Note: Descriptions are shown in the official language in which they were submitted.
CA 02588422 2007-05-11
AUTO-BALANCING DAMPER CONTROL
FIELD OF THE INVENTION
This invention generally relates to control systems for heating and air
conditioning,
and for methods of operating heating, ventilating, and air conditioning
systems for multi-
zone control.
BACKGROUND OF THE INVENTION
Heating, ventilating, and air conditioning (HVAC) systems provide comfort and
convenience for persons using modern residential, commercial and industrial
buildings.
This comfort and convenience comes with a cost, of course, for installing and
operating
the fans, furnaces, and air conditioners that make possible such comfort and
convenience.
There is a great variety of controls for operating these systems, but there
may be room for
improvement in any of them.
A common occurrence in many multiple floor dwellings is that comfort is
sac::f ced for cost in providing for HV A C comfcrt cor.irai and efflvlV llvy.
l llis sal~i t~ Vl
in efficiency usually equates to less than desirable performance for the
temperatures of the
upper and lower floors. The traditional method of improving these symptoms is
to control
or balance the airflow to a favored area. This can be done at additional cost
by using
automated controlled ducting vents to achieve improved temperature balance.
One example is U.S. Pat. No. 5,179,524, which describes a complicated HVAC
system. In this patent, a fan-powered mixing box with a master damper supplies
air from
a heating or cooling unit and sends a variable amount of air to each of a
plurality of zones.
Each zone has its own thermostat and damper for controlling the flow or air,
and thus the
temperature of the zone. While effective, this is a complicated and expensive
system to
install. In addition, the needs of the zones must be balanced since each has
its own
controlling thermostat.
Another way to control temperature and ventilation in a multi-zone facility is
shown in U.S. Pat. No. 5,413,165. Heating and cooling to an upper and a lower
floor are
adjusted by multiple dampers and a thermostat on each level. Temperature
differences
between the upper and lower levels may be evened out by directing air from the
upper
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level to the lower level. However, there may be high temperature differentials
between
the floors.
In another example, U.S. Pat. No. 5,860,473 discloses a climate control system
with separate zones, a separate damper for each zone, and interlocking
controls. Each
zone has its own thermostat and can individually call for heating or cooling.
In this
disclosure, however, if one zone is being heated, the other zones are not
allowed to call for
cooling; or if one zone is being cooled, the other zones are not allowed to
call for heating.
This system provides good control for each zone, but has a very high cost of
equipment
and installation. In U.S. Pat. No. 5,944,098, each zone also has its own
thermostat and
sets of contacts for calling for heating and cooling. The control system,
which does not
allow simultaneous heating and cooling, requires a separate damper for each
zone. This
will also be an expensive system to operate.
What is needed is a heating, ventilating, and air conditioning system that is
simple
and economical to operate, and which is also effective to control the
temperature in at least
two zones of a building.
BRIEF SUMMARY OF THE INVENTION
One embodiment is an automatic balancing damper control system. The damper
control system includes a single set point environmental controller, at least
two
temperature elements, each temperature element located in a separate zone and
in
communication with the environmental controller, and a control output for a
motorized
damper, the damper responsive to the controller and configured to control a
flow of air to
the separate zones, wherein the controller is configured to accept temperature
inputs from
the at least two temperature elements and to send the control output for
adjusting a
position of the damper in accordance with the single set point and inputs from
the at least
two temperature elements.
Another embodiment is an automatic balancing damper control system. The
damper control system includes a single set point environmental controller,
two
temperature elements, each temperature element located in a separate zone and
in
communication with the environmental controller, and a control output for a
motorized
damper, the damper responsive to the controller and configured to control a
flow of air to
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the separate zones, wherein the controller is configured to accept temperature
inputs from
the two temperature elements and to adjust a position of the damper in
accordance with the
single set point and inputs from the two temperature elements.
Another embodiment of the invention is a method for automatically controlling
a
temperature in a building. The method includes setting a single set point for
an
environmental control system, measuring a temperature of each of two zones
controlled by
the environmental control system, and adjustably controlling a flow of air to
the two zones
by adjusting a position of a damper.
Through the various embodiments of the present invention, value of improved
energy conservation is realized. That is, by improving airflow and waste from
over
heating or cooling other zones, an energy value can be realized. Embodiments
of the
system of the present invention also brings value by operating independently
as an
improved air circulatory system. Further, embodiments of the present invention
provides
value of when used to balance or offset natural convection airflow currents.
Other aspects, objectives and advantages of the invention will become more
apparent from the following detailed description when taken in conjunction
with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings incorporated in and forming a part of the
specification illustrate several aspects of the present invention and,
together with the
description, serve to explain the principles of the invention. In the
drawings:
Fig. 1 is a schematic view of a first embodiment;
Fig. 2 is an embodiment of a control scheme for operating a HVAC embodiment;
Fig. 3 is a schematic view of controls for operating an HVAC system according
to
the present invention;
Fig. 4 is an elevational view of a dwelling with an HVAC embodiment; and
Fig. 5 is a schematic view of a building with multiple zones to control.
While the invention will be described in connection with certain preferred
embodiments, there is no intent to limit it to those embodiments. On the
contrary, the
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CA 02588422 2007-05-11
intent is to cover all alternatives, modifications and equivalents as included
within the
spirit and scope of the invention as defined by the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
HVAC systems according to the present invention have a variety of advantages
over conventional systems. Not only do these systems provide for better
control of a two-
zone or multi-zone space, these systems are less expensive to install than
conventional
systems. In addition, retrofits of existing systems are also possible by
merely adding a
damper and a desired number of temperature detecting elements.
A temperature detecting element, also known as a temperature element, is
typically
a thermocouple or a thermistor. A thermocouple or thermistor may be placed in
each zone
and wired back to the HVAC controller. More than one thermocouple or
thermistor may
also be placed in each zone for closer control of the temperature in the zone.
It is
important to note that in various embodiments of the present invention, these
temperature
elements need not be thermostats, i.e., they need not be temperature
controllers. They are
merely detecting elements, detecting a nearby temperature and reporting the
temperature
to the HVAC controller. If it is desired, remote temperature elements in
communication
with the controller and not requiring wiring may be used instead. These
temperature
elements may communicate with the controller via an infrared link or a
wireless radio-
frequency (RF) link.
Fig. 1 depicts an HVAC system embodiment according to the present invention.
HVAC system 10 includes a controller 11, typically a microprocessor
controller, and a
thermostat 11 a, for setting a temperature set point for the system. The
system includes a
motor 12 and a damper 13 controlled by controller 11. Adjusting the position
of the
damper regulates or balances the flow of air from an HVAC system, such as a
furnace
with an air conditioning coil. The damper is preferably located at the outlet
of the furnace
plenum. This improved HVAC embodiment then has two separate outlet plenums,
one to
each zone. In this case, there is a lower plenum 18 for a lower floor of a
dwelling or
building, and an upper plenum 19 for an upper floor of the dwelling or
building. The
upper and lower floors each have a temperature sampling device 14, 15, such as
a
thermocouple, that is in communication with the controller 11.
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The controller receives signals from the temperature sampling devices and uses
these signals, a temperature set point, and a control algorithm stored in the
controller or in
a memory attached to the controller, to automatically turn on heating or
cooling from the
HVAC system and to adjust the position of the damper. A variety of control
algorithms
may be used in deciding the position of the damper, and how the damper control
is
integrated with the furnace/air conditioning controls. For example, the
purpose of having
a two-zone control is to equalize the temperatures in the zones. That is, the
control
algorithm may attempt to equalize the temperatures in the zones within a
certain range,
e.g., two degrees F. In one embodiment, if the temperature elements within
the two
zones are within two degrees of each other, say 70 F and 72 F, the controller
will make no
adjustments to the damper.
In this embodiment, the algorithm may be designed so that if the temperature
difference is three degrees or more, and the HVAC fan is running, the damper
position
will adjust a certain amount to route more air to the level requiring
additional heating or
cooling. The algorithm should he integrated with the control system for the
fiirnacP/air
conditioner, which will decide whether additional cooling or heating for both
zones is
required upon reaching a certain differential from the set point. Any desired
algorithm,
such as a proportional, integral and derivative (PID) algorithm, may be used
to control the
damper position and thus to adjust the relative temperatures of the zones.
A diagram outlining this HVAC control scheme is depicted in Fig. 2. Control
scheme 20 begins with a step 21 of sampling the temperatures of an upper and a
lower
floor of a building. Alternatively, the two zones may be on the same level of
a building,
such as a home, an office, or a retail store. The temperature information is
sent to a
HVAC controller with a control algorithm. The controller calculates the
difference
between the set point temperature and the temperatures indicated in the zones.
The
controller then calculates whether the zones require 22 heating or cooling.
The control
scheme then looks at the differential between the upper and lower temperatures
to see
whether the damper should be adjusted to favor (i.e., send more air to) the
lower level 24
or the upper level 25. If necessary, the controller directs a damper
adjustment. For
example, if the season requires heating and the lower level is cooler than the
upper level,
the damper position will move to allow more heated air to flow to the lower
level. If the
CA 02588422 2007-05-11
season requires cooling and the lower level is cooler than the upper level,
the damper
position will move to allow more cooled air to flow to the upper level. After
this iteration,
the control scheme will then return 25 to the main program 21 and the sampling
and
control cycle begins again.
Embodiments are not limited to the ones already described. For example, if the
zones are large, or if one zone is large, more than one temperature element
may be located
in a zone. Fig. 3 depicts an embodiment in which each zone has two temperature
elements. Environmental control system 30 includes a control housing 31 with a
microprocessor controller 32 which may include a memory. This system includes
a single
thermostat 34 for controlling a temperature. Each zone may have two or more
temperature
elements, preferably located separately in the zone. In this zone, the first
floor F 1 has two
temperature elements 35, 36 and the second floor F2 also has two temperature
elements
37, 38. The controller receives signals from the temperature elements and uses
this
information, the set point of thermostat 34, and a control algorithm to
determine and adjust
a position of damper 37.
The control algorithm may use the temperatures and the temperature differences
in
each zone in any desired manner. For instance, the algorithm may average the
two
temperatures on each floor or zone and make damper adjustments based on the
averages.
Control over the system temperature may be kept tighter if the algorithm uses
the extremes
of the temperature differences to adjust damper position. In such an
embodiment, there is
only one thermostat controlling the temperature set point. The temperature
elements in
this embodiment are not thermostats and do not independently control a
temperature. The
control system accepts inputs from a plurality of temperature elements and
uses these
inputs to calculate whether heating or cooling is required, and also to
calculate a desired
position of the damper. The control system then activates heating, cooling, or
an
adjustment of the damper position.
A preferred embodiment of an HVAC system is disclosed in Fig. 4. HVAC system
40 is installed in a two-zone building 41 that includes a first floor or zone
42a and a
second floor or zone 42b. Each zone has an HVAC air inlet plenum 47a, 47b, a
cold air
return 48a, 48b, and a temperature element 49a, 49b. The temperature elements
are in
communication with system controller 43, which is also in communication with a
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thermostat 43a which determines a temperature set point for the building. The
HVAC
system includes a furnace 45 with an air conditioning coil which is used to
heat and cool
building 41. Furnace with air conditioning coi145 receives the cold air
returns 48a, 48b
and blows heated and cooled air outputs through outlet plenum 46a, which is
located
directly atop furnace 45 and is split into zone inlet plenums 47a, 47b.
Motorized damper
46b is located directly atop plenum 46a for economy of installation.
Embodiments are not limited to two zones. The advantages of the present
discovery may be embodied in systems with more than two zones. An example with
three
zones is depicted schematically in Fig. 5. An HVAC system 50 for controlling
more than
two zones includes a controller 51, preferably a microprocessor controller
which may
include a memory for storing at least an algorithm for operating the system.
The system is
controlled by a single thermostat 51 a by which controller 51 receives a set
point for
heating or cooling. The heating and cooling, as well as ventilation, are
provided by
furnace 52 which includes heating elements and an air conditioning coil. A fan
53 moves
air that is heated or cooled or ventilates the buildine usinia system 50.
Furnace plenum 56 is preferably mounted atop furnace 52. First damper 57,
mounted atop plenum 56, splits the flow of air between first floor or zone 54a
and second
and third floors or zones 54b, 54c. Second damper 58 is mounted downstream and
further
splits the air stream between second and third floors 54b, 54c. The positions
of the
dampers are controlled by controller 51 using temperature signals received
from
temperature elements 55a, 55b, 55c located in each of the floors or zones. The
position of
damper 58 is controlled primarily by the difference between the temperatures
of elements
54b, 54c. The position of damper 57 is controlled primarily by the difference
between the
temperature of element 55a and the remaining temperature elements.
System 50 uses only a single HVAC temperature setting to control multiple
zones.
System 50 controls the temperature of the multiple zones, automatically
balancing the
temperatures of the zones, by using at least one temperature element in each
zone, and a
number of dampers that is equal to the number of zones, less one damper. As
noted
above, more than one temperature element may be used if the individual zones
are large,
or if only one zone is large and a closer degree of control over the damper(s)
that control
the flow of air to that zone.
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All references, including publications, patent applications, and patents cited
herein
are hereby incorporated by reference to the same extent as if each reference
were
individually and specifically set forth in its entirety herein.
The use of the terms "a" and "an" and "the" and similar referents in the
context of
describing the invention (especially in the context of the following claims)
is to be
construed to cover both the singular and the plural, unless otherwise
indicated herein or
clearly contradicted by context. The terms "comprising," "having,"
"including," and
"containing" are to be construed as open-ended terms (i.e., meaning
"including, but not
limited to,") unless otherwise noted. Recitation of ranges of values herein
are merely
intended to serve as a shorthand method of referring individually to each
separate value
falling within the range, unless otherwise indicated herein, and each separate
value is
incorporated into the specification as if it were individually recited herein.
All methods
described herein can be performed in any suitable order unless otherwise
indicated herein
or otherwise clearly contradicted by context. The use of any and all examples,
or
exemplary language (e.g., "such as") provided herein, is intended merelv to
better
illuminate the invention and does not pose a limitation on the scope of the
invention unless
otherwise claimed. No language in the specification should be construed as
indicating any
non-claimed element as essential to practicing the invention.
Preferred embodiments of this invention are described herein, including the
best
mode known to the inventors for carrying out the invention. Variations of
those preferred
embodiments may become apparent to those of ordinary skill in the art upon
reading the
foregoing description. The inventors expect skilled artisans to employ such
variations as
appropriate, and the inventors intend for the invention to be practiced
otherwise than as
specifically described herein. Accordingly, this invention includes all
modifications and
equivalents of the subject matter recited in the claims appended hereto as
permitted by
applicable law. Moreover, any combination of the above-described elements in
all
possible variations thereof is encompassed by the invention unless otherwise
indicated
herein or otherwise clearly contradicted by context.
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