Note: Descriptions are shown in the official language in which they were submitted.
CA 02769346 2012-02-24
PACKAGED HVAC SYSTEM FOR INDOOR INSTALLATION
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional patent
application serial
number 61/447361 filed February 28, 2011, the entire contents of which are
incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] This application relates generally to heating, ventilation, and cooling
(HVAC)
systems and particularly to a packaged HVAC system configured for indoor
installation. An
HVAC system typically comprises several components installed in distributed
locations both
inside and outside a home. For example, HVAC systems often include an air
handler
positioned inside a structure, the air handler having one or more fans or
blowers to move an
airstream through various system components and to distribute the conditioned
airstream via
a system of ducts. In such systems, an evaporator may be positioned within the
airstream in a
first location inside the home and may be configured to remove heat from the
airstream and
transfer that heat to a working fluid (e.g., R-410A refrigerant). The working
fluid may be
carried through a fluid line (e.g., copper pipe) through an exterior wall of
the home to a
compressor and a condenser where heat can be effectively released directly to
the
atmosphere. Such compressor/condenser units are often positioned outside the
structure on a
concrete slab, and electric service to the compressor is provided through an
electric line
passing through the exterior wall of the structure. Finally, the cooled,
compressed working
fluid is returned to the evaporator via another fluid line passing through the
exterior wall to
the inside of the structure.
[0003] To provide heating of the airstream, an electric heating element or a
gas heat
exchanger may also be positioned in the conditioned airstream, often near the
evaporator.
For gas-burning applications, combustion air is typically carried from outside
the home to a
burner, and, following a transfer of heat to the conditioned airstream, the
products of
combustion are exhausted outside the home. The gas heat exchanger is coupled
to a set of
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2
ducts that carry the combustion air and the products of combustion through an
exterior wall
to and from a location outside the home.
[0004] Thus, conventional HVAC systems often comprise a number of
interconnected
subsystem components positioned remotely from one another, both inside and
outside the
host structure. The subsystem components are coupled to one another via ducts
and fluid
lines and lines carrying electricity and gas. A common example of a
conventional HVAC
system is known as a split-system, which comprises an indoor unit that
includes an air
handler with an integrated heater and evaporator and an outdoor unit that
integrates the
compressor and condenser into a single packaged unit.
[0005] Due to the variety of available components making up a conventional
HVAC
system and the wide degree of variation in the structures into which
conventional HVAC
systems are installed, HVAC systems tend to be unique and widely varied. This
necessitates
a relatively high degree of skill for HVAC technicians to be able to properly
specify, adapt,
install, evaluate, and repair HVAC systems in individual homes. Moreover, due
to the
distributed nature of conventional HVAC systems, and the requirements that
fluid lines,
electrical lines, gas lines, and system ducts (i.e., mechanical
interconnections) connect with
the subsystem components and properly integrate with the structural and
mechanical
elements of the home, cooperation between many construction trades (e.g.,
framers/carpenters, electricians, plumbers, drywall contractors, etc., is
necessitated. It has
also been recognized that each of the lines and ducts passing through the
exterior walls of a
structure introduce the potential for air leaks and energy inefficiencies.
[0006] Thus, a need exists for a pre-packaged HVAC system that can reduce or
eliminate the need for external (i.e., positioned completely or partially
outside the HVAC
packaging) mechanical interconnections that may be exposed to the host
structure or that
interact with and/or interfere with and/or penetrate the host structure.
[0007] There is also a need for increased energy efficiency in home HVAC
systems,
and home designers are increasingly seeking to incorporate mechanical
ventilation systems,
often incorporating energy recovery features, into new homes. Such systems
carry ventilation
air from outside the host structure to the inside. A corresponding volume of
air is returned
CA 02769346 2012-02-24
3
from inside the structure to the outside. Such ventilation systems typically
require openings
in one or more exterior walls of the structure, through which the ventilation
and exhaust air is
passed. The incorporation of these additional ventilation systems exacerbates
the need for
simplification and integration of HVAC system components and for reduction of
external
mechanical interconnections.
BRIEF DESCRIPTION OF THE INVENTION
[0008] An embodiment is a pre-packaged air conditioning system for providing
heating, cooling, ventilation and energy recovery, the system comprising: an
energy recovery
ventilator (ERV), condenser, condenser fan, compressor, expansion device, flow
reversing
valve, evaporator and evaporator fan; an inlet for providing outside air to
the evaporator, the
inlet for extending beyond a wall of a host structure; and an exhaust duct for
exhausting air
outside of the host structure, the exhaust duct for extending beyond a wall to
the host
structure; wherein the energy recovery ventilator, condenser, condenser fan,
compressor,
evaporator and evaporator fan are housed within a single envelope configured
for installation
inside the host structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The subject matter which is regarded as the invention is particularly
pointed
out and distinctly claimed in the claims at the conclusion of the
specification. The foregoing
and other features, and advantages of the invention are apparent from the
following detailed
description taken in conjunction with the accompanying drawings in which:
[0010] FIG. 1 is a schematic drawing of an exemplary pre-packaged HVAC system
in
one embodiment;
[0011] FIG. 2 is a front view of an exemplary pre-packaged HVAC system in
another
embodiment; and
[0012] FIG. 3 is a front view of an exemplary pre-packaged HVAC system in
another
embodiment.
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4
DETAILED DESCRIPTION OF THE INVENTION
[0013] Embodiments provide a pre-packaged HVAC system that greatly reduces the
need for external mechanical interconnections that may be exposed within the
host structure
and that otherwise interact with and/or interfere with or require separate
penetrations to the
host structure. Embodiments also provide for integration with a mechanical
ventilation
system and for incorporation of energy recovery features, all while reducing
the need for
openings in the exterior walls of the host structure. Embodiments may also
provide for
simplified installation and reduced floor space.
[0014] In an exemplary embodiment, a fully integrated HVAC system includes an
energy recovery ventilator, condenser, condenser fan, and compressor, together
with an
evaporator and evaporator fan, all integrated into a single, prepackaged unit
that is configured
for installation inside the host structure. In accordance with this
embodiment, the airflow
over the condenser and its fan is acquired through the same external wall
opening that service
the air for the energy recovery ventilator. Incoming outside air may be
preheated or pre-
cooled, and energy may also be recovered from the stream of return air. As one
skilled in the
art will appreciate, the energy recovery ventilator may be configured to
transfer not only
thermal energy (heat or cool), but also moisture. To transfer moisture, the
system may
incorporate a membrane to recapture water from return air and transfer that
moisture to the
incoming stream of outside air.
[0015] Energy recovery may be accomplished through a variety of devices
including
a rotating wheel, and internal dampers may be included so as to effectuate
control of indoor
return air and outside ventilation air. The energy recovery system may recover
energy from
the return air. The volume of an exemplary pre-packaged HVAC system may be in
the range
of six to fifteen cubic feet. The capacity of an exemplary pre-packaged HVAC
system may
be in the range of five to twenty four thousand BTUs. Accordingly, as one
skilled in the art
will appreciate, a pre-packaged HVAC system tends to reduce the risk of
exposure to foreign
objects or other environmental contaminants inherent in split system
refrigerant piping
installation, particularly as the HVAC package is configured to provided a
substantially
sealed environment for the compressor.
CA 02769346 2012-02-24
[0016] An exemplary HVAC system may also include devices for providing one or
more economizer modes by manipulating or even disabling the rotational speed
of the energy
recovery wheel and/or by adjusting or closing bypass dampers.
[0017] In operation, the system transfers the stream of air used by the
condenser to
and from the outside of the host structure, and heat is transferred between
the air and the
condenser in a location inside the host structure, i.e., within the pre-
packaged, integrated
HVAC system. Moreover, the system of the employs a single system of ducts to
carry both
ventilation air and condenser airflow.
[0018] In accordance with an exemplary embodiment, and as shown in FIG 1, an
integrated, pre-packaged HVAC system 100 includes insulated inlet 110 (i.e.,
duct), through
which outside air stream 112 is received from the atmosphere 130 outside the
host structure.
Insulated inlet 110 passes through exterior wall 120 of a host structure such
as a home,
accepts air from the atmosphere 130, and provides outside air stream 112 to
inlet filter 140,
which filters outside air stream 112 before it is separated by inlet splitter
150 into outside air
stream 152 and condenser stream 154. In accordance with this embodiment, inlet
splitter 150
may be equipped with inlet core damper 156 and a bypass dampers 158 configured
so as to
control the flow rates of outside air stream 152 and condenser stream 154.
[0019] As one skilled in the art will appreciate, the flow rate of outside air
stream 152
should be adjusted to provide the amount of air needed for proper ventilation,
and the flow
rate of condenser stream 154 should be adjusted to provide the amount of air
for appropriate
heat transfer (with acceptable pressure loss) in condenser 160. For example,
inlet splitter 150
may be configured (and/or inlet core and bypass dampers 156 and 158 may be
positioned)
such that the flow rate of outside air stream 152 is approximately 100 cubic
feet per minute
(cfm) and the flow rate of condenser stream 154 is approximately 800 cfm.
[0020] After being split from condenser stream 154, outside air stream 152
flows
through heat recovery wheel 170, and is mixed with recirculation stream 180 in
mixer 190 to
form supply stream 177 before passing through evaporator 102, intake blower
104, and heater
106 and subsequently being provided to distribution system 108 for
distribution to
conditioned space 114 within the home or other host structure. It should be
noted that the
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order and positioning of evaporator 102, heater 106, and inlet blower 104 may
be adjusted to
suit system design requirements in individual systems. As one skilled in the
art will
appreciate, heater 106 may be electric, gas or any other known form of heater.
Energy
recovery wheel 170 is one form of energy recovery ventilator that may be used
in the
packaged system, and it is understood that other types of energy recovery
ventilators may be
used.
[0021] In accordance with this embodiment, a return stream 187 is extracted
from
conditioned space 114 and passes through return filter 122 before being
separated by return
splitter 124 into recirculation stream 180 and exhaust stream 128. In
accordance with this
embodiment, return splitter 124 may be equipped with exhaust damper 127 and
recirculation
damper 125 configured so as to control the flow rates of recirculation stream
180 and exhaust
stream 128. For example, splitter 124 may be configured, or dampers 125 and
127 may be
positioned, such that the flow rate of recirculation stream 180 is
approximately 300 cfm and
the flow rate of exhaust stream 128 is approximately 100 cfin. As described
above,
recirculation stream 180 is mixed with outside air stream 152 to form supply
stream 177 prior
to passage through evaporator 102 and heater 106.
[0022] After being split from recirculation stream 180, exhaust stream 128 is
passed
through heat recovery wheel 170 and is mixed with condenser stream 154 to form
combined
exhaust stream 182, which flows through exhaust blower 184 and condenser 160
before
passing through insulated exhaust duct 192, which passes through an exterior
wall 120 of the
host structure, and being released to the atmosphere 130.
[0023] As outside air stream 152 flows through heat recovery wheel 170,
thermal
energy is transferred between wheel 170 and outside air stream 152. Similarly,
as return
stream 128 passes through heat recovery wheel 170, thermal energy is
transferred between
wheel 170 and exhaust stream 128. In this way, thermal energy (heating or
cooling) is
effectively transferred between outside air stream 152 and exhaust stream 128.
As one
skilled in the art will appreciate, a number of mechanisms (e.g., a cross-flow
core heat
exchanger) could be employed - with or without a bypass damper to facilitate
an economizer
mode - so as to transfer heat between outside air stream 152 and exhaust
stream 128. It
should also be noted that the use of a rotating wheel or cross-flow core heat
exchanger and
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internal dampers allows for control of internal recirculation air, outside
ventilation air, and
allows for an economizer mode wherein the rotating energy recovery wheel is
disabled and
bypass dampers are closed.
[0024] As supply stream 177 passes through evaporator 102, heat is transferred
between supply stream 177 and a working fluid flowing inside fluid lines 194.
As one skilled
in the art will appreciate, compressor 195 moves the working fluid (e.g.,
refrigerant) through
fluid lines 194 from compressor 195, to condenser 160, expansion device 161
and evaporator
102. As combined exhaust stream 182 passes through condenser 160, heat is
transferred
between combined exhaust stream 182 and the working fluid. It is understood
that the
refrigerant system may be run in reverse (e.g., as a heat pump) such that
evaporator 102
serves as a condenser and condenser 160 serves as an evaporator. A flow
reversing valve 163
is included to enable operation as a heat pump.
[0025] Condenser 160, compressor 195, and fluid lines 194 are all contained
within
HVAC package 196, which may be hermetically sealed. In effect, insulated inlet
110 and
insulated exhaust 192 carry not only air for ventilation of the host
structure, but also air for
exchanging heat with condenser 160 and evaporator 102.
[0026] In accordance with an exemplary embodiment, pre-packaged HVAC system
100 may be located indoors (i.e., within the host structure such as a home or
office), and such
a placement is facilitated by incorporation of insulated inlet 110, which
passes through
exterior wall 120 of the host structure and accepts air from atmosphere 130,
and insulated
exhaust 192, which also passes through an exterior wall of the host structure
and releases
combined exhaust stream 182 to atmosphere 130.
[0027] In an alternative embodiment, inlet splitter 150 of integrated, pre-
packaged
HVAC system 100 also splits from outside air 152 stream a combustion air
stream 159. As
one skilled in the art will appreciate, combustion air stream 159 is adjusted
to facilitate
combustion in heater 106, which would incorporate a gas heat exchanger,
burner, and
combustion blower. In accordance with this embodiment, combustible fuel is
added to
combustion air stream 159 and heat is extracted from the products of
combustion. That heat
is then transferred to supply airstream 177 in the gas heat exchanger
contained within that
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embodiment of heater 106. Products of combustion may be mixed with flow 154
prior to, or
downstream of, the exhaust fan, preferably downstream of the ERV to avoid
migration of
combustion gas to indoor air.
[0028] FIG. 2 is a front view of an exemplary pre-packaged HVAC system in
another
embodiment. In this embodiment, the ERV 170 is in a housing 202 mounted on the
side of a
cabinet 200 containing the evaporator 102 and condenser 160. ERV 170 may be
any type of
ERV, including wheel or plate type, and include internal fans for moving air
through the
ERV core as known in the art. Housing 202 and cabinet 200 include openings to
allow return
air and outside to enter the ERV 170. Similarly, openings in the housing 202
and cabinet 200
allow for supply air and exhaust air to exit the ERV 170 and pass over the
evaporator 102 and
condenser 160, respectively. The housing 202 of ERV 170 is sealed to cabinet
200 to provide
a packaged unit in a sealed envelope. The packaged HVAC system of FIG. 2
interfaces with
inlet 110 and exhaust duct 192 as described above.
[0029] FIG. 3 is a front view of an exemplary pre-packaged HVAC system in
another
embodiment. In this embodiment, the ERV 170 is in a housing 202 mounted on top
of a
cabinet 200 housing the evaporator 102 and condenser 160. ERV 170 may be any
type of
ERV, including wheel or plate type, and include internal fans for moving air
through the
ERV core as known in the art. Housing 202 and cabinet 200 include openings to
allow return
air to enter the ERV 170 and supply air to exit the ERV 170. A first duct 210
couples the
outside air from cabinet 200 to housing 202, to provide outside air to the ERV
170. A second
duct 212 couples the exhaust air from housing 202 to cabinet 200. Ducts 210
and 212 may be
located within cabinet 200, rather than outside cabinet 200 as shown in FIG.
3. The housing
202 of ERV 170 is sealed to cabinet 200 to provide a packaged unit in a sealed
envelope.
The packaged HVAC system of FIG. 2 interfaces with an inlet 110 and exhaust
duct 192 as
described above.
[0030] As a result, embodiments provide a fully-integrated HVAC system that
combines the functionality of a high-efficiency heat pump with that of an
energy-recovery
ventilator, together with the condenser and condenser fan also integrated into
a single
packaged unit suitable for installation inside a host structure such as a home
or apartment.
Accordingly, embodiments provide a relatively high-efficiency, integrated,
heat-pump system
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9
that can meet emerging needs for relatively low capacity installations.
Embodiments
overcome the need for split heat-pump systems and the issues inherent with
distribution
throughout the inside and outside of a host structure. Embodiments eliminate
the need to
place a condenser, condenser fan, and compressor outside the host structure.
Embodiments
include the compressor, condenser, and condenser fan in an integrated indoor
unit and utilizes
an integrated ventilation system to provide necessary condenser airflow.
[0031] While the invention has been described in detail in connection with
only a
limited number of embodiments, it should be readily understood that the
invention is not
limited to such disclosed embodiments. Rather, the invention can be modified
to incorporate
any number of variations, alterations, substitutions or equivalent
arrangements not heretofore
described, but which are commensurate with the spirit and scope of the
invention.
Additionally, while various embodiments of the invention have been described,
it is to be
understood that aspects of the invention may include only some of the
described
embodiments. Accordingly, the invention is not to be seen as limited by the
foregoing
description, but is only limited by the scope of the appended claims.
