U.S. patent application number 11/287773 was filed with the patent office on 2006-04-13 for method and apparatus for delivering conditioned air using dual plenums.
This patent application is currently assigned to AirFixture L.L.C.. Invention is credited to Stanley J. Demster.
Application Number | 20060076425 11/287773 |
Document ID | / |
Family ID | 33434788 |
Filed Date | 2006-04-13 |
United States Patent
Application |
20060076425 |
Kind Code |
A1 |
Demster; Stanley J. |
April 13, 2006 |
Method and apparatus for delivering conditioned air using dual
plenums
Abstract
Multiple methods of supplying conditioned air to a room and
components therefor are provided. A dual plenum system has a supply
plenum for delivering supply air to the room and a return plenum
for returning room air to an air handling unit. Conduits are
provided to permit passage of the return air through the supply
plenum without breaching the integrity of the supply plenum.
Modular units permit a user to customize the supply and return
apparatuses. A terminal unit having a controllable damper blade can
be applied to a diffuser to permit the unit to be convertible
between a constant volume unit and a variable volume unit. A
thermostat generates signals that open and close the damper blade
at determined intervals.
Inventors: |
Demster; Stanley J.;
(Lenexa, KS) |
Correspondence
Address: |
SHOOK, HARDY & BACON LLP;INTELLECTUAL PROPERTY DEPARTMENT
2555 GRAND BLVD
KANSAS CITY,
MO
64108-2613
US
|
Assignee: |
AirFixture L.L.C.
|
Family ID: |
33434788 |
Appl. No.: |
11/287773 |
Filed: |
November 28, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10423648 |
Apr 25, 2003 |
6986708 |
|
|
11287773 |
Nov 28, 2005 |
|
|
|
10150266 |
May 17, 2002 |
6945866 |
|
|
10423648 |
Apr 25, 2003 |
|
|
|
Current U.S.
Class: |
236/49.3 ;
454/239 |
Current CPC
Class: |
F24F 11/65 20180101;
F24F 2221/14 20130101; F24F 13/06 20130101; F24F 2013/0616
20130101; F24F 2110/10 20180101; F24F 11/61 20180101; E04B 9/02
20130101; F24F 11/58 20180101; F24F 2221/44 20130101; F24F 2007/005
20130101; F24F 1/00075 20190201; F24F 11/30 20180101; F24F 7/08
20130101; F24F 11/75 20180101 |
Class at
Publication: |
236/049.3 ;
454/239 |
International
Class: |
F24F 7/00 20060101
F24F007/00; F24F 11/00 20060101 F24F011/00 |
Claims
1. A method for delivering conditioned air to a room having a space
located above a ceiling overlying the room and return air ductwork,
the method comprising: delivering conditioned air to the space;
discharging the conditioned air from the space into the room;
directing return air from the room into the return air ductwork;
and discharging the return air from the return air ductwork;
wherein the conditioned air is discharged from the space into the
room through an air register, wherein in the air register includes
a fan, and wherein the fan is selectively operable to discharge the
conditioned air from the space into the room.
2. The method of claim 1, wherein the fan is operatively connected
with a thermostat located within the room, wherein the thermostat
senses a temperature in the room, wherein the thermostat has a
user-adjustable desired temperature, wherein the thermostat
compares the temperature in the room with the desired temperature,
and wherein the thermostat selectively operates the fan to make the
temperature in the room equal to the desired temperature.
3. The method of claim 2, wherein the conditioned air is delivered
to the space via an air handling unit having a blower, wherein the
blower maintains the space at a pressure of zero gauge, and wherein
the fan is activated to force air from the space out into the room
through the register when the thermostat calls for conditioned air
into the room.
4. The method of claim 3, wherein the space is at least partially
defined by the ceiling.
5. A method for delivering conditioned air to a room having a space
located above a ceiling overlying the room, the method comprising:
separating the space into a supply plenum and a return plenum, the
supply and return plenums together occupying a substantial portion
of the volume of the space; delivering conditioned air to the
supply plenum; discharging the conditioned air from the supply
plenum into the room; directing return air from the room into the
return plenum; and discharging the return air from the return
plenum; wherein the ceiling is suspended from an overlying
structure and includes a plurality of horizontal tiles supported on
a grid work of suspended T-bars.
6. The method of claim 5, wherein the conditioned air is discharged
from the supply plenum into the room through a supply air
diffuser.
7. The method of claim 6, wherein the supply air diffuser includes
a damper operable to selectively permit or prevent the discharging
of conditioned air from the supply plenum into the room.
8. The method of claim 6, wherein the return air is directed from
the room into the return plenum through a return air diffuser,
wherein the return air diffuser creates a passage for the return
air through the supply plenum to the return plenum, and wherein the
passage prohibits the return air moving through the passage from
mixing with the air in the supply plenum.
9. The method of claim 8, wherein the supply air diffuser and the
return air diffuser are formed as part of a combination
supply/return fixture.
10. The method of claim 9, wherein the passage for the return air
is adjacent to an opening in the supply air diffuser through which
the conditioned air in the supply plenum passes.
11. The method of claim 5, wherein the space is separated into a
supply plenum and a return plenum by a partition and wherein the
partition is suspended from the overlying structure.
12. The method of claim 10, wherein the partition includes a
plurality of horizontal tiles supported on a grid work.
13. The method of claim 12, wherein the grid work for the partition
includes a plurality of structural crosses and wherein the ceiling
is suspended from the partition.
14. A method for delivering conditioned air to a room having a
space located above a ceiling overlying the room, the method
comprising: separating the space into a supply plenum and a return
plenum by a partition, the supply and return plenums together
occupying a substantial portion of the volume of the space;
delivering conditioned air to the supply plenum; discharging the
conditioned air from the supply plenum into the room; directing
return air from the room into the return plenum; and discharging
the return air from the return plenum; wherein the partition is
suspended from an overlying structure and includes a plurality of
horizontal tiles supported on a grid work and wherein the ceiling
is suspended from the partition and includes a plurality of
horizontal tiles supported on a grid work of suspended T-bars.
15. A method for delivering conditioned air to a room having a
space located above a ceiling overlying the room, the method
comprising: separating the space into a supply plenum and a return
plenum, the supply and return plenums together occupying a
substantial portion of the volume of the space; delivering
conditioned air to the supply plenum; discharging the conditioned
air from the supply plenum into the room; directing return air from
the room into the return plenum; and discharging the return air
from the return plenum; wherein the return air is directed from the
room into the return plenum through a return air diffuser, wherein
the return air diffuser creates a passage for the return air
through the supply plenum to the return plenum, wherein the passage
prohibits the return air moving through the passage from mixing
with the air in the supply plenum; and wherein the passage includes
a heating element and a fan for directing return air through the
heating element back into the room.
16. The method of claim 15, wherein the passage is divided into a
return air conduit and a heated air supply passage and wherein the
heating element is positioned within the heated air supply passage.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of pending application
Ser. No. 10/423,648 filed by Stanley J. Demster on Apr. 25, 2003
and entitled "Method and Apparatus for Delivering Conditioned Air
Using Dual Plenums", which was itself a continuation-in-part of
application Ser. No. 10/150,266 filed by Stanley J. Demster on May
17, 2002 and entitled "Method and Apparatus for Delivering
Conditioned Air Using Pulse Modulation", now U.S. Pat. No.
6,945,866.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
FIELD OF THE INVENTION
[0003] This invention relates in general to systems for the
delivery of conditioned air to occupied spaces in buildings and
deals more particularly with a method and apparatus for
distributing air in an economical and efficient manner, as well as
to improvements in various components and systems that are useful
in equipment for delivering conditioned air.
BACKGROUND OF THE INVENTION
[0004] Office buildings and various types of commercial buildings
are typically heated and cooled using rooftop, floor by floor, or
central station air handling units. Supply ducts are installed in
the interstitial space that is located above the ceiling and below
the structural roof. The supply ductwork extends from the air
handling unit to a number of air diffusers that are often mounted
on the ceiling. Suspended tile ceilings are common in this type of
building, and the diffusers are usually integrated into the ceiling
tile system, along with lights, sprinklers, smoke detectors,
electrical outlets and sometimes other devices such as cameras,
motion detectors, speakers and various other fixtures. The return
air system may include a number of return air grills that are built
into the ceiling tiles and connected with return air ductwork that
directs return air back to the air handling unit.
[0005] Although systems of this type have long been in widespread
use, they are not wholly free of problems. The need to install
extensive ductwork above the ceiling creates a large cost factor
and adds significantly to the labor costs that are involved in
constructing and finishing the space. The ductwork also occupies a
large amount of space and reduces the space that is available for
other components and equipment that must be installed in the
interstitial space. The delivery of conditioned air is often less
than ideal from an efficiency and comfort standpoint. In the latter
respect, the air return system can be significantly mismatched
relative to the supply system so that the rooms in the space can be
uncomfortably warm at times and uncomfortably cool at other times.
The need to provide separate fixtures for the supply and return
systems also increases the cost of fabrication, shipping, handling,
storage and installation of the fixtures. The need for two
different fixtures for the supply and return systems also adds to
the clutter on the ceiling and detracts from the ceiling
aesthetics.
[0006] Other problems with conventional air delivery systems can
arise from undue humidity in the supply ducts. This can lead to
fouling of the ductwork with mildew, mold, fungi, and various
micro-organisms that can create unhealthy conditions in the
occupied space.
[0007] Although a variety of styles, from large rectangular units
to rounded knobs, are available currently, most thermostats are
visually unappealing. Conventional thermostats are normally simple
rectangular boxes or dome structures that are mounted to protrude
from the wall and are designed as stand alone products. In fact, it
appears that thermostat manufacturers have not placed any great
emphasis on whether their devices could match the decoration of the
room where the device was located. In fact, the exterior color and
design of current devices appear arbitrary and directed to the
device as a stand-alone product.
[0008] Even though attempts have been made to enhance the
aesthetics of thermostats in recent years, their appearance has not
been integrated effectively into the overall decor of the room. The
color and design of the thermostat have not matched other common
wall mounted devices such as light switches, electrical
receptacles, telephone and cable television outlets, communications
devices such as intercoms, and other wall fixtures such as
occupancy sensors and the like. As a result, thermostats often
detract appreciably from the aesthetic appeal of the rooms in which
they are installed.
[0009] Recently, state and federal laws have addressed the mounting
height and accessibility of thermostats. These requirements make
the aesthetic functions and appearance of thermostats more
important because mounting height requirements often place the
thermostat directly adjacent to the light switch and other similar
electrical devices. Currently, most thermostats are intended for
surface mounting, either directly or using a sub-base that contains
wiring termination points. While some thermostats include adaptors
that allow the thermostats to be mounted on a standard electrical
junction box, these configurations do not produce an integrated
appearance with the other devices. It would be an aesthetic
improvement if the thermostat could match these electrical devices
in terms of size, color, shape and mounting method.
[0010] Thermostats have also suffered from relatively large dead
bands that can result in the actual room temperature fluctuating
5.degree. or more from the temperature setting. The need for
anticipation circuits has added to the cost and complexity of the
thermostat, as well as to problems with reliability.
[0011] In accordance with prevailing industry practices, many
buildings are separated into several different air delivery zones
that are each equipped with an individual air handling unit and
separate ductwork. For example, a building may be divided into four
separate quadrants that each has a peak requirement for a 25 ton
air handling unit. In such a case, four 25 ton units are installed,
each dedicated to its own zone and each connected with its own
separate system of supply and return ducts. Each of the zones is
subjected to its peak loading at a different time of day because of
the movement of the sun and change of the sun angle throughout the
day. Consequently, the overall simultaneous peak loading for the
building as a whole may be 80 tons. Nevertheless, each air handling
unit must be large enough to handle the maximum capacity for its
own zone, so four 25 ton units are required even though 80 tons is
the peak overall building load. The 20 tons of excess capacity adds
markedly to the equipment expense, the installation and maintenance
costs, and the energy that is used. The need for unduly large air
handling units also detracts from the aesthetics of the building
and increases the roof profile due to the need to install
relatively large air handling units there.
BRIEF SUMMARY OF THE INVENTION
[0012] The present invention is directed to a system for delivering
conditioned air in an improved manner and to various aspects of
conditioned air distribution that enhance the efficiency and
economics of its delivery and the comfort of occupants of the space
that receives the conditioned air.
[0013] It is an object of the invention to provide a method and
apparatus for delivering conditioned air that eliminates the need
for extensive ductwork.
[0014] Another object of the invention is to provide, in a system
for delivering conditioned air, a combination supply/return fitting
that is specially constructed to assure a proper match between the
supply air and the return air and to assure thorough mixing of the
supply air without short circuiting problems. The combination
supply/return fixture is particularly well suited for use in a dual
plenum system and eliminates the problems that are associated with
the need to supply separate fixtures for the air supply and air
return systems.
[0015] A further object of the invention is to provide, in an air
delivery system, a bypass path that accommodates a flow of bypass
air from the return air pathway to the supply pathway in order to
avoid excessive humidity in the supply path and also to make up for
air that is lost in the supply system due to leakage.
[0016] Still another object of the invention is to provide an
improved thermostat having enhanced aesthetic characteristics that
can be matched to the decor of the room in which it is installed
while functioning effectively to assure comfortable temperature
conditions in the room.
[0017] Yet another object of the invention is to provide an
improved temperature sensing and control device that has an
appearance, packaging and is mounted comparable to a typical light
switch device.
[0018] An additional object of the invention is to provide a
conditioned air delivery system that minimizes the capacity
requirements for air handling units in situations where multiple
air handling units are installed in accordance with prevailing
practices.
[0019] A still further object of the invention is to provide a
method and apparatus for delivering conditioned air wherein the
distribution and circulation of the supply air are enhanced while
avoiding short circuiting of the supply air to the return system
without mixing in the room.
[0020] Yet another object of the invention is to provide a method
and apparatus for delivering conditioned air wherein cool air and
heated air can be delivered alternatively in a manner to create
comfortable conditions in the room to which the air is
supplied.
[0021] Among the other objects of the invention are to provide an
air delivery system that is economical to construct and install and
energy efficient in operation, to provide an air delivery system
that readily accommodates various ceiling mounted devices without
unduly cluttering the ceiling or detracting significantly from its
aesthetics, to provide an air delivery system that readily
accommodates devices such as electrical wiring, sprinkler pipes and
the like without undue obstruction or installation difficulties,
and to provide a method and apparatus for delivering conditioned
air at low pressures and low pressure differentials.
[0022] In accordance with one aspect of the invention, an air
delivery system for applying conditioned air to a room makes use of
a partition which separates the interstitial space above the
ceiling of the room into separate supply and return plenums. The
two plenums are preferably sealed from one another and from the
room below. The ceiling may be a suspended ceiling, and the
partition may be another suspended structure spaced above the
suspended ceiling. By using the interstitial space in this manner
to provide separate plenums, the need for extensive ductwork is
avoided, along with the costs and problems associated with such
ductwork.
[0023] The conditioned air may be directed into the room from the
supply plenum through one or more ceiling air diffusers. The return
air system may include a decorative return grill on the ceiling and
a short return conduit that extends from the grill to the return
plenum to provide a sealed pathway for directing return air out of
the room to the air handling equipment. Preferably, the air
diffuser that discharges the supply air into the room is adjacent
to the return grill and may be constructed as part of a combination
supply/return fixture. The diffuser slot is arranged to throw the
supply air generally along the ceiling away from the return grill.
In this manner, the supply air is circulated efficiently throughout
the room and is mixed well without the potential for short
circuiting directly back to the return system.
[0024] While the supply/return fixture can have only one diffuser,
it is preferable for the supply/return fixture to include a pair of
diffusers located on opposite sides of the return grill and
constructed to direct the supply air in opposite directions away
from the return grill. By constructing the supply and return
fittings as single modular structures, the fittings can be
installed in place of standard ceiling tiles. Significantly, the
diffusers and the return conduit can be sized at the factory to
assure that the return air is automatically matched properly to the
supply air. This not only assures balancing of supply and return
air to a room, but also provides a method of assuring the correct
ratio of return to supply resistance necessary to maintain positive
pressure relative to outdoor ambient for both the return and supply
plenums. This arrangement assures that the return plenum can be
kept at a positive differential static pressure to the outside
ambient pressure, thereby reducing moisture infiltration, which in
turn limits the growth of mold and other potentially harmful
biological elements in the system.
[0025] By constructing the supply and return fittings as single
modular structures, the supply and return terminals are also
automatically located optimally relative to one another because
they are constructed as parts of a single modular fitting. The
modular fitting can be used either in a constant volume system or
in a variable volume system in which the diffusers are equipped
with control devices for varying the air discharge under the
control of a thermostat. The modular fittings are also beneficial
in that they can provide support and concealment for ceiling
mounted devices such as smoke detectors, cameras, motion detectors
and other equipment.
[0026] The dual plenum construction lends itself well to the
inclusion of various optional features that enhance the delivery of
air under differing conditions. For example, a bypass path between
the return plenum and the supply plenum can be provided. Air in the
return plenum can be applied directly to the supply plenum in the
desired amounts by operating a fan installed in the bypass system.
This serves to reduce the relative humidity in the supply plenum
and also to make up for air leakage. The humidity reduction can
inhibit the formation of mold, mildew and other humidity related
problems in the supply air. Another option is to direct the return
air from the return air plenum to the air diffusers through a
heating system when temperature conditions call for heating rather
than cooling.
[0027] In another aspect of the invention, an improved thermostat
is constructed in a manner allowing it to be matched in color and
appearance with light switches, electrical outlets and other items
commonly mounted on walls. As a result, the thermostat can add
aesthetically to the decor of the room instead of the more typical
current situation where the thermostat is an unsightly wall mounted
box or dome. At the same time, the thermostat of the present
invention incorporates functional improvements such as the absence
of a significant dead band and the elimination of the need for
anticipation circuits and other complexities that are
characteristic of existing thermostats.
[0028] Other and further objects of the invention, together with
the features of novelty appurtenant thereto, will appear in the
course of the following description.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0029] In the accompanying drawings which form a part of the
specification and are to be read in conjunction therewith and in
which like reference numerals are used to indicate like parts in
the various views:
[0030] FIG. 1 is a fragmentary sectional view diagrammatically
illustrating a room equipped with a conditioned air delivery system
constructed in accordance with one embodiment of the present
invention;
[0031] FIG. 2 is a fragmentary elevational view similar to FIG. 1
diagrammatically illustrating an air delivery system constructed
according to another embodiment of the invention;
[0032] FIG. 3 is a fragmentary elevational view similar to FIGS. 1
and 2 diagrammatically illustrating an air delivery system
constructed according to another embodiment of the invention;
[0033] FIG. 4 is a fragmentary elevational view similar to FIGS.
1-3 diagrammatically illustrating an air delivery system
constructed according to another embodiment of the invention;
[0034] FIG. 5 is a fragmentary elevational view similar to FIGS.
1-4 diagrammatically illustrating an air delivery system
constructed according to another embodiment of the invention;
[0035] FIG. 6 is a fragmentary elevational view on an enlarged
scale of the combination supply/return fixture depicted
diagrammatically in FIG. 1 and taken generally in the area
identified by numeral 6 in FIG. 1 with portions thereof cut away
for clarity;
[0036] FIG. 7 is an exploded perspective view of the combination
supply/return fixture of FIG. 6 that may be used in an air delivery
system constructed according to the present invention;
[0037] FIG. 8 is a fragmentary sectional view on an enlarged scale
of a diffuser of the combination supply/return fixture of FIG.
6;
[0038] FIG. 9 is a sectional view of an extruded member that forms
ends of the diffuser of FIG. 9;
[0039] FIG. 10 is a fragmentary sectional view of the combination
supply/return fixture taken generally along line 10-10 of FIG. 6 in
the direction of the arrows;
[0040] FIG. 11 is a fragmentary side elevational view of the
combination supply/return fixture taken generally along line 11-11
of FIG. 6 in the direction of the arrows;
[0041] FIG. 12 a fragmentary top plan view, partially in section,
of the combination supply/return fixture taken generally along line
12-12 of FIG. 6 in the direction of the arrows;
[0042] FIG. 13 is a fragmentary sectional view on an enlarged scale
taken generally in the area identified by numeral 13 in FIG. 6
illustrating the diffuser with a terminal unit associated
therewith;
[0043] FIG. 14 is a fragmentary perspective view, partially in
section, of a structural cross that can be provided in a partition
constructed according to the present invention in the interstitial
space to separate the supply and return plenums;
[0044] FIG. 15 is a fragmentary elevational view on an enlarged
scale of a bypass apparatus, depicted diagrammatically in FIG. 1
and taken generally in the area identified by numeral 15 in FIG. 1
with portions thereof cut away for clarity, that can be provided
between the return plenum and the supply plenum in an air delivery
system constructed according to the present invention;
[0045] FIG. 16 is a perspective view of the bypass apparatus
depicted in FIG. 15;
[0046] FIG. 17 is fragmentary sectional view of the combination
supply/return fixture of FIG. 6 illustrating a dual supply with
terminal units and with a return for use in a variable volume
system;
[0047] FIG. 18 is fragmentary sectional view of the fixture
modified to provide a dual supply with a return and with the
terminal units removed for use in a constant volume system;
[0048] FIG. 19 is fragmentary sectional view of the fixture
modified to provide a dual supply without a return and without the
terminal units for use in a constant volume system;
[0049] FIG. 20 is a top perspective view of the fixture depicted in
FIG. 19;
[0050] FIG. 21 is fragmentary sectional view of the fixture
modified to provide a dual supply with terminal units and without a
return for use in a variable volume system;
[0051] FIG. 22 is fragmentary sectional view of the fixture
modified to provide a single supply without a terminal unit and
with a return for use in a constant volume system;
[0052] FIG. 23 is fragmentary sectional view of the fixture
modified to provide a single supply with a terminal unit and with a
return for use in a variable volume system;
[0053] FIG. 24 is a fragmentary sectional view of the fixture
modified to provide a single supply with a terminal unit and
without a return for use in a variable volume system;
[0054] FIG. 25 is a fragmentary sectional view of the fixture
modified to provide a single supply without a terminal unit and
without a return for use in a constant volume system;
[0055] FIG. 26 is a fragmentary sectional view of the fixture
modified to provide a return only without a supply;
[0056] FIG. 27 is a perspective view of a modified combination
supply/return fixture with a heating system incorporated as
depicted diagrammatically in the delivery system illustrated in
FIG. 4;
[0057] FIG. 28 is a fragmentary sectional view of the modified
combination supply/return fixture taken generally along line 28-28
of FIG. 27 in the direction of the arrows;
[0058] FIG. 29 is a fragmentary top perspective view of an
alternate embodiment of a return conduit;
[0059] FIG. 30 is a fragmentary side elevational view of the return
conduit of FIG. 29 with portions thereof cut away for clarity;
[0060] FIG. 31 is a fragmentary elevational view of another
alternate embodiment of a return conduit;
[0061] FIG. 32 is a perspective view of the electrical connections
tile depicted in FIG. 33;
[0062] FIG. 33 is a fragmentary elevational view, partially in
section, showing a light fixture mounted on the ceiling of a room
equipped with an air delivery system in accordance with the present
invention and also illustrating an electrical connections tile with
electrical boxes that facilitate electrical connections;
[0063] FIG. 34 is perspective view of an electrical connections
panel having been modified to incorporate bypass paths;
[0064] FIG. 35 is a perspective view of a wall construction without
a wall covering illustrating a junction box with two thermostats of
the present invention and a light switch mounted therein;
[0065] FIG. 36 is an elevational view of the junction box of FIG.
35 with the wall finished and the face plate on;
[0066] FIG. 37 is a side view of a printed circuit board of the
thermostat with a variable resistor and a thermistor mounted
thereto;
[0067] FIG. 38 shows a timing diagram of an "on" signal and an
"off" signal produced by a first embodiment of the thermostat of
the present invention;
[0068] FIG. 39 shows a block diagram of the first embodiment of the
thermostat that produces the signals depicted in FIG. 38;
[0069] FIG. 40 shows a timing diagram of an "on" signal and an
"off" signal produced by a second embodiment of the thermostat of
the present invention;
[0070] FIG. 41 shows a block diagram of the second embodiment of
the thermostat that produces the signals depicted in FIG. 40;
and
[0071] FIG. 42 shows a block diagram of a third embodiment of the
thermostat of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0072] Referring now to the drawings in more detail and initially
to FIG. 1, the present invention is directed to the delivery of
conditioned air in a building 10 which may have a number of
separate rooms 12 formed within it. Each of the rooms 12 may have
an underlying floor 14 and walls 16. A ceiling which is generally
identified by numeral 18 overlies the room and may be suspended
from an overlying structure such as the roof 20 of the building. It
should be noted that the roof 20 need not be the top of the
building, but could simply be the structural ceiling of the room
12, such as a concrete slab that separates two floors of a
building. The ceiling 18 may include a plurality of horizontal
tiles 22 supported on a grid work of suspended T-bars 24. The bars
24 may be suspended from the roof 20 or another structure in a
conventional fashion. An interstitial space 26 is presented above
the ceiling 22 and below the roof 20. The T-bars 24 and tiles 22
may be constructed conventionally for the most part and installed
in the building 10 in the manner of conventional suspended
ceilings. However, as will be explained more fully, the tiles 22
are preferably sealed to the T-bars 24 in an airtight manner in
order to provide an airtight seal between the interstitial space 26
and the room 12.
[0073] In accordance with the embodiment of the invention shown in
FIG. 1, the interstitial space 26 is provided with a horizontal
partition which is generally identified by numeral 28 and which
divides the space 26 into a supply plenum 30 and a return plenum
32. The supply plenum 30 is located between the ceiling 18 and the
partition 28. The return plenum 32 is located between the roof 20
and the partition 28. The supply plenum 30 is located immediately
below and adjacent to the return plenum 32. Together, the supply
and return plenums 30 and 32 occupy substantially the entirety of
the interstitial space 26.
[0074] The partition 28 may be a suspended structure similar to the
ceiling 18 and may include a plurality of individual tiles 34
mounted on a grid work of T-bars or, preferably, structural crosses
36. The crosses 36 may be suspended from the overlying roof 20 or
supported in any other suitable way. The tiles 34 are preferably
sealed to the crosses 36 in order to seal the supply plenum 30 from
the return plenum 32. The tiles 22 and 34 may be conventional 24''
by 24'' square tiles of the type commonly used in suspended
ceilings. Other types of tiles and other types of constructions for
the ceiling 18 and partition 28 are also possible.
[0075] One or more air handling units such as the air handling unit
38 may be provided and may be roof mounted units as shown in FIG.
1. Each unit 38 is equipped with a fan or blower 40 having its
discharge side connected with a discharge conduit 42 that extends
downwardly to the supply plenum 30. The discharge conduit 42
extends through and is sealed from the return plenum 32. A suitable
seal (not shown) is provided where the discharge conduit 42
penetrates the partition 28. A return conduit 44 extends from the
return plenum 32 to the air handling unit 40 and supplies return
air to the intake side of the blower 40.
[0076] Conditioned air which is supplied by the air handling unit
38 is delivered by the blower and discharge conduit 42 to the
supply plenum 30 and is discharged from the supply plenum into the
room through ceiling mounted air registers that may take the form
of one or more air diffusers 46. The diffusers 46 may be formed as
part of a combination supply/return fixture which is generally
identified by numeral 48 and which may include a vertical air
return conduit 50 as well as one or more of the diffusers 46. The
return conduit 50 is covered at its lower end by a decorative grill
52 mounted on the ceiling. The fixture 48 may have a size to be
installed in place of one of the ceiling tiles 22. As will be
explained more fully, the return conduit 50 is provided with a seal
at the location where it penetrates the partition 28. The return
conduit 50 extends from the grill 52 to the return plenum 32 in
order to provide a pathway for return air flowing from the room 12
to the return plenum 32.
[0077] The fixture 48 may be equipped with a pair of air diffusers
46 located on opposite sides of the return conduit 50 and arranged
to direct the conditioned air from the supply conduit 30 generally
along the ceiling 18 in opposite directions away from the return
conduit 50, as indicated by the directional arrows 54 in FIG. 1.
Each of the diffusers 46 may be equipped with a terminal unit 56
that may be a damper operated device of the type disclosed in
pending application Ser. No. 10/150,266, filed on May 17, 2002 in
the name of Stanley Demster and entitled "Method and Apparatus for
Delivering Conditioned Air Using Pulse Modulation", which
application is incorporated herein by reference. The dampers in the
terminal units 56 are controlled by a thermostat as more
particularly described in the aforementioned pending application or
by one of the thermostats set forth below.
[0078] A bypass path 58 from the return plenum 32 to the supply
plenum 30 may be provided so that bypass air can be delivered
directly through the path 58 from the return plenum to the supply
plenum. A conventional fan 60 may be mounted in the bypass path 58
in order to provide selected amounts of bypass air. The fan 60 may
be a constant speed device or may be operated at varying rates of
speed in order to vary the amount of bypass air delivered to the
supply plenum 30.
[0079] In operation, the air delivery system of FIG. 1 provides air
from the blower 40 through the discharge conduit 42 to the supply
plenum 30 in a manner to normally maintain the supply plenum 30
with conditioned air during operation at a pressure from 0.0 to 0.1
inches water gauge ("wg") when compared to the pressure in the room
12, and preferably approximately 0.05 inches wg. It should be noted
that the pressures being discussed herein are static differential
water gauge pressures. As such, the outside pressure is the
reference pressure and is therefore 0.0 inches wg. The pressure in
the room 12 is from 0.001 to 0.03 inches wg, meaning it is positive
pressure when compared to the outside reference pressure. This is
desirable as a negative pressure would cause the building to try to
draw air into the building, thereby creating drafts. Relative to
the outside reference pressure, the supply plenum 30 would
therefore preferably be at 0.08 inches wg (0.05 inches wg supply
plenum 30 to room 12 differential+0.03 inches wg room 12 to outside
differential).
[0080] Under suitable thermostat control, the conditioned air is
discharged into the room 12 through the air diffusers 46 in a
direction away from the return grill 52. The conditioned air that
enters the room 12 through the air diffusers 46 flows generally
along the ceiling 18 and then disperses down the walls 16 and along
the floor 14 such that it mixes well with the air in the room
before reaching the vicinity of the return grill 52. The return
plenum 32 is connected with the intake side of the blower 40 and is
preferably maintained at a pressure of approximately -0.02 inches
wg when compared to the pressure of the room 12 (the return plenum
is therefore at approximately 0.01 inches wg differential static
pressure relative to the outside reference pressure) to thereby
draw return air up into the return plenum 32. Thus, a pressure
differential of approximately 0.07 inches wg between the supply
plenum 30 and the return plenum 32 is preferably provided. It is
preferred that the pressure in the supply plenum 30 be maintained
at 0.10 inches wg or less, and approximately 0.05 inches wg is
preferred. The return air is drawn through the grill 52 and the
return conduit 50 into the return plenum 32 and is then returned to
the air handling unit 38 through the return conduit 44.
[0081] By constructing the diffusers 46 and the return conduit 50
as part of a single combination fixture 48, the supply system and
return system can be properly sized and matched for optimal
performance. Also, the return conduit 50 can be properly located
relative to the diffusers 46 so that the diffused air is directed
away from the return conduit 50 to avoid significant short
circuiting of air, thus achieving good mixing of the conditioned
air in the room 12.
[0082] The bypass fan 60 can be activated if desired to apply
selected amounts of air directly from the return plenum 32 to the
supply plenum 30. This decreases the relative humidity of the
conditioned air in the supply plenum 30 and thus avoids humidity
related problems such as the formation of mold, mildew, fungi and
various types of microorganisms that thrive under humid conditions.
In addition, the bypass air serves to make up air that may be lost
from the supply plenum 30 due to leakage.
[0083] FIG. 2 depicts another embodiment of the invention which for
the most part is constructed in a manner similar to the embodiment
shown in FIG. 1. The principal difference is that the system shown
in FIG. 2 is a constant volume system that lacks a volume control
such as provided by the terminal units 56 in the system of FIG. 1.
In the FIG. 2 system, the conditioned air flows through the air
diffusers 46 at a constant rate. The system of FIG. 2 can be
provided with a bypass path and bypass fan such as the bypass 58
and fan 60 shown in FIG. 1.
[0084] FIG. 3 depicts an alternative embodiment of the invention
that includes only a supply plenum 30 in the interstitial space 26.
The return system includes a return register 62 that may be located
anywhere in the room 12 and connects with return ductwork 64
extending to the air handling unit 38 and the intake side of the
fan 40. The conditioned air is supplied to the room 12 from the
supply plenum 30 through an air register 66 installed in the
ceiling 18. The register 66 is equipped with a fan 68 having its
intake side connected with the supply plenum 30. The register 66
can be used to provide the bypass path 58 and fan 60 shown in FIG.
1. FIGS. 15 and 16 provide enlarged and more detailed views of an
embodiment of the register 66 of FIG. 3.
[0085] In the system of FIG. 3, blower 40 maintains the supply
plenum 30 at a pressure of zero gauge. When the thermostat calls
for conditioned air into the room 12, the fan 68 is activated to
force air from the plenum 30 out into the room 12 through the
register 66. Return air is drawn into the return register 62 and
directed back to the intake side of the fan 40 through the return
ductwork 64. A lower portion of the register 66 is covered by a
grill 70.
[0086] FIG. 4 depicts another embodiment of the invention that
makes use of dual plenums 30 and 32 in the interstitial space 26.
The system of FIG. 4 is similar to that of FIGS. 1 or 2, except
that a modified supply/return fixture 72 is used in the FIG. 4
embodiment instead of the fixture 48. The modified supply/return
fixture 72 is essentially the same as the fixture 48 except that
additional items have been added in the vertical air return conduit
50. As with the fixture 48, the fixture 72 includes one or more air
diffusers 46 (best illustrated in FIG. 27) that discharge
conditioned air from the supply plenum 30 into the room 12. The
fixture 72 illustrated in FIG. 4 is rotated 90.degree. from the
view of the fixture 48 illustrated in FIGS. 1 and 2 to permit
better viewing of the differences inside the return conduit 50.
Accordingly, one of the diffusers 46 may be positioned behind the
illustrated conduit 50 and one may be positioned in front of the
illustrated conduit 50. FIG. 27 provides an enlarged and more
detailed view of an embodiment of the fixture 72 of FIG. 4.
[0087] To modify the fixture 48 to make the fixture 72, a divider
74 is placed in the return conduit 50. The divider 74 divides the
return conduit 50 into a return air conduit 76 and a heated air
supply passage 78. The grill 52 is placed at a lower end of the
conduit 50 adjacent to the ceiling 18. The fixture 72 further
includes a fan 80 having its intake side connected with the return
plenum 32 and its discharge side directing air back into the room
12. A heating coil 82 may be provided between the fan 80 and the
grill 52. The coil 82 may be an electric coil, a steam coil or any
other suitable type of heating device that is activated in the
heating mode of the system.
[0088] Cooled conditioned air from the supply plenum 30 passes
through the air diffusers 46 (obstructed in FIG. 4) and into the
room 12 (in the method described above for FIGS. 1 or 2, depending
on whether it is a constant volume or variable volume system). When
cooling is called for by the thermostat, the fan 80 and heating
coil 82 are inactive in the cooling mode. The relatively negative
pressure in the return plenum 32 causes return air to be drawn
through the grill 52 and the return conduit 50 into the return
plenum 32 from which the return air is returned through conduit 44
to the intake side of the blower 40.
[0089] When the thermostat calls for heat, the fan 80 and heating
coil 82 are activated and the fan 80 operates to draw air from the
return plenum 32 into the heated air supply passage 78 past the
heating coil 82 and into the room 12 through the grill 52. Return
air then moves from the room 12 to the return plenum 32 through the
return air conduit 76. In this manner, heated or cooled air can be
supplied to the room under the control of the thermostat. The
dashed arrows in FIG. 4 illustrate the path air flows when the fan
80 is on in the heating mode.
[0090] FIG. 5 depicts an alternative embodiment of an air delivery
system that makes use of the dual plenums 30 and 32. In the system
of FIG. 5, a supply fixture 84 is provided along with a separate
return fixture 86. The supply fixture 84 includes a conduit 88 that
extends from a supply register 90 to the return plenum 32. The
upper end of the conduit 86 opens into the return plenum 32 and is
provided with a damper 92 that opens and closes the upper end of
the conduit 88. The conduit 88 also has an opening 94 that connects
with the supply plenum 30 and is provided with a damper 96 for
opening and closing the opening 94. A heating coil 98 is provided
in the conduit 88. A fan 100 may be operated under thermostat
control to direct air through conduit 88 from the return plenum 32
into the room 12 through the air register 90.
[0091] The return fixture 86 includes a return conduit 102 having a
grill 104 on its lower end adjacent to the ceiling 18. The conduit
102 extends from the grill 104 to the return plenum 32 in order to
deliver return air to the return plenum. Various embodiments of the
return conduit 102 are discussed in greater detail below. In the
system of FIG. 5, both the supply plenum 30 and the return plenum
32 are maintained at a pressure of zero gauge.
[0092] In the cooling mode of operation, the system of FIG. 5
causes the damper 96 to open and the damper 92 to close. The blower
40 operates to supply conditioned air to the supply plenum 30 and
from the supply plenum through opening 94, into the fixture 84,
through the register 90 and into the room 12. Return air is drawn
through the grill 104 and through conduit 102 to the return plenum
32 and from the return plenum through conduit 44 to the intake side
of the blower 40.
[0093] In the heating mode of operation, damper 96 is closed and
damper 92 is opened. The heating coil 98 and fan 100 are activated
to force air from the return plenum 32 downwardly through conduit
88 past the heating coil 98 and into the room 12 through the
register 90. In this manner, the air is heated by the coil 98 and
delivered into the room. Return air is drawn into the return plenum
32 through the grill 104 and the return conduit 102. Both dampers
92, 96 are illustrated in FIG. 5 in a partially open position for
ease of viewing only and, as discussed above, would not otherwise
both be open during operation.
[0094] FIG. 6 illustrates a more detailed view of the combined
supply and return fixture 48. In the particular embodiment
illustrated in FIG. 6, the fixture 48 includes two diffusers 46 for
directing the flow of air from the supply plenum 30 into the room
12. Each of the diffusers 46 also includes a terminal unit 56
associated therewith for selectively controlling the flow of the
air from the supply plenum 30 to the room 12. The fixture 48 also
includes the return conduit or chimney 50 located therebetween for
permitting the movement of air from the room 12 to the return
plenum 32.
[0095] The diffusers 46 are preferably part of a base unit 106
(best illustrated in FIG. 7) upon which a modular apparatus is
designed whereby a user can mix and match various components to
customize the apparatus depending on the user's particular needs.
The base unit 106 preferably includes, in the illustrated
embodiment, the two diffusers 46. The particular embodiment of the
base unit 106 illustrated in FIG. 7 is preferably constructed by
assembling six sections of extruded aluminum members 110. While the
members 110 have been indicated to be aluminum, it is well within
the scope of the present invention to have the members be of a
different material. Similarly, while the members 110 have been
indicated to be manufactured by an extrusion process, other
manufacturing processes are capable of providing the members 110 in
their desired shapes, are well within the scope of the present
invention and would be readily understood by one of ordinary skill
in the art. Likewise, the base unit could be formed as a single
integral piece.
[0096] When constructed in accordance with the illustrated
embodiment, the base unit 106 includes two interior sections 112,
two arced sections 114, and two end sections 116. As best
illustrated in FIG. 8, the interior sections 112 have a generally
upside down T-shaped cross-section. The interior section has a
vertical wall 118 which is generally perpendicular to a horizontal
base 120. The vertical wall 118 includes a jog 122 on an inner
surface 124 thereof. The jog 122 is for receiving a gasket 126 to
form a seal against an outer surface 128 of the conduit 50 when the
conduit 50 is received in the base unit 106.
[0097] The base 120 of the interior section 112 includes a inner
section 130 and an outer section 132. The inner section 130
includes upper surface 134 that provides a ledge upon which a lower
end 136 of the return conduit 50 rests during use.
[0098] The vertical wall 118 has an outer surface 138. When the
interior section 112 is extruded in accordance with an embodiment
of the present invention, the outer surface 138 can be provided
with screw bosses 140. The outer section 132 of the base 120 helps
direct the flow of air from the supply plenum 30 into the room
12.
[0099] The arced sections 114 include a vertical wall 142 and a
generally arcuate wall 144. In the embodiment illustrated, an inner
surface 146 of the vertical wall 142 can be provided with screw
bosses 140 to assist in assembly. The arcuate wall 144 has an outer
section 148 and an inner section 150. The outer section 148 is
preferably perpendicular to the vertical wall 142 and includes a
lower surface 152. During use, when the base unit 106 is received
in an opening 154 in the grid work of T-bars 24 in the ceiling 18,
a gasket 156 is positioned between the lower surface 152 of the
outer section 148 and an upper surface 158 of the T-bar 24. The
gasket 156 can also be used on the upper surface 158 on an opposite
side of the T-bars vertical member 160. In this manner, the gasket
156 seals the tiles 22 to the T-bars 24 in an airtight manner to
provide an airtight seal between the room 12 and the supply plenum
30. Similarly, the gaskets 156 can be used on the crosses 36 in the
partition 28, as discussed in greater detail below.
[0100] The end sections 116, as best viewed in FIG. 9, have a
vertical wall 162 that is substantially the same as the vertical
wall 118 of the interior sections 112. Consequently, the vertical
wall 162 includes a jog 164 therein and corresponds with the jog
122 for receiving the gasket 126. The vertical wall 162 also
preferably has the screw bosses 140 extruded therein. The end
section 116 has a base 166 with a lower surface 168. When the base
unit 106 is received in the opening 154, the end sections 116 are
supported by the T-bars 24 by the base 166 resting on a gasket 156
placed on the upper surface 158 of the T-bar.
[0101] When the six extruded members 110 are assembled in the
manner illustrated in FIG. 7 to provide the base unit 106, the two
interior sections 112 and the two end sections 116 cooperate to
define a center section 170 of the base unit 106. The jogs 122, 164
with the gasket 126 therein cooperate to define a seal around a
periphery of the center section 170. When the user desires to both
supply air from the supply plenum 30 and return room air to the
return plenum 32 in the same apparatus, as in the combination
supply return fixture 48, the air return conduit 50 is received in
the center section 170. The gasket 126 encircles the conduit 50 to
seal off the supply plenum 30 so that the conduit 50 provides a
sealed passage through the supply plenum 30 while maintaining its
integrity.
[0102] The conduit 50 is preferably a rectangular structure formed
by bending sheet metal into a desired orientation. The conduit has
an upper end 172 which protrudes into the return plenum 32 and the
lower end 136 that is received in the center section 170 of the
base unit 106. Portions of the conduit 50 at its ends 172, 136 are
preferably bent inward to provide upper and lower flanges 176, 178
respectively. The flanges 176, 178 not only provide structural
rigidity to the conduit 50, but they also define a space for
receiving insulation 180. The insulation can be sheets of duct
liner that is well known in the art and readily available. The
insulation 180 provides a thermal barrier between a return passage
182, defined by the conduit 50, and the supply plenum 30.
[0103] As best illustrated in FIGS. 6, 7 and 10, a mounting angle
184 is mechanically coupled to an outer surface 186 of the conduit
50. The mounting angle 184 has a vertical portion 188 and a
horizontal portion 190. The vertical portion 188 is provided with a
plurality of apertures 192 for receiving mounting screws 194
therethrough to couple the mounting angle 184 with the conduit 50.
The apertures 192 can be oblong or oval in nature in the vertical
orientation to permit the user to adjust the mounting angle 184 to
accommodate variations in the spacing between the ceiling 18 and
the partition 28. The sections of mounting angle 184 provided on
side walls 196 of the conduit 50 can be provided with a gasket 156
on an upper surface 198 of the horizontal portion 190 of the
mounting angle 184. A rectangular piece of tile 34 rests thereon
and extends between the conduit 50 and the adjacent cross 36 in the
partition 28, as best illustrated in FIG. 6. The sections of
mounting angle 184 on end walls 200 can be directly and
mechanically coupled with the adjoining crosses 36 via a rivet 202,
as best illustrated in FIG. 10, without the need for a gasket
therebetween.
[0104] FIG. 14 illustrates a cross section of a structural cross 36
in perspective view. In the illustrated embodiment, the cross 36 is
made by joining two readily available T-bars 24 together in a
face-to-face relationship. One of ordinary skill in the art would
readily understand that the cross 36 could easily be fabricated as
a single integral piece with a roll forming machine and a series of
punches made therein. However, the use of two T-bars 24 joined in
the manner illustrated has been found a cost effective alternative.
The two T-bars 24 are joined by pinching or crimping horizontal
portions 204 of the T-bars 24 together at regularly spaced
intervals, for example every six inches, to form a crimp 206. It is
readily understood that the two members could also be joined by
other known fastening means, such as rivets. A vertical portion 208
of the T-bars 24 and/or crosses 36 includes a plurality of holes
210 therethrough for receiving support wires 212 or ends of T-bars
24 that connect thereto in any of the common methods presently in
use in the art. A gasket 156 is placed on the upper surface 158
where needed (i.e., when a tile 34 rests thereon).
[0105] While the illustrated embodiment discloses the cross 36 for
use in forming the grid work for the partition 28, it is within the
scope of the present invention to use a standard T-bar 24 in the
partition 28. In such case, a modified support wire (not shown)
could be employed to suspend the ceiling 18 from the T-bars 24 in
the partition 28. In such an embodiment, the modified support wire
could take the shape of a strip of sheet metal bent to hook around
the horizontal portion 204 of the T-bar 24. However, the
illustrated embodiment has been found beneficial in maintaining the
integrity of the seal between the partition tiles 34 and the
crosses 36.
[0106] The terminal units 56 may be of the type more fully
disclosed in the above-referenced pending patent application. The
units 56, as illustrated in FIG. 13, preferably include a housing
214 for supporting a damper blade 216 on a horizontal shaft 218. As
the shaft 218 is turned, the damper blade 216 rotate between fully
open and fully closed positions. A motor 220 (FIGS. 11 and 12) for
rotating the damper blade 216 may also be mounted in the housing
214. The motor can be of the type more fully described in the
above-referenced pending patent application. The motor 220 may
alternatively be mounted on the outside of the housing 214 to
permit the damper blade 216 to run the length of the housing 214.
As will be readily understood, the housing 214 defines an opening
222 through which supply air from the supply plenum 30 passes when
the damper blade 216 is in an open position. Power can be provided
to the motor 220 by way of electrical wires 224.
[0107] The housing 214 is constructed with a lower portion 226
designed to permit coupling of the terminal unit 56 to an upper
surface 228 of a diffuser 46 when the user desires a variable
volume system as illustrated in FIG. 1. When the damper blade 216
is in its open position, supply air moves from the supply plenum 30
through the opening 222 in the terminal unit, then through an
opening 230 in the diffusers 46 and into the room 12. The opening
230 in the diffuser 46 through which the supply air passes is
defined on one side by the arcuate wall 144 of the arced section
114, on the other side by the interior section 112 and on the ends
by the end sections 116.
[0108] FIG. 15 illustrates an enlarged and more detailed view of
the bypass path 58 between the return plenum 32 and the supply
plenum 30 of FIG. 1. A partition tile 34 is replaced by a bypass
apparatus 232 to provide the bypass path 58 in the partition 28.
The bypass apparatus 232 includes a hood 234 and a fan unit 236.
The fan unit 236 can be the fan 60 illustrated in FIG. 1. The hood
234 can be dome shaped with a central opening 238 therein to permit
air to pass through the hood 234. The fan unit 236 preferably
includes a housing 240, a motor 242 and blades 244.
[0109] In the illustrated embodiment, the opening 238 in the hood
234 is preferably cylindrical. Accordingly, the housing 240 for the
fan unit 236 is also preferably cylindrical. The cylindrical
housing 240 has annular flanges 246 that permit mechanically
coupling the fan unit 236 to the hood 234. The motor 242 is an
axial motor and is located in a hub 248 from which the blades 244
extend radially outward. The motor 242 is supported by brackets
250. While the hood 234 of the bypass apparatus 232 has been
illustrated as being dome shaped, the hood could be flat in nature
with the housing 240 mounted on upper or lower surfaces of the hood
234, as discussed below.
[0110] The hood 234 can be provided with hanger holes 252 (FIG. 16)
to permit coupling of support wires 212 thereto so a user may
suspend the bypass apparatus 232 directly from the roof 20 when
local codes require independent suspension or support of non-tile
items placed in a suspended grid work. Along those lines, the upper
end 172 of the conduit 50 could similarly be provided with hanger
holes 252 (not shown) to permit suspending it directly from the
roof 20 where codes so require. The bypass apparatus 232 can be
used in the system illustrated in FIG. 3 and can be the air
register 66.
[0111] FIG. 2 illustrates a combination supply and return fixture
48 that is slightly different than the combination supply and
return fixture 48 illustrated in FIG. 1. In FIG. 1, as discussed
above, the combination supply and return fixture 48 is in use in a
variable volume system whereas the combination supply and return
fixture 48 in FIG. 2 is in use in a constant volume system.
Accordingly, the fixture 48 illustrated in FIG. 2 does not require
the presence of a terminal unit 56 to control the flow of air from
the supply plenum 30 to the room 12.
[0112] A beneficial feature of the combined supply/return fixture
48 is its modular design. FIGS. 17-26 illustrate a number of
variations that can be made to the fixture 48. FIG. 17, for
example, illustrates the fixture 48 with a dual supply and a return
for use in a variable volume system as illustrated in FIGS. 1, 6
and 7.
[0113] FIG. 18 illustrates the dual supply with a return fixture 48
for use in a constant volume system as illustrated in FIG. 2. In
this arrangement, the user has simply removed the terminal units
56. Similarly, by removing the conduit 50 and the grill 52 from the
center section 170 of the base unit 106 and replacing them with an
appropriately sized ceiling tile 22, the user can easily convert
the combination supply/return fixture 48 illustrated in FIG. 18
into the dual supply no return fixture 254 illustrated in FIG. 19.
FIG. 20 illustrates a top perspective view of the dual supply no
return fixture 254. By placing the two terminal units 56 back on
the diffusers 46 of the dual supply no return fixture 254 in FIG.
19, as illustrated in FIG. 21, the user can use the fixture 254 in
a variable volume system.
[0114] If the user does not need to supply the volume of air to the
room 12 that two diffusers 46 would supply, the user can provide a
fixture with only a single diffuser as illustrated in FIGS. 22-25.
FIG. 22 illustrates a single supply with return fixture 256 for use
in a constant volume system. By placing a terminal unit 56 on the
diffuser 46 in FIG. 22, as illustrated in FIG. 23, the single
supply with return fixture 256 can be used in a variable volume
system. In constructing the single supply with return fixtures 256
illustrated in FIGS. 22 and 23, one of the arced sections 114 of
the base unit 106 is replaced by a modified extruded member 258.
The modified extruded member 258 is essentially identical to the
extruded arced section 114 but for replacing the arced inner
section 150 with another outer section 148 to provide a ledge upon
which an appropriately sized tile 22 may rest. Similarly, the
interior section 112 on the same side where the arced section 114
was removed can be replaced by an end section 116 of appropriate
length. The end section 116 can be slightly modified to include a
base 166 on both sides of the vertical wall 162 and is thereby been
identified by the numeral 116'. Alternatively, the interior section
112 can be left and not replaced by the modified end section 116'
if desired.
[0115] When the user does not need the volume of air supplied by
two diffusers 46 and does not have the need for a return air
passage, the user can employ the arrangement illustrated in FIGS.
24 and 25. In this arrangement, the base unit 106 has been reduced
to simply a diffuser 46. The upper surface 134 of the inner section
130 which normally would support the grill 52 and the lower end 136
of the conduit 50 now supports an appropriately sized tile 22. The
gasket 156 on the opposite T-bar could be made thicker to
accommodate the resulting elevation difference.
[0116] FIG. 26 illustrates an embodiment of a return only fixture
260 for use when a user does not need to supply air from the supply
plenum 30 to the room 12. In this fixture 260 the base unit 106 has
had both arced sections 114 removed and replaced by sections of the
modified extruded member 258. Two tiles 22 of appropriate size are
placed between the modified extruded members 258 and the end
sections 116' (or interior sections 112).
[0117] FIGS. 27 and 28 (diagrammatically) illustrate the modified
supply/return fixture 72 used in the system illustrated in FIG. 4
and discussed above. The modified supply/return fixture 72 can be
provided with a wall 262 in the conduit 50 adjacent the divider 74
to cooperate therewith to define a static space 264 therebetween.
Temperature sensing components 266 can be provided therein to
determine the need for the modified supply return fixture 72 to be
in the heating or cooling mode by sensing the temperature of the
return air as it passes through the return air conduit 76. A probe
268 can protrude from the static space 264 through the divider 74
into the return air conduit 76 to sense the temperature. The wall
262 isolates the temperature sensing components 266 from the
heating coil 82. The fan 80 can be the fan unit 236 discussed
above.
[0118] FIGS. 29 and 30 illustrate an alternate embodiment of a
return only fixture 270. The fixture 270 includes upper and lower
frame members 272 coupled by an expandable accordion like tubing
274. The upper and lower frame members 272 can be identical pieces.
In such case a frame member 272 in the partition 28 is oriented to
point downwards while the frame member 272 in the ceiling 18 is
oriented in an upward direction. The frame member 272 has a
horizontal base 276 with upstanding structural walls 278 around its
periphery. A circular opening 280 is provided in the horizontal
base and an annular flange 282 projects through the opening 280
away from the horizontal base 276 opposite the walls 278.
[0119] An inner diameter of the tubing 274 is slightly larger than
an outer diameter of the protruding annular flange 282 such that
the tubing 274 may be received on the annular flange 282. A strap
284 can then be cinched around the tubing 274 to couple the tubing
274 with the frame members 272. The accordion like nature of the
tubing 274 provides adjustability should the distance between the
ceiling 18 and the partition 28 vary.
[0120] FIG. 31 illustrates yet another embodiment of a return only
fixture 286. In many applications involving a suspended ceiling, a
need often arises to penetrate the ceiling for various mechanical
components of the building, such as sprinklers. In a standard
sprinkler system, as illustrated, a horizontal water pipe 288 runs
below the roof 20 in the interstitial space 26. In the present
embodiment, the horizontal pipe would reside in the return plenum
32. A T-fitting 290 in the pipe 288 provides for a vertical branch
292 that terminates in or slightly above the room 12 with a
sprinkler head 294.
[0121] While the fixture 286 provides a return air passage 296, its
primary purpose is to provide a sealed penetration through the
supply plenum 30 to maintain its integrity. The fixture 286 has a
wall 298. In the illustrated embodiment, the wall 298 is preferably
a cylindrical tube having insulation 300 wrapped therearound. A
seal 302 seals the fixture 286 to the tiles 22, 34. The seal 302
could be caulk applied where the insulation 300 meets the tiles 22,
34 after installation. A decorative flange (not shown) could be
placed in the opening in the tile 22 adjacent the sprinkler head
294 for aesthetic purposes.
[0122] FIGS. 32 and 33 illustrate a structural panel used to
penetrate the partition 28 without compromising the integrity of
either the supply plenum 30 or the return plenum 32. The panel 304
has a flat base portion 306 which can be a piece of sheet metal. A
structural wall 308 is located around a periphery of the base
portion 306 of the panel 304 and increases the rigidity of the
panel 304. The panel also includes a structural rib 310 to further
increase the strength and rigidity of the panel 304. A plurality of
junction boxes 312 are provided on both upper and lower surfaces
314, 316 of the base portion 306.
[0123] A junction box 312 on the upper surface 314 is positioned
directly above a junction box 312 on the lower surface 316. With
the junction boxes still aligned, an opening 317 may be made in the
base portion 306 intermediate the aligned junction boxes 312 in the
space defined therebetween. The opening 317 permits a cable or
electrical wire 318 to pass through the panel 304 while the two
aligned junction boxes 312 cooperate to maintain the seal between
the supply plenum 30 and the return plenum 32. An electrical
conduit 319 can carry the wire 318 outside the junction boxes 312.
As is readily apparent to one of ordinary skill in the art, the
junction boxes 312 include knockouts 320 that can be used to gain
access to the interior of the junction boxes 312 and connectors 322
can be used to seal where the wire 318 enters the junction box 312
through a knockout 320 and/or where the electrical conduit 319
connects to the junction box 312. The panel 304 can be positioned
in the partition 28 above a light fixture 324 to permit the wire
318 from the light fixture to pass through the partition 28 without
breaking the seal between the supply and return plenums 30, 32.
[0124] FIG. 34 illustrates that the panel 304 can be used in
connection with a plurality of fan units 236, as opposed to the
hood 234, to provide an alternate embodiment of the bypass
apparatus 232. The junction boxes 312 can be used in connection
therewith, as illustrated, or can be left off.
[0125] To control the various systems illustrated in FIGS. 1-5, a
thermostat 326, illustrated in FIG. 35 and having multiple
embodiments discussed below, has been developed. The thermostat 326
of the present invention has been designed to be used with common,
existing and readily available electrical accessories and devices,
such as cover/face plates 328, junction boxes 330 and other similar
accessories common to existing electrical devices. The constraints
inherent in such a design require the thermostat 326 to sense and
control temperature while it is limited to the particular packaging
and mounting common to existing electrical devices, such as a light
switch 332. This design resolves many aesthetic objections to
thermostats and permits easy compliance with new mounting height
requirements. Also, it significantly reduces the cost of production
of the devices because low cost, high volume, existing accessories
can be used with the thermostats.
[0126] FIG. 35 illustrates two embodiments (for ease of
description) of the thermostat 326 of the present invention mounted
in a standard and readily available triple gang junction box 330
adjacent a light switch 332. The junction box 330 is attached to a
joist 334 by a nail 336 at the appropriate height from the floor 14
(not shown), as well known in the art. The junction box 330 has a
plurality of upper and lower internally threaded channels 338
(obstructed) for receiving mounting screws 340. The thermostats
326, as well as the light switch 332, have a mounting strip 342
with upper and lower mounting holes 344 (obstructed) for receiving
the mounting screws 340. The mounting holes 344 are spaced apart a
set distance to permit alignment with the channels 338 which are an
industry standard distance apart. The mounting strips 342 also have
a pair of upper and lower face plate attachment holes 346
intermediate the mounting holes 344. The distance between the face
plate attachment holes 346 is also determined by an industry
standard, i.e., the distance between screw holes 348 in the face
plate 328. By spacing the holes 344, 346 in the mounting strip 342
industry standard distances apart, the thermostat 326 can be
readily incorporated in existing devices and used with existing
accessories. A barrier 347 will most likely be required in the
junction box 330 by the National Electric Code. The barrier 347 is
used to separate the low voltage thermostats 326 from any high
voltage components, such as the light switch 332, in the junction
box 330. FIG. 36 illustrates the arrangement of FIG. 35 in a
finished wall 16 with the cover plate 328 in place adjacent a door
349.
[0127] Turning now to FIG. 37, the sensing and control electronics
of the thermostat 326 are placed on a single printed circuit board
350 that is sized to fit behind an industry standard single-gang or
double/multi-gang electrical cover plate 328. The circuit board 350
has a front side 352 and a component side 354. When mounted, the
front side 352 of the circuit board faces out of the junction box
330. A user setpoint adjustment control 356 is mounted to the
component side 354 in a manner that allows it to be accessed
through the front side 352. The user setpoint adjustment control
356 permits the user to adjust the desired temperature. In this
particular embodiment, the user setpoint adjustment control 356 is
a variable resistor, which is often called a potentiometer.
However,it should be understood that other adjustment controls,
such as digital controls that incorporate a momentary push button
and a display as discussed below, are within the scope of this
invention. Other components, and especially those discussed below,
are mounted to the component side 354, but for clarity these
components are not shown in FIG. 37.
[0128] Continuing with FIG. 37, a thermistor 358 is used to sense
the ambient temperature in the area surrounding the thermostat 326.
Importantly, the thermistor 358 is coupled to the front side 352 of
the printed circuit board 350, which places it on the opposite side
of the remaining components of the thermostat 326. In this manner,
the thermistor 358 is isolated from any heat generated by those
components. The placement of the thermistor 358 also allows it to
be either in contact with the cover plate 328 covering the junction
box 330 in which the circuit board 350 is mounted or in close
proximity to the cover plate 328 when the circuit board 350 is in
place. Thus, with this position, the thermistor 358 will sense and
reflect the temperature of the cover plate 328, which reflects the
temperature of the air surrounding the cover plate 328 and in turn
the room 12, and not be affected by the temperature of the
remaining thermostat components.
[0129] The various embodiments of the thermostat 326 of the present
invention provide the user interfaces, signals, protocols and
methodologies required to control the systems and the terminal unit
56 mentioned above. As should be understood, generally, the
terminal unit 56 is controlled by two electrical signals: an on
signal that causes the terminal unit 56 to open its damper blade
216; and an off signal that causes the terminal unit 56 to close
its damper blade 216. For this discussion, and without limiting the
invention, the on and off signals will be voltage signals, and the
falling edge of the on signal will cause the terminal unit 56 to
open its damper blade 216 while the falling edge of the off signal
will cause the terminal unit 56 to close its damper blade 216. Many
other types of electrical signals may be employed and are within
the scope of this invention.
[0130] In a first embodiment, the thermostat 326 controls the
average amount of air delivered by the terminal unit 56 by altering
the ratio of the time the damper blades 216 of the terminal units
56 are open and closed. FIG. 38 shows a typical timing diagram for
this first embodiment of the thermostat 326. Specifically, signal
360 is an on signal and signal 362 is an off signal. At time 0, on
signal 360 goes high while off signal 362 stays low. At time 1, on
signal 360 goes low with the falling edge of on signal 360 causing
the terminal unit 56 to open its damper blade 216. At time 2, off
signal 362 goes high. When, at time 3, off signal 362 returns to a
low value, the falling edge of this signal causes the terminal unit
56 to close its damper blade 216. The damper blades 216 will remain
closed until time 5 when on signal 360 returns to a low state after
going high at time 4. In this example, therefore, for the time
period that extends from time 1 to time 5, the terminal unit 56 had
its damper blade 216 open from time 1 to time 3 and closed from
time 3 to time 5. By changing the times when on signal 360 and off
signal 362 change states, the thermostat 326 controls the amount of
air delivered.
[0131] A block diagram of one embodiment of the thermostat 326 that
may be utilized to produce the signals discussed in the first
embodiment of the thermostat is shown in FIG. 39. This embodiment
of the thermostat 326 includes a thermistor 364 and a user setpoint
adjustment 366. Both the thermistor 364 and the user setpoint
adjustment 366, either alone or in combination with other commonly
understood components or circuits (which are not shown), provide a
variable voltage as an output.
[0132] The thermistor 364 is operable to change its resistance in
response to a change in the ambient temperature. More specifically,
as the temperature of the thermistor 364 rises, its resistance
decreases. The user setpoint adjustment 366 is also operable to
change resistance to provide a variable voltage output, except that
the user setpoint adjustment 366 is manually operable. As stated
above, a variable resistor is one device that may be utilized as a
user setpoint adjustment 366. In FIGS. 35 and 36, the leftmost
thermostat 326 incorporates a variable resistor which terminates in
a user engagable knob 368. By rotating the knob 368, the user can
vary the resistance and thereby vary the voltage output.
Accordingly, a user can vary the desired temperature of the room 12
by rotating the knob 368. Consequently, the user can make the room
12 hotter by rotating the knob 368 one direction and colder by
rotating the knob 368 the other direction.
[0133] The user setpoint adjustment 366 also may be a digital
module that incorporates a display. For example, the thermostat 326
in FIGS. 35 and 36 immediately to the left of the light switch 332
has two momentary push buttons 370 that are electronically coupled
to a digital circuit that includes a liquid crystal display 372. In
this embodiment of the user setpoint adjustment 366, one of the
push buttons 370 (preferably the upper one) would allow a user to
increase the setpoint (i.e., raise the desired temperature) while
the other push button 370 (preferably the lower one) would allow
the user to decrease the setpoint (i.e., lower the desired
temperature). The display 372 would show a number that corresponds
to the setpoint. The digital circuit also would output a voltage
that corresponds to the setpoint. In this embodiment of the
thermostat 326, the user setpoint adjustment 366 has a face 373
that is accessible and viewable by a user in the room 12 when the
cover plate 328 is attached to the junction box 330, as illustrated
in FIG. 36. The face 373 has an outer periphery 375 that is sized
to fit through an opening 377 in the cover plate 328. The opening
377 in the cover plate 328 is of an industry standard size.
Accordingly, by dimensioning the face 373 to fit through the
industry standard sized opening 377 in the cover plate 328, readily
available cover plates can be used. Preferably, the face 373 is
approximately 1.3 inches wide by 2.6 inches tall and is more
preferably 1.310 inches wide by 2.630 inches tall.
[0134] Continuing with FIG. 39, the output of thermistor 364 is
electronically coupled to the input of a voltage amplifier 374. It
should be understood that the voltage amplifier 374 is operable to
proportionally increase the voltage output from the thermistor 364
so that it falls within a range that is usable by the remainder of
the thermostat components, and specifically by an "on" time timer
circuit 376, since the output of voltage amplifier 374 is
electronically coupled to this circuit. Of course, voltage
amplifier 374 may not be necessary if the output voltage of
thermistor 364 falls within the range of voltages acceptable as an
input to the "on" time timer circuit 376. The output of the "on"
time timer circuit 376 is electronically coupled to a first pulse
generation timer circuit 378, and the output of the first pulse
generation timer circuit 378 is electronically coupled to a modular
plug 380.
[0135] On the second portion of the thermostat 326, the output of
the user setpoint adjustment 366 is electronically coupled to an
"off" time timer circuit 382. In a manner similar to "on" time
timer circuit 376 and pulse generation timer circuit 378, the
output of the "off" time timer circuit 382 is electronically
coupled to a second pulse generation timer circuit 384, and the
output of the second pulse generation timer circuit 384 is coupled
to the modular plug 380. Finally, the output of the first pulse
generation timer circuit 378 is electronically coupled to the "off"
time timer circuit 382 while the output of the pulse generation
timer circuit 384 is electronically coupled to the "on" time timer
circuit 376.
[0136] It should be understood that the timer circuits 376, 378,
382 and 384 preferably are based on one timer from a 558 quad
timer. The operation of 558 timers is well known, as are the
circuits used and the components necessary to generate a pulse with
a variable length.
[0137] In operation, when power is applied to the thermostat 326,
the output of the second pulse generation timer circuit 384 goes
high for a predetermined length of time. This signal (on signal 360
in FIG. 38) triggers the "on" signal timer circuit 376 which
signals the terminal unit 56 to open the damper blade 216.
Thereafter, the "on" signal timer circuit 376 produces an output
signal with a length that is controlled by the output from the
thermistor 364, after being amplified by the voltage amplifier 374.
In FIG. 38, the length of this signal is from time 1 to time 2.
This output is used to trigger the first pulse generation timer
circuit 378, which produces an output high signal of predetermined
length (off signal 362 in FIG. 38) that signals to the terminal
unit 56 to close the damper blade 216. The output of the first
pulse generation timer circuit 378 also triggers the "off" time
timer circuit 382, which produces a high signal with a length
controlled by the output from the user setpoint adjustment 366. In
FIG. 38, the length of this signal is from time 3 to time 4.
[0138] The output of the "off" time timer circuit 382 triggers the
second pulse generation timer circuit 384 to produce a high signal
of predetermined length (on signal 360 in FIG. 38) that signals to
the terminal unit 56 to open the damper blade 216. Thus, the timer
circuits are interconnected so that the completion of the "on" time
timer signal triggers the signal that closes the damper blade 216
and the completion of the "off" time timer signal triggers the
signal that opens the damper blade. Similarly, the completion of
the "on" time output signal triggers the "on" time timer signal
while the completion of the "off" time output signals triggers the
"off" time timer signal. This interconnection causes the "on" and
"off" pulses to repeat indefinitely.
[0139] It should be understood that the specific embodiment
discussed with regard to FIG. 39 is one of several possible analog
configurations. The timing and control signals could also be
provided by a microprocessor or microcontroller that is programmed
to provide the same functions.
[0140] In a second embodiment, the thermostat 326 produces the
signals shown in FIG. 40. This embodiment illustrates a traditional
"on-off" method in which for cooling mode the terminal unit 56 is
open so long as the temperature is above the user setpoint and
closed whenever the temperature is at of below the user setpoint.
For heating mode, the conditions are reversed. In FIG. 40, the
output signal for cooling mode are presented. When the temperature
is above the setpoint, an on signal 386, which is a pulse that is
generated periodically, opens the damper blade 216 of the terminal
unit 56 and an off signal 388 remains low. When the temperature is
below the setpoint, an off signal 390, which also is a pulse that
is generated periodically, closes the damper blade 216 of the
terminal unit 56 and an on signal 392 remains low.
[0141] A block diagram of one embodiment of a thermostat 326 that
may be utilized to produce the signals discussed in the second
embodiment of the thermostat is shown in FIG. 41. This embodiment
of the thermostat 326 includes a thermistor temperature sensor 394
and a user setpoint adjustment 396. The outputs of these two
devices are electronically coupled to a voltage comparator 398. As
is known, a voltage comparator is a device that is operable to
compare the voltage levels of two inputs and provide an output that
is indicative of which input is higher. The voltage comparator 398
is configured so that the output is high if the thermistor output
voltage is higher than the user setpoint adjustment output voltage
and low if the opposite is true.
[0142] Continuing with FIG. 41, the output of the voltage
comparator 398 is electronically coupled to an invertor circuit 400
and on switch circuit 402. The invertor circuit 400 is operable to
provide an output that is the inverse of the input. Thus, if the
input to the invertor circuit 400 is high, then the output of
invertor circuit 400 is low. The output of the invertor circuit 400
is electronically coupled to an off switch circuit 404. Switch
circuits 402 and 404 are operable to allow the signal to pass
through a signal input if the control level is high and block the
signal input if the control level is low. As shown in FIG. 41, if
the output of the voltage comparator 398 is high then the on switch
circuit 402 passes its signal input though while the off switch
circuit 404 blocks its signal input. If the output of the voltage
comparator 398 is low then the off switch circuit 404 passes its
signal input though while the on switch circuit 402 blocks its
signal input. The output of both the on switch circuit 402 and the
off switch circuit 404 are electronically coupled to a modular plug
406.
[0143] Also present in FIG. 41 are a timer circuit 408 and a pulse
generation circuit 410. These two circuits are operable to produce
the on and off signals shown in FIG. 40. Preferably, these circuits
408 and 410 are based on one timer from a 558 quad timer. Thus, the
output of the timer circuit 408 is electronically coupled to the
trigger of the pulse generation circuit 410. The output of the
pulse generation circuit 410 is tied to the signal inputs of the on
switch circuit 402, the off switch circuit 404 and to the trigger
of the timer switch circuit 408.
[0144] In operation, as indicated above, if the thermistor output
voltage is higher than the user setpoint adjustment output voltage,
which would indicate that the space needs cooling, then the output
of the voltage comparator 398 is high. This high output causes the
on switch circuit 402 to pass its signal input and the off switch
circuit 404 to block its input. In this manner, the terminal unit
56 receives a signal that causes it to open its damper blade 216.
Similarly, if the user setpoint adjustment output voltage is higher
than the thermistor output voltage, which would indicate that the
space needs heating, then the output of the voltage comparator 398
is low. This low output causes the off switch circuit 404 to pass
its signal input and the on switch circuit 402 to block its input.
In this manner, the terminal unit 56 receives a signal that causes
it to close its damper blade 216.
[0145] The first and second embodiments of the thermostat 326
discussed above are zone thermostats. There are applications,
however, that require a thermostat to control a roof top unit or an
air-handling unit. The control functions of this type of thermostat
must comply with established control conventions for the equipment
controlled. A third embodiment of the thermostat 326 complies with
these conventions.
[0146] In FIG. 42, a block diagram of the third embodiment of the
thermostat 326 is shown. This embodiment of the thermostat 326
retains the physical shape and dimensions of the first and second
embodiments so that it too fits within the packaging common to
existing electrical devices. This embodiment of the thermostat 326
includes a thermistor temperature sensor 412 and a user setpoint
adjustment 414. It should be understood that any of the user
setpoint adjustments described herein could take the form of any of
the embodiments therefor known or described herein (e.g. the
variable resistor or the momentary push buttons). The output of
thermistor 412 is electronically coupled to a first voltage
comparator 416 and a second voltage comparator 418. The output of
the user setpoint adjustment 414 is electronically coupled to first
voltage comparator 416 and to a deadband selector dip switch
420.
[0147] Continuing with FIG. 42, the outputs of the voltage
comparators 416 and 418 are electronically coupled to a first "and"
circuit 422. In addition, the output of first voltage comparator
416 is electronically coupled to a first invertor circuit 424 while
the output of second voltage comparator 418 is electronically
coupled to a second invertor circuit 426. The outputs of both
invertor circuits 424 and 426 are electronically coupled to a
second "and" circuit 428. It should be understood that an "and"
circuit is operable to compare two inputs and provide a high output
if the two inputs are high. If either input is low, then the output
of an "and" circuit is low.
[0148] Continuing with FIG. 42, the outputs of both "and" circuits
422 and 428 are electronically coupled to a latch circuit 430. The
latch circuit 430 has two outputs, one that is electronically
coupled to a heating relay 432 and one that is electronically
coupled to a cooling relay 434. Also, the output of a timer circuit
436 is electronically coupled to the latch circuit 430. Finally,
both the output of heating relay 432 and the output of cooling
relay 434 are electronically coupled to a modular plug 438.
[0149] In operation, the voltage output of the user setpoint
adjustment 414 and the output of the thermistor 412 are compared by
both the first voltage comparator 416 and the second voltage
comparator 418. Two comparators are used with a preset and fixed
voltage difference between them because the system must have a
deadband between heating and cooling functions. The deadband
selector dip switch 420 allows selection of the value of this
resistance which ultimately is equal to the temperature difference
or deadband selected by the two comparators 416, 418. For cooling
to occur both the first voltage comparator 416 and the second
voltage comparator 418 must sense that the output of the thermistor
412 is above the output of the user setpoint adjustment 414 and for
heating to occur both the first voltage comparator 416 and the
second voltage comparator 418 must sense that the output of the
thermistor 412 is below the output of the user setpoint adjustment
414. To prevent short cycling, the temperature result is sampled by
means of the timer circuit 436 and the latch circuit 430.
Preferably, the output of the comparators 416 and 418 are latched
approximately once every five minutes. The timer circuit 436 and
the latch circuit 430 prevent a change in the state of the output
of the relays 432 and 434 from occurring for a time interval less
than five minutes.
[0150] Not shown is a switch for the unit fan (such as blower 40)
that can be built into the user setpoint adjustment 414 so that the
fan is turned on whenever the switch is positioned to a particular
setting. The deadband settings selected by the deadband selector
dip switch 420 generally are two degrees and five degrees to comply
with user requirements and ASHRAE requirements. The output of
relays 432 and 434 can be rated for 24 VAC, 1 ampere duty common to
most HVAC applications.
[0151] While all of the embodiments of the thermostat 326 have been
designed and described as being for installation and use in a wall
16, it would be readily understood by one of ordinary skill in the
art and is within the scope of the present invention that the
components of the various embodiments of the thermostat 326 could
be used to control the various systems while contained in a stand
alone device mounted separately on the wall 16 in the manner
typical of the prior art.
[0152] From the foregoing it will be seen that this invention is
one well adapted to attain all ends and objects hereinabove set
forth together with the other advantages which are obvious and
which are inherent to the structure. It will be understood that
certain features and subcombinations are of utility and may be
employed without reference to other features and subcombinations.
This is contemplated by and is within the scope of the
invention.
[0153] Since many possible embodiments may be made of the invention
without departing from the scope thereof, it is to be understood
that all matter herein set forth or shown in the accompanying
drawings is to be interpreted as illustrative of applications of
the principles of this invention, and not in a limiting sense.
* * * * *