HEATING AND HOT WATER SUPPLY DEVICE

Abstract

In a heating and hot water supply device comprising a burning means, a first heat exchanger, a circulation passage for circulating a heating thermal medium, a circulation pump, a first bypass passage, a second heat exchanger for hot water supply, a hot water supply passage, a second bypass passage bypassing the second heat exchanger, and a control unit, a distribution means is provided at a first branching portion of the first bypass passage and is capable of adjusting its distribution ratio for heating, or hot water supply, or simultaneous heating/hot water supply, during heating operation, the hot water supply passage is closed by a flow rate adjustment means provided in the hot water supply passage.

Description

TECHNICAL FIELD

The present invention relates to a heating and hot water supply device that performs heating operation (i.e. room heating etc.) by applying heat produced by combustion to a heating thermal medium, and that also performs supply of hot water by applying heat to cold water by heat exchange with the heating thermal medium, and in particular relates to such a heating and hot water supply device that is capable of performing heating operation and hot water supply operation simultaneously.

BACKGROUND ART

From the past, heating and hot water supply devices that are capable of simultaneously performing heating operation and hot water supply operation have been widely utilized. As for example disclosed in Patent Document #1, this type of heating and hot water supply device is provided with a main heat exchanger and a heating apparatus, and there are also provided a circulation passage through which a heating thermal medium is circulated by a circulation pump between the main heat exchanger and the heating apparatus, and a bypass passage that branches off from the circulation passage and bypasses the heating apparatus.

A heat exchanger for hot water supply is provided in this bypass passage, and heat can be applied by the heating thermal medium to water flowing along a hot water supply passage through the heat exchanger for hot water supply. A distribution flow rate adjustment means is provided at the portion where the circulation passage and the bypass passage branch apart, so that it is possible to adjust the distribution ratio between the heating thermal medium that goes to the heating apparatus and the heating thermal medium that goes to the heat exchanger for hot water supply.

During heating operation, fuel is combusted, and heat is applied to the heating thermal medium by the main heat exchanger, and the distribution flow rate adjustment means is adjusted so that the heating thermal medium circulates entirely within the circulation passage. And, after the heating thermal medium to which heat has been applied dissipates heat in the heating apparatus, it returns back to the main heat exchanger.

When hot water supply operation is to be performed, the distribution flow rate adjustment means is adjusted so that part or all of the heating thermal medium to which heat has been applied circulates in the bypass passage, and hot water is supplied by heat being applied to the water flowing in the hot water supply passage by the heat exchanger for hot water supply that is provided in the bypass passage. Moreover, there are also some systems in which, instead of a distribution valve being provided, hot water supply operation is performed by operating a three way valve, so that all of the heating thermal medium circulates in the bypass passage.

A hot water supply bypass passage that bypasses the heat exchanger for hot water supply is provided to the hot water supply passage, and the hot water supply temperature is adjusted by mixing fresh water that flows in the hot water supply bypass passage into the hot water that has been heated by the heat exchanger for hot water supply. As for example disclosed in Patent Document #1, the flow rate of the cold water flowing in the hot water supply bypass passage may be regulated by providing a bypass valve in the hot water supply bypass passage, and the hot water supply temperature may be adjusted by mixing the cold water into the water to which heat has been applied. Alternatively, a mixing valve may be provided at the portion where the hot water supply passage and the hot water supply bypass passage join together, so that the mixing ratio between the water to which heat has been applied and the cold water can be adjusted, and thereby the hot water supply temperature is adjusted by mixing together the water to which heat has been applied and the cold water.

PRIOR ART DOCUMENT

Patent Document

Patent Document #1: Japanese Laid Open Patent Publication 2005-337632.

SUMMARY OF INVENTION

Technical Problem

When a heating and hot water supply device of this type performs heating operation, the heating thermal medium circulates at high temperature between the heating apparatus and the main heat exchanger. However, the distribution valve or three way valve that is provided at the branching portion between the circulation passage and the bypass passage is not generally a distribution valve or a three way valve having a fully closing function which is usually high in price, so that, during heating operation, it is not possible perfectly to shut off outflow of the heating thermal medium to the bypass passage. Because of this, heat is applied to the water within the heat exchanger for hot water supply by the heating thermal medium at high temperature which flows out into the bypass passage due to heating operation.

Furthermore, even outside the heat exchanger for hot water supply, the temperature of the water within the hot water supply passage is elevated by hot water heat transfer. For example, with the heating and hot water supply device of Patent Document #1, the temperature of the water in the hot water supply passage on the upstream side and on the downstream side than the heat exchanger for hot water supply, and also the temperature of the water in the hot water supply bypass passage, are both elevated by such heat transfer. When hot water supply is started in this state, there is a risk that perhaps the hot water provided will be hotter than the user anticipates, since the temperature of the water in the hot water supply passage and the temperature of the water in the hot water supply bypass passage are unduly high directly after the hot water supply starts.

Moreover, one expedient for preventing this type of hot water output at unduly high temperature is for the distribution valve or the three way valve at the portion where the circulation passage and the bypass passage branch apart to be provided as a distribution valve or a three way valve having a fully closing function, so that the heating thermal medium is positively prevented from flowing out, but this is not a preferred solution because it increases the manufacturing cost.

The object of the present invention is to provide a heating and hot water supply device that is capable of avoiding output of hot water at excessively high temperature even when hot water is being supplied during heating operation, without employing any distribution valve or three way valve having a fully closing function.

Means to Solve the Problem

The present invention presents a heating and hot water supply device, comprising a combustion means, a main heat exchanger, a circulation passage connected to the main heat exchanger and to a heating apparatus, a circulation pump provided in the circulation passage, a first bypass passage that branches off from the circulation passage and bypasses the heating apparatus, a heat exchanger for hot water supply provided in the first bypass passage, and a hot water supply passage for supplying cold water to the heat exchanger for hot water supply, and for supplying hot water heated by the heat exchanger for hot water supply to a predetermined set hot water supply temperature wherein: a distribution means is provided at a first branching portion of the first bypass passage, and a distribution ratio of the distribution means can be adjusted so that heating operation, or hot water supply operation, or simultaneous heating operation and hot water supply operation become possible; and a second bypass passage that bypasses the heat exchanger for hot water supply is provided in the hot water supply passage; a flow rate detection means provided on an upstream side than a second braching portion of the second bypass passage; a flow rate adjustment means for the hot water supply passage is provided at the second branching portion or on the downstream side than the second branching portion and also at the upstream side than the heat exchanger for hot water supply; and, during heating operation, the hot water supply passage is closed by the flow rate adjustment means.

According to the constitution described above, since the hot water supply passage is closed by the flow rate adjustment means during heating operation, therefore heat transfer to the water is prevented by the flow rate adjustment means. Accordingly, even if the temperature of water within the hot water supply passage is elevated by the heating thermal medium that has flowed out from the distribution means during heating operation via the heat exchanger for hot water supply, it is still possible to suppress elevation of the temperature of the water on the upstream side than the flow rate adjustment means. When hot water is supplied in this state, since the water whose temperature has been prevented from rising is supplied as hot water through the second bypass passage, accordingly it is possible to avoid supply of output hot water at an excessively high temperature.

The flow rate adjustment means may be a distribution valve provided at the second branching portion.

According to the constitution described above, during the heating operation, along with the hot water supply passage being closed by the distribution valve, the second bypass passage is opened. Therefore, even if during heating operation the temperature of the water in the hot water supply passage is elevated by the heating thermal medium, transmission of heat is prevented by the distribution valve, and it is possible to suppress elevation of the temperature of the water on the upstream side than the distribution valve. Moreover, when supply of hot water is started in this state, since this water whose temperature has been prevented from rising is supplied as hot water via the second bypass passage, accordingly it is possible to avoid supply of output hot water at an excessively high temperature.

The flow rate adjustment means may be a flow rate regulation valve provided more downstream than the second branching portion and moreover on the upstream side of the heat exchanger for hot water supply, and the bypass flow rate regulation valve may be provided in the second bypass passage; and, during heating operation, the bypass flow rate regulation valve may be opened.

According to the constitution described above, during the heating operation, the flow rate regulation valve closes the hot water supply passage, and the second bypass passage is opened. Therefore, even if during heating operation the temperature of the water in the hot water supply passage is elevated by the heating thermal medium, transmission of heat is prevented by the flow rate regulation valve, and it is possible to suppress elevation of the temperature of the water on the upstream side than the flow regulation valve. Moreover, when supply of hot water is started in this state, since the water whose temperature has been prevented from rising is supplied as hot water via the second bypass passage, accordingly it is possible to avoid supply of output hot water at an excessively high temperature.

Advantages of Invention

According to the present invention, it is possible to provide a heating and hot water supply device that is capable of avoiding output of hot water at excessively high temperature when supplying hot water during heating operation, without employing a high priced distribution valve or three way valve having a fully closing function.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a figure schematically showing a heating and hot water supply device according to the present invention;

FIG. 2 is a graph showing the hot water supply temperature when a hot water supply passage is closed during heating operation;

FIG. 3 is a graph showing the hot water supply temperature when a hot water supply passage is not closed during heating operation according to the prior art; and

FIG. 4 is a figure schematically showing a heating and hot water supply device according to a second embodiment.

DESCRIPTION OF EMBODIMENTS

In the following, implementations of the present invention will be explained on the basis of embodiments.

First Embodiment

First, the overall constitution of the heating and hot water supply device 1 of the present invention will be explained with reference to FIG. 1.

The heating and hot water supply device 1 performs heating operation by circulating a heating thermal medium, to which heat has been applied by heat exchange with combustion gases generated by a combustion unit 2, to a heating apparatus (not shown in the figures), and also performs hot water supply operation by supplying cold water to which heat has been applied by heat exchange with the heating thermal medium, while adjusting its temperature to a set hot water supply temperature.

The heating and hot water supply device 1 comprises a combustion unit 2 which is a combustion means that mixes fuel gas and air together and combusts them, a main heat exchanger 10 that applies heat to the heating thermal medium by heat exchange with the combustion gases generated by the above combustion, a circulation passage 4 that connects the main heat exchanger 10 with the heating apparatus, a circulation pump 11 that circulates the heating thermal medium through the circulation passage 4, and so on.

Moreover, the heating and hot water supply device 1 further comprises a first bypass passage 12 that branches off from the circulation passage 4 and bypasses the heating apparatus, a heat exchanger for hot water supply 20 that is provided in the first bypass passage 12, a hot water supply passage 21 for supplying fresh water to the heat exchanger for hot water supply 20 and for supplying hot water to which heat has been applied by the heat exchanger for hot water supply 20, and so on. And a first distribution valve 15 (a distribution means) is provided in the first branching portion where the first bypass passage 12 branches off from the circulation passage 4.

Furthermore, the heating and hot water supply device 1 comprises a control unit 7 that receives detection signals from temperature sensors etc. and controls heating operation and hot water supply operation etc. by operating the various units described above, and also comprises a box shaped casing 8 that receives the devices described above and so on.

Next, the combustion unit 2 will be explained.

The combustion unit 2 comprises an intake passage 40 that takes in air for combustion, a fuel gas passage 41 that supplies fuel gas provided from the exterior into the intake passage 40, a combustion fan 24 that blows the resulting mixture of air and fuel gas through the intake passage 40, and a burner 43 that combusts the mixture gas that has been blown in by the combustion fan 42.

The flow rate of the air for combustion is controlled by the rotational speed of the combustion fan 42. Moreover, a venturi mixer 44 is provided at the downstream end of the fuel gas passage 41, and controls the flow rate of the fuel gas supplied by the rotational speed of the combustion fan 42. An electromagnetic valve 45 is provided in the fuel gas passage 41, and, by opening and closing the electromagnetic valve 45, the fuel gas supply is started or stopped.

The burner 43 starts combustion by igniting the mixture gas blown by the combustion fan 42 with an ignition device 46 that is provided below the burner 43. Moreover, a combustion sensor 47 is provided below the burner 43 and detects the state of combustion.

The main heat exchanger 10 is provided below the ignition device 46 and the combustion sensor 47. This main heat exchanger 10 and the burner 43 etc. are housed within a housing 48 that defines a passage for the combustion gases. The combustion gases generated by combustion of the mixture gas in the burner 43 are sent to the main heat exchanger 10, and, after having exchanged heat with the heating thermal medium, are exhausted to the exterior via an exhaust passage 49 that extends from the lower portion of the housing 48. An exhaust temperature sensor 50 is provided at the downstream end portion of the exhaust passage 49, and is capable of detecting the temperature of the exhausted combustion gases.

The main heat exchanger 10 comprises a primary heat exchanger 10a that recovers sensible heat from the combustion gases, and a secondary heat exchanger 10b that recovers latent heat from the combustion gases. These two heat exchangers 10a,10b are connected so that the heating thermal medium to which heat has first been applied by the secondary heat exchanger 10b then receives further application of heat from the primary heat exchanger 10a. A drainage passage 51 is provided at the bottom portion of the housing 48, and discharges drainage water that has been condensed in the secondary heat exchanger 10b to the exterior. In order to prevent the combustion gases from flowing out, a drainage trap 52 is provided at the downstream end portion of the drainage passage 51.

Next, the circulation passage 4 will be explained.

A first temperature sensor 13 which is capable of detecting the temperature of the heating thermal medium flowing into the main heat exchanger 10 is provided in the circulation passage 4 between the circulation pump 11 and the main heat exchanger 10. And a second temperature sensor 14 that is capable of detecting the temperature of the heating thermal medium to which heat has been applied by the main heat exchanger 10 is provided on the downstream side of the main heat exchanger 10.

A first distribution valve 15 is provided at the first portion where the first bypass passage 12 branches off from the circulation passage 4, at the downstream side of the main heat exchanger 10. The first distribution valve 15 is capable of performing distribution while adjusting the distribution ratio of the heating thermal medium to which heat has been applied by the main heat exchanger 10 between the circulation passage 4 and the first bypass passage 12. The first bypass passage 12 rejoins the circulation passage 4 at the upstream side of the circulation pump 11.

A pressure relief valve 16 that relieves the pressure in the circulation passage 4 is provided between the main heat exchanger 10 and the first distribution valve 15. And a heating return temperature sensor 17 that is capable of detecting the temperature of the heating thermal medium returning from the heating apparatus is provided at the upstream side of the circulation pump 11. Moreover, a replenishment passage 18 for replenishing the heating thermal medium is connected between the circulation pump 11 and the heating return temperature sensor 17.

Next, the heat exchanger for hot water supply 20 will be explained. The heat exchanger for hot water supply 20 provided in the first bypass passage 12 is a plate type heat exchanger. In such a plate type heat exchanger, a plurality of heat exchange plates are laminated together so that passages are defined between the heat exchange plates. Within the heat exchanger for hot water supply 20, the heating thermal medium and the supply water for hot water flow through alternate passages defined between the heat exchange plates, arranged so that these flows oppose one another and do not mix with one another. The surface area of each of the heat exchange plates is formed with irregular roughnesses, in order to enhance the heat exchange efficiency.

Next, the hot water supply passage 21 will be explained. The hot water supply passage 21 is capable of supplying fresh water to the heat exchanger for hot water supply 20, and also is capable of supplying hot water to which heat has been applied by the heat exchanger for hot water supply 20 to a hot water supply faucet etc., and moreover a second bypass passage 22 is provided that branches off from the hot water supply passage 21 and bypasses the heat exchanger for hot water supply 20. A second distribution valve 23, which is equivalent to a flow rate adjustment means, is provided at the second branching portion between the hot water supply passage 21 and the second bypass passage 22. The second distribution valve 23 is capable of fresh water distribution by adjusting the distribution ratio between the hot water supply passage 21 and the second bypass passage 22. Due to this, the second distribution valve 23 is capable of adjusting the flow rate of fresh water flowing into the hot water supply passage 21.

A flow rate regulation valve 24, a hot water supply amount sensor 25, and an intake water temperature sensor 26 are provided at the upstream side than the second distribution valve 23. The flow rate regulation valve 24 is capable of regulating the flow rate of the fresh water that passes into the second distribution valve 23. The hot water supply amount sensor 25 is capable of detecting the flow rate of the fresh water that has been thus regulated. And the intake water temperature sensor 26 is capable of detecting the temperature of the fresh intake water that passes into the second distribution valve 23.

An output hot water temperature sensor 27 is provided between the location where the hot water supply passage 21 and the second bypass passage 22 join together and the heat exchanger for hot water supply 20. The output hot water temperature sensor 27 is capable of detecting the temperature of the hot water outputted from the heat exchanger for hot water supply 20. And a hot water supply temperature sensor 28 is provided downstream of the location where the hot water supply passage 21 and the second bypass passage 22 join together. The hot water supply temperature sensor 28 is capable of detecting the temperature of the mixture water that results from the mixing together of the hot water to which heat has been applied by the heat exchanger for hot water supply 20 and the fresh water flowing through the second bypass passage 22.

Next, the control unit 7 will be explained.

Although not shown in figures, the control unit 7 is capable of receiving detection signals from the various temperature sensors etc. provided within the heating and hot water supply device 1, and moreover is connected to the circulation pump 11 and the first distribution valve 15 etc. so as to be capable of controlling them. Moreover, the control unit 7 is connected to an operation device (operation terminal) that is provided within the building to which the heating and hot water supply device 1 is provided, so as to be capable of communicating therewith. The operation device may, for example, comprise a display unit that is capable of displaying, for example, temperature and operating status and so on, and an operating unit for performing setting of the heating temperature and the hot water supply temperature, and for performing starting actuation and stopping actuation for heating operation and so on.

Next, the operation and the advantageous effects of the heating and hot water supply device 1 will be explained with reference to FIGS. 1 through 3. When heating operation is started, the control unit 7 adjusts the first distribution valve 15 so that the heating thermal medium circulates only in the circulation passage 4, and, along with operating the circulation pump 11 and causing the heating thermal medium to circulate in the circulation passage 4, also operates the combustion fan 42 and the ignition device 46 and combusts mixture gas with the burner 43. The combustion gases that are generated apply heat to the heating thermal medium in the main heat exchanger 10. And, during the heating operation, the control unit 7 adjusts the second distribution valve 23 so that, along with the hot water supply passage 21 being closed, the second bypass passage 22 is opened. Due to the heating operation being continued, the heating thermal medium comes to be circulated at a predetermined temperature.

FIG. 2 is a graph showing one example of the temperature detected by the output hot water temperature sensor 27 and the temperature detected by the hot water supply temperature sensor 28 before and after hot water supply operation starts during heating operation, as the opening amount of the second distribution valve 23 changes over the passage of time. The opening amount of the second distribution valve 23 is expressed by a number of steps along the second vertical axis; for example, the completely closed state when the hot water supply passage 21 is closed is step 1700, while the state in which the distribution ratio between the hot water supply passage 21 and the second bypass passage 22 is 2:3 is step 1000. At this time, the temperature of the fresh water is 22° C.

During heating operation, a part of the heating thermal medium that is circulating flows out from the first distribution valve 15 and flows into the first bypass passage 12. Heat is applied to the water in the hot water supply passage 21 by the heating thermal medium in the heat exchanger for hot water supply 20, and the temperature of the water within the hot water supply passage 21 that is detected by the output hot water temperature sensor 27 that is close to the heat exchanger for hot water supply 20 is raised to around 64° C., and the temperature of the water detected by the hot water supply temperature sensor 28 becomes around 33° C. Although not shown in the figure, since the hot water supply passage 21 is closed by the second distribution valve 23 so that transfer of heat from the water that has been heated by the heat exchanger for hot water supply 20 to the water on the upstream side of the second distribution valve 23 is prevented, accordingly the temperature more upstream than the second distribution valve 23 is low.

Supply of hot water is started near the elapsed time of 3 seconds in FIG. 2; that is, hot water supply operation is started when, due to a hot water supply faucet etc. being opened, the hot water supply amount sensor 25 detects a flow rate greater than or equal to the predetermined flow rate. The control unit 7 adjusts the first distribution valve 15 so that the heating thermal medium circulates only in the first bypass passage 12, and thereby heat is applied by the heating thermal medium to the water in the heat exchanger for hot water supply 20. Since, even after the hot water supply operation has started, the hot water supply passage 21 remains closed for one second, for example, rising of temperature at the upstream side than the second distribution valve 23 is suppressed and hot water is supplied via the second bypass passage 22. Accordingly, although the water at the upstream side of the hot water supply temperature sensor 28 whose temperature has been raised is supplied as hot water whose temperature has been elevated by about +4° C., since the amount of this elevation is small and water is immediately supplied as hot water via the second bypass passage 22, accordingly it is possible to avoid supply of hot water at an excessively high temperature.

Next, after for example one second has elapsed from the start of hot water supply, the control unit 7 gradually adjusts the opening amount of the second distribution valve 23, for example from 1700 steps to 1000 steps in three seconds, so that fresh water gradually flows into the hot water supply passage 21. Since the water at high temperature in the heat exchanger for hot water supply 20 is gradually outputted as hot water, accordingly the output hot water temperature is elevated. However, the amount of elevation of the hot water supply temperature is low, because this output hot water at high temperature and the cold water at low temperature are mixed together.

Since, in this manner, the water in the hot water supply passage 21 whose temperature has been elevated during the heating operation is supplied as hot water while being mixed a little at a time with fresh water passing through the second bypass passage 22, accordingly it is possible to avoid the output of hot water at an excessively high temperature due to the water in the hot water supply passage 21 whose temperature has been elevated during the heating operation. Moreover when, on the basis of the set hot water supply temperature and the output hot water temperature detected by the output hot water temperature sensor 27 etc., the control unit 7 determines that simultaneous heating operation and hot water supply operation are possible, then the control unit 7 adjusts the distribution ratio of the first distribution valve 15 and performs simultaneous heating operation and hot water supply operation.

FIG. 3 is a graph showing one example of change over the passage of time of the output hot water temperature and the hot water supply temperature, when, in order to recreate the operation of a prior art heating and hot water supply device, the second distribution valve 23 is fixed at 1000 steps, and the hot water supply passage 21 is not closed during space heating operation. The temperature of the fresh water at this time is 24° C.

Since the hot water supply passage 21 is not closed during the space heating operation, accordingly the temperature of the water in the heat exchanger for hot water supply 20 is elevated by the heating thermal medium and convection takes place, and water at high temperature flows in the hot water supply passage 21 and in the second bypass passage 22. Due to this, heat is transmitted to the upstream side and the downstream side of the heat exchanger for hot water supply 20, and the water in the hot water supply passage 21 and in the second bypass passage is heated up to a high temperature. The temperature of the water more downstream than the portion where the hot water supply passage 21 and the second bypass passage 22 come together is also elevated due to the water at high temperature, and the temperature detected by the hot water supply temperature sensor 28 goes up to around 49° C., which is a higher temperature than in the case of FIG. 2. Although not shown in the figure, in a similar manner, heat is also transmitted to the water at the upstream side of the second distribution valve 23, which accordingly also goes to high temperature.

When in FIG. 3 the hot water supply is started at around 3 seconds elapsed time, since the second distribution valve 23 is not closing the hot water supply passage 21, accordingly the fresh water that is taken in by the second distribution valve 23 as intake water is distributed to the hot water supply passage 21 and to the second bypass passage 22. Therefore, the water at high temperature in the heat exchanger for hot water supply 20 is outputted, and the output hot water temperature rises. And, when at around 6 seconds elapsed time this water at high temperature passes down the second bypass passage 22 and mixes with the water whose temperature has been raised and is supplied as hot water, the hot water supply temperature is elevated. Since the temperature of the water that is mixed in through the second bypass passage 22 is high, accordingly the magnitude of this elevation is around +14° C., which is large as compared with the case of FIG. 2. Accordingly, in the case of FIG. 3, the hot water continues to be supplied at a high temperature for a considerable while after the start of hot water supply, and there is a danger of output of hot water at an excessively high temperature, since the hot water supply temperature rises greatly partway through this supply.

As explained above, with the heating and hot water supply device 1 of the present invention, due to the fact that the hot water supply passage 21 is closed by the second distribution valve 23 during the space heating operation, it is possible to suppress elevation of the temperature of the water in the hot water supply passage 21, so that it is possible to avoid outputting of excessively hot water. Moreover, since the water within the hot water supply passage 21 whose temperature has become elevated during heating operation is gradually mixed with fresh water supplied via the second bypass passage 22 and is then supplied as hot water, accordingly it is possible to avoid any outputting of excessively hot water.

Second Embodiment

Next, a heating and hot water supply device 1A according to a second embodiment will be explained with reference to FIG. 4.

In the heating and hot water supply device 1A, instead of the second distribution valve 23 of the first embodiment which is an adjustment means for adjusting the flow rate in the hot water supply passage 21, it is possible to adjust the hot water supply flow rate with a flow rate regulation valve 23A provided in a hot water supply passage 21A and with a bypass flow rate regulation valve 24A provided in a second bypass passage 22A. The second bypass passage 22A branches off from between a flow rate adjustment valve 23A and a hot water supply amount sensor 25A.

Next, the operation and the advantageous effects of the heating and hot water supply device 1A will be explained.

During heating operation, the control unit 7A closes the flow rate adjustment valve 23A and opens the bypass flow rate regulation valve 24A so that the hot water supply passage 21A is closed and the second bypass passage 22A is opened. Even if the temperature of the water in the hot water supply passage 21A becomes elevated during the heating operation by the heating thermal medium, rise of the temperature of the fresh water at the upstream side than the flow rate adjustment valve 23A is suppressed, since the flow rate adjustment valve 23A is closed.

When in this state hot water supply operation is started, since fresh water rising of whose temperature has been suppressed is supplied via the second bypass passage 22A, accordingly it is possible to avoid output of hot water at an excessively high temperature when hot water supply starts. Moreover, the control unit 7A adjusts the flow rate adjustment valve 23A so that a lot of fresh water flows into the hot water supply passage 21 gradually. Since in this manner, during space heating operation, the water in the hot water supply passage 21A whose temperature has been elevated is mixed with fresh water a little bit at a time for supply of hot water, accordingly it is possible to avoid the output of hot water at an excessively high temperature due to the hot water in the hot water supply passage 21A. Moreover when, on the basis of the set hot water supply temperature and the output hot water temperature detected by the output hot water temperature sensor 27A and so on, the control unit 7A is able to determine that simultaneous heating operation and hot water supply operation are possible, then the control unit adjusts the distribution ratio of the first distribution valve 15A and performs simultaneous space heating operation and hot water supply operation.

Apart from the above, for a person skilled in the art, it would be possible to implement the present invention by adding various changes to the embodiments described above without deviating from the gist of the invention, and the present invention is to be understood as including such variant embodiments.

DESCRIPTION OF REFERENCE NUMERALS

• 1: heating and hot water supply device
• 2: combustion unit (combustion means)
• 4: circulation passage
• 7: control unit
• 8: case
• 8a: bottom plate
• 10: main heat exchanger
• 11: circulation pump
• 12: first bypass passage
• 15: first distribution valve (distribution means)
• 20,20A: heat exchanger for hot water supply
• 21,21A: hot water supply passage
• 22,22A: second bypass passage
• 23: second distribution valve (flow rate adjustment means)
• 23A: flow rate adjustment valve
• 24,24A: flow rate regulation valve
• 25,25A: hot water supply amount sensor
• 27: output hot water temperature sensor
• 28: hot water supply temperature sensor

Claims

1. A heating and hot water supply device, comprising a combustion means, a main heat exchanger, a circulation passage connected to the main heat exchanger and to a heating apparatus, a circulation pump provided in the circulation passage, a first bypass passage that branches off from the circulation passage and bypasses the heating apparatus, a heat exchanger for hot water supply provided in the first bypass passage, and a hot water supply passage for supplying cold water to the heat exchanger for hot water supply, and for supplying hot water heated by the heat exchanger for hot water supply to a predetermined set hot water supply temperature, wherein:

a distribution means is provided at a first branching portion of the first bypass passage, and a distribution ratio of the distribution means can be adjusted so that heating operation, or hot water supply operation, or simultaneous heating operation and hot water supply operation, become possible; and

a second bypass passage that bypasses the heat exchanger for hot water supply is provided in the hot water supply passage; a flow rate detection means is provided on an upstream side than a second branching portion of the second bypass passage; a flow rate adjustment means for the hot water supply passage is provided at the second branching portion or on the downstream side than the second branching portion and also at an upstream side than the heat exchanger for hot water supply; and, during heating operation, the hot water supply passage is closed by the flow rate adjustment means.

2. The heating and hot water supply device according to claim 1, wherein the flow rate adjustment means is a distribution valve provided at the second branching portion.

3. The heating and hot water supply device according to claim 1, wherein the flow rate adjustment means is a flow rate regulation valve provided more downstream than the second branching portion and moreover on the upstream side than the heat exchanger for hot water supply, and the bypass flow rate regulation valve is provided in the second bypass passage; and in that, during heating operation, the bypass flow rate regulation valve is opened.