water in the heat exchanger 25 is frozen, the deterioration and breakage of the heat exchanger 25 can be prevented.

  On the other hand, the hot water temperature THa output from the hot water temperature monitoring unit 42 is continuously higher than the freezing danger temperature THf for a predetermined time, and the temperature rise width (THa-THo) of the hot water temperature THa within the predetermined time is higher than the freezing evaluation temperature THs. (NO in step S4), it can be determined that water is being heated in the heat exchanger 25, so the freezing determination unit 44 outputs a non-freezing signal to the combustion control unit 41, and the combustion control unit 41 Based on the hot water temperature THa monitored by the hot water temperature monitoring unit 42, the gas amount is adjusted by adjusting the opening degree of the proportional solenoid valve 30 and opening / closing the switching electromagnetic valve 33, and the water amount is adjusted by the water amount servo 9, thereby Hot water supply control is performed so that the temperature THa becomes a predetermined hot water supply set temperature (step S7). The hot water temperature THa is lower than the freezing danger temperature THf, but the temperature rise width (THa-THo) of the hot water temperature THa is equal to or higher than the freezing evaluation temperature THs, or the hot water temperature THa is equal to or higher than the freezing danger temperature THf. Even if the temperature rise width (THa-THo) of the tapping temperature THa is less than the freezing evaluation temperature THs (NO in step 4), the freezing determination unit 44 determines that the heat exchanger 25 is not frozen and the same. The non-freezing signal is output to the combustion control unit 41, and the combustion control unit 41 continues the heating operation to perform hot water supply control (step S6). That is, in the winter season, when cold water is supplied to the water supply pipe 5, the hot water supply set temperature is low, and the combustion amount of the gas burner 21 is small, the hot water temperature THa detected by the hot water temperature sensor 12 may be lower than the freezing danger temperature THf. As described above, if the temperature rise width (THa-THo) of the tapping temperature THa is equal to or higher than the freezing evaluation temperature THs, water flows through the heat exchanger 25, and the water is heated by the heat exchanger 25. Can be judged. In addition, when the hot water supply set temperature is low and the amount of combustion of the gas burner 21 is small, it may be considered that the temperature rise width (THa-THo) of the tapping temperature THa is less than the freezing evaluation temperature THs, but the tapping temperature THa is the freezing danger temperature THf. If it is above, it can be judged that the possibility that the water of the heat exchanger 25 is frozen is low. Thereby, since the stop of an unnecessary heating operation can be prevented, the smooth heating operation of a hot water supply apparatus is not prevented.

(Other embodiments)
Although the forced exhaust type hot water supply apparatus has been described in the above embodiment, the present invention can also be used for a forced exhaust type hot water supply apparatus.

It is a schematic block diagram which shows an example of the hot water supply apparatus which concerns on embodiment of this invention. It is a flowchart for demonstrating operation | movement of the hot water supply apparatus which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot water supply apparatus 2 Heating unit 4 Hot water supply control means 5 Water supply pipe 6 Hot water discharge pipe 7 Bypass pipe 8 Flowing water sensor 12 Hot water temperature sensor 21 Gas burner 25 Heat exchanger 26 Combustion fan 27 Exhaust cylinder 41 Combustion control part 42 Hot water temperature monitor part 43 Water quantity judgment Part 44 Freezing judgment part

Claims (1)

A water pipe,
A heat exchanger that heats water supplied by the water supply pipe, a gas burner that heats the heat exchanger, a combustion fan that supplies combustion air to the gas burner, and a heat exchanger that communicates with the gas burner; A heating unit having an exhaust pipe for discharging the burned combustion exhaust gas to the outside;
A tapping pipe from which the hot water heated by the heat exchanger is tapped,
A bypass pipe for mixing a part of water supplied from the water supply pipe into the hot water pipe without passing through the heat exchanger;
A water flow sensor that is provided in the water supply pipe and detects the amount of water disposed upstream of the joint between the water supply pipe and the bypass pipe;
A tapping temperature sensor that is provided in the tapping pipe and detects a tapping temperature disposed downstream of a junction between the tapping pipe and the bypass pipe;
A water amount determination unit that determines whether or not the amount of water detected by the flowing water sensor is equal to or greater than a minimum working water amount, a tapping temperature monitoring unit that monitors a tapping temperature THa detected by the tapping temperature sensor, and detected by the flowing water sensor. Combustion control for starting the heating operation of the heating unit when the amount of water is equal to or greater than the minimum working water amount and performing hot water supply control so that the hot water temperature THa monitored by the hot water temperature monitoring unit matches a predetermined hot water supply set temperature Even if the amount of water flowing through the water supply pipe detected by the flow sensor and the water flow sensor is equal to or higher than the minimum operating flow rate, the hot water temperature THa output from the hot water temperature monitoring unit continues below the freezing danger temperature THf within a predetermined time. And when the temperature rise width of the tapping temperature THa within the predetermined time is less than the freezing evaluation temperature THs, freezing for stopping the heating operation of the heating unit Water heater comprising: a hot water supply control means having a cross-sectional portion.

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