SPACE AND WATER HEATING APPARATUS

Abstract

To reduce remaining air bubbles, a space and water heating apparatus includes external and internal circulation channels, including a shared portion, to respectively circulate a heating medium through space heating equipment and a water-heating heat exchanger, a discharger that discharges air bubbles, and a circulation switcher (three-way valve) that switches among a space heating operation mode, a water heating operation mode, and a simultaneous operation mode to respectively circulate the heating medium along the external circulation channel, the internal circulation channel, and both the external and internal circulation channels. Feeding the heating medium is followed by a test operation including external- and internal-channel discharge processes to respectively discharge air bubbles from the external and internal circulation channels by circulating the heating medium. In the internal-channel discharge process, the water heating or simultaneous operation mode is switched to the space heating operation mode during operation of a circulation pump.

Claims

1. A space and water heating apparatus for performing a space heating operation and a water heating operation, the space heating operation being an operation in which a heating medium is circulated by a circulation pump through space heating equipment for space heating, the water heating operation being an operation in which the heating medium circulated in the space heating operation is circulated through a water-heating heat exchanger to heat, by heat exchange with the heating medium, water supplied to the water-heating heat exchanger, the apparatus comprising: an external circulation channel to circulate the heating medium through the space heating equipment; an internal circulation channel to circulate the heating medium through the water-heating heat exchanger, the internal circulation channel including a shared portion shared with the external circulation channel; a heater configured to heat the heating medium in the shared portion; a temperature sensor configured to detect a temperature of the heating medium in the shared portion; a circulation switcher configured to switch among a space heating operation mode in which the heating medium is circulated along the external circulation channel, a water heating operation mode in which the heating medium is circulated along the internal circulation channel, and a simultaneous operation mode in which the heating medium is circulated along the external circulation channel and the internal circulation channel; a discharger configured to discharge air bubbles contained in the heating medium; and a test operation controller configured to control a test operation to be performed after the heating medium is fed, the test operation being an operation in which the heating medium is circulated to facilitate discharge of the air bubbles, wherein the test operation includes an external-channel discharge process to facilitate discharge of the air bubbles from the external circulation channel and an internal-channel discharge process to facilitate discharge of the air bubbles from the internal circulation channel, and in the internal-channel discharge process, the circulation switcher switches from the water heating operation mode or the simultaneous operation mode to the space heating operation mode during operation of the circulation pump.

2. The space and water heating apparatus according to claim 1, wherein in the internal-channel discharge process, the circulation switcher switches from the water heating operation mode to the space heating operation mode during operation of the circulation pump.

3. The space and water heating apparatus according to claim 1, wherein in the external-channel discharge process, the circulation pump is operated while the circulation switcher maintains the space heating operation mode, and the test operation controller performs the internal-channel discharge process after performing the external-channel discharge process.

4. The space and water heating apparatus according to claim 1, wherein the test operation controller performs a plurality of the internal-channel discharge processes in each of which the circulation switcher switches to the space heating operation mode at a different timing or the circulation pump circulates the heating medium at a different flow velocity.

5. The space and water heating apparatus according to claim 1, wherein the test operation includes a heating-discharge process in which the heating medium heated by the heater is circulated along at least one of the external circulation channel or the internal circulation channel, and the test operation controller performs the heating-discharge process after performing the external-channel discharge process and the internal-channel discharge process.

6. The space and water heating apparatus according to claim 5, wherein in the heating-discharge process, the heater heats the heating medium until the temperature detected by the temperature sensor reaches a predetermined temperature, and the predetermined temperature is set to a higher temperature of a target temperature of the heating medium in the space heating operation or a target temperature of the heating medium in the water heating operation.

7. The space and water heating apparatus according to claim 2, wherein in the external-channel discharge process, the circulation pump is operated while the circulation switcher maintains the space heating operation mode, and the test operation controller performs the internal-channel discharge process after performing the external-channel discharge process.

8. The space and water heating apparatus according to claim 2, wherein the test operation controller performs a plurality of the internal-channel discharge processes in each of which the circulation switcher switches to the space heating operation mode at a different timing or the circulation pump circulates the heating medium at a different flow velocity.

9. The space and water heating apparatus according to claim 2, wherein the test operation includes a heating-discharge process in which the heating medium heated by the heater is circulated along at least one of the external circulation channel or the internal circulation channel, and the test operation controller performs the heating-discharge process after performing the external-channel discharge process and the internal-channel discharge process.

10. The space and water heating apparatus according to claim 9, wherein in the heating-discharge process, the heater heats the heating medium until the temperature detected by the temperature sensor reaches a predetermined temperature, and the predetermined temperature is set to a higher temperature of a target temperature of the heating medium in the space heating operation or a target temperature of the heating medium in the water heating operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a diagram of a space and water heating apparatus 1 according to an embodiment.

[0020] FIGS. 2A, 2B, and 2C are each a cross-sectional view of a three-way valve 29 in the present embodiment.

[0021] FIG. 3 is a diagram of space heating equipment according to the present embodiment.

[0022] FIG. 4 is a table describing a sequence in a test operation in the space and water heating apparatus 1 according to the present embodiment.

DETAILED DESCRIPTION

[0023] FIG. 1 is a diagram of a space and water heating apparatus 1 according to an embodiment. As illustrated, the space and water heating apparatus 1 includes a combustion unit 4 housed in a housing 2. The combustion unit 4 incorporates a burner 3 that burns a gas mixture of fuel gas and combustion air. The combustion unit 4 is connected to a combustion fan 5 to feed the gas mixture to the combustion unit 4.

[0024] The combustion fan 5 has an intake connected to a joint 6 at which an air supply channel 7 for supplying combustion air joins a gas supply channel 8 for supplying fuel gas. The gas supply channel 8 includes a valve (not shown) that opens and closes the gas supply channel 8 and a zero governor 9 that lowers the pressure of fuel gas fed from upstream under pressure to the atmospheric pressure. The joint 6 incorporates a control valve that regulates the ratio of combustion air and fuel gas flowing into the combustion fan 5. When the combustion fan 5 is driven, the air in the housing 2 and the fuel gas in the gas supply channel 8 downstream from the zero governor 9 are drawn into the combustion fan 5 through the joint 6 at a predetermined ratio, and the resultant gas mixture is fed to the combustion unit 4.

[0025] In the combustion unit 4, the burner 3 incorporated in the combustion unit 4 burns the gas mixture. In the illustrated example, the burner 3 ejects the gas mixture downward to generate flames downward and emits exhaust gas downward. The combustion fan 5 is electrically connected to a controller 40 that controls the overall operation of the space and water heating apparatus 1. The controller 40 controls the combustion level of the burner 3 by changing the rotational speed of the combustion fan 5 based on the amount of heat to be used.

[0026] The combustion unit 4 includes a spark plug 11 that produces sparks in the burner 3 through high-voltage discharge, a flame rod 12 that detects the flames (ignition) of the burner 3, and a check valve 13 that blocks a backflow from the combustion unit 4 to the combustion fan 5. The spark plug 11 and the flame rod 12 are electrically connected to the controller 40.

[0027] A first heat exchanger 15 is located below the burner 3. A second heat exchanger 16 is located below the first heat exchanger 15. The exhaust gas produced from combustion with the burner 3 is emitted downward and passes through the first heat exchanger 15 and the second heat exchanger 16 in this order. The first heat exchanger 15 recovers sensible heat from the exhaust gas, and the second heat exchanger 16 recovers latent heat from the exhaust gas.

[0028] After passing through the first heat exchanger 15 and the second heat exchanger 16, the exhaust gas flows through an exhaust duct 17 and is discharged through an exhaust port 18 protruding from the top of the housing 2. In the illustrated example, the housing 2 has an air supply port 19 at the top. The air supply port 19 allows air to be drawn into the housing 2, in which the air is supplied to the joint 6 through the air supply channel 7.

[0029] The upstream end of the first heat exchanger 15 is connected to the downstream end of the second heat exchanger 16. The downstream end of the first heat exchanger 15 is connected to the upstream end of space heating equipment (described later) through an outgoing channel 21. The upstream end of the second heat exchanger 16 is connected to the downstream end of the space heating equipment (described later) through a return channel 22. The return channel 22 includes a circulation pump 23 that pumps the heating medium toward the second heat exchanger 16 and a return temperature sensor 24 that detects the temperature of the heating medium flowing into the second heat exchanger 16 (hereafter, a return temperature). The circulation pump 23 and the return temperature sensor 24 are electrically connected to the controller 40. Although the space and water heating apparatus 1 according to the present embodiment uses hot water as the heating medium, the heating medium may be, for example, silicone oil.

[0030] The circulation pump 23 is operated to deliver the heating medium to the second heat exchanger 16, which preheats the heating medium using latent heat recovered from the exhaust gas from the burner 3. The preheated heating medium is then delivered to the first heat exchanger 15. The first heat exchanger 15 heats the heating medium using sensible heat recovered from the exhaust gas from the burner 3. The resultant high-temperature heating medium is supplied to the space heating equipment through the outgoing channel 21. The outgoing channel 21 includes an outgoing temperature sensor 25 that detects the temperature of the heating medium flowing out of the first heat exchanger 15 (hereafter, an outgoing temperature). The outgoing temperature sensor 25 is electrically connected to the controller 40. The controller 40 determines the amount of heat to be used based on the temperature detected by the outgoing temperature sensor 25, and controls combustion in the burner 3. The outgoing temperature sensor 25 in the present embodiment corresponds to a temperature sensor in one or more aspects of the present invention. The burner 3, the first heat exchanger 15, and the second heat exchanger 16 in the present embodiment correspond to a heater in one or more aspects of the present invention.

[0031] The heating medium passes through the space heating equipment, returns to the circulation pump 23 through the return channel 22, and is delivered to the second heat exchanger 16 again to circulate. The circulation pump 23 in the present embodiment is operated at a constant rotational speed to pump the heating medium. The outgoing channel 21 includes an air vent 26 at the upper end to discharge air bubbles (air) contained in the heating medium. The air vent 26 in the present embodiment corresponds to a discharger in one or more aspects of the present invention.

[0032] The air vent 26, which may be a typically known float air vent, includes a valve cavity having an orifice and accommodating a float. When the heating medium flows into the valve cavity, the liquid level rises to cause the float on the liquid to block the orifice. This closes the valve. When air bubbles contained in the heating medium float upward and flow into the valve cavity, the liquid level lowers to cause the float to move away from the orifice. This opens the valve. When the air in the valve cavity is discharged, the liquid level rises, closing the valve again. While the circulation pump 23 is being operated, air bubbles circulate together with the heating medium and are less easily discharged. While the circulation pump 23 is stopped, air bubbles float upward and are easily discharged.

[0033] A branch channel 27 branches from the outgoing channel 21 downstream from the outgoing temperature sensor 25. The branch channel 27 is connected to the return channel 22 upstream from the circulation pump 23. The branch channel 27 includes a water-heating heat exchanger 28. The branch channel 27 and the return channel 22 include a three-way valve 29 at their connection. The three-way valve 29 is electrically connected to the controller 40. The three-way valve 29 can switch the circulation route of the heating medium flowing out of the first heat exchanger 15. More specifically, the three-way valve 29 can switch among a route through the space heating equipment (hereafter, an external circulation channel), a route through the water-heating heat exchanger 28 (hereafter, an internal circulation channel), and a route through both the external circulation channel and the internal circulation channel. The structure of the three-way valve 29 will be described later with reference to other figures. The three-way valve 29 in the present embodiment corresponds to a circulation switcher in one or more aspects of the present invention. A section downstream from the connection between the return channel 22 and the branch channel 27 and upstream from the connection between the outgoing channel 21 and the branch channel 27 in the present embodiment corresponds to a shared portion in one or more aspects of the present invention.

[0034] The water-heating heat exchanger 28 is a liquid-liquid heat exchanger, to which a water inlet channel 30 and a hot-water outlet channel 31 are connected. The water inlet channel 30 allows clean water to flow to the water-heating heat exchanger 28, at which the clean water is heated by heat exchange with the heating medium, and the resultant hot water flows out into the hot-water outlet channel 31. The water inlet channel 30 includes a water flow sensor 32 that measures the flow rate of clean water flowing into the space and water heating apparatus 1, a water flow servo 33 that adjusts the flow rate of clean water, and a water inlet temperature sensor 34 that detects the temperature of clean water. The hot-water outlet channel 31 includes a heat-exchanger outlet temperature sensor 35 that detects the temperature of hot water immediately after flowing out of the water-heating heat exchanger 28. The water flow sensor 32, the water flow servo 33, the water inlet temperature sensor 34, and the heat-exchanger outlet temperature sensor 35 are electrically connected to the controller 40.

[0035] The space and water heating apparatus 1 according to the present embodiment includes a bypass channel 36 connecting a section of the water inlet channel 30 downstream from the water inlet temperature sensor 34 and a section of the hot-water outlet channel 31 downstream from the heat-exchanger outlet temperature sensor 35. The clean water flowing into the space and water heating apparatus 1 can partly flow through the bypass channel 36 without flowing to the water-heating heat exchanger 28, with the remaining clean water flowing to the water-heating heat exchanger 28. The water heated by the water-heating heat exchanger 28 mixes with the clean water passing through the bypass channel 36, and then flows out of the space and water heating apparatus 1. The bypass channel 36 and the hot-water outlet channel 31 include a bypass servo 37 at their connection. The bypass servo 37 is electrically connected to the controller 40. The bypass servo 37 can change the mixing ratio between the water heated by the water-heating heat exchanger 28 and the clean water passing through the bypass channel 36.

[0036] The hot-water outlet channel 31 includes a hot-water outlet temperature sensor 38 downstream from the bypass servo 37 to detect the temperature of hot water flowing out of the space and water heating apparatus 1. The hot-water outlet temperature sensor 38 is connected to the controller 40. As described above, the clean water in the water inlet channel 30 can partly flow into the hot-water outlet channel 31 through the bypass channel 36 without flowing through the water-heating heat exchanger 28. Thus, the temperature detected by the hot-water outlet temperature sensor 38 is lower than the temperature detected by the heat-exchanger outlet temperature sensor 35. The bypass servo 37 can adjust the mixing ratio to reduce temperature fluctuations of the hot water flowing out of the space and water heating apparatus 1.

[0037] The controller 40 is also connected to a water-heating remote control 41 and a space-heating remote control 42. The user can operate the water-heating remote control 41 to turn on or off the water heating operation or set the hot water temperature. The user can also operate the space-heating remote control 42 to provide an instruction to start or stop the space heating operation or set the temperature for space heating.

[0038] FIGS. 2A to 2C are each a cross-sectional view of a three-way valve 29 in the present embodiment. As illustrated, the three-way valve 29 includes a valve cavity 50 that can be open in three directions. In the illustrated example, the valve cavity 50 has a left opening connecting with the branch channel 27, a right opening connecting with a section of the return channel 22 closer to the space heating equipment than the connection with the branch channel 27 (hereafter, an equipment return channel 22a), and an upper opening connecting with a section of the return channel 22 closer to the second heat exchanger 16 than the connection with the branch channel 27 (hereafter, a heat-exchanger return channel 22b).

[0039] The valve cavity 50 accommodates a water-heating valve element 51 that opens and closes the branch channel 27 and a space-heating valve element 52 that opens and closes the equipment return channel 22a. The water-heating valve element 51 and the space-heating valve element 52 are attached in a reversed manner to a movable shaft 53 that can reciprocate laterally. The movable shaft 53 is driven by a drive 54. The drive 54 in the present embodiment incorporates a stepper motor and converts its rotation to axial (lateral) movement of the movable shaft 53.

[0040] In FIG. 2A, the movable shaft 53 is moved to the left, with the water-heating valve element 51 closing the branch channel 27 and the space-heating valve element 52 opening the equipment return channel 22a. In this state, the heating medium forced out of the first heat exchanger 15 by the circulation pump 23 circulates through the space heating equipment (external circulation channel) without being distributed to the water-heating heat exchanger 28. This is a space heating operation mode.

[0041] When the movable shaft 53 is driven by the drive 54 to move to the right as shown in FIG. 2B, the space-heating valve element 52 closes the equipment return channel 22a, and the water-heating valve element 51 opens the branch channel 27. In this state, the heating medium forced out of the first heat exchanger 15 by the circulation pump 23 circulates through the water-heating heat exchanger 28 (internal circulation channel) without being distributed to the space heating equipment. This is a water heating operation mode.

[0042] When the movable shaft 53 is placed between the position for the space heating operation mode in FIG. 2A and the position for the water heating operation mode in FIG. 2B as shown in FIG. 2C, both the branch channel 27 and the equipment return channel 22a are open. In this state, the heating medium forced out of the first heat exchanger 15 by the circulation pump 23 circulates through both the space heating equipment (external circulation channel) and the water-heating heat exchanger 28 (internal circulation channel). This is a simultaneous operation mode. The space heating operation mode, the water heating operation mode, and the simultaneous operation mode in the present embodiment refer to the switching modes of the three-way valve 29 and do not refer to space heating or water heating that is actually performed. Thus, these operation modes may or may not be accompanied by combustion with the burner 3 to heat the heating medium.

[0043] FIG. 3 is a diagram of the space heating equipment according to the present embodiment. In the example shown in FIG. 3, the outgoing channel 21 and the return channel 22 are connected to a low-loss header 60 that temporarily stores the heating medium. When the three-way valve 29 is set to circulate the heating medium from the first heat exchanger 15 along the external circulation channel, the heating medium circulates through the low-loss header 60. The low-loss header 60 is connected to the upstream end and the downstream end of a space heating channel 61 to form a secondary circuit that is different from a primary circuit formed by the outgoing channel 21 and the return channel 22. The low-loss header 60 reduces a pressure loss in the primary circuit caused by the flow channel resistance in the secondary circuit, and allows a sufficient amount of heating medium to circulate through the primary circuit.

[0044] As illustrated, the space heating channel 61 in the present embodiment branches into two channels, or specifically, a first space heating channel 61a and a second space heating channel 61b, which then join into a single channel. The first space heating channel 61a includes a first pump 62 that causes the heating medium from the low-loss header 60 to circulate through the first space heating channel 61a and a first radiator 63a incorporated in a baseboard heating unit 63. In the baseboard heating unit 63, the heating medium delivered by the first pump 62 radiates heat for space heating while passing through the first radiator 63a. The second space heating channel 61b includes a second pump 64 that causes the heating medium from the low-loss header 60 to circulate through the second space heating channel 61b and a second radiator 65a incorporated in an air handling unit 65. In the air handling unit 65, the heating medium delivered by the second pump 64 radiates heat for space heating while passing through the second radiator 65a. The space heating equipment incorporating the first radiator 63a and the second radiator 65a is not limited to the baseboard heating unit 63 and the air handling unit 65, and may be floor heating units or fan convectors.

[0045] In the example shown in FIG. 3, the space heating channel 61 includes a dirt trap 66 downstream from the point at which the first space heating channel 61a and the second space heating channel 61b join together. The dirt trap 66 removes foreign matter contained in the heating medium. The space heating channel 61 also includes an air separator 67 upstream from the point at which the space heating channel 61 branches into the first space heating channel 61a and the second space heating channel 61b. The air separator 67 discharges air bubbles (air) contained in the heating medium. As is known, the air separator 67 typically includes a mesh. When the heating medium passes through the mesh, air bubbles contained in the heating medium are trapped on the mesh and discharged. Thus, circulating the heating medium can facilitate discharge of air bubbles at the air separator 67.

[0046] The air separator 67 in the present embodiment is connected to an expansion tank 69 with a connection channel 68. The expansion tank 69 can accommodate the heating medium when the heating medium expands with an increase in temperature. The connection channel 68 is connected to a feed channel 70 including a feed valve 71 that opens and closes the feed channel 70. In the space and water heating apparatus 1 according to the present embodiment, the heating medium is fed by an installer connecting a heating medium supply pipe (not shown) to the feed channel 70 and manually opening the feed valve 71 after installing the space and water heating apparatus 1. The outgoing channel 21 in the present embodiment includes a pressure sensor 72 that detects the pressure of the heating medium in the outgoing channel 21. The heating medium is fed until the pressure detected by the pressure sensor 72 reaches a predetermined pressure.

[0047] In the space and water heating apparatus 1 with this structure, air may remain in, for example, the first heat exchanger 15, the second heat exchanger 16, the outgoing channel 21, the return channel 22, the branch channel 27, the water-heating heat exchanger 28, and the low-loss header 60 after the heating medium is fed. Such remaining air may circulate in the form of air bubbles together with the heating medium, possibly causing failure. For example, the burner 3 may be turned off when the heating medium partly boils with concentration of heat around air bubbles passing through the first heat exchanger 15. The burner 3 may be turned on when the temperature detected by the outgoing temperature sensor 25 decreases with air bubbles passing by the outgoing temperature sensor 25. The burner 3 may be repeatedly turned on and off under unstable temperatures detected by the outgoing temperature sensor 25. Air bubbles remaining particularly in the internal circulation channel, which circulates the heating medium through the water-heating heat exchanger 28, may disrupt the temperature adjustment for the heating medium during the water heating operation. This may destabilize the temperature of hot water flowing out of the space and water heating apparatus 1 and decrease user comfort. Such air bubbles may thus have more negative effects than air bubbles remaining in the external circulation channel, which circulates the heating medium through the space heating equipment. To reduce such failure caused by air bubbles remaining particularly in the internal circulation channel, the space and water heating apparatus 1 according to the present embodiment performs a test operation after its installation. In the test operation, the heating medium is circulated to facilitate discharge of air bubbles in the manner described below.

[0048] FIG. 4 is a table describing a sequence in the test operation in the space and water heating apparatus 1 according to the present embodiment. The test operation is performed under the control of the controller 40. The controller 40 in the present embodiment functions as a test operation controller in one or more aspects of the present invention. First, in a feed preparation process in STEP 1, the three-way valve 29 is switched to the position for the simultaneous operation mode in FIG. 2C in response to a test operation button (not shown) being pressed. In the space and water heating apparatus 1 according to the present embodiment, the three-way valve 29 is initially set to the position for the space heating operation mode in FIG. 2A. The three-way valve 29 is thus driven by the drive 54 to switch from the space heating operation mode to the simultaneous operation mode.

[0049] In a feed process in STEP 2, the three-way valve 29 is maintained at the position for the simultaneous operation mode while the heating medium is being fed by the installer who has installed the space and water heating apparatus 1. As described above, the heating medium is fed by the installer connecting the heating medium supply pipe to the feed channel 70 and manually opening the feed valve 71. With the three-way valve 29 at the position for the simultaneous operation mode, the fed heating medium flows into the internal circulation channel (water-heating heat exchanger 28), in addition to the external circulation channel. This allows less air to remain in the water-heating heat exchanger 28 when the feeding of the heating medium ends. In the space and water heating apparatus 1 according to the present embodiment, the feed channel 70 is connected to the connection channel 68 branching from the space heating channel 61. However, the feed channel 70 may be connected to another channel, such as the outgoing channel 21 or the return channel 22.

[0050] In a pressure identification process in STEP 3, the pressure of the heating medium in the outgoing channel 21 detected by the pressure sensor 72 is identified. When the detected pressure reaches a pressure higher than or equal to a predetermined pressure and is maintained at such a pressure for a predetermined duration, the three-way valve 29 is switched from the position for the simultaneous operation mode in FIG. 2C to the position for the space heating operation mode in FIG. 2A. When the pressure detected by the pressure sensor 72 reaches a pressure higher than or equal to the predetermined pressure and is maintained at such a pressure for the predetermined duration, such information may be provided to the installer through a display or a voice.

[0051] In an external-channel discharge process in STEP 4, the circulation pump 23 is operated to facilitate discharge of air bubbles from the external circulation channel that circulates the heating medium through the space heating equipment. As described above, the space and water heating apparatus 1 according to the present embodiment includes the air separator 67 for the space heating equipment (space heating channel 61) to discharge air bubbles in the heating medium while the heating medium is circulating (passing) through the air separator 67. With the space heating equipment having different specifications depending on the types, the space heating equipment (space heating channel 61) may have no air separator 67, although typically having the air separator 67. The air separator 67 may be replaced with an air vent that can discharge air bubbles when the circulation of the heating medium is stopped. The external-channel discharge process in the present embodiment can sufficiently discharge air bubbles using the air vent (the air vent 26 incorporated in the space and water heating apparatus 1 or another air vent installed for the space heating equipment) when the space heating equipment has no air separator 67.

[0052] First, in the illustrated example, an on-off operation in which the circulation pump 23 is operated for 20 seconds and then stopped for 10 seconds is repeated three times. As described above, air bubbles are less easily discharged from the air vent 26 while the circulation pump 23 is being operated. Thus, the on-off operation of the circulation pump 23 is repeatedly performed to circulate (move) air bubbles together with the heating medium while the circulation pump 23 is being operated and also to allow air bubbles to float upward to facilitate discharge of the air bubbles while the circulation pump 23 is stopped. When the space heating equipment has the air separator 67 as in the space and water heating apparatus 1 according to the present embodiment, the first pump 62 or the second pump 64 may be operated together with the circulation pump 23 to facilitate discharge of air bubbles from the space heating equipment using the air separator 67.

[0053] Subsequently, an on-off operation in which the circulation pump 23 is operated for 15 seconds and then stopped for 10 seconds is repeated three times. Further, an on-off operation in which the circulation pump 23 is operated for 10 seconds and then stopped for 10 seconds is repeated three times. The circulation pump 23 thus have different operation periods. With a fixed operation period, air bubbles may return to positions at which the air bubbles are less easily discharged. With different operation periods, air bubbles can circulate at different timings and can float upward at positions at which the air bubbles are easily discharged. This facilitates discharge of air bubbles. In the space and water heating apparatus 1 according to the present embodiment, the circulation pump 23 has a constant rotational speed and different operation periods. However, the circulation pump 23 may have a fixed operation period and different rotational speeds to cause air bubbles to circulate at different timings.

[0054] In an internal-channel discharge process in STEP 5, the position of the three-way valve 29 is switched during operation of the circulation pump 23 to facilitate discharge of air bubbles from the internal circulation channel that circulates the heating medium through the water-heating heat exchanger 28. In the illustrated example, while the circulation pump 23 is being continuously operated, the three-way valve 29 is switched from the position for the space heating operation mode in FIG. 2A to the position for the water heating operation mode in FIG. 2B, maintained at this position for 15 seconds, switched to the position for the space heating operation mode, and then maintained at this position for 5 seconds. This series of processes is repeated twice. Switching the position of the three-way valve 29 in this manner can facilitate discharge of air bubbles from the internal circulation channel. More specifically, for example, while the three-way valve 29 is at the position for the water heating operation mode, air bubbles remaining in the water-heating heat exchanger 28 are circulating together with the heating medium. The three-way valve 29 can then be switched to the position for the space heating operation mode before the air bubbles reach the connection between the outgoing channel 21 and the branch channel 27 after flowing through the second heat exchanger 16 and the first heat exchanger 15. This allows the air bubbles to be guided to the space heating equipment (external circulation channel) without returning to the water-heating heat exchanger 28 (internal circulation channel), thus facilitating discharge of the air bubbles from the internal circulation channel.

[0055] As described above, air bubbles remaining in the internal circulation channel have more negative effects than air bubbles remaining in the external circulation channel. Thus, air bubbles are guided to the external circulation channel to reduce failure caused by air bubbles remaining in the internal circulation channel. Further, in the external circulation channel in the present embodiment, the space heating channel 61 includes the air separator 67. The air separator 67 can discharge the air bubbles guided to the external circulation channel while the first pump 62 or the second pump 64 is being operated. The external circulation channel may also not include the air separator 67. With the external circulation channel typically having a larger amount of heating medium than the internal circulation channel, air bubbles circulating along the external circulation channel take a longer time to reach the first heat exchanger 15 or the outgoing temperature sensor 25 than air bubbles circulating along the internal circulation channel. This can extend the cycle of disruption of the temperature adjustment for the heating medium caused by air bubbles. The movement of air bubbles from the internal circulation channel to the external circulation channel can also allow the air bubbles to be dispersed rather than staying in the internal circulation channel and reduce the proportion of air bubbles to the heating medium. This can reduce the frequency of disruption of the temperature adjustment for the heating medium caused by air bubbles.

[0056] In an external-channel discharge process in STEP 6, an on-off operation of the circulation pump 23 is performed as in STEP 4 described above. This facilitates discharge of air bubbles through the air vent 26 (and the air separator 67) while circulating air bubbles along the external circulation channel together with the heating medium. In STEP 6, an on-off operation in which the circulation pump 23 is operated for 10 seconds and then stopped for 10 seconds is repeated three times, with the operation period of the circulation pump 23 unchanged. In some embodiments, the operation period of the circulation pump 23 may be changed in STEP 6 as well.

[0057] In an internal-channel discharge process in STEP 7, the position of the three-way valve 29 is switched during operation of the circulation pump 23 to guide air bubbles from the internal circulation channel to the external circulation channel and facilitate discharge of air bubbles from the internal circulation channel, as in STEP 5 described above. In STEP 7, the three-way valve 29 is switched from the position for the space heating operation mode to the position for the water heating operation mode, maintained at this position for 10 seconds, switched to the position for the space heating operation mode, and then maintained at this position for 5 seconds. This series of processes is repeated twice. Thus, the duration of the water heating operation mode is shorter in STEP 7 than in STEP 5.

[0058] When the three-way valve 29 has a fixed duration of the water heating operation mode, the three-way valve 29 may be switched to the position for the space heating operation mode always after air bubbles from the water-heating heat exchanger 28 return to the water-heating heat exchanger 28 through the second heat exchanger 16 and the first heat exchanger 15 while circulating together with the heating medium. This may cause air bubbles to be included in the water-heating heat exchanger 28 all the time. Thus, the three-way valve 29 has different durations of the water heating operation mode and is thus switched to the space heating operation mode at different timings. The three-way valve 29 can thus be switched to the position for the space heating operation mode before air bubbles return to the water-heating heat exchanger 28. This allows the air bubbles to be guided to the external circulation channel. In the space and water heating apparatus 1 according to the present embodiment, the circulation pump 23 has a constant rotational speed, and the three-way valve 29 has different durations of the water heating operation mode. However, the three-way valve 29 may have a fixed duration of the water heating operation mode, and the circulation pump 23 may have different rotational speeds. When the circulation pump 23 has different rotational speeds, the circulating heating medium flows at different flow velocities. This varies the time taken for air bubbles from the water-heating heat exchanger 28 to return to the water-heating heat exchanger 28 through the second heat exchanger 16 and the first heat exchanger 15 while circulating together with the heating medium. The three-way valve 29 can thus be switched to the position for the space heating operation mode before the air bubbles return to the water-heating heat exchanger 28. This allows the air bubbles to be guided to the external circulation channel.

[0059] In an external-channel discharge process in STEP 8, an on-off operation in which the circulation pump 23 is operated for 10 seconds and then stopped for 10 seconds is repeated three times, as in STEP 6. This facilitates discharge of air bubbles through the air vent 26 (and the air separator 67) while circulating air bubbles along the external circulation channel together with the heating medium.

[0060] In an internal-channel discharge process in STEP 9, the three-way valve 29 has a still shorter duration of the water heating operation mode than in STEP 7. During operation of the circulation pump 23, the three-way valve 29 is switched from the position for the space heating operation mode to the position for the water heating operation mode, maintained at this position for 5 seconds, switched to the position for the space heating operation mode, and then maintained at this position for 5 seconds. This series of processes is repeated twice to facilitate discharge of air bubbles from the internal circulation channel.

[0061] In an external-channel discharge process in STEP 10, an on-off operation in which the circulation pump 23 is operated for 10 seconds and then stopped for 10 seconds is repeated three times, as in STEPs 6 and 8. This facilitates discharge of air bubbles through the air vent 26 (and the air separator 67) while circulating air bubbles along the external circulation channel together with the heating medium.

[0062] In a heating-discharge process in STEP 11, the heating medium passing through the second heat exchanger 16 and the first heat exchanger 15 is heated by combustion with the burner 3 while the circulation pump 23 is being operated to circulate the heating medium. After the air bubbles are discharged in the external-channel discharge process or the internal-channel discharge process as described above, the heating medium may still contain dissolved air (nitrogen and oxygen). Thus, the heating medium is heated to cause the dissolved air to form air bubbles and facilitate discharge of the air bubbles. With the heating medium containing less dissolved air, air bubbles are less likely to form when the heating medium is heated during the space heating operation or the water heating operation in actual use of the space and water heating apparatus 1. This reduces failure caused by air bubbles.

[0063] In the illustrated example, the three-way valve 29 can be switched to the position for the simultaneous operation mode, in which the circulation pump 23 is operated continuously and combustion is performed with the burner 3. This can simultaneously heat the heating medium in both the external circulation channel and the internal circulation channel, thus efficiently reducing the dissolved air. The combustion with the burner 3 is performed until the temperature detected by the outgoing temperature sensor 25 reaches a temperature higher than or equal to a predetermined temperature and is maintained at such a temperature for a predetermined duration. The predetermined temperature is set to the higher one of the target temperature for the outgoing temperature in the space heating operation or the target temperature for the outgoing temperature in the water heating operation. The heating medium is thus heated to the higher temperature expected to be reached when the space and water heating apparatus 1 is in use, causing the dissolved air to form air bubbles. This reduces air bubbles that may be generated from the heating medium in the heating process in actual use, and thus reduces failure caused by air bubbles. In STEP 11 as well, the on-off operation of the circulation pump 23 may be repeatedly performed to facilitate discharge of air bubbles through the air vent 26.

[0064] As described above, the space and water heating apparatus 1 according to the present embodiment performs the test operation in which the heating medium is circulated to facilitate discharge of air bubbles after installation. The test operation includes the external-channel discharge process to facilitate discharge of air bubbles from the external circulation channel that circulates the heating medium through the space heating equipment, and includes the internal-channel discharge process to facilitate discharge of air bubbles from the internal circulation channel that circulates the heating medium through the water-heating heat exchanger 28. In the internal-channel discharge process, during operation of the circulation pump 23, the three-way valve 29 is switched from the position for the water heating operation mode in which the heating medium is circulated along the internal circulation channel to the position for the space heating operation mode in which the heating medium is circulated along the external circulation channel.

[0065] In the space and water heating apparatus 1 according to the present embodiment, the three-way valve 29 can be at the position for the water heating operation mode during operation of the circulation pump 23. This allows air bubbles remaining in the water-heating heat exchanger 28 (internal circulation channel) to circulate together with the heating medium. The three-way valve 29 can be switched to the position for the space heating operation mode before the air bubbles reach the connection between the outgoing channel 21 and the branch channel 27 after flowing through the second heat exchanger 16 and the first heat exchanger 15 (the shared portion shared by the external circulation channel and the internal circulation channel). This causes the air bubbles to be guided to the space heating equipment (external circulation channel), thus facilitating discharge of the air bubbles from the internal circulation channel. With the external circulation channel typically having a larger amount of heating medium than the internal circulation channel, air bubbles circulating along the external circulation channel take a longer time to reach the first heat exchanger 15 or the outgoing temperature sensor 25 in the shared portion than air bubbles circulating along the internal circulation channel. This can extend the cycle of failure (disruption of the temperature adjustment for the heating medium) caused by air bubbles. The movement of air bubbles from the internal circulation channel to the external circulation channel can also allow the air bubbles to be dispersed rather than staying in the internal circulation channel and reduce the proportion of air bubbles to the heating medium. This can reduce the frequency of failure caused by air bubbles.

[0066] In the external-channel discharge process in the space and water heating apparatus 1 according to the present embodiment, the circulation pump 23 is operated while the three-way valve 29 is maintained at the position for the space heating operation mode. After the external-channel discharge process is performed, the internal-channel discharge process is performed. The external-channel discharge process is thus performed to discharge air bubbles from the space heating equipment (external circulation channel) before the internal-channel discharge process is performed. This can reduce air bubbles flowing from the space heating equipment into the second heat exchanger 16 and the first heat exchanger 15 (the shared portion shared by the external circulation channel and the internal circulation channel) when the three-way valve 29 is switched to the position for the space heating operation mode in the internal-channel discharge process.

[0067] Further, the space and water heating apparatus 1 according to the present embodiment performs multiple internal-channel discharge processes in each of which the three-way valve 29 has a different duration of the water heating operation mode. The three-way valve 29 is thus switched to the position for the space heating operation mode at different timings in the different internal-channel discharge processes. This avoids the situation in which, while air bubbles from the water-heating heat exchanger 28 are circulating together with the heating medium, the three-way valve 29 is switched to the position for the space heating operation mode always after the air bubbles return to the water-heating heat exchanger 28 through the second heat exchanger 16 and the first heat exchanger 15. Instead of the three-way valve 29 having different durations of the water heating operation mode, the circulation pump 23 may have different rotational speeds to allow the circulating heating medium to flow at different flow velocities. This varies the time taken for air bubbles from the water-heating heat exchanger 28 to return to the water-heating heat exchanger 28 through the second heat exchanger 16 and the first heat exchanger 15 while circulating together with the heating medium. The three-way valve 29 can thus be switched to the position for the space heating operation mode before the air bubbles return to the water-heating heat exchanger 28. This allows the air bubbles to be guided to the external circulation channel.

[0068] Further, in the space and water heating apparatus 1 according to the present embodiment, the test operation includes the heating-discharge process in which the heating medium passing through the second heat exchanger 16 and the first heat exchanger 15 is heated by combustion with the burner 3 while the circulation pump 23 is being operated to circulate the heating medium. The heating-discharge process is performed after the external-channel discharge process and the internal-channel discharge process are performed. After the external-channel discharge process or the internal-channel discharge process is performed, the heating medium may contain dissolved air (nitrogen and oxygen). Thus, the heating medium is heated to cause the dissolved air to form air bubbles and facilitate discharge of the air bubbles. Thus, air bubbles are less likely to form when the heating medium is heated during the space heating operation or the water heating operation in actual use of the space and water heating apparatus 1. This reduces failure caused by air bubbles.

[0069] In the space and water heating apparatus 1 according to the present embodiment, in particular, the combustion with the burner 3 is performed until the temperature detected by the outgoing temperature sensor 25 reaches a predetermined temperature in the heating-discharge process. The predetermined temperature is set to the higher one of the target temperature for the outgoing temperature in the space heating operation or the target temperature for the outgoing temperature in the water heating operation. The heating medium is thus heated to the higher temperature expected to be reached when the space and water heating apparatus 1 is in use, causing the dissolved air to form air bubbles in advance. This reduces air bubbles generated from the heating medium in the heating process in actual use, and thus reduces failure caused by air bubbles.

[0070] The space and water heating apparatus 1 according to the present embodiment has been described. However, the present invention is not limited to the above embodiment and may be implemented in various manners without departing from the spirit and scope of the invention.

[0071] For example, in the internal-channel discharge process in the above embodiment, the three-way valve 29 is switched from the position for the water heating operation mode to the position for the space heating operation mode during operation of the circulation pump 23. However, in the internal-channel discharge process, the three-way valve 29 may be switched from the position for the simultaneous operation mode to the position for the space heating operation mode during operation of the circulation pump 23. The simultaneous operation mode is the mode in which the heating medium is circulated along both the external circulation channel and the internal circulation channel. Such switching can also facilitate discharge of air bubbles from the internal circulation channel. More specifically, while the three-way valve 29 is at the position for the simultaneous operation mode during operation of the circulation pump 23, air bubbles remaining in the water-heating heat exchanger 28 (internal circulation channel) are circulating together with the heating medium. The three-way valve 29 can then be switched to the position for the space heating operation mode before the air bubbles reach the connection between the outgoing channel 21 and the branch channel 27 after flowing through the second heat exchanger 16 and the first heat exchanger 15 (shared portion). This allows the air bubbles to be guided to the space heating equipment (external circulation channel), thus facilitating discharge of the air bubbles from the internal circulation channel. However, the three-way valve 29 may be switched from the position for the water heating operation mode to the position for the space heating operation mode during operation of the circulation pump 23, as in the above embodiment. This allows all the heating medium circulated by the circulation pump 23 to flow through the water-heating heat exchanger 28, allowing air bubbles to be more easily pushed out of the water-heating heat exchanger 28. This more effectively reduces air bubbles remaining in the internal circulation channel.

[0072] In the above embodiment, the three-way valve 29 has different durations of the water heating operation mode in the respective internal-channel discharge processes in STEPs 5, 7, and 9. In some embodiments, in the internal-channel discharge process in each of STEPs 5, 7, and 9, the three-way valve 29 may be switched from the water heating operation mode to the space heating operation mode multiple times, with the duration of the water heating operation mode being different for each switching. In some embodiments, the circulation pump 23 may have a different rotational speed for each switching.

[0073] In the heating-discharge process in the above embodiment, the heating medium in both the external circulation channel and the internal circulation channel is heated simultaneously while the three-way valve 29 is at the position for the simultaneous operation mode. However, in the heating-discharge process, the heating medium in either the external circulation channel or the internal circulation channel alone may be heated. For example, the heating medium in the external circulation channel may be heated with higher priority, with the external circulation channel typically having a larger amount of heating medium than the internal circulation channel. This can effectively reduce the dissolved air in the heating medium. In summer, the heating medium in the internal circulation channel alone may be heated for use of the water heating operation, with the space heating operation being expected to remain unused for the time being. When the heating medium in the external circulation channel alone is heated, the predetermined temperature may be set to the target temperature for the outgoing temperature in the space heating operation. When the heating medium in the internal circulation channel alone is heated, the predetermined temperature may be set to the target temperature for the outgoing temperature in the water heating operation. When the heating medium in both the external circulation channel and the internal circulation channel is heated, the heating for these channels may not be performed simultaneously. The heating medium in one of the channels may be heated first, and then the other may be heated.

[0074] In the heating-discharge process in the above embodiment, the combustion with the burner 3 is performed until the temperature detected by the outgoing temperature sensor 25 reaches a temperature higher than or equal to the predetermined temperature and is maintained at such a temperature for the predetermined duration. However, the combustion with the burner 3 may be performed in other manners. For example, the combustion with the burner 3 may be performed at its minimum capacity to heat the heating medium slowly to minimize the difference between the outgoing temperature and the return temperature of the heating medium (in other words, to heat the heating medium uniformly). The combustion with the burner 3 may be stopped when the temperature detected by the outgoing temperature sensor 25 reaches a predetermined temperature.

[0075] In the above embodiment, the heating-discharge process (STEP 11) is performed after the external-channel discharge process (STEPs 4, 6, 8, and 10) and the internal-channel discharge process (STEPs 5, 7, and 9) are performed. However, an additional external-channel discharge process or an additional internal-channel discharge process may be performed after the heating-discharge process is performed. Such an additional process can facilitate discharge of air bubbles (air bubbles formed from the dissolved air) generated when the heating medium is heated in the heating-discharge process.

[0076] In the above embodiment, the three-way valve 29 is installed at the connection between the return channel 22 and the branch channel 27. In some embodiments, the three-way valve 29 may be installed at the connection between the outgoing channel 21 and the branch channel 27.

[0077] In the above embodiment, the heating medium is fed by the installer connecting the heating medium supply pipe to the feed channel 70 and manually opening the feed valve 71 after installing the space and water heating apparatus 1. However, the heating medium may be fed automatically. More specifically, the outgoing channel 21 or the return channel 22 may be connected to a heating medium supply pipe with an electromagnetic valve that opens and closes the pipe. The electromagnetic valve may be controlled by the controller 40 to feed the heating medium automatically.

[0078] In the above embodiment, the air vent 26 is installed in the shared portion shared by the external circulation channel and the internal circulation channel to serve as the discharger that discharges air bubbles contained in the heating medium. In place of the air vent 26, the circulation pump 23 in the shared portion may serve as the discharger to discharge air bubbles.

[0079] In the above embodiment, the first radiator 63a in the baseboard heating unit 63 and the second radiator 65a in the air handling unit 65 are connected to the space heating channel 61 as the secondary circuit connected to the low-loss header 60. However, the first radiator 63a in the baseboard heating unit 63 and the second radiator 65a in the air handling unit 65 may be directly connected to the outgoing channel 21 and the return channel 22.

REFERENCE SIGNS LIST

[0080] 1 space and water heating apparatus

[0081] 2 housing

[0082] 3 burner

[0083] 4 combustion unit

[0084] 5 combustion fan

[0085] 6 joint

[0086] 7 air supply channel

[0087] 8 gas supply channel

[0088] 9 zero governor

[0089] 11 spark plug

[0090] 12 flame rod

[0091] 13 check valve

[0092] 15 first heat exchanger

[0093] 16 second heat exchanger

[0094] 17 exhaust duct

[0095] 18 exhaust port

[0096] 19 air supply port

[0097] 21 outgoing channel

[0098] 22 return channel

[0099] 22a equipment return channel

[0100] 22b heat-exchanger return channel

[0101] 23 circulation pump

[0102] 24 return temperature sensor

[0103] 25 outgoing temperature sensor

[0104] 26 air vent

[0105] 27 branch channel

[0106] 28 water-heating heat exchanger

[0107] 29 three-way valve

[0108] 30 water inlet channel

[0109] 31 hot-water outlet channel

[0110] 32 water flow sensor

[0111] 33 water flow servo

[0112] 34 water inlet temperature sensor

[0113] 35 heat-exchanger outlet temperature sensor

[0114] 36 bypass channel

[0115] 37 bypass servo

[0116] 38 hot-water outlet temperature sensor

[0117] 40 controller

[0118] 41 water-heating remote control

[0119] 42 space-heating remote control

[0120] 50 valve cavity

[0121] 51 water-heating valve element

[0122] 52 space-heating valve element

[0123] 53 movable shaft

[0124] 54 drive

[0125] 60 low-loss header

[0126] 61 space heating channel

[0127] 61a first space heating channel

[0128] 61b second space heating channel

[0129] 62 first pump

[0130] 63 baseboard heating unit

[0131] 63a first radiator

[0132] 64 second pump

[0133] 65 air handling unit

[0134] 65a second radiator

[0135] 66 dirt trap

[0136] 67 air separator

[0137] 68 connection channel

[0138] 69 expansion tank

[0139] 70 feed channel

[0140] 71 feed valve

[0141] 72 pressure sensor