Technical Field
[0001] The present invention relates to a hot-water supply apparatus supplying hot water
to a bathtub.
Background Art
[0002] With recent advancement in functionality of hot water supply apparatuses, some of
them now can not only generate hot water but also adjust temperature of supplied hot
water to appropriate temperature and fill a bathtub with an appropriate amount of
hot water. Another known hot-water supply apparatus can reheat hot water in a bathtub
by delivering the hot water in the bathtub to the hot-water supply apparatus with
a pump and make the hot water exchange heat with hot water generated by the hot-water
supply apparatus.
[0003] Patent Literature 1 discloses a hot-water supply apparatus that makes hot water in
a bathtub exchange heat with hot water stored in a hot-water tank provided to the
hot-water supply apparatus and thereby recovers heat of the hot water in the bathtub
to achieve energy saving. Patent Literature 2 discloses a hot-water supply apparatus
that washes a bathtub by heating hot water in the bathtub and generating microbubbles
and circulating them in the bathtub.
Citation List
Patent Literature
[0004]
Patent Literature 1: Japanese Patent No. 5126432
Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2016-048130
Summary of Invention
Technical Problem
[0005] For increased energy efficiency and convenience, there has been an increasing demand
for a hot-water supply apparatus that can perform both of heat recovery and bathtub
washing. However, performing both of heat recovery and bathtub washing means increase
in functions of the hot-water supply apparatus, which may lead to increase in the
number of parts and device size and resultant increase in product costs.
[0006] The present invention has been made in view of the above problems and aims to provide
a hot-water supply apparatus that can perform both of heat recovery and bathtub washing
without increase in product costs.
Solution to Problem
[0007] According to one embodiment of the present invention, there is provided a hot-water
supply apparatus including: a hot-water tank configured to store water; a heat exchanger
configured to allow the water stored in the hot-water tank and water stored in a bathtub
to exchange heat with each other; a bathtub circulation passage configured to allow
the water stored in the bathtub to flow out of the bathtub and return to the bathtub
via the heat exchanger; a bathtub circulation pump provided to the bathtub circulation
passage and configured to circulate the water stored in the bathtub through the bathtub
circulation passage; and a controller configured to perform a heat recovery operation
in which heat of the water stored in the bathtub is recovered into the water stored
in the hot-water tank, and a washing operation in which an inside of the bathtub is
washed, wherein, in both the heat recovery operation and the washing operation, the
bathtub circulation pump is activated to circulate the water stored in the bathtub
through the bathtub circulation passage.
Advantageous Effects of Invention
[0008] In both of the heat recovery operation and the washing operation, the hot-water supply
apparatus according to one embodiment of the present invention drives the bathtub
circulation pump to make the hot water in the bathtub circulate in the bathtub circulation
passage. This means that the same configuration is shared by the heat recovery operation
and the washing operation. This allows to perform both of the heat recovery operation
and the washing operation without increase in product costs due to increased parts
and device size.
Brief Description of Drawings
[0009]
[Fig. 1] Fig. 1 is a schematic configuration diagram of a hot-water supply apparatus
in Embodiment 1.
[Fig. 2] Fig. 2 shows a hardware configuration of a controller.
[Fig. 3] Fig. 3 is a functional block diagram of the controller.
[Fig. 4] Fig. 4 shows hot water flow during a heat recovery operation.
[Fig. 5] Fig. 5 shows hot water flow during a washing operation.
[Fig. 6] Fig. 6 is a flowchart of the heat recovery operation and the washing operation
in Embodiment 1.
[Fig. 7] Fig. 7 is a flowchart of the heat recovery operation and the washing operation
in Embodiment 2.
[Fig. 8] Fig. 8 is a flowchart of the heat recovery operation and the washing operation
in Embodiment 3.
Description of Embodiments
[0010] Embodiments of the present invention will be described below with reference to the
drawings. Throughout the figures as referred to in the present specification, same
reference numerals refer to similar elements. In the present specification, the term
"hot water" collectively refers to hot water and water.
Embodiment 1
[0011] Fig. 1 is a schematic configuration diagram of a hot-water supply apparatus 100 in
Embodiment 1 of the present invention. The hot-water supply apparatus 100 of the present
embodiment is configured to heat low-temperature water supplied from a water supply
end 101 and supply hot water of a temperature desired by a user from a hot water supply
end 102. The hot water supply end 102 is, for example, a water supply port of a bathtub
200, a faucet or a shower head in a bathroom, or a faucet in a lavatory or a kitchen.
[0012] The hot-water supply apparatus 100 includes a heat pump unit 110 for heating low-temperature
water, a hot-water tank 120 for storing high-temperature water heated by the heat
pump unit 110, and a heat exchanger 130 for exchanging heat between hot water in the
hot-water tank 120 and hot water in the bathtub 200. The hot-water supply apparatus
100 further includes a bathtub circulation passage 140 to allow the hot water to be
discharged from the bathtub 200 to return to the bathtub 200 through the heat exchanger
130, and a tank circulation passage 150 to allow the hot water discharged from the
hot-water tank 120 to return to the hot-water tank 120 through the heat exchanger
130. The hot-water supply apparatus 100 further includes a controller 160 controlling
overall operations of the hot-water supply apparatus 100, and a remote control 170.
The hot-water supply apparatus 100 further includes a boiling passage to allow the
hot water in the hot-water tank 120 to circulate through the heat pump unit 110, a
hot water supply passage to supply the hot water in the hot-water tank 120 to the
bathtub 200, and three-way vales, on-off valves, and check valves installed in the
above passages, though these components are not essential in the present invention.
[0013] For example, the heat pump unit 110 is a refrigeration cycle device that uses CO
2 or hydrofluorocarbon (HFC) as refrigerant. The heat pump unit 110 includes a compressor,
a first heat exchanger exchanging heat between the refrigerant and water, an expansion
valve, a second heat exchanger exchanging heat between outside air and the refrigerant,
a fan, a temperature sensor, and a control board. The compressor, the first heat exchanger,
the expansion valve, and the second heat exchanger are circularly connected, forming
a refrigeration cycle circuit (also called a refrigerant circuit) for circulation
of the refrigerant.
[0014] The hot-water tank 120 is a cylindrical tank made of metal, such as stainless steel,
or resin. The outside of the hot-water tank 120 is covered with a heat insulator (not
shown). This allows to keep the temperature of high-temperature water in the hot-water
tank 120 over a long period. The hot-water tank 120 is connected at its lower part
to the water supply end 101 through a pipe provided with a pressure reducing valve
103. Low-temperature water supplied from the water supply end 101 has its pressure
adjusted by the pressure reducing valve 103 to a predetermined pressure before flowing
into the hot-water tank 120. Lower and upper parts of the hot-water tank 120 are connected
to the heat pump unit 110 through the boiling passage. This allows low-temperature
water discharged from the lower part of the hot-water tank 120 to undergo heat exchange
in the first heat exchanger of the heat pump unit 110 to be high-temperature water
and then return to the upper part of the hot-water tank 120. This circulation forms
a boiling circuit. Also, inside the hot-water tank 120, there is temperature stratification
where upper layers of hot water in the vertical direction has higher temperature and
lower layers of hot water in the vertical direction has lower temperature.
[0015] Plural hot water storage temperature sensors 121 and 122 are attached to a surface
of the hot-water tank 120 at different heights. The hot water storage temperature
sensors 121 and 122 detect temperature distribution of hot water in the hot-water
tank 120. Detection results of the hot water storage temperature sensors 121 and 122
are sent to the controller 160, which in turn figures out the amount of hot water
stored in the hot-water tank 120 and uses that information for control of start and
stop of a boiling operation (described later). The number of hot water storage temperature
sensors is not limited to two and may be more than two.
[0016] The heat exchanger 130 exchanges heat between the hot water in the bathtub 200 and
the hot water in the hot-water tank 120. More specifically, the heat exchanger 130
is located on the bathtub circulation passage 140 and the tank circulation passage
150 and exchanges heat between the hot water flowing in the bathtub circulation passage
140 and the hot water flowing in the tank circulation passage 150.
[0017] The bathtub circulation passage 140 includes pipes connecting the hot-water supply
apparatus 100 and the bathtub 200. The bathtub circulation passage 140 made up of
a bathtub return pipe 141 and a bathtub supply pipe 142. On the bathtub circulation
passage 140, there is a bathtub circulation pump 145 to circulate the hot water in
the bathtub 200. Driving the bathtub circulation pump 145 causes the hot water to
circulate between the hot-water supply apparatus 100 and the bathtub 200. More specifically,
driving the bathtub circulation pump 145 causes the hot water in the bathtub 200 to
flow into the hot-water supply apparatus 100 through the bathtub return pipe 141 and
then go from the hot-water supply apparatus 100 and return into the bathtub 200 through
the bathtub supply pipe 142.
[0018] The bathtub supply pipe 142 is provided with an adding device 148 to add an additive
to the hot water in the bathtub 200 during a washing operation. In response to control
signals from the controller 160, the adding device 148 adds the additive to the hot
water in the bathtub 200. Examples of the additive include one having a surface-activating
effect. Circulating the hot water including the additive in the bathtub 200 during
a washing operation in this way can enhance the washing effect for the bathtub 200.
[0019] The tank circulation passage 150 includes pipes connecting the upper and middle parts
of the hot-water tank 120 through the heat exchanger 130. The tank circulation passage
150 is provided with a tank circulation pump 155 to deliver the hot water in the hot-water
tank 120 to the heat exchanger 130. The tank circulation passage 150 is also provided
with a three-way valve 151, a first four-way valve 152, and a second four-way valve
153. Switching each of the three-way valve 151, the first four-way valve 152, and
the second four-way valve 153 allows to switch the circulation passages for the hot
water in the hot-water tank 120.
[0020] The bathtub circulation pump 145 and the tank circulation pump 155 each include
an inverter circuit (not shown) and are driven in response to control signals from
the controller 160. Changing the rotation speed of the bathtub circulation pump 145
and the tank circulation pump 155 allows to change the amount of hot water flowing
in the bathtub circulation passage 140 and the tank circulation passage 150.
[0021] The controller 160 is communicably connected to each unit of the hot-water supply
apparatus 100. In response to a user operating the remote control 170, the controller
160 controls each unit of the hot-water supply apparatus 100. Specifically, the controller
160 controls operations of the heat pump unit 110, the bathtub circulation pump 145,
the tank circulation pump 155, and the adding device 148 and switching of the three-way
valve 151, the first four-way valve 152, and the second four-way valve 153. The controller
160 also causes the remote control 170 to display operating conditions of the hot-water
supply apparatus 100 and a screen for operating the hot-water supply apparatus 100.
Details of the controller 160 will be described later.
[0022] The remote control 170 includes a display for displaying information such as operating
conditions of the hot-water supply apparatus 100, and an operation part for receiving
the user's operations on the hot-water supply apparatus 100. The operation part includes
a bathtub washing switch 171 to instruct start of a washing operation. Operations
on the remote control 170 are transmitted to the controller 160.
[0023] Now a detailed description will be given on a configuration of the controller 160
of the hot-water supply apparatus 100. Fig. 2 shows a hardware configuration of the
controller 160. As shown in Fig. 2, the controller 160 includes a central processing
unit (CPU) 601, a communication interface 602, a read only memory (ROM) 603, a random
access memory (RAM) 604, and a secondary storage device 605. The CPU 601, the communication
interface 602, the ROM 603, the RAM 604, and the secondary storage device 605 are
connected to each other via a bus 606. The CPU 601 centrally controls the controller
160. Functions implemented by the CPU 601 will be described later.
[0024] The communication interface 602 includes a network interface card/controller (NIC)
for wired or wireless communication. The communication interface 602 is communicably
connected to the remote control 170, the heat pump unit 110, the bathtub circulation
pump 145, the tank circulation pump 155, and the adding device 148. The controller
160 receives data of the user's operations on the remote control 170 through the communication
interface 602 and sends control signals to each unit of the hot-water supply apparatus
100 through the communication interface 602.
[0025] The ROM 603 stores plural pieces of firmware or data used in executing the pieces
of firmware. The RAM 604 provides a working area for the CPU 601.
[0026] The secondary storage device 605 may be a readable and writable nonvolatile semiconductor
memory, such as electrically erasable programmable read-only memory (EEPROM) and flash
memory, or a hard disk drive. The secondary storage device 605 stores programs for
controlling operations of the hot-water supply apparatus 100 and data used in executing
these programs. The data used in executing the programs include various parameters
for controlling operation modes of the hot-water supply apparatus 100 and data indicating
control of the bathtub circulation pump 145 and the tank circulation pump 155.
[0027] Fig. 3 is a functional block diagram of the controller 160. As shown in Fig. 3, in
terms of functional units, the controller 160 includes a user interface unit 611,
a device state acquisition unit 612, a device control unit 613, and an operation mode
execution unit 614. These functional units are implemented by the CPU 601 executing
one or more programs stored in the secondary storage device 605.
[0028] The user interface unit 611 performs user interface processing through the remote
control 170. In other words, the user interface unit 611 receives the user's operations
on the remote control 170. The user interface unit 611 also sends information to be
presented to the user (e.g., information indicating operating conditions of the hot-water
supply apparatus 100) to the remote control 170, which in turn displays that information.
[0029] The device state acquisition unit 612 acquires data from the heat pump unit 110 including
its operating conditions and measured temperatures and data from the bathtub circulation
pump 145 and the tank circulation pump 155 indicating their driving conditions, at
predetermined time intervals such as every 30 seconds. The device state acquisition
unit 612 also acquires temperature of the hot water in the hot-water tank 120 from
the hot water storage temperature sensors 121 and 122.
[0030] The device control unit 613 controls operations of the hot-water supply apparatus
100 as a whole according to the user's operations on the remote control 170. Specifically,
the device control unit 613 sends control signals to the heat pump unit 110 to control
the compressor, the expansion valve, the fan, and other components. The device control
unit 613 also sends control signals to the bathtub circulation pump 145, the tank
circulation pump 155, and the adding device 148 during a heat recovery operation and
a washing operation to control start and stop of the operations. The device control
unit 613 also sends control signals to the three-way valve 151, the first four-way
valve 152, and the second four-way valve 153 to switch the flow paths.
[0031] The operation mode execution unit 614 causes the device control unit 613 to perform
control corresponding to an operation mode selected by the user's operations on the
remote control 170. Specifically, the operation mode execution unit 614 reads from
the secondary storage device 605 programs and data for control of the heat pump unit
110 or the bathtub circulation pump 145 and the tank circulation pump 155 corresponding
to a selected operation mode and causes the device control unit 613 to perform that
control. The selected operation mode is, for example, a boiling operation, a heat
recovery operation, or a bathtub washing operation.
[0032] A description will now be given on a heat recovery operation and a washing operation
of the hot-water supply apparatus 100 of the present embodiment. The heat recovery
operation is an operation for the hot-water supply apparatus 100 to recover heat of
the hot water in the bathtub 200. The washing operation is an operation to wash the
bathtub 200.
<Heat recovery operation>
[0033] First, the heat recovery operation of the hot-water supply apparatus 100 of the present
embodiment will be described. Fig. 4 shows hot water flow during the heat recovery
operation. In the heat recovery operation, both of the bathtub circulation pump 145
and the tank circulation pump 155 are driven, so that hot water flows in both of the
bathtub circulation passage 140 and the tank circulation passage 150. The flow of
hot water in the bathtub 200 is as follows. The hot water discharged from the bathtub
200 passes through the bathtub return pipe 141 and has its pressure increased by the
bathtub circulation pump 145 before entering the heat exchanger 130. The hot water
then flows out of the heat exchanger 130 and passes through the bathtub supply pipe
142 to return to the bathtub 200.
[0034] The flow of hot water in the hot-water tank 120 will be explained. The hot water
discharged from the lower part of the hot-water tank 120 passes through the three-way
valve 151 and has its pressure increased by the tank circulation pump 155. After having
its pressure increased by the tank circulation pump 155, the hot water passes through
the first four-way valve 152 and then the second four-way valve 153 and enters the
heat exchanger 130. The hot water then flows out of the heat exchanger 130 and enters
the hot-water tank 120 from a middle part thereof. When the three-way valve 151, the
first four-way valve 152, and the second four-way valve 153 are opened in a specific
direction, they are assumed to be closed in the other directions. During the heat
recovery operation, the three-way valve 151, the first four-way valve 152, and the
second four-way valve 153 are switched so that the hot water flows through the hot-water
tank 120, the three-way valve 151, the tank circulation pump 155, the first four-way
valve 152, the second four-way valve 153, the heat exchanger 130, and the hot-water
tank 120 in this order.
[0035] In the heat exchanger 130, heat is exchanged between the hot water in the bathtub
200 and the hot water in the hot-water tank 120. This allows to recover the heat of
the hot water in the bathtub 200 into the hot water in the hot-water tank 120 when
temperature of the hot water in the bathtub 200 is higher than that of the hot water
in the lower part of the hot-water tank 120.
<Washing operation>
[0036] Now, a description will be given on the washing operation of the hot-water supply
apparatus 100 of the present embodiment. Fig. 5 shows hot water flow during the washing
operation. During the washing operation, the bathtub circulation pump 145 is driven,
so that the hot water flows in the bathtub circulation passage 140. The hot water
flowing out of the bathtub 200 passes through the bathtub return pipe 141 and has
its pressure increased by the bathtub circulation pump 145 before entering the heat
exchanger 130. The hot water then flows out of the heat exchanger 130 and passes through
the bathtub supply pipe 142 to return to the bathtub 200. Circulating the hot water
in this way generates a water current in the bathtub 200, whereby the bathtub 200
can be washed. During the washing operation, the adding device 148 adds the additive
to the hot water in the bathtub 200. This means that the hot water including the additive
circulates in the bathtub 200, which can enhance the washing effect for the bathtub
200.
[0037] The washing operation does not require heat exchange between the hot water in the
bathtub 200 and the hot water in the hot-water tank 120, and thus the tank circulation
pump 155 is not driven. Accordingly, the hot water in the hot-water tank 120 does
not flow in the tank circulation passage 150.
[0038] As described above, the hot-water supply apparatus 100 of the present embodiment
can perform both of the heat recovery operation and the washing operation. In both
of these operations, the bathtub circulation pump 145 and the bathtub circulation
passage 140 are used. This means that the heat recovery operation and the washing
operation can share the same configuration, which eliminates the need for individual
circulation passages and circulation pumps for these operations. This allows to perform
both of the heat recovery operation and the washing operation while avoiding increase
in the number of parts of the hot-water supply apparatus 100 and in its size and also
resultant increase in product costs. As the heat recovery operation and the washing
operation share the same configuration, no complicated control is required, which
realizes efficient heat recovery and washing operations.
[0039] When the heat recovery operation and the washing operation share the same configuration
as in the present embodiment, the heat recovery operation and the washing operation
may interfere with each other depending on how the user uses the hot-water supply
apparatus 100. This may compromise optimal operations. In view of this, the hot-water
supply apparatus 100 of the present embodiment automatically controls the timing of
performing the heat recovery operation and the washing operation for optimization
of these operations.
[0040] Fig. 6 is a flowchart of the heat recovery operation and the washing operation in
the present embodiment. To implement the flowchart of Fig. 6, the CPU 601 executes
one or more programs stored in the secondary storage device 605. First, it is determined
whether start of the washing operation has been instructed (S11). The determination
is made based on whether the bathtub washing switch 171 of the remote control 170
has been operated. When start of the washing operation has been instructed (S11: YES),
the device control unit 613 switches channels of the three-way valve 151, the first
four-way valve 152, and the second four-way valve 153 so that the hot water in the
hot-water tank 120 flows in the tank circulation passage 150 (S12). Then, the adding
device 148 adds the additive to the hot water in the bathtub 200 in response to control
signals from the device control unit 613 (S13).
[0041] The device control unit 613 drives the bathtub circulation pump 145 and the tank
circulation pump 155 (S14). This causes the hot water in the bathtub 200 to circulate
in the bathtub circulation passage 140 and causes the hot water in the hot-water tank
120 to circulate in the tank circulation passage 150. At this time, heat exchange
takes place in the heat exchanger 130 between the hot water in the bathtub 200 and
the hot water in the hot-water tank 120. This results in the heat of the hot water
in the bathtub 200 being recovered into the hot water in the hot-water tank 120, whereby
the heat recovery operation is performed. Also, the hot water added with the additive
circulates in the bathtub circulation passage 140 and the bathtub 200, whereby the
washing operation is performed.
[0042] After a lapse of a predetermined period T (S15: YES), the device control unit 613
stops the bathtub circulation pump 145 and the tank circulation pump 155 (S16), which
finishes the heat recovery operation and the washing operation. The predetermined
period T is preset and stored in the secondary storage device 605. Alternatively,
the predetermined period T may be set by the user as desired or may be varied according
to the device state acquired by the device state acquisition unit 612.
[0043] As described above, in the present embodiment, the heat recovery operation and the
washing operation are simultaneously performed in response to the operation of the
single switch, namely the bathtub washing switch 171. This can not only simplify the
operation but also shorten the operation time of the bathtub circulation pump 145,
as compared to a case when the heat recovery operation and the washing operation are
individually performed. As a result, this can optimize these operations and reduce
power consumption.
[0044] Adding the additive to the hot water in the bathtub 200 can reduce channel resistance
of the bathtub circulation passage 140 due to the surface-activating effect of the
additive. This can reduce input from the bathtub circulation pump 145 at a given equivalent
circulation rate, as compared to a case when the heat recovery operation is performed
alone. This can make the heat recovery operation more energy-efficient, as compared
to a case when the heat recovery operation is performed alone.
[0045] The bathtub circulation pump 145 and the tank circulation pump 155 may be stopped
at other times than when the predetermined period T has elapsed. For example, the
bathtub circulation pump 145 and the tank circulation pump 155 may be stopped when
the temperature of the hot water in the bathtub 200 falls to or below a predetermined
temperature (e.g., 30 degrees C). Alternatively, the bathtub circulation pump 145
and the tank circulation pump 155 may be stopped when no difference is observed between
the temperature of the hot water in the bathtub 200 and the temperature of the hot
water stored in the lower part of the hot-water tank 120, which is detected by the
hot water storage temperature sensor 122. Also, the bathtub circulation pump 145 and
the tank circulation pump 155 are not necessarily stopped simultaneously; one of the
bathtub circulation pump 145 and the tank circulation pump 155 may be stopped earlier
than the other.
Embodiment 2
[0046] Embodiment 2 of the present invention will be described below. The present embodiment
differs from Embodiment 1 in terms of when the heat recovery operation and the washing
operation are performed. The configuration of the hot-water supply apparatus 100 and
the hot water flow during the heat recovery operation and the bathtub washing operation
are similar to those in Embodiment 1.
[0047] Fig. 7 is a flowchart of the heat recovery operation and the washing operation in
the present embodiment. In the present embodiment, the heat recovery operation is
started after the washing operation has been started. First, it is determined whether
start of the washing operation has been instructed (S21). Similarly to Embodiment
1, this determination is made based on whether the bathtub washing switch 171 of the
remote control 170 has been operated. When start of the washing operation has been
instructed (S21: YES), the device control unit 613 sends control signals to the adding
device 148, which in turn adds the additive to the hot water in the bathtub 200 (S22).
The device control unit 613 then drives the bathtub circulation pump 145 (S23). This
causes the hot water including the additive to circulate in the bathtub circulation
passage 140 and the bathtub 200, whereby the washing operation is performed.
[0048] The washing operation is continued until a predetermined period T
1 elapses (S24: NO). After a lapse of the predetermine period T
1 (S24: YES), the device control unit 613 switches channels of the three-way valve
151, the first four-way valve 152, and the second four-way valve 153 so that the hot
water in the hot-water tank 120 flows in the tank circulation passage 150 (S25). The
device control unit 613 then drives the tank circulation pump 155 (S26), causing the
hot water in the hot-water tank 120 to circulate in the tank circulation passage 150.
Thus, heat exchange takes place in the heat exchanger 130 between the hot water in
the bathtub 200 and the hot water in the hot-water tank 120, whereby the heat recovery
operation is performed.
[0049] The washing operation and the heat recovery operation are continued until a predetermined
period T
2 elapses (S27: NO). After a lapse of the predetermined period T
2 (S27: YES), the device control unit 613 stops the bathtub circulation pump 145 and
the tank circulation pump 155 (S28), which finishes the heat recovery operation and
the washing operation.
[0050] As described above, in the present embodiment, the washing operation and the heat
recovery operation are successively performed in response to operation of the single
switch. In the washing operation, higher temperature of the hot water in the bathtub
200 provides a higher washing effect. The temperature of the hot water in the bathtub
200 drops as a result of performing the heat recovery operation. In view of these,
performing the heat recovery operation after the start of the washing operation as
in the present embodiment can keep the water temperature high during washing, and
this can provide a high washing effect.
[0051] The tank circulation pump 155 may be driven at other times than when the predetermine
period T
1 has elapsed after driving of the bathtub circulation pump 145. For example, the timing
to drive the tank circulation pump 155 may be determined based on the temperature
of the hot water stored in the hot-water tank 120 or the bathtub 200. Specifically,
the tank circulation pump 155 may be driven to start the heat recovery operation when
the temperature of the hot water stored in the bathtub 200 falls to or below 35 degrees
C or when temperature difference between the hot water stored in the bathtub 200 and
the hot water stored in the lower part of the hot-water tank 120 falls within 5 degrees
C. This ensures the minimum heat recovery amount in the heat recovery operation. Also,
the bathtub circulation pump 145 and the tank circulation pump 155 are not necessarily
stopped simultaneously; one of the bathtub circulation pump 145 and the tank circulation
pump 155 may be stopped earlier than the other.
Embodiment 3.
[0052] Embodiment 3 of the present invention will be described below. The present embodiment
differs from Embodiment 1 in terms of when the heat recovery operation and the washing
operation are performed. The configuration of the hot-water supply apparatus 100 and
the hot water flow during the heat recovery operation and the bathtub washing operation
are similar to those in Embodiment 1.
[0053] Fig. 8 is a flowchart of the heat recovery operation and the washing operation in
the present embodiment. In the present embodiment, the washing operation is performed
after the heat recovery operation has been started. First, it is determined whether
start of the washing operation has been instructed (S31). Similarly to Embodiment
1, this determination is made based on whether the bathtub washing switch 171 of the
remote control 170 has been pressed. If start of the washing operation has been instructed
(S31: YES), the device control unit 613 switches channels of the three-way valve 151,
the first four-way valve 152, and the second four-way valve 153 so that the hot water
in the hot-water tank 120 flows in the tank circulation passage 150 (S32).
[0054] The device control unit 613 then drives the bathtub circulation pump 145 and the
tank circulation pump 155 (S33). This causes the hot water in the bathtub 200 to circulate
in the bathtub circulation passage 140 and causes the hot water in the hot-water tank
120 to circulate in the tank circulation passage 150. Thus, heat exchange takes place
in the heat exchanger 130 between the hot water in the bathtub 200 and the hot water
in the hot-water tank 120, whereby the heat recovery operation is performed.
[0055] The heat recovery operation is continued until a predetermined period T
3 elapses (S34: NO). After a lapse of the predetermine period T
3 (S34: YES), the device control unit 613 sends control signals to the adding device
148, which in turn adds the additive to the hot water in the bathtub 200 (S35). At
this time, the hot water in the bathtub 200 has already been circulating in the bathtub
circulation passage 140, and adding the additive to the hot water means start of the
washing operation with a high washing effect.
[0056] After a lapse of a predetermined period T
4 (S36: YES), the tank circulation pump 155 is stopped (S37) to finish the heat recovery
operation. Further, after a lapse of a predetermined period T
5 (S38: YES), the bathtub circulation pump 145 is stopped (S39) to finish the washing
operation.
[0057] As described above, in the present embodiment, the heat recovery operation and the
washing operation are successively performed in response to operation of the single
switch. Depending on the kind, the additive added to the bathtub 200 may negatively
affect heat transfer performance of the heat exchanger 130. In that case, performing
the heat recovery operation with the additive added to the bathtub 200 may not produce
a high heat recovery effect. In view of this, performing the washing operation after
the start of the heat recovery operation as in the present embodiment can prevent
deterioration of the heat transfer performance of the heat exchanger 130 during heat
recovery and produce a high energy-saving effect.
[0058] The additive may be added at other times than when the predetermined period T
3 has elapsed after driving of the bathtub circulation pump 145 and the tank circulation
pump 155. For example, the timing to add the additive may be determined based on the
temperature of the hot water stored in the hot-water tank 120 or the bathtub 200.
Specifically, when the temperature of the hot water in the bathtub 200 falls to or
below a predetermined temperature (e.g., 35 degrees C), the additive may be added
to ensure washing effect. Alternatively, when temperature difference between the hot
water stored in the bathtub 200 and the hot water stored in the lower part of the
hot-water tank 120 falls within 2 degrees C, the additive may be added as no heat
recovery effect will be expected from such temperature difference any more.
[0059] After a lapse of the predetermined period T
4 from the addition of the additive to the bathtub 200, the tank circulation pump 155
is stopped. However, this is not restrictive. For example, the timing to stop the
tank circulation pump 155 may be determined based on the temperature of the hot water
stored in the hot-water tank 120 or the bathtub 200 or power consumption of the tank
circulation pump 155. For example, when temperature difference between the hot water
stored in the bathtub 200 and the hot water stored in the lower part of the hot-water
tank 120 falls within 2 degrees C, the tank circulation pump 155 may be stopped to
terminate the heat recovery operation as no heat recovery effect will be expected
from such temperature difference any more. Alternatively, when the amount of power
saved by the heat recovery, whose amount can be derived from the temperature of the
hot water stored in the bathtub 200 and the hot water stored in the lower part of
the hot-water tank 120, is less than the power consumed by the tank circulation pump
155, the tank circulation pump 155 may be stopped to finish the heat recovery operation.
[0060] The present invention is not limited to the above embodiments and may be modified
and applied in various ways within the scope of the present invention. For example,
while the hot-water supply apparatus 100 of the above Embodiments 1 to 3 is a heat
pump hot-water supply apparatus that uses the heat pump unit 110 as a heat source
apparatus, the hot-water supply apparatus 100 may use an electric heater or gas combustion
as a heat source instead of the heat pump unit 110.
[0061] In Embodiments 1 to 3, a configuration is explained in which the washing operation
and the heat recovery operation are simultaneously or successively performed since
the controller judges that heat start of recovery operation is instructed due to pressing
of the bathtub washing switch 171 of the remote control 170. However, this is not
restrictive. For example, the remote control 170 may include both of the bathtub washing
switch 171 and a bathtub heat recovery switch (not shown), and in response to pressing
of either button, the washing operation and the heat recovery operation may be simultaneously
or successively performed. Also, the bathtub washing switch 171 and the bathtub heat
recovery switch (not shown) are not limited to physical switches, and software key
or voice instruction may also be used. The remote control 170 of the hot-water supply
apparatus 100 is not essential, and the controller 160 may be capable of communicating
with an external terminal other than the remote control 170. The instruction to start
the washing operation may be sent from the external terminal. Further, the instruction
to start the washing operation or the heat recovery operation is not limited to one
given by the user, and may be automatically given by the operation mode execution
unit 614 according to schedule information or other data stored in the secondary storage
device 605.
[0062] The adding device 148 of the hot-water supply apparatus 100 is also not essential
to the present invention, and the user may put the additive into the bathtub 200.
In this case, one exemplary method to clean the bathtub 200 using the hot-water supply
apparatus 100 may be as follows: the user first adds the additive to the hot water
in the bathtub 200, and then operates the bathtub washing switch 171 to simultaneously
perform the heat recovery operation and the washing operation. Alternatively, the
washing operation may be performed without the addition of the additive. Still alternatively,
a device to generate bubbles for increased washing effect may replace the adding device
148. The device may generate bubbles in the hot water in the bathtub 200 in response
to control signals from the controller 160, similarly to the adding device 148.
Reference Signs List
[0063] 100 hot-water supply apparatus 101 water supply end 102 hot water supply end 103
pressure reducing valve 110 heat pump unit 120 hot-water tank 121, 122 hot water storage
temperature sensor 130 heat exchanger 140 bathtub circulation passage 141 bathtub
return pipe 142 bathtub supply pipe
145 bathtub circulation pump 148 adding device 150 tank circulation passage 151 three-way
valve 152 first four-way valve 153 second four-way valve 155 tank circulation pump
160 controller 170 remote control 171 bathtub washing switch 200 bathtub 601 CPU 602
communication interface 603 ROM 604 RAM 605 secondary storage device 606 bus 611 user
interface unit 612 device state acquisition unit 613 device control unit 614 operation
mode execution unit
1. A hot-water supply apparatus comprising:
a hot-water tank configured to store water;
a heat exchanger configured to allow the water stored in the hot-water tank and water
stored in a bathtub to exchange heat with each other;
a bathtub circulation passage configured to allow the water stored in the bathtub
to flow out of the bathtub and return to the bathtub via the heat exchanger;
a bathtub circulation pump provided to the bathtub circulation passage and configured
to circulate the water stored in the bathtub through the bathtub circulation passage;
and
a controller configured to perform
a heat recovery operation in which heat of the water stored in the bathtub is recovered
into the water stored in the hot-water tank, and
a washing operation in which an inside of the bathtub is washed,
in both the heat recovery operation and the washing operation, the bathtub circulation
pump being activated to circulate the water stored in the bathtub through the bathtub
circulation passage.
2. The hot-water supply apparatus of claim 1, wherein the controller is configured to
perform both of the heat recovery operation and the washing operation in response
to operation of a single switch.
3. The hot-water supply apparatus of claim 1 or 2, wherein the controller is configured
to perform the heat recovery operation and the washing operation either simultaneously
or successively.
4. The hot-water supply apparatus of claim 3, wherein the controller is configured to
perform the heat recovery operation successively after the washing operation.
5. The hot-water supply apparatus of claim 4, wherein the controller is configured to
start the heat recovery operation when a predetermined period elapses after start
of the washing operation; temperature of the water in the bathtub falls to or below
a predetermined temperature; or temperature difference between the water in the bathtub
and the water stored in a lower part of the hot-water tank falls to or below a predetermined
temperature.
6. The hot-water supply apparatus of claim 3, wherein the controller is configured to
perform the washing operation successively after the heat recovery operation.
7. The hot-water supply apparatus of claim 6, wherein the controller is configured to
start the washing operation when a predetermined period elapses after start of the
heat recovery operation; temperature of the water in the bathtub falls to or below
a predetermined temperature; or temperature difference between the water in the bathtub
and the water stored in a lower part of the hot-water tank falls to or below a predetermined
temperature.
8. The hot-water supply apparatus of claim 7, further comprising:
a tank circulation passage configured to allow the water discharged from the hot-water
tank to return to the hot-water tank through the heat exchanger; and
a tank circulation pump provided to the tank circulation passage and configured to
circulate the water in the hot-water tank through the tank circulation passage, wherein
the controller is configured to stop the heat recovery operation when predetermined
period elapses after start of the washing operation; temperature difference between
the water in the bathtub and the water stored in the lower part of the hot-water tank
falls to or below predetermined temperature; or an amount of power saved by heat recovery,
which is derived from temperature of the water in the bathtub and temperature of the
water stored in the lower part of the hot-water tank, is less than power consumed
by the tank circulation pump.
9. The hot-water supply apparatus of any one of claims 1 to 7, further comprising:
a tank circulation passage configured to allow the water discharged from the hot-water
tank to return to the hot-water tank through the heat exchanger; and
a tank circulation pump provided to the tank circulation passage and configured to
circulate the water in the hot-water tank through the tank circulation passage, wherein
the controller is configured to drive the tank circulation pump and the bathtub circulation
pump in the heat recovery operation, and
the controller is configured to drive the bathtub circulation pump and not to drive
the tank circulation pump in the washing operation.
10. The hot-water supply apparatus of any one of claims 1 to 9, further comprising an
adding device configured to add an additive for enhancing a washing effect in the
washing operation into the water stored in the bathtub.
11. The hot-water supply apparatus of claim 10, wherein the additive has a surface-activating
effect.
12. A method of washing a bathtub using the hot-water supply apparatus of claim 1, the
method comprising:
adding an additive for enhancing a washing effect into water stored in the bathtub;
and
simultaneously performing both of the heat recovery operation and the washing operation.