U.S. patent application number 11/492459 was filed with the patent office on 2008-01-31 for device and method for managing indoor air quality via filtration and dehumidification.
Invention is credited to Roger Dale Clearman.
Application Number | 20080022705 11/492459 |
Document ID | / |
Family ID | 38984759 |
Filed Date | 2008-01-31 |
United States Patent
Application |
20080022705 |
Kind Code |
A1 |
Clearman; Roger Dale |
January 31, 2008 |
Device and method for managing indoor air quality via filtration
and dehumidification
Abstract
A device and method are specified for managing indoor air
quality. More particularly, to promote health, comfort, and air
quality, a device and method are proposed for filtering and
dehumidifying air in an indoor environment, e.g., air that flows
through an HVAC system.
Inventors: |
Clearman; Roger Dale;
(Acworth, GA) |
Correspondence
Address: |
J. Andrew Huffman;#227
5251 C Highway 153
Hixson
TN
37343
US
|
Family ID: |
38984759 |
Appl. No.: |
11/492459 |
Filed: |
July 25, 2006 |
Current U.S.
Class: |
62/173 |
Current CPC
Class: |
F24F 8/22 20210101; F24F
3/1405 20130101; F24F 8/10 20210101 |
Class at
Publication: |
62/173 |
International
Class: |
F25B 29/00 20060101
F25B029/00 |
Claims
1. In an environment supplied by an airflow, a method comprising:
Determining a satisfactory level of an environmental humidity;
Monitoring said environmental humidity; So long as said
environmental humidity exceeds said satisfactory level:
continuously filtering said airflow to remove particulate matter
therefrom, and continuously dehumidifying said airflow to remove
moisture therefrom; When said environmental humidity reaches a
satisfactory level, ceasing to continuously filter and dehumidify
said airflow.
2. A method according to claim 1, wherein said dehumidifying
comprises: causing said airflow to pass a first time through an
air-to-air heat exchanger to lower the temperature of said airflow;
causing said airflow to pass through an evaporative
dehumidification coil stage to remove moisture from said airflow;
causing said airflow to pass a second time through said air-to-air
heat exchanger to raise the temperature of said airflow; and
causing said airflow to pass through a condensing reheat coil
stage.
3. A method according to claim 2, further comprising adding to said
airflow a supply of air from outside said environment.
4. A method according to claim 3, further comprising irradiating
said airflow.
5. A method according to claim 4, wherein said filtering comprises:
causing said airflow to pass through a pre-filtering stage to
remove larger particulate matter therefrom; causing said airflow to
pass through a fine-filtering stage to remove smaller particulate
matter therefrom; removing from said airflow at least about 99.97%
of all particulate matter greater than about 0.3 microns in
diameter.
6. A method according to claim 1, wherein said filtering comprises:
causing said airflow to pass through a pre-filtering stage to
remove larger particulate matter therefrom; causing said airflow to
pass through a fine-filtering stage to remove smaller particulate
matter therefrom; removing from said airflow at least about 99.97%
of all particulate matter greater than about 0.3 microns in
diameter.
7. A method according to claim 6, wherein said dehumidifying
comprises: causing said airflow to pass a first time through an
air-to-air heat exchanger to lower the temperature of said airflow;
causing said airflow to pass through an evaporative
dehumidification coil stage to remove moisture from said airflow;
causing said airflow to pass a second time through said air-to-air
heat exchanger to raise the temperature of said airflow; and
causing said airflow to pass through a condensing reheat coil
stage.
8. A method according to claim 6, further comprising adding to said
airflow a supply of air from outside said environment.
9. A method according to claim 6, further comprising irradiating
said airflow.
10. A method according to claim 7, further comprising adding to
said airflow a supply of air from outside said environment.
11. For an environment, a device comprising: A blower to divert an
airflow from said environment and cause said airflow to pass
through said device; An intake stage for receiving said airflow
into said device; A filtration stage coupled to said airflow intake
stage; A dehumidification stage coupled to said filtration stage;
An output stage for returning said airflow to said environment; A
control stage for monitoring at least one characteristic of said
environment and for regulating operation of said device.
12. A device according to claim 11, wherein said dehumidification
stage comprises an air-to-air heat exchanger for pre-cooling said
airflow; a compressor for compressing a refrigerant; a
dehumidification coil for removing moisture from said airflow; and
a reheat coil.
13. A device according to claim 12, wherein said filtration stage
comprises a pre-filter for removing larger particulate matter from
said airflow and a fine filter for removing smaller particulate
matter from said airflow.
14. A device according to claim 13, wherein said intake stage
comprises means for receiving a supplemental airflow from outside
said environment and combining said supplemental airflow with said
airflow received from said environment.
15. A device according to claim 14, further comprising an
ultraviolet lamp for irradiating said airflow and at least a part
of said device.
16. For an environment to which a duct network is connected, a
device comprising: A blower to divert an airflow from said duct
network and cause said airflow to pass through said device; An
intake stage for receiving said airflow into said device; A
filtration stage coupled to said airflow intake stage; A
dehumidification stage coupled to said filtration stage; An output
stage for returning said airflow to said duct network; A control
stage for monitoring at least one characteristic of said
environment and for regulating operation of said device.
17. A device according to claim 16, wherein said filtration stage
comprises a pre-filter for removing larger particulate matter from
said airflow and a fine filter for removing smaller particulate
matter from said airflow.
18. A device according to claim 17, further comprising an
ultraviolet lamp for irradiating said airflow and at least a part
of said device.
19. A device according to claim 18, wherein said intake stage
comprises means for receiving a supplemental airflow from outside
said environment and said ductwork, and combining said supplemental
airflow with said airflow received from said ductwork.
20. A device according to claim 19, wherein said dehumidification
stage comprises an air-to-air heat exchanger for pre-cooling said
airflow; a compressor for compressing a refrigerant; a
dehumidification coil for removing moisture from said airflow; and
a reheat coil.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to managing indoor air
quality, especially in connection with heating, ventilation, and
air conditioning (HVAC) systems. More particularly, a device and
method are proposed for filtering and dehumidifying air in an
enclosed (indoor) space--for example, the air that flows through an
HVAC system--so as to improve indoor air quality and promote health
and comfort.
[0002] Managing indoor air quality is a well-established but
continually evolving field of technology. Particularly in
industrialized nations, populations have become largely "indoor
societies," with many people spending substantial portions of most
days indoors. Millions of people work in homes or offices. Millions
attend schools. Many senior citizens spend a majority of their day
indoors. Many young children spend large amounts of time indoors,
whether at home or in other indoor environments.
[0003] Consequently, indoor air quality is an area of growing
importance and concern. The United States Environmental Protection
Agency (EPA) has identified indoor air pollution as one of the top
five serious environmental health risks, and mold as a health
threat of growing concern within the indoor environment. "Most
Americans do not have a clear sense of the significant health risks
of indoor pollution. They also do not know what they can do to
reduce risk for asthma, cancer, and other serious diseases caused
by indoor pollutant exposure." See Healthy Buildings, Healthy
People, EPA Document #402-K-01-003 (October 2001).
[0004] A variety of indoor air pollutants are known to exist. Some
of these include bioaerosols, dust mites, animal dander, volatile
organic compounds, carbon monoxide, mold, bacteria, viruses, fungi,
etc. In some circumstances and concentrations, air pollutants are
capable of producing a variety of effects undesirable to humans.
Certain environmental factors are known or suspected to play a role
in either inhibiting or promoting the proliferation of such
pollutants in an indoor setting. Regulating or compensating for
such factors is known as environmental control or management of air
quality.
[0005] Ventilation is a primary consideration in managing indoor
air quality. Without ventilation, pollutants within a closed
environment have little means of escape and can become more
concentrated over time. Appropriate ventilation, then, can be an
important step toward reducing indoor air pollution. Outside air
may be introduced into an indoor air space, subject to whatever
additional environmental control processes may be in use.
[0006] Filtration of indoor air is another important component in
maintaining acceptable air quality. Mechanical filtration systems
are commonly rated according to the size of airborne particulates
they are capable of removing and their particulate arrestance
percentage. The American Society of Heating, Refrigerating, and
Air-Conditioning Engineers (ASHRAE) has promulgated a widely-used
"Minimum Efficiency Reporting Value" (MERV) Standard 52.2 to
quantify these filter performance characteristics. For example,
commonly recommended air filtration systems for newer commercial
and residential buildings might typically carry a rating around
MERV 11, indicating a capability to remove particles about 1 to 3
microns in diameter with an arrestance rate of about 95% or better.
To remove even smaller particulates, a more discriminating filter
such as a High Efficiency Particulate Air (HEPA) filter with a
rating at or near MERV 20 can be employed. To meet HEPA standards,
a filtration device must be able to capture at least 99.97% of all
airborne particles 0.3 microns or more in diameter that enter
it.
[0007] Irradiation may also offer certain environmental control
benefits. Naturally occurring sunlight includes ultraviolet (UV)
rays which inhibit the growth of many microbes in out-of-doors
environments. Artificial germicidal UV light can be similarly
applied in indoor air quality management to inhibit the growth of
bacteria, viruses, molds, etc. UV-C, the germicidal wavelength of
UV light, can damage the nucleic acid of microorganisms by forming
covalent bonds between certain adjacent bases in their DNA. The
formation of such bonds prevents the DNA from being unzipped for
replication, hindering the organism from reproducing.
[0008] Proper humidity control is an important but often-overlooked
consideration in indoor air quality management. Various organisms,
health concerns, and other reactions can increase or decrease with
the indoor relative humidity level. See Criteria for Human Exposure
to Humidity in Occupied Buildings, Dr. Elia Sterling (1985).
"Biological air pollutants are found to some degree in every home,
school, and workplace." "A number of factors allow biological
agents to grow and be released into the air. Especially important
is high relative humidity, which encourages house dust mite
populations to increase and allows fungal growth on damp surfaces."
See Indoor Air Pollution, EPA Document #402-R-94-007 (1994). The
basic refrigeration process that allows dehumidification of
moisture-laden air has been known for some time--i.e., compressing
and condensing refrigerant gas and then allowing this gas to
evaporate in a controlled manner through some pressure-drop
metering device--but effectively integrating targeted
dehumidification into the overall processes of indoor air quality
management is not common at this time.
[0009] The basic process of refrigeration to achieve
dehumidification can be understood by description of a typical
implementation of this process. A simple dehumidification system
would typically include a refrigerant compressor, an evaporative
coil (a refrigerant-to-air heat exchanger, also known as a
dehumidification coil), a condenser coil (another
refrigerant-to-air heat exchanger, also known as a reheat coil), a
refrigerant metering device, assorted tubing connecting the system
components so as to make a sealed or closed system, and an air
blower or fan. The blower or fan operates in conjunction with the
compressor and moves air that is to be dehumidified through the
system. The refrigeration system, being closed, recycles the
refrigerant through several system components so that various
changes of state are induced to achieve the removal, addition, and
conversion of energy in the form of latent and sensible heat.
[0010] In such a system the compressor receives superheated vapor
and compresses this vapor to a point beyond its condensing or
liquefying point, yet this compressed gas will not condense to a
liquid state without the removal of heat; heat is removed as the
gas moves through the condenser coil where the energy required to
condense is exchanged with the moving air stream. The liquid's
temperature is further reduced (sub-cooled) before leaving the
condenser. The sub-cooled liquid being at relative high pressure in
the system is passed through a metering device (e.g., a valve,
capillary tube, or other specialized orifice) to create a drop in
pressure, allowing the refrigerant to change state and evaporate.
The evaporation process requires energy (heat) to be added back to
the refrigerant, and this occurs in the evaporator coil. The source
of the energy or heat is a stream of air moving through the system;
because the evaporator is colder that the air stream, heat (both
sensible and latent) is removed from the air. The latent heat
removal results in water being removed from the air stream in the
form of liquid, typically referred to as condensate. Thus some
dehumidification of the air has been achieved. The gas--now
super-heated beyond its point of evaporation--is returned the
compressor, where the cycle is then repeated.
[0011] Such a dehumidification process can be enhanced to higher
operational efficiency with the addition of an air-to-air heat
exchanger (AXA) in the system. With the addition of an AXA the
ratio of sensible and latent heat removed can be adjusted.
Increasing the latent heat removal capacity allows for a greater
volume of moisture removal in each system cycle without the need to
increase the overall operational capacity of the refrigeration
system. The AXA pre-cools the incoming air stream before the air
enters the evaporator coil, and because of the air is pre-cooled
the coil itself may typically operate at a lower temperature so
that it will be removing a greater amount of latent heat from the
air. As a result more water will condense and be removed from the
air. The air stream is then directed back through the AXA where it
is reheated while serving as the source ("sink") to cool the
incoming air stream. In other aspects this high-efficiency
dehumidification process operates similarly to the basic process
described before.
[0012] The present invention provides several novel combinations of
some of the above air quality management techniques, in a manner
suited to achieve improved performance over many existing
environmental control systems. That the present invention is a
distinct improvement over solutions in the prior art will become
more apparent from this specification.
SUMMARY OF THE INVENTION
[0013] To adequately handle the challenges of managing indoor air
quality, more than temperature must be addressed. Yet in the
majority of air conditioned buildings today, temperature is the
only air quality variable that is precisely monitored or regulated.
Successfully controlling the sources of indoor air pollution must
involve precise regulation of at least humidity as well. Systems
disclosing temperature and/or humidity control are exemplified by
such references as U.S. Pat. No. 5,598,715, issued Feb. 4, 1997, to
Edmisten; U.S. Pat. No. 5,088,295, issued Feb. 18, 1992, to
Shapiro-Baruch; and U.S. Pat. No. 2,255,292, issued Sep. 9, 1941,
to Lincoln.
[0014] Humidity control is a basic building block of the present
invention. Humidity that is too low can promote proliferation of
some indoor pollutants such as ozone and certain bacteria and
viruses. At extremely low humidity levels, incidence of respiratory
infections tends to rise. On the other hand, humidity that is too
high can promote proliferation of many indoor pollutants as well,
including fungi, dust mites, and certain bacteria and viruses.
Humidity control to improve overall indoor air quality thus becomes
something of a balancing act of avoiding relative humidity extremes
at either end of the range. Current data and experience suggest
that an optimally balanced indoor humidity level for many
environments may fall in the area of 40% to 60% relative humidity.
Adjusting this range in either direction may be desirable in some
applications, e.g., where certain specific pollutants are
considered to be of greater significance and concern than others.
Dehumidification aspects of the invention are further described
below.
[0015] In addition to temperature and humidity control, air should
be filtered and circulated to remove airborne particulate matter,
and fresh outside air may be introduced to dilute concentrations of
volatile organic compounds. Other treatments such as irradiation
may be employed as well. The present invention addresses some of
these important indoor air quality control factors, resulting in
improved indoor air quality and further resulting in potential
health and comfort benefits.
[0016] Filtration alone will not achieve the full air quality
benefits of the present invention, yet filtration remains an
important component of the overall device and method. Filtration
can remove airborne particulate matter and thus help improve air
quality. Particulate matter comprises very small particles of
solids or liquids that vary in size, chemical composition, and
source. Such particles can remain suspended in air for long periods
of time; the smaller a particle, the longer it may remain airborne.
When inhaled, some fine particles may be deposited in the lower
respiratory tract and the gas-exchanging portions of the lung, and
can damage respiratory airways.
[0017] While various approaches to air filtration exist, certain
preferred embodiments of the invention employ one or more
mechanical filtration stages including, e.g., a HEPA filter.
Another preferred embodiment includes a rubberized gasket around at
least one mechanical filter, to form a tight seal inside the system
and ensure that air passes through the filter and not around it. In
still another embodiment, a system control device incorporating a
humidistat will monitor and regulate environmental humidity and may
also include an indicator to indicate when a mechanical filter or
other expendable system components should be changed.
[0018] To achieve suitable ventilation, fresh outside air may be
introduced into the indoor air space in a variation of the
invention. Preferably the outside air enters the system via a path
that allows it to be at least partially filtered and dehumidified
before entering the conditioned indoor airspace. Incorporating such
ventilation into the process or system of the invention can be a
significant step in improving the quality of indoor air, by
diluting accumulated indoor pollutants.
[0019] Germicidal irradiation is implemented in a further optional
embodiment of the invention. An embodiment employs a lamp producing
UV light on the order of 265 nanometers, which is considered a
wavelength lethal to many airborne microorganisms such as bacteria,
viruses, and molds. Wavelength and other lamp characteristics may
be modified in accordance with the needs of particular
applications. The lamp preferably is positioned so as to expose the
evaporator, drain pan, and condensate water to germicidal UV light
radiation. Airflow may also be subjected to the radiation. Various
safety and convenience features may be included with the UV lamp,
such as a lamp shutoff switch, a sight glass for safe and easy lamp
inspection, and a protective cover with a safety interlock switch
to deactivate the lamp before a person can access or service the
device. Preferably the UV lamp is constructed to high quality
standards to achieve suitable performance and reliability,
including the use of hard glass tubing adapted to optimize UV
transmittance levels.
[0020] In most variations of the device of the invention, an
advanced combination of environmental control techniques is
implemented in connection with a separate HVAC system. This can be
achieved, for example, by integrating the environmental control
solutions into a module that can be relatively easily installed in
interface with an existing HVAC system to enhance its operation and
utilize its air distribution system (e.g., fans, vents, and
ductwork). A common installation configuration places the module in
parallel with an existing HVAC airflow path, and may utilize a
blower and/or damper to direct airflow through the module at
appropriate times. The module may be arranged in a horizontal,
vertical, or other configuration as needs may dictate. Enhancement
of process control may be achieved through the use of dampers and
by providing electrical blower interlock with an existing HVAC
system blower. A similar module may be installed somewhere within
an indoor air space, for example in a stand-alone
configuration.
[0021] Embodiments of the device and method of the invention
trigger an environmental control process at a suitable time (e.g.,
when a humidistat or other feedback mechanism senses environmental
conditions outside some preselected range). HVAC airflow optionally
is at least in part diverted so as to be subjected to aspects of
the process. HVAC airflow (together with fresh outside airflow, in
some embodiments) is directed through a filtration process for
removing airborne particulate matter. Dehumidification is achieved
as airflow is directed through stages of an AXA that first cause
flowing air to give up some sensible heat, reducing air temperature
so that it approaches the dew point. (In some conditions dew point
may be reached in the AXA and moisture may condense, a condition
which should preferably be accommodated by the device's design,
e.g., by appropriate placement of a drain pan.) The air then passes
through the first of two refrigeration heat exchanger coils, which
preferably operates just above the freezing point to achieve
primarily moisture condensation or latent heat removal. The air
exits at a low temperature and passes over an irradiating UV lamp,
if applicable, then passes through a second stage of the AXA, where
it begins a reheating process. Once exiting the AXA, the air is
directed through a second refrigeration heat exchanger where it is
reheated and the excess heat of refrigeration is added. The air is
pulled through a blower and reintroduced (as cleaner, dehumidified
air) through the HVAC system to the climate-controlled indoor
space. The cycle is continued until a desired humidity level is
achieved.
[0022] The invention and some of its variations may be more fully
understood with reference to the accompanying drawings.
DRAWINGS REFLECTING SOME EMBODIMENTS
[0023] FIG. 1 is a side sectional view of a module embodying at
least part of a device of the invention, depicted in a horizontal
configuration, indicating with arrows a typical airflow.
[0024] FIG. 2A is a perspective view of a module embodying at least
part of a device of the invention, depicted in a vertical
configuration.
[0025] FIG. 2B is a front sectional view of the same embodiment as
FIG. 2A.
[0026] FIG. 2C is a side sectional view of the same embodiment as
FIGS. 2A & 2B.
[0027] FIG. 2D is an input end view of the embodiment in FIG.
2E.
[0028] FIG. 2E is a side sectional view of a horizontally
configured embodiment that is essentially the same as FIG. 1,
without arrows depicting airflow.
[0029] FIG. 2F is an output end view of the embodiment in FIG.
2E.
[0030] FIG. 3 is a simplified side view of an embodiment of the
invention as in FIGS. 1 & 2E, installed in connection with an
existing HVAC ductwork system.
[0031] FIG. 4 is a simplified side view of an embodiment of the
invention as in FIGS. 1 & 2E, installed partially in connection
with an existing HVAC ductwork system, and shown with outside air
outside air ventilation and crawl space options.
[0032] FIG. 5 is a simplified side view of an embodiment of the
invention as in FIGS. 1 & 2E, installed partially in connection
with an existing HVAC ductwork system, and shown with outside air
ventilation and crawl space options. Also shown is added ductwork
for a dedicated airflow return path.
[0033] FIG. 6 is a flowchart depicting a method in accordance with
the invention.
DESCRIPTION OF SOME EMBODIMENTS
[0034] With reference to the drawings, it will be seen that a basic
embodiment of the device of the invention consists of a closed
refrigeration system including a compressor, dehumidification coil
(evaporator), reheat coil (condenser), refrigerant metering device,
associated tubing connecting these components (typically copper),
and a drain pan (e.g., of stainless steel). Some of the smaller and
standardized elements of the system are not labeled in the drawings
or given special attention in the discussion of the drawings, such
elements being well known in the arts of refrigeration and HVAC
engineering. Further aspects of the device of the invention may
include a blower, an air-to-air heat exchanger, a pre-filter, a
main HEPA filter, and a germicidal UV lamp.
[0035] FIGS. 1 and 2E illustrate a basic embodiment of the device
of the invention, shown in a horizontal configuration. FIGS. 2D and
2F show opposite end views of the same embodiment.
[0036] FIGS. 2A, 2B, and 2C illustrate a functionally similar
embodiment of the device of the invention, but in a vertical rather
than horizontal configuration. Element labeling numbers for this
alternate configuration will be mentioned below in parentheses.
See, e.g., blower 190 (290).
[0037] The functionality of the elements of these embodiments will
be discussed with reference to an airflow passing through the
device. Airflow 10 originates in the environment for which air
quality is to be regulated, and enters module 100 (200) at intake
opening 110 (210). External airflow 5 (from outside ventilation)
can optionally be combined with airflow 10. In a preferred
embodiment providing more than one filtration step, the airflow 10
(together with external airflow 5, if applicable) passes first
through a high-efficiency pre-filter 120 (220) to remove larger
airborne particles, and then through a main HEPA filter 130 (230)
to remove smaller airborne particles. Various filtration devices
could be used interchangeably in the invention, but the
configuration illustrated here is a presently preferred
embodiment.
[0038] Having passed through the filtration devices, airflow 10 is
now depicted as filtered airflow 20. Filtered airflow 20 enters an
air-to-air heat exchanger 140 (240) and is cooled. Cooled airflow
30 passes across the dehumidification coil/evaporator 150 (250) so
that moisture will be removed from the air. In a well-known
refrigeration process, refrigerant contained within the system is
compressed in compressor 170 (270) and metered through evaporator
150 (250). Moisture from the airflow 30 thus condenses and collects
by the operation of gravity in a drain pan 160 (260), which is
preferably constructed of stainless steel or another non-corrosive
material. UV lamp 165 optionally irradiates the airflow passing by,
as well as the drain pan and the liquid collected in it, tending to
destroy certain pollutants that might otherwise collect or pass
through.
[0039] The dehumidified airflow 40 returns through the AXA 140
(240) as described above, being warmed by and in turn cooling
airflow 20. The warmed, dehumidified airflow 50 then passes through
the reheat coil/condenser 180 (280) where heat is transferred from
compressed refrigerant in the condensor 180 (280) to the airflow 50
and it passes on as airflow 60. Blower 190 (290), which serves to
actuate the airflows through the overall system, now forces the
dehumidified air 60 back toward the indoor environment for which
the air quality is being regulated (e.g., by way of ductwork).
Electrical controls for the overall system are centralized in
control box 185 (285). Other control elements not depicted in the
drawings could include a humidistat and other remote sensors and
controls, which typically would be in electrical communication with
control box 185 (285).
[0040] FIG. 3 illustrates how the module 100 (200) can be
integrated into existing HVAC ductwork. In a typical HVAC system
installation, return duct 300 carries air from the controlled
environment back to an air handler, furnace, or similar equipment
(not shown). When a device according to the invention is integrated
into such a system, air duct material is used to construct a
diversion path 310 to carry a portion of the HVAC system return
airflow through module 100, and after this diverted airflow has
been filtered and dehumidified in module 100 it is returned to the
HVAC system return duct 300 by way of insertion path 320.
[0041] FIG. 4 elaborates on the illustration of FIG. 3 by showing
some additional optional features for integrating the invention
into an existing HVAC system. The primary additional feature in
this embodiment is the provision of an outside air ventilation
input to the system. Intake hood 330 (preferably screened) is
provided outside the structure of the environment to admit fresh
outside air into the system. Outside air path 332 is constructed to
carry this air into the system. Manual damper 334 allows for
closing the air flow when necessary. Optional power damper 336 can
be integrated into the system control set. Thus, outside air enters
through hood 330, passes through path 332 and past damper(s) 334,
336 (when open), into module 100, to be mixed with indoor air for
filtration and dehumidification. Another feature here illustrated
is an optional partial air return of dehumidified air to an area
such as a crawl space or unconditioned basement. Path 342 diverts a
fraction of the output airflow from module 100, carrying some air
past manual damper 344 and backflow damper 346 (when these are
open) into the unconditioned space 340.
[0042] FIG. 5 represents an additional variation in which for
whatever reason a separate input airflow path into module 100 is
needed, rather than a diversion from existing HVAC ductwork 300.
Here, a dedicated air return 350 is added, which carries air from
the conditioned space to low intake of module 100. The filtered,
dehumidified air is then sent back toward the conditioned
environment through insertion path 320 via ductwork 300.
[0043] Many modifications or expansions upon the invention itself
and the various illustrative embodiments herein described still
fall within the spirit and scope of the invention, and should be so
considered.
* * * * *