JP2013217604A - Hot water heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot water heating device capable of efficiently performing combustion operation of a burner while combustion operation and fire extinction of the burner are repeated at adequate time intervals without causing excessiveness or insufficiency thereof.SOLUTION: A controller 4 provided in a hot water heating device 1 is provided with a means for identifying a circulation flow rate of hot water circulating between a heat exchanger 6 and a radiator 3 via an outward path side hot water conduit 17 and a return path side hot water conduit 18, a means for determining a lower limit combustion range used for combustion operation of a burner 5 capable of changing the magnitude of a combustion range, according to the identified circulation flow rate, and a means for controlling a combustion amount of the burner 5 within a magnitude of the lower limit combustion range or more, and performing a stop of combustion operation due to a rise of outward path side hot water temperature and a restart of combustion operation due to reduction of the outward path side hot water temperature after the stop.

Description

  The present invention relates to a hot water heater.

  In a hot water heating apparatus for heating by supplying hot water heated through a heat exchanger by combustion heat of a burner to a radiator (heating load) such as a floor heating apparatus while circulating, the temperature of the hot water (outward side) When the temperature of the hot water rises to a predetermined fire extinguishing temperature, the combustion operation of the burner is stopped, and when the temperature of the hot water drops to a predetermined reignition temperature, the combustion operation of the burner is restarted. What controls the temperature of heating object is known conventionally.

  And in this kind of warm water heating apparatus, what is equipped with the burner which can change a combustion area in multiple steps as a burner for heating warm water is known conventionally, for example, as seen in patent documents 1 Yes.

JP 2006-336939 A

  Although the burner as shown in Patent Document 1 can reduce the minimum combustion amount by performing combustion in a small combustion area, in such a combustion state, the combustion is performed even in a region where combustion is not performed. Since the working air is supplied, the combustion efficiency tends to be lowered.

  For this reason, in order to increase the combustion efficiency, it is desirable to perform the combustion operation of the burner with a combustion area as large as possible.

  However, the number or capacity of radiators to be supplied with hot water is generally different. For this reason, the flow rate (circulation flow rate) of hot water required for heating also covers a wide range.

  In order to increase the combustion efficiency of the burner, if the combustion operation of the burner is performed in a state where the combustion area is as large as possible, in the situation where the circulating flow rate of hot water is small, the forward path side supplied from the heat exchanger to the radiator side Therefore, the temperature of the warm water on the outward path is likely to rise to the fire extinguishing temperature before the temperature of the warm water on the return path reaches the reignition temperature.

  As a result, the temperature of the warm water on the forward path after extinguishing the burner is likely to decrease to the reignition temperature in a short time, and the burner combustion operation and extinguishing are likely to be repeated frequently at short time intervals. Become. As a result, there is an inconvenience that the opening and closing sound of the electromagnetic valve provided in the fuel supply passage of the burner is frequently generated or the durability of the electromagnetic valve is likely to be lowered.

  Further, in order to prevent such inconvenience, in a situation where the temperature of the hot water is a temperature between the fire extinguishing temperature and the reignition temperature, if the combustion operation of the burner is performed in a state where the combustion area is small, In a situation where the circulation flow rate of the hot water is relatively large, there is a disadvantage that the combustion operation in a state where the combustion efficiency is low may be continuously performed for a long time.

  The present invention has been made in view of such a background, and the burner combustion operation and the fire extinguishing can be efficiently performed while being repeated at an appropriate time interval that does not become excessive or insufficient. An object is to provide a hot water heater.

In order to achieve the above object, the hot water heating apparatus of the present invention is a burner capable of selectively changing the size of the combustion range to a plurality of stages, and a heat exchanger for heating the hot water by the combustion heat of the burner. And an outward-side hot water channel for supplying hot water heated by the heat exchanger from the heat exchanger to one or more radiators, and hot water supplied to the radiator from the radiators to the heat exchanger. In a hot water heating apparatus comprising a return-side hot water channel to be refluxed, and a circulation pump for circulating hot water between the heat exchanger and the radiator via an outward-side hot water channel and a return-side hot water channel,
A flow rate specifying flow rate specifying data for specifying a circulating flow rate that is a flow rate of hot water circulating between the heat exchanger and the radiator, and specifying the circulating flow rate based on the acquired flow rate specifying data Specific means,
A means for determining a lower limit combustion range which is a combustion range of a lower limit size used for the combustion operation of the burner among the combustion ranges of the plurality of stages of the burner according to the specified circulation flow rate. Lower limit combustion range determining means for selectively determining the lower limit combustion range such that the larger the circulating flow rate is, the larger the lower limit combustion range is;
A forward-side hot water temperature detecting means for detecting a forward-side hot water temperature, which is a temperature of hot water supplied from the heat exchanger to the radiator, in the forward-side hot water path;
Combustion of the burner in a state in which the combustion range at the time of the combustion operation of the burner is limited to a combustion range that is greater than or equal to the determined lower limit combustion range of the plurality of stages of combustion ranges. The amount is feedback-controlled according to the detected value of the forward-side hot water temperature and a preset target temperature of the forward-side hot water temperature, and the detected value of the forward-side hot water temperature is higher than the target temperature. The combustion operation of the burner is stopped when the fire extinguishing temperature is increased, and when the detected value of the forward-side hot water temperature is lowered to a predetermined reignition temperature lower than the target temperature after the stop, Combustion control means for resuming the combustion operation is provided (first invention).

  According to the first aspect of the present invention, when the detected value of the forward-side hot water temperature rises to a predetermined fire extinguishing temperature higher than the target temperature during the burner combustion operation, the burner combustion operation is stopped (the burner is extinguished). Thereafter, when the detected value of the forward-side hot water temperature falls to a predetermined reignition temperature lower than the target temperature, the combustion operation of the burner is resumed.

  Here, when the number of radiators supplying hot water from the heat exchanger is small, or when the capacity of the radiator supplying hot water is small, the circulation flow rate specified by the flow rate specifying means is relatively small. In the situation, the lower limit combustion range determined by the lower limit combustion range determination means is a relatively small combustion range.

  For this reason, during the combustion operation of the burner in a situation where the circulation flow rate is relatively small, the combustion amount of the burner that is feedback-controlled by the combustion control means in accordance with the detected value of the outward hot water temperature and the target temperature is set. At least when the detected value of the forward-side hot water temperature is close to the target temperature, the combustion amount can be controlled to a relatively low combustion amount within the variable combustion amount range that can be achieved by the burner. As a result, the amount of heat given from the burner to the hot water through the heat exchanger can be suppressed to a lower amount of heat.

  Therefore, in a situation where the circulation flow rate is relatively small, the amount of heat given to the hot water via the heat exchanger is prevented, and the temperature of the hot water circulating from the radiator to the heat exchanger is It is possible to prevent the detected value of the forward-side hot water temperature from rising too quickly to the fire extinguishing temperature as much as possible before the temperature is raised to the reignition temperature or higher.

  In addition, when the number of radiators supplying hot water from the heat exchanger is large, or when the capacity of the radiator supplying hot water is large, the circulation flow rate specified by the flow rate specifying means is relatively large. Then, the lower limit combustion range determined by the lower limit combustion range determination means is a relatively large combustion range.

  For this reason, during the burner combustion operation in a situation where the circulation flow rate is relatively large, the combustion amount of the burner that is feedback-controlled by the combustion control means in accordance with the detected value of the outward hot water temperature and the target temperature is set. Even when the detected value of the forward-side hot water temperature is close to the target temperature, the combustion amount can be limited to a relatively high combustion amount within the variable range of the combustion amount that can be achieved by the burner. As a result, the amount of heat given from the burner to the hot water through the heat exchanger is prevented from becoming too small, and the hot water having a large circulation flow rate can be heated at an appropriate temperature rising rate.

  Therefore, according to the first invention, the burner combustion operation and the fire extinguishing (stopping the combustion operation) are excessively frequently performed in both cases where the circulating flow rate of the hot water is relatively small and relatively large. It is possible to prevent the combustion operation of the burner from continuing for a long time and to repeat the combustion operation and extinguishing of the burner at appropriate time intervals.

  In addition, the burner combustion operation in a smaller combustion range (in other words, the combustion operation with relatively low combustion efficiency) can be prevented from continuing for a long time, so that the burner combustion operation can be performed efficiently. .

  Therefore, according to the first invention, the burner combustion operation and the fire extinguishing can be efficiently performed while being repeated at an appropriate time interval that does not become excessive or insufficient.

  In the first invention, the lower limit combustion range is preferably determined in the following manner.

  That is, the lower limit combustion range determining means is configured to provide heat from the radiator in the return-side hot water channel when the burner is operated with a minimum combustion amount in each of the combustion ranges of a plurality of stages. The circulation necessary for preventing the forward-side hot water temperature from rising to the fire-extinguishing temperature before the return-side hot water temperature, which is the temperature of the warm water returning to the exchanger, rises to a temperature equal to or higher than the reignition temperature. Means for determining a required minimum circulating flow rate, which is a minimum value of the flow rate, according to the fire extinguishing temperature and the reignition temperature, and the combustion range other than the minimum size among the multiple ranges of the combustion range When the necessary minimum circulation flow rate corresponding to any one or more of the combustion ranges is equal to or less than the identified circulation flow rate, the necessary minimum circulation flow rate is equal to or less than the identified circulation flow rate. Of the one or more combustion ranges, a maximum combustion range is determined as the lower limit combustion range, and all of the multiple-stage combustion ranges other than the minimum combustion range are determined. When the necessary minimum circulation flow rate corresponding to each combustion range is larger than the specified circulation flow rate, it is preferable to determine the minimum combustion range as the lower limit combustion range (second). invention).

  According to the second aspect of the invention, since the lower limit combustion range is determined as described above, the specified circulation flow rate is too small so as to be less than the necessary minimum circulation amount corresponding to the minimum size combustion range. As long as the flow rate is not a flow rate, the lower limit combustion range can be determined so that the necessary minimum circulation amount corresponding to the lower limit combustion range becomes a flow rate equal to or less than the specified circulation flow rate.

  Here, the necessary minimum circulation amount is required to prevent the forward-side hot water temperature from rising to the fire-extinguishing temperature before the backward-side hot water temperature rises to a temperature equal to or higher than the reignition temperature. This is the minimum circulating flow rate.

  Therefore, before the return-side hot water temperature rises to a temperature equal to or higher than the re-ignition temperature, the forward-side hot water temperature is prevented from rising to the fire extinguishing temperature (and thus the combustion operation of the burner is stopped). In addition, it is possible to perform the burner combustion operation with high certainty.

  Further, the lower limit combustion range is determined to be the maximum combustion range among the one or more combustion ranges in which the necessary minimum circulation flow rate is equal to or less than the specified circulation flow rate. It is possible to raise the temperature of the forward-side hot water inside so that the rate of temperature rise does not become too slow with the highest possible combustion efficiency.

  Therefore, according to the second invention, it is possible to realize the burner combustion operation efficiently with higher certainty while the burner combustion operation and the fire extinguishing are repeated at appropriate time intervals.

  In the first invention or the second invention, the circulation flow rate can be specified by various methods.

  For example, the circulation flow rate may be directly detected using a flow rate sensor interposed in the outward path side hot water path or the return path side hot water path. However, in that case, pressure loss in the flow sensor is likely to occur, and it is disadvantageous in terms of cost.

  Therefore, in the first invention or the second invention, for example, the following configuration is preferably adopted. That is, it further comprises a return-side hot water temperature detecting means for detecting a return-side hot water temperature, which is a temperature of the hot water flowing back from the radiator to the heat exchanger, in the return-side hot water path, and the flow rate specifying means includes the outbound path A detected value of the side hot water temperature, a detected value of the return side hot water temperature, and data indicating the combustion amount and combustion range of the burner controlled by the combustion control means are acquired as the flow rate specifying data, The combustion flow control unit is configured to specify the circulation flow rate based on the flow rate specifying data, and the combustion control means has a predetermined value between the fire extinguishing temperature and the reignition temperature when the detected value of the forward path side hot water temperature is between After reaching the temperature, the combustion range at the time of the combustion operation of the burner is limited to a combustion range larger than the lower limit combustion range (third invention).

  Here, during the burner combustion operation, in a state in which the forward-side hot water temperature and the return-side hot water temperature are stable, the difference between the forward-side hot water temperature and the return-side hot water temperature is mainly from the burner. It depends on the amount of heat (heat amount per unit time) given to the hot water through the exchanger and the circulation flow rate. The amount of heat given from the burner to the hot water through the heat exchanger depends on the burner combustion amount and the combustion range.

  Therefore, in the third aspect of the invention, a return path side hot water temperature detecting means is further provided. The flow rate specifying means includes the detected value of the forward-side hot water temperature, the detected value of the return-side hot water temperature, and data indicating the combustion amount and combustion range of the burner controlled by the combustion control means. Obtained as the flow rate specifying data, the circulating flow rate is specified based on the flow rate specifying data.

  Thereby, the circulation flow rate can be specified with an inexpensive configuration without increasing the pressure loss.

  However, in this case, the circulation flow rate specified as described above is such that the forward-side hot water temperature and the return-side hot water temperature have not yet reached stable temperatures (for example, the forward-side hot water temperature is lower than the reignition temperature). In a state where the temperature is rising from the temperature toward the target temperature, the reliability is low.

  Therefore, in the third aspect of the invention, the combustion control means is configured so that the detected value of the forward-side hot water temperature becomes a temperature within a predetermined range between the fire extinguishing temperature and the reignition temperature, and then the burner is operated during combustion operation. The combustion range is limited to a combustion range having a size equal to or larger than the lower limit combustion range.

  Thereby, the restriction | limiting of the combustion range at the time of the combustion operation of the said burner can be performed appropriately.

The figure which shows the structure of the hot water heating apparatus of one Embodiment of this invention. The block diagram which shows the structure regarding control of the hot water heating apparatus of embodiment. The graph which shows the combustion characteristic of the burner of the hot water heating apparatus of embodiment. The block diagram which shows the control processing of the controller shown in FIG. The graph which shows roughly the form of the time-dependent change of the outward path side hot water temperature of the hot water heating apparatus of embodiment, and a return path side hot water temperature.

  An embodiment of the present invention will be described below with reference to FIGS.

  The hot water heating apparatus 1 according to the present embodiment includes a heat source unit 2 that heats hot water, one or a plurality of (in the illustrated example) radiators 3 that are hot water supply targets, and an operation of the hot water heating apparatus 1. And a controller 4 that performs control. Each radiator 3 is composed of a heating device such as a floor heating device or a hot air heating device.

  The heat source unit 2 includes a burner (gas burner) 5 for burning fuel gas and a heat exchanger 6 heated by the combustion heat of the burner 5.

  The burner 5 is composed of two burner units 5a and 5b for burning fuel gas. The burner units 5a and 5b have different combustion areas (combustion range sizes), and the burner unit 5a has a larger combustion area than the burner unit 5b.

  The burner units 5a and 5b are each supplied with fuel gas from a common gas supply path 7 via separate branch paths 8a and 8b. The gas supply path 7 is provided with a main valve 9 that is an electromagnetic valve that opens and closes the gas supply path 7 and a proportional valve 10 that adjusts the total amount of fuel gas supplied to the burner 5. Further, switching valves 11a and 11b, which are electromagnetic valves for opening and closing each of the branch paths 8a and 8b, are interposed.

  Depending on the combination of the open / closed states of the switching valves 11a and 11b with the main valve 9 opened, the burner 5 has an overall combustion range size (combustion area) of three stages (large, medium, and small) (three types). It is possible to selectively switch to the size of.

  That is, in a state where both of the switching valves 11a and 11b are opened, the combustion operation of both the burner units 5a and 5b becomes possible, and the entire combustion area of the burner 5 in this state is large (= burner units 5a and 5b). The total combustion area of each). Further, in a state in which the switching valve 11a is opened and the switching valve 11b is closed, only the burner unit 5a can be operated by combustion, and the entire combustion area of the burner 5 in this state is a combustion area ( = Combustion area of burner unit 5a). Further, when the switching valve 11a is closed and the switching valve 11b is opened, the combustion operation of only the burner unit 5b is possible, and the combustion area of the burner 5 in this state is small (= the burner unit 5b Combustion area).

  Hereinafter, the combustion of the burner 5 when the combustion area becomes large, medium, and small is referred to as large combustion, medium combustion, and small combustion, respectively. In addition, the number of stages (size types) of the combustion area when the combustion area is large, medium, and small is referred to as three stages, two stages, and one stage, respectively.

  And in any combustion state of the burner 5 in the large combustion, medium combustion, and small combustion, the amount of the total fuel gas supplied to the burner 5 by controlling the opening degree of the proportional valve 10, and consequently the burner 5 The amount of combustion is controlled. In this case, the combustion amount of the burner 5 can be controlled within a predetermined variable range (a range in which normal combustion can be performed without causing misfires) for each number of stages of the combustion area. The minimum combustion amount and the maximum combustion amount in the variable range of the combustion amount of the burner 5 in the combustion area of each stage number increase as the combustion area increases (the stage number increases).

  Note that a spark plug 13 that generates a spark discharge by the operation of the igniter 12 is assembled to the heat source device 2 in the vicinity of the burner 5. The burner 5 is ignited by generating spark discharge in the spark plug 13 with the fuel gas being supplied to the burner 5.

  The heat source unit 2 is assembled with an exhaust pipe 14, an air supply pipe 15 provided so as to surround the outer periphery of the exhaust pipe 14, and a fan 16 that supplies combustion air to the burner 5. The fan 16 sucks external combustion air (outside air) from the air supply pipe 15 by the rotation operation, and supplies the sucked combustion air to the burner 5, and the combustion exhaust gas of the burner 5 through the exhaust pipe 14. And send it out. In this case, the combustion air is supplied to the entire burner 5 (both burner units 5a and 5b) regardless of whether the burner 5 is in the large combustion, medium combustion, or small combustion state. ing.

  Here, the graph of FIG. 3 shows the rotation speed of the fan 16 (or the amount of combustion air supplied to the burner 5 defined by the rotation speed) and the combustion area of each of the first to third stages of the burner 5. It shows the relationship with the heating capacity (specifically, the amount of heat per unit time given to the hot water from the burner 5 through the heat exchanger 6) realized when the combustion operation is performed.

  The minimum heating capacity in the combustion area of each stage is the heating capacity that is realized when the burner 5 is operated with the minimum amount of combustion in the combustion area of that stage, and the maximum heating capacity in the combustion area of each stage. The heating capacity is a heating capacity that is realized when the burner 5 is operated with the maximum combustion amount in the combustion area of the number of stages.

  As shown in the figure, even if the rotation speed of the fan 16 (and hence the amount of combustion air supplied to the burner 5) is constant, the heating capacity decreases as the number of stages of the combustion area decreases (the combustion area decreases). . This is because the combustion air is supplied to the burner 5 by the rotation operation of the fan 16 to the entire burner 5, so that the lower the number of stages of the combustion area (the smaller the combustion area), the more the combustion of the burner 5. This is because the amount of combustion air supplied to the region is substantially reduced and the combustion efficiency of the burner 5 is lowered.

  And the minimum heating capability in the combustion area of each stage number becomes large, so that a combustion area is large (a stage number is large).

  Returning to FIG. 1, the heat exchanger 6 is disposed between the burner 5 and the inlet of the exhaust pipe 14 so as to absorb the combustion heat of the burner 5. The forward-side hot water passage 17 and the return-side hot water passage 18 are connected to the outlet and the inlet of the heat absorption pipe 6a of the heat exchanger 6, respectively. One or a plurality of the radiators 3 are connected between the forward-side hot water passage 17 and the return-side hot water passage 18.

  In the present embodiment, a circulation pump 19 is interposed in the return-side hot water passage 18. And the warm water heated with the heat exchanger 6 with the combustion heat of the burner 5 is supplied to each radiator 3 from the heat exchanger 6 through the outward path warm water channel 17 by the operation of the circulation pump 19, The hot water supplied to the radiator 3 is refluxed from the radiator 3 to the heat exchanger 6 through the return-side hot water channel 18. Thereby, warm water circulates between the heat exchanger 6 and the radiator 3.

  Note that the flow of hot water in each radiator 3 is blocked by a thermal valve or a manual valve (not shown) provided in the radiator 3 when the operation of the radiator 3 is stopped.

  In addition, the forward-side hot water channel 17 is provided with an outward-side hot water temperature sensor 20 as a forward-side hot water temperature detecting means for detecting the temperature of the hot water supplied to the radiator 3, and the return-side hot water channel 18 is radiated with heat. A return-side hot water temperature sensor 21 is mounted as a return-side hot water temperature detecting means for detecting the temperature of the hot water flowing back from the vessel 3 to the heat exchanger 6.

  The controller 4 is composed of an electronic circuit unit including a CPU, RAM, ROM and the like. As shown in FIG. 2, the controller 4 receives detection data (detection data of the respective hot water temperatures on the forward path side and the return path side) of the forward path side hot water temperature sensor 20 and the return path side hot water temperature sensor 21. The set temperature as the target temperature of the forward-side hot water temperature set by the user is input by an operating device such as a remote controller (not shown).

  Then, the controller 4 uses these input value data to control the operation of the main valve 9, the proportional valve 10, the switching valves 11a and 11b, the fan 16, the igniter 12, and the circulation pump 19, thereby providing hot water heating. Operation control of the apparatus 1 is performed.

  In this case, the controller 4 has a flow rate of hot water circulated between the heat exchanger 6 and the radiator 3 as a main function (function related to the present invention) realized by an installed program or hardware configuration (function related to the present invention). Specifically, the lower limit combustion area used for the combustion operation of the burner 5 and the flow rate specifying unit 25 for specifying the circulation flow rate that is the total flow rate of hot water supplied from the heat exchanger 6 to all the radiators 3 that operate. Is provided with a lower limit combustion range determination unit 26 for determining the number of stages (1 stage, 2 stages, or 3 stages) and a combustion control unit 27 for controlling the combustion operation of the burner 5.

  The flow rate specifying unit 25, the lower limit combustion range determining unit 26, and the combustion control unit 27 correspond to the flow rate specifying unit, the lower limit combustion range determining unit, and the combustion control unit in the present invention, respectively.

  In addition, the hot water heating apparatus 1 of this embodiment is also provided with the mechanism for performing hot water supply. However, since the structure and operation of the mechanism relating to the hot water supply are not the gist of the present invention, description thereof will be omitted.

  Next, the operation of the hot water heating apparatus 1 will be described focusing on the control process of the controller 4 related to the heating operation.

  During any operation (heating operation) of the radiator 3, the controller 4 executes a control process shown in the flowchart of FIG.

  First, the controller 4 executes the control processes of STEP 1 to 3 by the combustion control unit 27.

  In STEP 1, the combustion control unit 27 of the controller 4 starts the combustion operation of the burner 5 with the circulation pump 19 being operated. In this case, the combustion control unit 27 controls the opening of the main valve 9 and the switching valve 11b, and controls the proportional valve 10 to a predetermined opening for ignition. Thereby, supply of the fuel gas to the burner 5 is started.

  In this state, the combustion control unit 27 operates the igniter 12 to cause the spark plug 13 to generate a spark discharge. Thereby, the burner unit 5b is ignited and the combustion operation of the burner 5 (small combustion combustion operation) is started.

  Next, in STEP 2, the combustion control unit 27 sets the current forward path hot water temperature (detected value) indicated by the output (detection signal) of the forward path hot water temperature sensor 20 to the set temperature (target temperature) set by the user. It is determined whether or not the center is within a predetermined range (for example, a range of set temperature ± 1 ° C.), that is, whether or not the current forward-side hot water temperature (detected value) substantially matches the set temperature.

  And the combustion control part 27 performs the process of STEP3 until the judgment result of STEP2 becomes affirmative.

  In STEP 3, the combustion control unit 27 performs feedback control (FB control) of the combustion amount of the burner 5 so that the forward-side hot water temperature (detected value) approaches the set temperature set by the user.

  In this case, the combustion control unit 27 gradually increases the combustion amount of the burner 5 in accordance with the deviation from the set-point temperature of the forward-side hot water temperature (detected value) in order to prevent boiling of the hot water, and thereafter As the hot water temperature (detection value) approaches the set temperature, the target combustion amount of the burner 5 and the number of stages of the combustion area (any one of the first to third stages) are set so as to decrease the combustion amount. To decide. The combustion control unit 27 controls the opening degree of the proportional valve 10 according to the determined target combustion amount, and also controls the opening and closing of the switching valves 11a and 11b according to the determined number of stages.

  Further, the combustion control unit 27 shows the rotation speed of the fan 16 corresponding to the determined target combustion amount and the number of stages (the heating capacity according to the target combustion amount and the number of stages shown in the graph of FIG. 3). The rotational speed having the relationship is determined, and the fan 16 is operated at the rotational speed.

  As a result, the combustion amount of the burner 5 is feedback-controlled (FB control) so that the temperature of the forward-side hot water (detected value) is raised toward the set temperature.

  If the determination result in STEP 2 becomes affirmative, the controller 4 next executes the process in STEP 4 by the flow rate specifying unit 25. In STEP 4, the flow rate specifying unit 25 of the controller 4 specifies (estimates) the current circulating flow rate of hot water between the heat exchanger 6 and the radiator 3.

  In this process, the flow rate specifying unit 25 detects the current forward-side hot water temperature (detected value) indicated by the output of the outward-side hot water temperature sensor 20 and the current return-side hot water temperature indicated by the output of the return-side hot water temperature sensor 21. From the (detected value) and the current heating capacity, the circulation flow rate is estimated by the following equation (1).

Circulation flow rate = Current heating capacity ÷ (Outward hot water temperature-Return hot water temperature)
...... (1)

In this case, the current heating capacity used for the calculation of the right side of Equation (1) is calculated from the current target combustion amount of the burner 5 and the number of stages of the combustion area, using reference data stored and held in advance in the controller 4. The

  Here, when the processing of STEP 4 is executed, the forward-side hot water temperature (detected value) has been raised to a temperature near the set temperature, so that the forward-side hot water temperature and the return-side hot water temperature are stable (steady). Temperature). For this reason, the circulation flow rate can be accurately estimated by the above equation (1).

  Next, the controller 4 executes the processing of STEP 5 by the lower limit combustion range determination unit 26. In STEP 5, the lower limit combustion range determination unit 26 of the controller 4 determines the lower limit combustion area stage used in the combustion operation of the burner 5 according to the circulation flow rate estimated in STEP 4 (the minimum allowable stage number. Corresponding to the lower limit combustion range in the invention).

  More specifically, in the process of STEP 5, the lower limit combustion range determination unit 26 first uses the fire extinguishing temperature and the reignition temperature determined according to the current set temperature (target temperature) of the outward path side hot water temperature, using the following equation: From (2), the required minimum circulating flow rate corresponding to each stage number of the combustion area of the burner 5 is calculated. The calculation of the necessary minimum circulating flow rate corresponding to the first stage may be omitted.

Necessary minimum circulation flow rate corresponding to n stages = Minimum heating capacity in n stages ÷ (fire extinguishing temperature−reignition temperature) + α (2)
(However, n = 1, 2, 3)

Here, the above-mentioned fire extinguishing temperature is a temperature at which the burner 5 is extinguished (combustion operation is stopped), and is determined to be a temperature higher by a predetermined value ΔT1 (> 0) than the set temperature. The reignition temperature is a temperature at which the combustion operation of the burner 5 is restarted after the burner 5 is extinguished, and is determined to be a temperature lower than the set temperature by a predetermined value ΔT2 (> 0). For example, when the set temperature is 60 ° C, the fire extinguishing temperature and the reignition temperature are set to 63 ° C and 45 ° C, respectively.

  The predetermined values ΔT1 and ΔT2 may be constant values, but may be different depending on the set temperature.

  Further, the minimum heating capacity in each stage number (n stage) of the combustion area of the burner 5 is determined in advance by the controller 4 from the stage number (or combustion area) and a predetermined minimum combustion amount of the burner 5 in the combustion area of the stage number. It is calculated using the stored reference data (reference data used when calculating the heating capacity in the equation (1)).

  In addition, α in the above formula (2) compensates for the influence of variations in the calorific value of the fuel gas and the secondary pressure, or variations in output characteristics of the outward-side hot water temperature sensor 20 and the return-side hot water temperature sensor 21. Are constants experimentally determined in advance.

  The required minimum circulation flow rate calculated by the above equation (2) is such that when the burner 5 is operated with the minimum combustion amount in the combustion area corresponding to the number of stages (n stages), the return side hot water temperature is restored. This corresponds to the minimum circulating flow rate necessary to prevent the forward-side hot water temperature from rising to the fire extinguishing temperature before rising to the ignition temperature.

  Then, the lower limit combustion range determination unit 26 is based on a comparison between the circulation flow rate specified (estimated) in STEP 4 and the above-described required minimum circulation amount corresponding to the combustion area of each stage number of the burner 5 (3a) , (3b), (3c), the lower limit number of stages used for the combustion operation of the burner 5 is determined.

If the estimated circulating flow rate is the minimum circulating flow rate corresponding to 3 stages
Lower limit number of steps = 3 steps (3a)
If the minimum circulating flow rate corresponding to the third stage> the estimated circulating flow rate ≧ the minimum circulating flow rate corresponding to the second stage,
Lower limit number of steps = 2 steps (3b)
If the estimated circulating flow <the minimum circulating flow corresponding to the second stage,
Lower limit number of steps = 1 step (3c)

Accordingly, the estimated value of the circulation flow rate is the estimated value of the actual circulation flow rate corresponding to the combustion area of any number of stages (two or three stages) other than one of the first to third stages. In the case of the following flow rate, among the number of stages (2 stages, 3 stages, or 3 stages) where the required minimum circulation flow is less than or equal to the estimated value of the circulation flow, the number of stages with the largest combustion area (2 or 3 stages) Stage) is determined as the lower limit number of stages.

  In addition, when the necessary minimum circulation flow rate corresponding to each of the combustion areas of all the stages (2 stages and 3 stages) other than one stage is larger than the estimated value of the actual circulation flow, the minimum combustion flow The number of steps of the area (one step) is determined as the lower limit number of steps.

  Note that the first stage combustion area is the minimum circulation flow rate calculated corresponding to the first stage combustion area according to the equation (2), and the minimum circulation flow rate that can be assumed in the hot water heating apparatus 1 (the circulation flow rate in STEP 4). It is designed to be larger than the minimum circulation flow rate that may be actually calculated as an estimated value of Therefore, basically, the estimated value of the actual circulation flow rate does not fall below the required minimum circulation flow rate calculated corresponding to the combustion area of one stage.

  After determining the lower limit number of the combustion area of the burner 5 in STEP 5 as described above, the controller 4 executes the processing of STEPs 6 to 10 by the combustion control unit 27.

  In STEP 6, the combustion control unit 27 of the controller 4 performs feedback control (FB control) on the combustion amount of the burner 5 while limiting the number of stages of the combustion area of the burner 5 to the number of stages equal to or lower than the lower limit set in STEP 5.

  More specifically, the combustion control unit 27 determines the target combustion amount of the burner 5 and the number of stages (the number of stages equal to or greater than the lower limit number of stages) according to the deviation between the forward-side hot water temperature (detected value) and the set temperature. In this case, when the forward side hot water temperature (detected value) is lower than the set temperature, the target combustion amount and stage number of the burner 5 are determined so as to increase the combustion amount of the burner 5, and the forward side hot water temperature ( When the detected value becomes higher than the set temperature, the target combustion amount and the number of stages of the burner 5 are determined so as to reduce the combustion amount of the burner 5.

  However, the number of stages of the combustion area of the burner 5 determined in STEP 6 is limited to the number of stages equal to or higher than the lower limit number of stages. That is, when the lower limit number of stages is three, the number of stages of the burner 5 combustion area is determined to be only three. Further, when the lower limit number of stages is two, the number of stages of the combustion area of the burner 5 is determined to be two or three. When the lower limit number of stages is one, the number of stages of the burner 5 is determined to be one, two, or three.

  And the target combustion amount of the burner 5 is determined in the range more than the minimum combustion amount of the burner 5 in the combustion area of the minimum number of stages.

  The combustion control unit 27 controls the opening degree of the proportional valve 10 according to the target combustion amount thus determined, and also controls the opening and closing of the switching valves 11a and 11b according to the determined number of stages.

  Further, the combustion control unit 27 shows the rotation speed of the fan 16 corresponding to the determined target combustion amount and the number of stages (the heating capacity according to the target combustion amount and the number of stages shown in the graph of FIG. 3). The rotational speed having the relationship is determined, and the fan 16 is operated at the rotational speed.

  Thereby, the combustion amount of the burner 5 is feedback-controlled (FB control) in accordance with the deviation between the forward-side hot water temperature (detected value) and the set temperature.

  In this way, the combustion control unit 27 performs feedback control of the combustion amount of the burner 5 in STEP 6 and determines in STEP 7 whether or not the forward-side hot water temperature (detected value) has risen to a temperature equal to or higher than the fire extinguishing temperature. If the determination result is negative, the controller 4 repeats the processing from STEP4 to STEP7.

  On the other hand, if the determination result in STEP 7 is affirmative, the combustion control unit 27 of the controller 4 extinguishes the burner 5 in STEP 8 (stops the combustion operation of the burner 5). Specifically, the combustion control unit 27 shuts off the supply of the fuel gas to the burner 5 by closing the main valve 9. As a result, the burner 5 is extinguished and the combustion operation of the burner 5 is stopped.

  After this extinguishing, the combustion control unit 27 determines in STEP 9 whether or not the forward-side hot water temperature (detected value) has decreased to a temperature equal to or lower than the reignition temperature, and the burner 5 until the determination result becomes affirmative. Maintain fire extinguishing conditions.

  And if the judgment result of STEP9 becomes affirmative, the combustion control part 27 will restart the combustion driving | operation of the burner 5. FIG. Specifically, the combustion control unit 27 controls the opening of the main valve 9 and the switching valve that was opened immediately before the fire extinguishing of STEP 8 among the switching valves 11a and 11b, and the proportional valve 10 is used for ignition. The predetermined opening is controlled. Thereby, supply of the fuel gas to the burner 5 is restarted.

  In this state, the combustion control unit 27 operates the igniter 12 to cause the spark plug 13 to generate a spark discharge. As a result, the burner 5 is ignited and the combustion operation of the burner 5 is resumed with the combustion area of the number of stages immediately before the extinguishing of STEP 8. Thereafter, the controller 4 repeats the processing of STEPs 4 to 10.

  The above is the control process of the controller 4 in this embodiment.

  According to the embodiment described above, as shown in the graph of FIG. 5, basically, the combustion operation of the burner 5 is performed so that the forward-side hot water temperature repeatedly increases and decreases between the fire extinguishing temperature and the reignition temperature. Fire extinguishing is repeated.

  FIG. 5 schematically shows a form of a temporal change in the outward path side hot water temperature and the return path side hot water temperature during operation of the hot water heater 1.

  In this case, after the operation of the hot water heater 1 is started (after the start of the heating operation of the radiator 3), the forward-side hot water temperature rises to a temperature within a predetermined range between the fire extinguishing temperature and the reignition temperature (STEP 2). When the burner 5 is in a combustion operation after the determination result of (1) becomes affirmative, the stage number (size) of the combustion area of the burner 5 is greater than the lower limit stage number determined as described above according to the estimated value of the circulation flow rate. The combustion operation of the burner 5 is performed by limiting the number of stages.

  For this reason, when the number of radiators 3 that perform the heating operation is large, or when the capacity of the radiator 3 that performs the heating operation (the required flow rate of hot water) is large, the estimated value of the circulation flow rate is relatively large. Then, the combustion operation of the burner 5 with the number of stages having a large combustion area is performed, and the combustion operation of the burner 5 with the number of stages having a small combustion area is prohibited.

  Further, when the number of radiators 3 that perform heating operation is small, or when the capacity of the radiator 3 that performs heating operation is small, or the like, the estimated value of the circulation flow rate is relatively small. Is in a state close to the set temperature, the burner 5 is burned with a small combustion area.

  For this reason, regardless of whether the circulating flow rate is relatively large or relatively small, during the combustion operation of the burner 5, the forward-side hot water temperature is excessively raised to the fire extinguishing temperature, or It is possible to prevent a situation in which the forward-side hot water temperature does not rise to the fire extinguishing temperature or takes too long to rise.

  Further, the lower limit number of stages of the combustion area is determined so that the minimum circulating flow rate calculated by the above formula (2) corresponding to the lower limit number of stages is equal to or less than the estimated value of the actual circulating flow rate. As shown in the graph of FIG. 5, the return-side hot water temperature can be raised to a temperature that is somewhat higher than the re-ignition temperature before the forward-side hot water temperature rises from the re-ignition temperature to the fire-extinguishing temperature.

  Therefore, after the burner 5 is extinguished, it is possible to prevent the outward hot water temperature from being excessively lowered to the reignition temperature and restarting the combustion operation of the burner 5.

  As a result, the combustion operation (ON) and extinguishing (OFF) of the burner 5 are prevented from being repeated at an excessively short time interval, or the combustion operation of the burner 5 is continued for a long time. The ON / OFF of the burner 5 can be repeated at appropriate time intervals. Further, such ON / OFF repetition of the burner 5 can be stably performed.

  As a result, frequent opening / closing noises of the main valve 9 can be prevented. Moreover, the opening and closing frequency of the main valve 9 can be suppressed, and the early deterioration of the durability of the main valve 9 can be prevented.

  In addition, the lower limit stage number is determined to be the maximum number of stages in the combustion range among the stages where the required minimum circulating flow rate is less than or equal to the estimated value of the actual circulating flow rate. The temperature can be raised with a combustion efficiency as high as possible so that the rate of temperature rise does not become too slow.

  In the embodiment described above, the circulation flow rate is estimated (specified) using the detected values of the forward-side hot water temperature and the return-side hot water temperature. However, for example, the circulation flow rate may be directly detected using a flow sensor. Is possible. However, in that case, pressure loss is likely to occur, and it is disadvantageous in terms of cost as compared with the embodiment.

  Further, when the controller 4 can communicate with each radiator 3, for example, the controller 4 appropriately receives the operating state and specifications of each radiator 3, and receives the received data as a flow rate. The circulating flow rate may be specified using the specifying data.

  In the embodiment, the burner 5 can change the combustion area (the size of the combustion range) in three stages, but the burner 5 can change the combustion area in two stages or more than four stages. May be.

  In the above embodiment, the burner 5 uses fuel gas as fuel, but may use liquid fuel such as kerosene.

  DESCRIPTION OF SYMBOLS 1 ... Hot water heating apparatus, 3 ... Radiator, 5 ... Burner, 6 ... Heat exchanger, 17 ... Outward side hot water channel, 18 ... Return side hot water channel, 19 ... Circulation pump, 20 ... Outward side hot water temperature sensor (outward side) (Warm water temperature detection means), 21 ... return side hot water temperature sensor (return path side hot water temperature detection means), 25 ... flow rate specifying part (flow rate specifying means), 26 ... lower limit combustion range determination part (lower limit combustion range determination means), 27 ... Combustion control unit (combustion control means).

Claims (3)

A burner capable of selectively changing the size of the combustion range to a plurality of stages, a heat exchanger for heating hot water by the combustion heat of the burner, and hot water heated by the heat exchanger A forward-side hot water channel that supplies one or more radiators from the heat source, a return-side hot water channel that recirculates the hot water supplied to the radiator from the radiator to the heat exchanger, the heat exchanger and the radiator, In a hot water heating apparatus comprising a circulation pump that circulates hot water through the forward-side hot water channel and the return-side hot water channel between
A flow rate specifying flow rate specifying data for specifying a circulating flow rate that is a flow rate of hot water circulating between the heat exchanger and the radiator, and specifying the circulating flow rate based on the acquired flow rate specifying data Specific means,
A means for determining a lower limit combustion range which is a combustion range of a lower limit size used for the combustion operation of the burner among the combustion ranges of the plurality of stages of the burner according to the specified circulation flow rate. Lower limit combustion range determining means for selectively determining the lower limit combustion range such that the larger the circulating flow rate is, the larger the lower limit combustion range is;
A forward-side hot water temperature detecting means for detecting a forward-side hot water temperature, which is a temperature of hot water supplied from the heat exchanger to the radiator, in the forward-side hot water path;
Combustion of the burner in a state in which the combustion range at the time of the combustion operation of the burner is limited to a combustion range that is greater than or equal to the determined lower limit combustion range of the multiple-stage combustion ranges The amount is feedback-controlled according to the detected value of the forward-side hot water temperature and a preset target temperature of the forward-side hot water temperature, and the detected value of the forward-side hot water temperature is higher than the target temperature. The combustion operation of the burner is stopped when the fire extinguishing temperature is increased, and when the detected value of the forward-side hot water temperature is lowered to a predetermined reignition temperature lower than the target temperature after the stop, A hot water heating apparatus comprising combustion control means for resuming combustion operation. The hot water heater according to claim 1,
The lower limit combustion range determining means is configured to provide a heat exchanger from the radiator in the return-side hot water channel when the burner is operated with a minimum combustion amount in each of a plurality of stages of combustion ranges. Before the return-side hot water temperature, which is the temperature of the warm water returning to the re-ignition temperature, rises to a temperature equal to or higher than the re-ignition temperature, the circulation flow rate required to prevent the forward-side hot water temperature from rising to the fire extinguishing temperature Means for determining a required minimum circulating flow rate that is a minimum value in accordance with the extinguishing temperature and the reignition temperature, and out of the combustion ranges of the plurality of stages other than the combustion range of the minimum size When the required minimum circulation flow rate corresponding to each of the one or more combustion ranges is equal to or less than the specified circulation flow rate, the required minimum circulation flow rate is equal to or less than the specified circulation flow rate. Of the above combustion ranges, the maximum combustion range is determined as the lower limit combustion range, and all the combustion ranges other than the minimum combustion range among the plurality of stages of combustion ranges are respectively determined. When the corresponding minimum necessary circulation flow rate is larger than the specified circulation flow rate, the combustion range having the minimum size is determined as the lower limit combustion range. The hot water heating apparatus according to claim 1 or 2,
It further comprises return-side hot water temperature detection means for detecting the return-side hot water temperature, which is the temperature of the warm water flowing back from the radiator to the heat exchanger, in the return-side hot water channel,
The flow rate specifying means includes the detected value of the forward-side hot water temperature, the detected value of the return-side hot water temperature, and data indicating the combustion amount and combustion range of the burner controlled by the combustion control means. Acquired as specifying data, and configured to specify the circulating flow rate based on the flow specifying data,
The combustion control means sets the combustion range at the time of the combustion operation of the burner after the detected value of the forward-side hot water temperature becomes a temperature within a predetermined range between the fire extinguishing temperature and the reignition temperature, as the lower limit. A hot water heater characterized by being limited to a combustion range having a size greater than or equal to the size of the combustion range.

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