Note: Descriptions are shown in the official language in which they were submitted.
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HEAT-PUMP SYSTEM WITH REFRIGERANT CHARGE DIAGNOSTICS
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Utility Application No.
14/244,967,
filed on April 4, 2014, and the benefit of U.S. Provisional Application No.
61/808,688, filed on
April 5, 2013.
FIELD
[0002] The present disclosure relates to a heat-pump system having
refrigerant
charge diagnostics.
BACKGROUND
[0003] This section provides background information related to the present
disclosure and is not necessarily prior art.
[0004] A climate-control system such as, for example, a heat-pump system, a
refrigeration system, or an air conditioning system, may include a fluid
circuit having an
outdoor heat exchanger, an indoor heat exchanger, an expansion device disposed
between
the indoor and outdoor heat exchangers, and a compressor circulating a
working fluid (e.g.,
refrigerant or carbon dioxide) between the indoor and outdoor heat exchangers.
Maintaining
proper amounts of working fluid in the system (i.e., refrigerant charge
levels) is desirable for
effective and efficient operation of the climate-control system.
SUMMARY
[0005] This section provides a general summary of the disclosure, and is
not a
comprehensive disclosure of its full scope or all of its features.
[0006] In one form, the present disclosure provides a method that may
include
determining a working-fluid-charge condition of a heat-pump system based on at
least one of
a supply-air temperature and a return-air temperature. In some embodiments,
the working-
fluid charge condition may be determined by a cloud-based processing device.
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[0007] In another form, a
monitor may be provided for a heat-pump
circuit. The heat-pump circuit may include an indoor heat exchanger, an
outdoor
heat exchanger, a compressor circulating a working fluid between the indoor
and
outdoor heat exchangers, and an expansion device between the indoor and
outdoor heat exchangers. The monitor may include a return-air temperature
sensor, a supply-air temperature sensor, and a processor. The return-air
temperature sensor may be adapted to measure a first air temperature of air
upstream of the indoor heat exchanger. The supply-air temperature sensor may
be adapted to measure a second air temperature of air downstream of the indoor
heat exchanger. The processor may be in communication with the return-air
temperature sensor and the supply-air temperature sensor. The processor may
be programmed to determine a working-fluid-charge condition of the heat-pump
system based on the first and second air temperatures.
[0008] In some embodiments, the processor is programmed to
determine the working-fluid-charge condition based on a difference between the
second air temperature and the first air temperature and a comparison of the
difference with a predetermined value.
[0009] In some embodiments,
the monitor includes a working-fluid
temperature sensor disposed between the expansion device and the indoor heat
exchanger and adapted to measure a working-fluid temperature of working fluid
flowing between the indoor heat exchanger and the expansion device when the
heat-pump system is operating in a heating mode. The processor may be in
communication with the working-fluid temperature sensor and may be
programmed to determine the working-fluid-charge condition of the heat-pump
system based on the working-fluid temperature.
[0010] In some embodiments, the processor is programmed to
determine the working-fluid-charge condition based a first difference between
the
second air temperature and the working-fluid temperature.
[0011] In some embodiments, the processor is programmed to
determine the working-fluid-charge condition based on a second difference
between the second air temperature and the first air temperature.
[0012] In some embodiments,
the processor is programmed to
determine the working-fluid charge condition based only on a first comparison
of
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the first difference with a first predetermined value and a second comparison
of
the second difference with a second predetermined value.
[0013] In some embodiments,
the processor is programmed to
determine the working-fluid-charge condition based a third difference between
the working-fluid temperature and the second air temperature.
[0014] In some embodiments,
the processor is programmed to
determine the working-fluid charge condition based on a first comparison of
the
first difference with a first predetermined value, a second comparison of the
second difference with a second predetermined value, and a third comparison of
the third difference with a third predetermined value.
[0015] In some embodiments,
the processor is in communication with
a notification device configured to generate a first alert indicating that a
fault
condition of the heat-pump system is related to the working-fluid-charge
condition and a second alert indicating that the fault condition of the heat-
pump
system is unrelated to an amount of working fluid in the heat-pump system.
[0016] In some embodiments, the processor is a cloud-based
processor. The notification device may include a mobile, wireless computing
device, for example.
[0017] In some embodiments,
the processor is in communication with
a notification device configured to generate an alert indicating the working-
fluid-
charge condition.
[0018] In some embodiments, the processor is a cloud-based
processor disposed remotely from the compressor, the return-air temperature
sensor and the supply-air temperature sensor.
[0019] In another form, the
present disclosure provides a method of
monitoring a heat-pump system. The heat-pump system may include indoor and
outdoor heat exchangers, a compressor adapted to circulate a working fluid
between the indoor and outdoor heat exchangers, and an expansion device
disposed between the indoor and outdoor heat exchangers. The method may
include receiving a first air temperature value of air upstream of the indoor
heat
exchanger from a return-air temperature sensor; receiving a second air
temperature of air downstream of the indoor heat exchanger from a supply-air
temperature sensor; and determining a working-fluid-charge condition of the
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heat-pump system using a processor programmed to determine the working-
fluid-charge condition based on the first and second air temperatures.
[0020] In some embodiments,
the working-fluid-charge condition is
determined based on the first and second air temperatures and a working-fluid
temperature measured by a working-fluid temperature sensor disposed
downstream the indoor heat exchanger when the heat-pump system is in a
heating mode.
[0021] In some embodiments,
the first and second air temperature
values are acquired while the heat-pump system is operating in a heating mode.
[0022] In some embodiments,
the working-fluid temperature sensor is
disposed between the indoor heat exchanger and the expansion device.
[0023] In some embodiments,
the processor is programmed to
determine the working-fluid-charge condition based on a difference between the
second air temperature and the first air temperature and a comparison of the
difference with a predetermined value.
[0024] In some embodiments,
the method may include receiving a
working-fluid temperature of working-fluid flowing between the indoor and
outdoor heat exchangers. The processor may be programmed to determine the
working-fluid-charge condition of the heat-pump system based on the working-
fluid temperature.
[0025] In some embodiments, the method includes receiving a
working-fluid temperature of working-fluid flowing between the indoor heat
exchanger and the expansion device when the heat-pump system is operating in
a heating mode. The processor may be programmed to determine the working-
fluid-charge condition of the heat-pump system based on the working-fluid
temperature.
[0026] In some embodiments,
the processor is programmed to
determine the working-fluid-charge condition based a first difference between
the
second air temperature and the working-fluid temperature.
[0027] In some embodiments,
the processor may be programmed to
determine the working-fluid-charge condition based on a second difference
between the second air temperature and the first air temperature.
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[0028] In some embodiments,
the processor is programmed to
determine the working-fluid charge condition based only on a first comparison
of
the first difference with a first predetermined value and a second comparison
of
the second difference with a second predetermined value.
[0029] In some embodiments,
the processor is programmed to
determine the working-fluid-charge condition based a third difference between
the working-fluid temperature and the second air temperature.
[0030] In some embodiments,
the processor is programmed to
determine the working-fluid charge condition based on a first comparison of
the
first difference with a first predetermined value, a second comparison of the
second difference with a second predetermined value, and a third comparison of
the third difference with a third predetermined value.
[0031] In some embodiments,
the method includes generating a first
alert with a notification device indicating that a fault condition of the heat-
pump
system is related to the working-fluid-charge condition; and generating a
second
alert with the notification device indicating that the fault condition of the
heat-
pump system is unrelated to an amount of working fluid in the heat-pump
system.
[0032] In another form, the
present disclosure provides a working-fluid
circuit having a processor in communication with a return-air temperature
sensor
and a supply-air temperature sensor, a compressor circulating a working fluid
between the indoor and outdoor heat exchangers, and an expansion device
between the indoor and outdoor heat exchangers. The processor may be
programmed to determine a working-fluid-charge condition of the working-fluid
circuit based on a first air temperature of air upstream of the indoor heat
exchanger from the return-air temperature sensor and a second air temperature
of air downstream of the indoor heat exchanger from the supply-air temperature
sensor.
[0033] Further areas of
applicability will become apparent from the
description provided herein. The description and specific examples in this
summary are intended for purposes of illustration only and are not intended to
limit the scope of the present disclosure.
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[0033a] According to one aspect of the present invention, there is provided a
monitor for a heat-pump circuit having indoor and outdoor heat exchangers, a
compressor circulating a working fluid between the indoor and outdoor heat
exchangers, and an expansion device between the indoor and outdoor heat
exchangers, the monitor comprising: a return-air temperature sensor adapted to
measure a first air temperature of air upstream of the indoor heat exchanger;
a
supply-air temperature sensor adapted to measure a second air temperature of
air
downstream of the indoor heat exchanger; a working-fluid temperature sensor
disposed between the expansion device and the indoor heat exchanger and
adapted
to measure a working-fluid temperature of working fluid flowing between the
indoor
heat exchanger and the expansion device when the heat-pump system is operating
in
a heating mode; and a processor in communication with the return-air
temperature
sensor, the supply-air temperature sensor and the working-fluid temperature
sensor,
the processor programmed to determine a first difference between the second
air
temperature and the working-fluid temperature, a second difference between the
second air temperature and the first air temperature, and a third difference
between
the working-fluid temperature and the first air temperature, the processor
configured
to determine a working-fluid-charge condition of the heat-pump system based on
a
first comparison of the first difference with a first predetermined value and
one of: a
second comparison of the second difference with a second predetermined value
and
a third comparison of the third difference with a third predetermined value.
[0033b] According to another aspect of the present invention, there is
provided a method of monitoring a heat-pump system having indoor and outdoor
heat
exchangers, a compressor adapted to circulate a working fluid between the
indoor
and outdoor heat exchangers, and an expansion device disposed between the
indoor
and outdoor heat exchangers, the method comprising: receiving a first air
temperature value of air upstream of the indoor heat exchanger from a return-
air
temperature sensor; receiving a second air temperature of air downstream of
the
indoor heat exchanger from a supply-air temperature sensor; receiving a
working-
fluid temperature of working-fluid flowing between the indoor heat exchanger
and the
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expansion device when the heat-pump system is operating in a heating mode; and
determining a working-fluid-charge condition of the heat-pump system using a
processor programmed to determine the working-fluid-charge condition based on
the
first and second air temperatures and a first difference between the second
air
temperature and the working-fluid temperature.
[0033c] According to still another aspect of the present invention, there is
provided a working-fluid circuit having a processor in communication with a
return-air
temperature sensor adapted to measure a first air temperature of air upstream
of an
indoor heat exchanger, a supply-air temperature sensor adapted to measure a
second air temperature of air downstream of the indoor heat exchanger, and a
working-fluid temperature sensor, a compressor circulating a working fluid
between
the indoor heat exchanger and the outdoor heat exchanger, and an expansion
device
between the indoor and outdoor heat exchangers, the working-fluid temperature
sensor disposed between the expansion device and the indoor heat exchanger and
adapted to measure a working-fluid temperature or working fluid flowing
between the
indoor heat exchanger and the expansion device when the heat-pump system is
- operating in a heating mode, the processor programmed to determine a
first
difference between the second air temperature and the working fluid
temperature and
a second difference between the second air temperature and the first air
temperature,
the processor configured to determine a working-fluid-charge condition of the
heat-
pump system based on a first comparison of the first difference with a first
predetermined value and a second comparison of the second difference with a
second predetermined value.
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DRAWINGS
[0034] The drawings
described herein are for illustrative purposes only
of selected embodiments and not all possible implementations, and are not
intended to limit the scope of the present disclosure.
[0035] Figure 1 is a
schematic representation of a heat-pump system
according to the principles of the present disclosure;
[0036] Figure 2 is a
schematic representation of a plurality of sensors
associated with the heat-pump system communicating with a remote processing
device; and
[0037] Figure 3 is a flow
chart illustrating a method of determining a
charge level according to the principles of the present disclosure.
[0038] Corresponding
reference numerals indicate corresponding parts
throughout the several views of the drawings.
DETAILED DESCRIPTION
[0039] Example embodiments
will now be described more fully with
reference to the accompanying drawings.
[0040] Example embodiments
are provided so that this disclosure will
be thorough, and will fully convey the scope to those who are skilled in the
art.
Numerous specific details are set forth such as examples of specific
components, devices, and methods, to provide a thorough understanding of
embodiments of the present disclosure. It will be apparent to those skilled in
the
art that specific details need not be employed, that example embodiments may
be embodied in many different forms and that neither should be construed to
limit the scope of the disclosure. In some example embodiments, well-known
processes, well-known device structures, and well-known technologies are not
described in detail.
[0041] The terminology used
herein is for the purpose of describing
particular example embodiments only and is not intended to be limiting. As
used
herein, the singular forms "a," "an," and "the" may be intended to include the
plural forms as well, unless the context clearly indicates otherwise. The
terms
"comprises," "comprising," "including," and "having," are inclusive and
therefore
specify the presence of stated features, integers, steps, operations,
elements,
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and/or components, but do not preclude the presence or addition of one or more
other features, integers, steps, operations, elements, components, and/or
groups
thereof. The method steps, processes, and operations described herein are not
to be construed as necessarily requiring their performance in the particular
order
discussed or illustrated, unless specifically identified as an order of
performance.
It is also to be understood that additional or alternative steps may be
employed.
[0042] When an element or
layer is referred to as being "on," "engaged
to," "connected to," or "coupled to" another element or layer, it may be
directly
on, engaged, connected or coupled to the other element or layer, or
intervening
elements or layers may be present. In contrast, when an element is referred to
as being "directly on," "directly engaged to," "directly connected to," or
"directly
coupled to" another element or layer, there may be no intervening elements or
layers present. Other words used to describe the relationship between elements
should be interpreted in a like fashion (e.g., "between" versus "directly
between,"
"adjacent" versus "directly adjacent," etc.). As used herein, the term
"and/or"
includes any and all combinations of one or more of the associated listed
items.
[0043] Although the terms
first, second, third, etc. may be used herein
to describe various elements, components, regions, layers and/or sections,
these elements, components, regions, layers and/or sections should not be
limited by these terms. These terms may be only used to distinguish one
element, component, region, layer or section from another region, layer or
section. Terms such as "first," "second," and other numerical terms when used
herein do not imply a sequence or order unless clearly indicated by the
context.
Thus, a first element, component, region, layer or section discussed below
could
be termed a second element, component, region, layer or section without
departing from the teachings of the example embodiments.
[0044] Spatially relative
terms, such as "inner," "outer," "beneath,"
"below," "lower," "above," "upper," and the like, may be used herein for ease
of
description to describe one element or feature's relationship to another
element(s) or feature(s) as illustrated in the figures. Spatially relative
terms may
be intended to encompass different orientations of the device in use or
operation
in addition to the orientation depicted in the figures. For example, if the
device in
the figures is turned over, elements described as "below" or "beneath" other
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elements or features would then be oriented "above" the other elements or
features. Thus, the example term "below" can encompass both an orientation of
above and below. The device may be otherwise oriented (rotated 90 degrees or
at other orientations) and the spatially relative descriptors used herein
interpreted accordingly.
[0045] With reference to
Figure 1, a heat-pump system 10 is provided
that may include a compressor 12, a reversing valve 14, an indoor heat
exchanger 16, an expansion device 18, and an outdoor heat exchanger 20. The
compressor 12 can be a scroll compressor, a reciprocating compressor, or a
rotary vane compressor, for example, or any other type of compressor. The
reversing valve 14 may be a four-way valve operable to control a direction of
working fluid flow through the heat-pump system 10. A controller (not shown)
may switch the reversing valve 14 between a first position (not shown)
corresponding to a cooling mode and a second position corresponding to a
heating mode (shown in Figure 1).
[0046] In the cooling mode,
the outdoor heat exchanger 20 may
operate as a condenser or as a gas cooler and may cool discharge-pressure
working fluid received from the compressor 12 by transferring heat from the
working fluid to ambient air, for example. In the heating mode, the outdoor
heat
exchanger 20 may operate as an evaporator.
[0047] In the cooling mode,
the indoor heat exchanger 16 may operate
as an evaporator and may transfer heat from a space to be cooled (e.g., a room
within a house or building) to the working fluid in the indoor heat exchanger
16.
In the heating mode, the indoor heat exchanger 16 may operate as a condenser
or as a gas cooler and may transfer heat from working fluid discharged from
the
compressor 12 to a space to be heated. During operation of the heat-pump
system 10, a fan 22 may draw air from the space to be heated or cooled through
a return-air duct 24 and force the air across the indoor heat exchanger 16 to
transfer heat between the working fluid in the indoor heat exchanger 16 and
the
air. From the indoor heat exchanger 16, the heated or cooled air may be forced
through a supply-air duct 26 to the space to be heated or cooled.
[0048] The heat-pump system
10 may also include a return-air
temperature sensor 30, a supply-air temperature sensor 32, a liquid-line
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temperature sensor 34, and an outside-air temperature sensor 38. The return-
air temperature sensor 30 may be disposed in the return-air duct 24 and may
measure a temperature of the air flowing therethrough. The
supply-air
temperature sensor 32 may be disposed in the supply-air duct 26 and may
measure a temperature of the air flowing therethrough. The liquid-line
temperature sensor 34 may be disposed between the indoor heat exchanger 16
and the expansion device 18 and may measure a temperature of the working
fluid flowing therebetween. The outside-air temperature sensor 38 may be
disposed in any suitable location to measure a temperature of ambient air
outside of the house or building.
[0049] As shown in Figure 2,
the sensors 30, 32, 34, 38 may be in
communication with a remotely located or on-site processing device 40. In some
embodiments, any or all of the sensors 30, 32, 34, 38 may be installed in the
locations described above. In some embodiments, any or all of the sensors 30,
32, 34, 38 may be handheld sensors that a technician may temporarily place in
the locations described above, obtain temperature measurements in those
locations, and transmit the data to the processing device 40. Any or all of
the
sensors 30, 32, 34, 38 may be incorporated into a newly installed heat-pump
system, or any or all of the sensors 30, 32, 34, 38 may be retrofitted to a
pre-
existing heat-pump system that has already been installed within a house or
building. In some configurations, the outside-air temperature sensor 38 could
be
a thermometer or other sensor of a weather monitoring and/or weather reporting
system or entity. In such configurations, the processor 40 may obtain the
outside-air temperature measured by the sensor 38 from the weather monitoring
and/or weather reporting system or entity via an internet, Bluetoothe or
cellular
connection, for example.
[0050] The processing device
40 may include a cloud-computing
module having hardware (e.g., a processor and/or memory) and software
capable of carrying the functionality described below. The processing device
40
may be in communication with a server that may receive data from the sensors
30, 32, 34, 38 via an internet connection or cellular network, for example.
The
processing device 40 may receive data from the sensors 30, 32, 34, 38 on
demand, intermittently or in real time. In some embodiments, the processing
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device 40 may be located on a contractor or technician's portable computing
device (e.g., a laptop, tablet, smartphone or other device), or may be located
within the house or building in which the heat-pump system 10 is installed
(e.g.,
in a thermostat (not shown) or a control module (not shown) for the heat-pump
system 10).
[0051] The processing device
40 may also be in communication with
one or more notification devices 42 that may be disposed remotely from the
processing device 40 and/or the sensors 30, 32, 34, 38. The notification
devices
42 may include any of a desktop computer, a laptop computer, a hand-held
computing device, a tablet, or a smartphone, for example, or any other
computing device or electronic information display device. In
some
embodiments, the one or more notification devices 42 may be a part of a wall-
mounted thermostat unit.
[0052] As will be
subsequently described, the processing device 40
may, based on data received from one or more of the sensors 30, 32, 34, 38,
diagnose faults conditions (e.g., undercharge conditions, overcharge
conditions
and/or flow restriction conditions) of the heat-pump system 10, verify a
charge
level of the heat-pump system 10, and/or provide guidance to a technician
during
initial installation of the heat-pump system 10 for adding an appropriate
amount
of working fluid into the heat-pump system 10. Notifications, alerts, updates
and/or other information output from the processing device 40 may be
transmitted to one or more notification devices 42 and may be accessed or
displayed thereon. In some embodiments, the notifications, alerts, updates
and/or other information output from the processing device 40 may be
transmitted to the notification device 42 via email, text message, instant
message, multimedia message. In some embodiments, the notification device
42 may include a mobile application (e.g., a smartphone or tablet application)
that provides notifications, alerts, updates, and/or other information based
on
output from the processing device 40.
[0053] With reference to
Figures 1-3, a method of diagnosing a fault
condition when the heat-pump system 10 is in a heating mode will be described
in detail. The method may include determining whether a reason for inefficient
and/or ineffective operation of the heat-pump system 10 is an undercharge
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condition (i.e., not enough working fluid in the heat-pump system 10), an
overcharge condition (i.e., too much working fluid in the heat-pump system
10),
or a flow restriction in the heat-pump system 10 (e.g., a working-fluid-flow
restriction in the liquid line or an airflow restriction at the outdoor heat
exchanger
20 or at the indoor heat exchanger 16).
[0054] At step 110, the
return-air temperature sensor 30, supply-air
temperature sensor 32, and the liquid-line temperature sensor 34 may detect
temperatures at their respective locations and transmit this data to the
processing device 40. As described above, detecting and transmitting this data
may be done on-demand, intermittently, averaged over a time period, or in real
time. At step 120, the processing device 40 may determine a value equal to
supply-air temperature minus a liquid-line temperature. When the heat-pump
system 10 is operating in the heating mode, the liquid-line temperature may be
a
temperature detected by the liquid-line temperature sensor 34.
[0055] At step 130, the
processing device 40 may determine if the
value calculated at step 120 (supply-air temperature minus liquid-line
temperature) is higher or lower than a first predetermined value. The first
predetermined value may correspond to a particular heat pump system and/or
may be based on a current outside-air temperature determined by the outside-
air
temperature sensor 38.
[0056] If the processing
device 40 determines (at step 130) that the
value determined at step 120 is lower than the first predetermined value, the
processing device 40 may calculate, at step 140, a value equal to liquid-line
temperature minus a return-air temperature. At step 150, the processing device
40 may determine if the value calculated at step 140 (liquid-line temperature
minus return-air temperature) is higher or lower than a second predetermined
value. The second predetermined value may correspond to a particular heat-
pump system and/or may be based on a current outside-air temperature
determined by the outside-air temperature sensor 38. If, at step 150, the
processing device 40 determines that the value calculated at step 140 is lower
than the second predetermined value, then the processing device 40 may, at
step 160, send a notification to the notification device 42 indicating that
the heat-
pump system 10 is undercharged and working fluid should be added to the heat-
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pump system 10. If, at step 150, the processing device 40 determines that the
value calculated at step 140 is higher than the second predetermined value,
then
the processing device 40 may, at step 170, determine that the system charge is
adequate and/or any system fault may not be related to system charge.
[0057] If, at step 130, the
processing device 40 determines that the
value determined at step 120 is higher than the first predetermined value, the
processing device 40 may calculate, at step 180, a value equal to supply-air
temperature minus return-air temperature. At step 190, the processing device
40 may determine if the value calculated at step 180 (supply-air temperature
minus return-air temperature) is higher or lower than a third predetermined
value. The third predetermined value may correspond to a particular heat-pump
system and/or may be based on a current outside-air temperature determined by
the outside-air temperature sensor 38. If, at step 190, the processing device
40
determines that the value calculated at step 180 is lower than the third
predetermined value, then the processing device 40 may, at step 200, send a
notification to the notification device 42 indicating that there is a working
fluid
flow restriction in the heat-pump system 10. If, at step 190, the processing
device 40 determines that the value calculated at step 180 is higher than the
third predetermined value, then the processing device 40 may, at step 210,
send
a notification to the notification device 42 indicating that the heat-pump
system
10 is overcharged and an amount of working fluid in the heat-pump system 10
should be reduced.
[0058] In addition to
diagnosing a fault of the heat-pump system 10,
the processing device 40 may perform the above method steps to verify a
charge of the heat-pump system 10 on-demand or at predetermined time
intervals, for example. If the processing device 40 determines that the heat-
pump system 10 is overcharged, undercharged and/or some other fault condition
exists, the processing device 40 may send an appropriate notification to the
notification device 42, as described above.
[0059] The processing device
40 and notification device 42 may also
be used by a technician to perform an initial charge of the heat-pump system
10
during the initial installation of the heat-pump system 10 into the house or
building. That is, real time supply-air, return-air, liquid-line and outside-
air
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temperature measurements can be processed by the processing device 40 and
real-time feedback from the processing device 40 can be provided to the
technician via the notification device 42 that indicates when the heat-pump
system 10 has reached an optimum charge level (i.e., when the technician
should stop adding working fluid to the heat-pump system 10).
[0060] For example, the
processing device 40 may monitor (in real
time) a value of liquid-line temperature minus return-air temperature. This
value
may continue to increase as the technician adds working fluid during the
initial
system charge until an optimum charge level is achieved. Once the optimum
charge level is achieved, adding more working fluid to the heat-pump system 10
may cause the value of liquid-line temperature minus return-air temperature to
decrease. Therefore, the processing device 40 and notification device 42 may
notify the technician as soon as the value of liquid-line temperature minus
return-
air temperature starts to decrease. When
the technician receives this
notification, he or she may stop adding working fluid to the heat-pump system
10.
[0061] The first, second and
third predetermined values described
above may be chosen to correspond to a particular heat-pump system and may
be determined through experimentation or from look-up tables, for example.
[0062] In this application,
including the definitions below, the term
module may be replaced with the term circuit. The term module may refer to, be
part of, or include an Application Specific Integrated Circuit (ASIC); a
digital,
analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed
analog/digital integrated circuit; a combinational logic circuit; a field
programmable gate array (FPGA); a processor (shared, dedicated, or group) that
executes code; memory (shared, dedicated, or group) that stores code executed
by a processor; other suitable hardware components that provide the described
functionality; or a combination of some or all of the above, such as in a
system-
on-chip.
[0063] The foregoing
description is merely illustrative in nature and is
in no way intended to limit the disclosure, its application, or uses. The
broad
teachings of the disclosure can be implemented in a variety of forms.
Therefore,
while this disclosure includes particular examples, the true scope of the
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disclosure should not be so limited since other modifications will become
apparent upon a study of the drawings, the specification, and the following
claims. As used herein, the phrase at least one of A, B, and C should be
construed to mean a logical (A or B or C), using a non-exclusive logical OR.
It
should be understood that one or more steps within a method may be executed
in different order (or concurrently) without altering the principles of the
present
disclosure.
[0064] The foregoing
description of the embodiments has been
provided for purposes of illustration and description. It is not intended to
be
exhaustive or to limit the disclosure. Individual elements or features of a
particular embodiment are generally not limited to that particular embodiment,
but, where applicable, are interchangeable and can be used in a selected
embodiment, even if not specifically shown or described. The same may also be
varied in many ways. Such variations are not to be regarded as a departure
from
the disclosure, and all such modifications are intended to be included within
the
scope of the disclosure.
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