Note: Descriptions are shown in the official language in which they were submitted.
AUTOMATED BYPASS CONTROLLER FOR HEATING, VENTILATION, AND
COOLING SYSTEMS
TECHNICAL FIELD
[0ool] The present disclosure relates to methods, techniques, apparatuses
and
systems for controlling roof mounted ventilation systems and, in particular,
to
methods, apparatuses techniques, and systems for automatically controlling
economizers in rooftop HVAC appliances to control outside air intake.
BACKGROUND
[0002] Existing heating, ventilation, and cooling (HVAC) systems are
commonly
installed on rooftops of buildings and control the input of outside air and
the mixing
of outside air with vented air from the building (return air flow) to deliver
heated or
cooled air to the building. Economizers, such as the Honeywell Jade TM,
Siemens
P0L220, and Johnson Controls PEAKTM economizers, reduce air conditioning costs
by using free outside air (OA) for free cooling rather than mechanically air-
conditioned air. Economizers simply cause the HVAC compressor to run less
often.
Economizers move the dampers (louvers that allow outside air to flow into the
HVAC
unit) towards maximum ventilation position when outside air conditions are
favorable
for cooling and towards minimum ventilation position when outside air
conditions are
not. Programming, environmental sensors, and mechanical connections must be
installed properly and optimally for an economizer system to effectively save
energy
and money for a building.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Figure 1 is an example block diagram of an existing rooftop HVAC
unit.
[0004] Figure 2 is an example block diagram of rooftop HVAC unit modified
to
include an Economizer Bypass Controller.
[0005] Figure 3 is an example block diagram of components of an example
Economizer Bypass Controller.
[0006] Figure 4 is an example Economizer Bypass Controller board showing
example inputs and outputs.
[0007] Figures 5A-5D is flow diagram of example bypass mode and override
selection routine of an example Economizer Bypass Controller to provide bypass
and override capabilities between an economizer and a damper actuator.
[0008] Figure 6 is an example flow diagram of an increased ventilation
mode routine
of an example Economizer Bypass Controller using a temperature sensor to
modulate increased damper ventilation.
[0009] Figure 7 is an example flow diagram of an increased ventilation
mode routine
of an example Economizer Bypass Controller using a CO2 sensor to modulate
increased damper ventilation.
[cm o] Figure 8 is an example flow diagram of a passthrough pulse mode
routine of
an example Economizer Bypass Controller that provides increased ventilation
for
set cycles of time (pulsed increased ventilation).
[0011] Figure 9 is an example flow diagram illustrating handling of
floating controller
economizer adaptation.
[0012] Figure 10 an example block diagram of an example Economizer Bypass
Controller as a computing system used to communicate in a networked
environment.
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DETAILED DESCRIPTION
[cm 3] Existing HVAC Economizers are designed to minimize energy use.
They are
designed to use as much outside air as possible rather than
mechanically processing a building's recirculating air, whenever it makes
economic
sense to do so. Their automated nature, in conjunction with improvements in
construction and the strong economic incentive to buy as little energy as
possible,
along with the moral imperative to do what's right, has resulted in highly
efficient buildings. However, these highly efficient buildings do not
necessarily
produce healthy building environments. For example, a phenomenon known as
"sick building syndrome" has emerged in which building occupants experience
acute
health and comfort effects that appear to be linked to time spent in a
building, but no
specific illness or cause can be identified. In addition, HVAC economizers
have no
knowledge of emergency conditions and therefore cannot adapt to such. For
example, they are unable to adapt to health emergency conditions such as to
increase ventilation responsive to, for example, a COVID-19 pandemic where
greater outside air is desirable or to decrease ventilation as responsive to,
for
example, smokey conditions of a wildfire wherein outside air is undesirable.
[cm 4] As well, a building that is too uncomfortably ventilated (either
as too hot or
too cold) is difficult to occupy. Increased ventilation accomplished by simply
opening
windows does not solve the aforementioned difficulties because it is
economically
impractical to heat or cool every building while windows are wide open.
Moreover,
existing installed HVAC systems aren't necessarily equipped with sufficient
"horsepower" to comfortably maintain temperatures with all of the windows
open,
even if it were economically feasible to do so.
[cm 5] Embodiments described herein provide methods, techniques, and
apparatuses for controlling HVAC ventilation using a bypass mechanism called
the
Economizer Bypass Controller ("EBC"). A particular example implementation
described herein is called the EconologixTM Economizer Bypass Controller. The
EBC is designed to be installed into any HVAC (rooftop) system, regardless of
the
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capabilities of the economizer. Thus, it may be installed in systems varying
from
simple to complex. The EBC provides "bypass functionality" as needed between
an
economizer and a damper mechanism to control the amount of outside air
ventilation
regardless of what the actual economizer is set up to do. Thus, the EBC can be
used to meet ASHRAE (American Society of Heating, Refrigerating and Air-
Conditioning Engineers) safety standards as they evolve, OSHA, and CDC
guidelines as well as temporary or permanent health emergency bypass
strategies
such as to address increased or decreased ventilation needs due to, for
example,
pandemic emergencies or smokey conditions from wildfires. As well, the EBC can
implement bypass strategies to address other communications or control such as
a
vacation setting capable of shutting down the system for some period of time,
remote
controlled overrides, or based upon detection of "alarm" conditions (a sensor
sensing that some aspect of the HVAC unit is not working properly).
[cm 6] An EBC installation provides its own temperature and environmental
sensors
to enable the EBC to operate regardless of the capabilities and structure of
the
economizer. Therefore, the EBC can be effectively retrofitted into an existing
HVAC
rooftop unit as well as placed in a new HVAC installation. In addition, the
EBC can
be used with any kind of economizer including "dumb" economizers up to
electronically smart controlled economizers. Moreover, the EBC is economizer
agnostic and damper mechanism agnostic because it sits between the outputs of
the economizer and generates inputs to the damper mechanism. It includes a
variety of bypass modes, including the ability to simply pass through the
existing
economizer signal, and includes a variety of special override conditions,
which can
be used to override the bypass conditions as well as other override conditions
depending upon how the modes and overrides are configured.
[cm 7] In an example EBC installation, there are at least two temperature
sensors.
One sensor is placed to sense the temperature of the air entering the
mechanical
cooling section of the HVAC unit to control the dampers to prevent the cooling
coils
from freezing. The second temperature sensor is placed to sense the
temperature
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of the return air as a proxy measurement for the air temperature in the
building
(occupied spaces) to determine when to stop certain bypass modes (e.g., full
open
dampers) because the HVAC system cannot keep up with cooling/heating needs to
regulate the occupied space temperature. Some bypass (and bypass override)
modes take these temperatures into account, others do not.
[0018] Several types of environmental sensors may also be present in an
EBC
installation, including sensors for detecting and monitoring CO2, CO, VOC,
S02, and
NO2. Other sensors may also be similarly incorporated.
[0019] Figure 1 is an example block diagram of an existing rooftop HVAC
unit.
HVAC roof top unit (RTU) 100 comprises an economizer controller 101 and damper
unit 104 arranged in a feedback loop. Outside air 110 enters the damper unit
104
through damper louvers 106, which are controlled by a damper actuator 105. The
economizer controller 101, based upon temperature and environmental sensor
input
103, controls the opening and closing of damper louvers 106 by controlling the
damper actuator 105. It's a closed-loop system designed to meet some
predefined
goal; return air from the building 111 is mixed in the air mixer and other
HVAC
components 102 with some controlled amount of outside air 110, and the
resultant
mixed air 112 is sent back into the building. When the damper louvers 106 are
fully
shut, the indoor building air is recirculated. When the damper louvers 106 are
fully
open, cool air is mixed with building air to service the building.
[0020] In general operation, the RTU (or indoor air handler) 100 is
notified by a
thermostat to cool a building. If an economizer 101 is present, and the
outside air
110 is better than recirculated indoor air for cooling the building, the
outside air
damper 104 will open to allow the outside air 110 to enter the building. This
is
referred to as "Free Cooling" because the condensing unit compressor in the
HVAC
unit 100 is not required to run (or at least not as often) to cool the space.
Other than
a fan or blower, no energy is consumed, and therefore minimal cost is incurred
to
cool the building. Anytime the conditions outdoors are better than indoors
(cooler
and/or drier), "Free Cooling" is available. Only when the outdoor temperature
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Date Recue/Date Received 2022-04-13
to 56 F or lower and the indoor heat is removed do you get "True Free
Cooling." If
the outside air temperature is not cool enough, or in some cases a high level
of
humidity is present, the economizer 101 will not open the damper louvers 106
and
the cooling will have to be achieved mechanically (through the compressor).
[0021] An example economizer (for example, an existing Honeywell
device)
measures inside and outside air temperatures and other parameters and controls
the dampers to maximize energy efficiency targeting the goal of "True Free
Cooling."
Extensive programming, electrical wiring, and mechanical connections are
employed to create an actual working economizer system. It is well recognized
that
outdoor air can be both healing or harmful depending on what is happening both
outside and inside a building. The United States Environmental Protection
Agency
(EPA) and other advising bodies have issued advice for indoor air quality that
advocates, in one case, minimizing fresh air intake into building and, in
another case,
maximizing fresh air intake during temporary emergency health conditions.
[0022] This advice is not contradictory. In the case of mitigating the
risk of spreading
airborne illnesses such as the COVID-19 virus, it is important to maximize
fresh air
intake to reduce potential airborne transmission of the virus. See for
example,
"https://www.epa.gov/coronavirus/indoor-air-and-coronavirus-covid-19". In the
case
of wildfire smoke affecting indoor air quality, it is important to minimize
fresh air
intake
"https://www.epa.gov/indoor-air-quality-iaq/wildfires-and-indoor-air-quality-
iaq" to minimize smoke exposure to the building occupants.
[0023] Figure 2 is an example block diagram of rooftop HVAC unit
modified to
include an Economizer Bypass Controller. HVAC RTU 200 is shown with the
existing closed feedback loop described with reference Figure 1, including the
existing economizer controller 101, temperature and environments sensors 103,
damper unit 104, and air mixer and other HVAC components 102. HVAC RTU 200
is an improved HVAC unit modified to include the Economizer Bypass Controller
202
(the EBC). The EBC 202 is located between the economizer controller 101 and
the
damper unit 104. It is wired to intercept output signals from the economizer
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controller 101, perform bypass computations based upon them, and subsequently
output signals to control the damper actuator 105 to either close, open, in
full or in
part, the damper louvers 106 to control the amount of outside air 110 intake.
In this
manner, the EBC 202 is able to "bypass" the effects of the economizer
controller
101 when it is deemed appropriate to do so.
[0024] Adding an EBC 202 to the control circuit for controlling a damper
unit 104
adds several features including the ability to bypass an economizer for
health,
wildfire, or other emergency reasons. For example, to address a COVID-19
emergency, the EBC 202 leverages an existing economizer's energy savings
strategy while overlaying a temporary health emergency bypass strategy to
maximize outside air ventilation. Similarly, to address a wildfire emergency,
the EBC
202 leverages the existing economizer's energy savings strategy while
overlaying a
temporary health emergency bypass strategy to minimize outside air
ventilation.
[0025] The EBC 202 also solves current issues that attempt to employ
opening or
closing windows to control air temperature. A building that is too
uncomfortably
ventilated (either as too hot or too cold) isn't worth occupying. Nor does the
world
have enough money to heat or cool every building while the windows are wide
open.
Nor is there necessarily enough HVAC horsepower in an already installed system
to comfortably maintain temperatures with all those windows open, even if one
had
the money.
[0026] Currently, in response to health emergencies, a typical protocol
involves:
(1) Upon detection of an initial emergency condition:
= Reprogram economizer to emergency mode
= Modify electrical control wiring
= Modify mechanical connections
(2) Upon notification of an end of the emergency condition:
= Reprogram economizer to initial setting
= Un-Modify electrical control wiring
= Un-Modify mechanical connections
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each time an emergency occurs.
[0027] Instead, the addition of an EBC 202 to the RTU 200, allows a
revised protocol
that involves:
(1) Upon detection of an initial emergency condition:
= Add EBC to control wiring
= Switch to EBC Bypass Mode
(2) Upon notification of an end of the emergency condition:
= Switch to EBC Passthrough Mode
[0028] Of note, once an EBC 202 is added to a roof top unit 200, it can
be controlled
using a variety of mechanisms including remotely, by a computer system
connected
via a network (wired or wirelessly), mechanically, through a remote control
device,
and the like. In "Bypass Mode" the damper unit 104 can be controlled by local
manual adjustment by local programming. In "Passthrough Mode" the economizer
controls the damper using its normal energy efficient strategy.
[0029] Thus, the EBC provides a unique solution to controlling bypassing
the
economizer controller 101 transparent to the occupants in the building. To
provide
this bypass capability, the EBC offers a variety of EBC ventilation modes,
discussed
further below with respect to Figures 5A-8, that determine, based upon
received
inputs from its own bypass controller temperature and environmental sensors
201,
whether to pass the signal along directly from the economizer controller 101,
produce a different signal, or override one of its own bypass modes (or
further its
own other override settings). By including its own bypass controller
temperature and
environmental sensors 201, the EBC 202 is able to perform totally
independently
from any existing economizer controller 101 and as such is economizer
controller
"agnostic." The EBC 202 can be added to a completely operational, well-tuned
economizer system and still choose the best bypass mode to produce the best
results. Alternatively, EBC 202 can be attached to an inoperative,
malfunctioning,
missing, inefficient, or obsolete economizer that does nothing or little to
nothing,
select a simple EBC ventilation mode, and still produce a solution that meets
real
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needs for increased ventilation in emergency enhanced ventilation COVID times
or
reduced ventilation in smoke condition times. That means that existing
economizers
that are designed to be efficient can be nudged off that design point towards
increased ventilation for COVID safety and decreased ventilation for smoke
conditions by the EBC 202. Thus, the EBC 202 can operate virtually anywhere
and
in virtually every situation.
[0030] In one example EBC 202, the sensors 201 are at the end of six-foot
cables
(or at least at a sensical length) so they can be stretched out and reach into
the
correct physical space in and around the air mixing device 102. These cables
are
shown as return air temperature cable 204 and outside air intake temperature
sensor
cable 203. The outside air intake temperature sensor cable 203 is placed to
sense
the temperature of the air that is entering the mechanical cooling section of
the
HVAC unit 102. If that air gets too cold because of its percent of outside air
then no
matter what the economizer controller's goal or the EBC's goal, the damper
louvers
106 must be throttled down so that the cooling coils of the HVAC unit 200
don't
freeze. The other temperature probe attached to cable 204 is placed to sense
the
temperature of the return air from the building 111. Return air temperature is
a pretty
good proxy measurement for the air temperature in the occupied spaces (in the
building).
[0031] Accordingly, the EBC 202 uses the input from the sensor attached
to cable
204 to measure return air temperature from the building to signal to the EBC
202
when it is time to stop overriding the existing economizer control signal. For
example, the EBC 202 may use this signal to stop overriding (bypassing) the
economizer control signal to force increased ventilation, because there isn't
enough
energy in the HVAC system 200 to keep the space temperature at a particular
level,
and by proxy the return air temperature 111, at a stable setting.
[0032] Other EBC bypass ventilation modes do not take the return air
temperature
into consideration. They are designed to address the cases such as where a
relevant
authority dictates a condition something like, "fix the outside air damper at
82.5%
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open." or "never let the dampers close to more than 77% open." There are many
different modes available and contemplated, even those beyond those discussed
here.
[0033] Figure 3 is an example block diagram of components of an example
Economizer Bypass Controller. The EBC 202 shown in Figure 3, is one with a
plethora of components that can interface to other devices as do other
computer
systems. An example EBC 202 such as the ECONOLOGIXTM Economizer Bypass
Controller may take a variety of forms. Other versions of an EBC 202 include a
subset of one or more of these components including a simplified device that
is
controlled without using a microprocessor. The examples described here are
often
regarding those that have a fully equipped EBC, but it is to be understood
that they
too can be simplified although in some instances this will impact available
functionality. For example, a very simplified EBC without a microcontroller
will likely
not be controllable by a remote control device.
[0034] The example EBC 202 illustrated includes EBC logic (computer
instructions
301), an input control signal 302, temperature sensor and contact closure
inputs
303, analog inputs 304, output control signals 306, and relay and relay
control output
305. In addition, many other components 310 may be present, including computer
system controller components 311, hardware interfaces, displays and switches
312,
bi-directional communication modules 313, communications modules 314, other
common modular computing components 315, and other modules 316.
[0035] In one example EBC 202, the input control signal 302 comes from an
existing
economizer controller such as economizer controller 101 and contains the 0-
10V, 0-
20mA, pneumatic, floating, or other standard industrial control signal that
controls
the existing economizer damper unit 104 by sending signals to damper actuator
105.
[0036] The simplest bypass (override) EBC ventilation modes do not use
this signal.
Other EBC ventilation modes use this signal to apply all the existing system
"brains"
for most effective control of the existing economizer dampers under the
selected
bypass override mode.
Date Recue/Date Received 2022-04-13
[0037] The temperature sensor and contact closure inputs 303 map to the
EBC
temperature and environmental sensors 201 in Figure 2. This allows the EBC 202
to operate independently of the existing economizer control with respect to
basic
temperature inputs as explained above. Two fundamental temperatures are needed
to be sensed by the EBC: the temperature of the air blowing into the cooling
section
(as measured via cable 203). If this air is too cold the cooling section of
the HVAC
unit 200 could freeze up. The other fundamental temperature is the temperature
of
the air returning from the occupied spaces (as measure via cable 204), which
as
explained is used as a proxy for the temperature within the occupied spaces.
[0038] As well, the engineering of temperature sensing also allows these
inputs to
detect short and open circuits. Therefore, unused temperature inputs can be
used
as "dry" switch contacts. A "dry" switch contact is a simple switch closure
that carries
no voltage or current. It simply connects an open or short circuit between the
contacts. This method of interfacing industrial devices leverages the existing
system
design requiring only a simple switch.
[0039] Other universal inputs (e.g., analog inputs 304), for example that
input signals
in the 0-10V range can be used to improve the performance of the EBC by adding
additional information. Examples of signals that can be attached to universal
inputs
include CO, CO2, VOC, S02, and NO2 level monitoring signals, switching
signals,
humidity level signal. However, many of these inputs are digital networked
devices
so the input will come as digital information over the network connection.
[0040] Using the two input types, including the temperature sensor inputs
that can
detect open and closed circuits and the 0-10V universal inputs, the following
inputs
can be measured:
- Signal to close damper for emergencies, fire, maintenance.
- Signal to open damper for building flush operations.
- Signal to force passthrough mode operation.
- Signal showing building occupancy.
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- Signal implying "bad" air, perhaps high CO2 or other compounds, long
occupied time without flush, occupancy levels.
- Signal showing heat energy of air (Enthalpy Sensor).
- Other signals that become available.
Existing HVAC systems implement these communication signals in a variety of
ways
depending on the existing HVAC system's design. For example, the building
occupied signal, a simple two-state "yes" or "no" signal can be implemented in
a
variety of ways. It might be implemented as a "dry switched" open or short
circuit, a
0 or 10VDC signal, or a 0 or 24VAC signal (switching of the same voltage that
powers the EBC as it might be the only non-zero electrical signal available).
These
signals are equally valid ways to represent the building occupied state and
they are
easily transduced from one to another. Depending upon the hardware available
in
any specific EBC implementation, this type of signal can be detected in
multiple
ways. A CO2 level input, as a contrasting example, is a true analog signal
where a
specific voltage represents a specific CO2 level. Therefore, analog CO2
signals must
be received from a universal 0-10V input.
[0041] When advanced, network communications are available in an EBC and
connected to reliable networked sensors and a reliable network, all the inputs
could
come from networked sources, instead of, in addition to, or in some mix with
the
analog inputs 304.
[0042] The EBC logic 301 is where all the work of the economizer bypass
controller
occurs. The EBC logic 301 includes the circuits, processor, memory,
components,
logic, firmware, circuits, and/or software to implement the bypass and
override mode
functions as described further below.
[0043] The output control signal 306 is the reconstructed input control
signal 302 as
modified by the logic 301 implemented in the selected mode connecting to the
damper actuator 105. Thus, signal 306 is sometimes referred to as the
"calculated"
output signal. This signal will be of the same format as the signal from the
existing
economizer controller 101. The existing damper actuator 105 will not "know"
that the
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calculated output signal coming from the EBC is anything other than its input
control
signal (it is the same to the damper actuator 105 regardless of whether its
input
control signal comes from the existing economizer 101 or the EBC 202).
[0044] In some EBC 202 examples, additional analog output signals (not
shown) are
made available depending upon the hardware available in any specific EBC
implementation. For example, the EBC 202 can output analog information
pertaining to the performance of the EBC 202 itself. For example, when
operating
as a "floating control" device, the equivalent analog output (e.g., 0-10V
representing
0-100% damper opening) can be produced for display or confirmation. Other
examples of outputs include self-detected error or alarm indications, such as
a
temperature probe failure or a temperature out of range notification.
[0045] Relay and relay control output 305 is used when the EBC 2020 is
operating
as a floating control device. The relays are used to manage the open and close
actuator signals for the damper actuator 105. The relay and relay control
signals
305 can be used to provide alarm notification as well. The difference between
the
relay and relay control signals is that the relay control signal is a logic
level signal
that is "ON" when the relay is energized. This logic-level signal can be used
directly
for signaling if it is more convenient than the relay outputs, or it can be
used to power
SCR switching devices.
[0046] Other components 310 may be present. For example, computer system
components 311 contains all the physical hardware, firmware, circuit, and
software
components necessary and traditional for implementing, developing,
maintaining,
updating, and using computing device-based controller. When reducing the
features
of an EBC 202 down to those can be implemented without a processor components
311 represents the pedestrian components that are necessary and traditional
for
creating a non-processor-based controller.
[0047] Onboard hardware interfaces, displays and switches 312 comprises
the
important user feedback and control components of the EBC 202. Other
bidirectional
communication methods may exist but it is always important to have some level
of
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user control and feedback at the physical device level. Because these user
interface
components are implemented in hardware it is important to keep them simple and
low-cost yet sufficiently powerful to control and understand the device.
[0048] Bi-directional communication modules 313 comprise multiple
physical
communication methods, hardware, and interfaces that have become standard and
traditional on computing devices. More and more are "free" on microcomputing
platforms. Some are limited by speed or distance, others can connect to the
internet
and distance becomes irrelevant.
[0049] Communication modules 314 includes many types of network and other
communications logic, protocols, and interfaces for connectivity purposes. For
example, following logic, drivers, interfaces, etc. may be present in any EBC
implementation:
- Serial - Long tradition of use in computer systems and industrial control
applications. Extremely cheap and can transmit information over long
distances using an inexpensive 3-wire cable. There is no "standard"
communication protocol for serial communications. Logic Level, RS-232,
and RS-485 signal levels are possible with appropriate hardware
implementations.
- I2C - A serial bus protocol that is usually used within an imbedded
controller device but can be used to extend the capacity of the device with
other input and output peripherals over a very short distance, no more
than a few meters.
- SPI - Another serial protocol that has been a standard for a very long
time. Also for short distance communications. Faster than I2C but has 4
wires.
- USB - The Universal Serial Bus is the most common interface between
computers and other devices. Often the USB cable is used for the power
feature that is part of the specification.
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- Bluetooth - A standardized wireless technology use for sending data
between two devices using radio waves.
- Ethernet - A physical wire connection that allows computing devices to
connect to the internet.
- WiFi - A standardized wireless technology that allows computing devices
to connect to the internet without a cable.
[0050]
Over the internet connections there are a variety communication protocols
that have been implemented, some proprietary, some open. The Ethernet
Industrial
Protocol, or Ethernet/IP, uses the open Ethernet link layer (wires and WiFi)
and
Internet Protocol networking layers with the potentially additional
applications layers
below:
- Modbus TCP - An extension of the standard Modbus communication
protocol that operates over the internet is considered by many to be the
de facto standard of industrial electronic devices.
- OMG - An IOT protocol that is currently in the process of becoming a
recognized standard.
- BACnetTM - This protocol is specifically designed for Building Automation
and Control networks for applications such as HVAC, lighting, access, fire
detection, and related control. This protocol allows all devices to share
information without regard to the service they perform. ASHRAE
(American Society of Heating, Refrigerating and Air-Conditioning
Engineers) owns the BACnetTM protocol.
- MQTT - The Message Queuing Telemetry Transport protocol is an ISO
standard protocol that transports messages between devices used
primary in the IOT industry. Products like IBM's Node-RED development
tool use this protocol. It is being implemented in more and more
automation and control applications.
Date Recue/Date Received 2022-04-13
- EtherCAT (Ethernet for Control Automation Technology) - An open-
source protocol optimized for automation requiring fast data
communication times. It promises reduced hardware costs.
- Ethernet Powerlink - A real-time protocol for standard Ethernet.
- CC-Link Open Automation Networks - Originally developed by Mitsubishi
Electric Corporation and released as an open network so that others could
incorporate the standard into their products. It is interoperable with
PROF IN ET.
[0051] It is noted that newer sensor technology likely will move towards
digital
networked protocols, especially for sensors that require significant
electronics to
implement. Some such sensors include CO, CO2, VOC, S02, NO2, and humidity
level signals. Even simple temperature sensors will probably move towards
digital
network protocols rather than analog signals as they can be monitored in
multiple
locations without additional wiring.
[0052] The bi-directional communications physical modules 313 in
conjunction with
one or more of the communication modules 314 (protocols, languages, logic,
etc.)
support output datalogging of all input data, output data, and internal device
performance data. The physical communication method and the protocol format of
the datalogging is controllable to the extent of the capacity of the hardware
and
software implementation supported by modules 313 and 314. Combining output
datalogging and a remote control interface using the capabilities of the
components
313 and 314 allows for the possibility of implementing totally new algorithms
in the
cloud" in other EBC implementations. For example, it is contemplated that
cloud-
based software could integrate weather conditions and predictions using
existing
internet sources and implement adaptive, "intelligent" strategies for further
EBC
ventilation modes. Further, integration with internet-enabled building sensors
that
may or may not even exist could be implemented and incorporated in an EBC.
[0053] Other common modular computing components 315 may also be present
in
some example EBCs. Some modular microcontroller designs have become so
16
Date Recue/Date Received 2022-04-13
integrated that other common computing modules are almost "free". In the
context
of the EBC some of the modules that are useful include a SATA and SD Bus for
non-volatile input and output datalogging as well as storing internal device
performance data. This is useful for evaluating the performance of the
existing
economizer controller and the EBC in the actual context. Having audio capacity
can
improve the human interface. The TFT display modules can provide plug-in
enhanced displays for maintenance work. The addition of a camera has can
provide
remote inspection capacity that would lower maintenance costs.
[0054] An important modular computing component for higher-end EBC
implementations is an on-board battery backup mechanism to ensure the
computing
device has enough powered time after loss of power to bring the control signal
outputs, alarm signal outputs, by-directional communications subsystems (and
the
last alarm messages to be sent out over them), and the device's own operating
system to a clean, ready-to-be-shutdown state. This interacts with the fault
detection
and compliance block when appropriate.
[0055] Other modules 316 may also be included in an EBC implementation.
For
example, the EBC 202 may also include (not shown) pre-programmed sequences
(which are stored), scheduling and remote control interface. Pre-programmed
damper control sequences provide shortcuts for maintenance and emergent
situations. Typical damper actuators take over 90 seconds to completely open
or
close the dampers. Pre-programming sequences translate directly into time
savings
for technicians on the roof. Coupled to a modular camera and an internet
connected
device, remote maintenance can be applied to HVAC systems that are difficult
and
expensive to check more than absolutely necessary. Further, pre-programmed
sequences can be initiated by relatively untrained people because the human
interface skills needed to activate a pre-programmed sequence are much simpler
than the specialized training needed to open up and tinker with a running HVAC
device.
17
Date Recue/Date Received 2022-04-13
[0056] The scheduling and remote control interfaces (not shown) is a
generalization
of the pre-programmed sequences function that can be implemented on
sufficiently
powerful EBC implementations that allows for an arbitrary schedule of mode
changes, pre-programmed sequence changes, and parameter changes. These
schedule elements are stored in the EBC device's memory so that they can be
implemented even if communications are not working. Examples of scheduling
events may include work week / weekend schedules, holiday schedules, scheduled
maintenance, and the like.
[0057] Secure remote control operations allow for both complete remote
setup of the
device and ad hoc mode, pre-programmed sequence, and parameter changes. With
sufficiently clever remote-control software, robust scheduling, including
integration
to external scheduling software, can be implemented in an EBC. Additionally,
with
sufficiently clever remote-control software, ad hoc maintenance, testing,
verification,
and override operations can be implemented. The industry term, "Direct Digital
Control" (DDC) describes this lowest level of control. Over time and
manufacturer
implementations, the term DDC describes the idea that the EBC can be fully
controlled remotely.
[0058] Pre-programmed sequences, scheduling, and remote control interface
capacity are implemented may be present in a variety of EBC devices, all the
way
down to the most simple hardware implementation where only serial output is
available.
[0059] In some example EBCs, fault detection and reporting is available.
In some
example EBCs, the EBC translates specific measured faults and creates alarm
notifications via email, universal outputs and LEDs. Fault detection may
include loss
of power, low return air temperature, temperature probe failure or a
temperature out
of range, failed damper positioning, freezing conditions, loss of output
signal ¨ when
the detection of such faults is possible.
[0060] Some EBC devices offer simplified EBC setup for some economizer
controllers with demand ventilation control options (such as existing Trane
and
18
Date Recue/Date Received 2022-04-13
Honeywell economizer controllers). A default EBC setup conceptually is a drop
in,
"cut & place" operation between an existing economizer and its existing damper
actuator. This allows the EBC to be used on almost any economizer setup,
especially considering when floating control capability built into the system.
[0061] These existing economizers have an override feature built into the
economizer controller/actuator system, usually called something like "remote
set
point". This is envisioned as an upgrade path for larger, more integrated
control
systems. However, this same feature can be used as a very simple connection to
the EBC output. Whenever a control signal is presented at the "remote set
point" this
signal bypasses the existing economizer/actuator logic and presents this
signal
directly to the damper actuator.
[0062] When operating in this mode, the EBC would have no existing
economizer
input so only the fixed output modes, or total Direct Digital Control (DDC)
operation
(as described with reference to Figures 5A-5D) would be meaningful. However,
the
extreme installation simplicity of not having to cut any wires at all and
inserting the
EBC into an existing economizer system and simply connecting the output of the
bypass controller to the remote set point input, and the cost savings of an
EBC model
sometimes may justify the reduced features available.
[0063] Figure 4 is an example Economizer Bypass Controller board showing
example inputs and outputs. Figure 4 is an example of a simplified EBC 202
without
a microprocessor. No changes are necessary to the existing economizer
controller
or the damper unit to install the EBC 202. The wiring requirements can be
completed
quickly. Specifically, the EBC 202 is connected to the economizer-to-damper
control
signal wire 401. The EBC 202 is also connected to the supply air temperature
sensor 402. The 24VAC or VDC power and common wires 403 are then connected
to the EBC 202. Installation time onsite is about one hour, including health
emergency specific settings. Typical onsite time to change a settings averages
less
than 10 minutes. As shown on the board, there is a single switch 405 to change
19
Date Recue/Date Received 2022-04-13
between bypass and passthrough modes. There are no physical changes required
to economizer, damper, mechanical linkages, or other electrical connections.
[0064] Emergency bypass ventilation settings are accomplished by simple
manual
positioning of outside air damper using slide control and LED feedback. For
smoke
conditions, the damper position is adjusted to a desired minimum (closed)
setting.
For increased ventilation needs (e.g., for COVID-19), the damper position is
adjusted to a desired maximum (open) setting.
[0065] As described above, the EBC 202 even in its pared down
configuration
provides protection in passthrough mode. Below approximately 50 F supply air
in
bypass mode, the EBC 202 outputs a zero-signal closing the outside air dampers
limiting equipment damage from freezing conditions and comfort issues from
admitting cold outside air into the controlled space.
[0066] The examples described herein often refer to retrofitting an
existing
economizer controller into an existing HVAC rooftop unit. It is to be
understood that
the techniques described herein can also be integrated into new (e.g., not yet
installed or newly manufactured) HVAC RTUs. In addition, the concepts and
techniques described are applicable to other controllers, including other
types of
HVAC systems including Heat Pump Systems, Air Handling Units (AHU) (e.g.,
which
generally include a larger implementation of a packaged rooftop unit), Unit
Ventilators (Uni-Vent) (often used in smaller environments such as school
classrooms), Variable Air Volume (VAV Systems), Energy Recovery Ventilators
(ERV), Make Up Air Unit (MUA) (often used in kitchens, warehouses, and
gymnasiums), and the like. Essentially, the concepts and techniques described
are
applicable to any environment that requires comfort cooling or ventilation
where free
cooling or economizers (using outside in conjunction with mechanical cooling)
are
used to maintain temperatures and/or improve indoor air quality in occupied
building
spaces.
[0067] Also, although certain terms are used primarily herein, other
terms could be
used interchangeably to yield equivalent embodiments and examples. In
addition,
Date Recue/Date Received 2022-04-13
terms may have alternate spellings which may or may not be explicitly
mentioned,
and all such variations of terms are intended to be included.
[0068] Example embodiments described herein provide applications, tools,
data
structures and other support to implement an EBC device to be used for
bypassing
and/or overriding economizer controller output and other emergencies. Other
embodiments of the described techniques may be used for other purposes. In the
following description, numerous specific details are set forth, such as data
formats
and code sequences, etc., in order to provide a thorough understanding of the
described techniques. The embodiments described also can be practiced without
some of the specific details described herein, or with other specific details,
such as
changes with respect to the ordering of the logic, different logic, etc. Thus,
the scope
of the techniques and/or functions described are not limited by the particular
order,
selection, or decomposition of aspects described with reference to any
particular
routine, module, component, and the like.
[0069] As described in Figures 1-4, one of the functions of a Economizer
Bypass
Controller is to bypass the economizer controller through bypass ventilation
modes.
[0070] Figures 5A-5D is flow diagram of example bypass mode and override
selection routine of an example Economizer Bypass Controller to provide bypass
and override capabilities between an economizer and a damper actuator. In
overview, the logic illustrated therein describes two main operating
conditions of an
example EBC, such as EBC 202. The first is "normal" bypass conditions and the
second are "override" conditions. Of note, all bypass conditions and overrides
that
don't just pass through an existing economizer controller output signal are
considered "overrides" of the economizer controller. These two conditions are
intended for describing overrides of the bypass controller (e.g., EBC 202)
itself.
Thus, depending upon how the override condition logic is ordered, the EBC can
implement a hierarchy of override conditions based upon the first override
condition
encountered. Alternatively, a hierarchy of override conditions can be coded
into the
21
Date Recue/Date Received 2022-04-13
logic itself. Also of note, one could structure the same logic as all bypass
modes. All
such alternatives are contemplated.
[0071] Controls to enter these EBC operating conditions come either from
a human
interface of the device, input signals coming into the device (e.g., from
sensors or
from the economizer controller outputs), or some type of communication
information
received by the device using the communications modules and protocols
described
above with respect to Figure 3 (modules 313 and 314). Almost every operating
condition can be entered multiple ways. The logic does not try to describe
"how" a
state is entered, only the effects of operating in that specific state. For
example, a
human interface may be used to put the EBC into a particular mode.
[0072] The bypass modes and override conditions shown in Figs. 5A-5D are
examples. Others may be included and some may be changed or omitted. For all
bypass modes and override conditions, the single-wire proportional percentage
or
two-wire floating control type is maintained. Both humans and the EBC's
internal
algorithms use a concept of "percent open" as the main control variable.
Floating
control devices operate with two different signals but these two signals are
integrated to calculate the percentage signal used for inputs and recreated to
make
the required floating control output signal. Thus, in the following
description,
"calculated" input or output values refer to incorporating these conversions
from and
to proportional percentages as need.
[0073] Note, when an existing floating controller type economizer is used
and the
EBC is in a non-overridden, not absolute pass-through mode case, the output
signals to the damper actuator are not necessarily matching the input signals
from
the existing economizer. This means that the existing economizer's re-indexing
operations must be monitored and recreated for the damper actuator. Re-
indexing
operations are implemented as pre-programmed sequences and initiated
internally
when an existing economizer re-indexing operation is detected.
[0074] In Figures 5A-5D, bypass mode selector and override logic 500
operates as
follows. Again, this is an example of how they EBC logic may be programmed and
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Date Recue/Date Received 2022-04-13
other equivalent logic may be incorporated. In essence, blocks 501 and 522-535
implement a check for each bypass mode and blocks 503-521 implement logic for
the currently recognized override conditions. The user interface of an EBC
device
may be used to set certain default parameters.
[0075] In block 501, the logic checks to see if the EBC has entered
absolute
passthrough mode. If so, the logic continues in block 502 to enter absolute
passthrough mode. If not, the logic continues to block 503. Absolute
passthrough
mode connects the input control signal from the existing economizer (single-
wire
proportional percentage or two-wire floating control to the output going to
the damper
actuator (matching single-wire proportional percentage or two-wire floating
control)
without any change for any reason. This mode may be used when the existing
system is working perfectly for the situation. The EBC does nothing to the
signal in
any way. Specifically, in block 502 the logic sets the calculated output value
sent to
the damper actuator to the EBC's calculated input value. The logic then
completes.
[0076] In block 503, the EBC logic checks for the presence of override
conditions
which determine whether the current operating mode needs to be changed for a
specific reason. The absolute passthrough mode is the only mode that does not
check for override conditions first. All other modes described below include
examination for override conditions first. Blocks do not consider the priority
of the
override condition, just the main override conditions that may arise. Other
override
conditions, or other orders can be similarly accommodated. In some EBC
implementations, these orders and conditions are configurable via an EBC user
interface (not shown).
[0077] If an override condition is present, then the EBC checks which
override
condition is present, otherwise continues to block 522. Blocks 504-521
implement
these override conditions.
[0078] Specifically, in block 504, the EBC logic determines whether the
override
condition indicates to force the damper to a fully open position. If so, the
logic
continues in block 505 to set the damper to its full open position, which
means setting
23
Date Recue/Date Received 2022-04-13
the calculated output value to "open," and then ends. For example, this
override
could be used for building flush, maintenance, floating control indexing. A
physical
input for this override condition is a priority for all but the simplest
hardware
implementations. If this override condition is not present, the EBC logic
continues
to block 506.
[0079] In block 506, the EBC logic determines whether the override
condition
indicates to force the damper to a fully closed position. If so, the logic
continues in
block 507 to set the damper to its full closed position, which means setting
the
calculated output value to "closed" and then ends. For example, this override
could
be used for emergency shutdown, fire, extreme low temperature, maintenance,
floating control indexing. A physical input for this override condition is a
priority for
all but the simplest hardware implementations. If this override condition is
not
present, the EBC logic continues to block 508.
[0080] In block 508, the EBC logic determines whether the override
condition
indicates to force the damper to a passthrough mode so that the output exactly
matches the input. If so, the logic continues in block 509 to set the EBC
calculated
output value (to control the damper actuator) to the EBC calculated input
value, and
then ends. For example, this override could be used for maintenance, testing,
and
to take advantage of advanced features or control implemented in the existing
economizer system when no override strategy is needed. Advanced features could
include taking advantage of existing scheduling capacity in the existing
economizer.
If this override condition is not present, the EBC logic continues to block
510.
[0081] In block 510, the EBC logic determines whether the override
condition
indicates to force the damper to a specified fixed position already set in the
device's
non-volatile memory (such as, for example, result of user configuration). If
so, the
logic continues in block 511 to set the EBC calculated output value to this
fixed value
parameter, and then ends. For example, this override could be used for
testing,
maintenance, or when a specific need arises for the dampers to be in a
specific,
preset position. The specific position could be fully closed or fully open
meaning this
24
Date Recue/Date Received 2022-04-13
override mode is a general way to preset the damper to any fixed position,
which
may be configurable in any particular EBC implementation. If this override
condition
is not present, the EBC logic continues to block 512.
[0082] Of note, whether or not explicitly mentioned in a logic block of
Figures 5A-5D,
setting the damper to some parameter or to some position implies that the EBC
calculated output value is being set as input to the damper actuator. For ease
of
description, this calculation is not shown in further logic blocks of Figures
5A-5D
although it is assumed to be present.
[0083] In block 512, the EBC logic determines whether the override
condition
indicates to force the damper to a position already set in the device's non-
volatile
memory (such as, for example, result of user configuration) reflecting that
the
building is unoccupied. If so, the logic continues in block 513 to set the EBC
calculated output value to this unoccupied parameter to set the damper
accordingly,
and then ends. For example, this override could be used for ease of temporally
overriding the currently running mode and change to the unoccupied damper
position. The specific position could be fully closed or fully open meaning
this
override mode represents a general way to preset the damper to any independent
fixed position, which may be configurable in any particular EBC
implementation. If
this override condition is not present, the EBC logic continues to block 514.
[0084] In block 514, the EBC logic determines whether the override
condition
indicates to force the damper to an amount indicated by a remote control
device. If
so, the logic continues in block 515 to set the EBC calculated output value to
the
value communicated in a remote control message to set the damper accordingly,
and then ends. This override is functionally the same as the fixed overrides
in
blocks 510-513 with the difference that the entry method is sent to the EBC by
some
external communication method and the damper actuator position is communicated
with the override message. Therefore, this override method can be considered a
more dynamic override method. Terminating this override method must be
provided
Date Recue/Date Received 2022-04-13
by another communication message to do the next thing. If this override
condition
is not present, the EBC logic continues to block 516.
[0085] In block 516, the EBC logic determines whether the override
condition
indicates to initiate a pre-programmed sequence to control the damper unit. If
so,
the logic continues in block 517 to execute the pre-programmed sequence to set
the
damper accordingly, and then ends. When the pre-programmed sequence is
finished the override is complete and the device returns to the current non-
overridden mode. Floating control re-indexing maneuvers are an example of pre-
programmed sequences. If this override condition is not present, the EBC logic
continues to block 518.
[0086] In block 518, the EBC logic determines whether the override
condition
indicates to initiate direct digital control to control the damper unit. If
so, the logic
continues in block 519 to execute the direct digital control to set the damper
accordingly, and then ends. This override condition represents an even more
generalized override method that not only changes the EBC's output but can
update
the EBC's non-volatile memory to change settings and operational parameters.
If
this override condition is not present, the EBC logic continues to block 520.
[0087] In block 520, the EBC logic determines whether the override
condition
indicates to initiate that some type of hardware "alarm" or malfunction
condition has
occurred. If so, the logic continues in block 521 to set the damper to a fully
closed
position (or some other configured parameter corresponding to the alarm
condition,
and then ends. If this override condition is not present, the EBC logic
continues to
block 522.
[0088] In block 522, after all of the override conditions have been
accounted for, the
EBC logic determines whether to enter passthrough mode. If so, the logic
continues
in block 523 to enter passthrough mode, and then ends. This mode connects the
input control signal from the existing economizer to the output going to the
damper
actuator. This is used when bypass conditions are not required (such as health
requirements are not indicative of increased or decreased ventilation) and
sets the
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Date Recue/Date Received 2022-04-13
damper similarly to block 502 described above. If this passthrough condition
is not
present, the EBC logic continues to block 524.
[0089] In block 524, the EBC logic determines whether to enter fixed
output mode.
If so, the logic continues in block 525 to set the damper to a predetermined
value,
for example, configured as a parameter and operates similar to block 511
described
above, and then ends. This mode sends a fixed output signal to the damper
actuator. This is used when the bypass requirements are expressed as fixed
percentages or settings. For example, set the damper to 87% open. This mode
can
also be used when the existing economizer is turned off or has malfunctioned
to
provide a fixed damper opening. If this fixed output condition is not present,
the EBC
logic continues to block 526.
[0090] In block 526, the EBC logic determines whether to enter unoccupied
mode.
If so, the logic continues in block 527 to set the damper to a predetermined
value
corresponding to an unoccupied building setting, for example, configured as a
parameter and operates similar to block 513 described above, and then ends.
This
mode provides another fixed output setting specifically designed for long
unoccupied
periods. In an example EBC, there are two different user interface settings
for fixed
and unoccupied modes so that they can be used independently and switched
between as needed. If this unoccupied condition is not present, the EBC logic
continues to block 528.
[0091] In block 528 the EBC logic determines whether to enter a clipped
output
mode. If so, the logic continues in block 529 to set the damper to a
predetermined
value corresponding to a clipped output setting, for example, configured as a
parameter, and then ends. This mode may be considered the simplest of the
intelligent modes to optimize the best performing existing economizer systems
with
health considerations. Here the existing features of the existing economizer
are used
to control the damper actuator ¨ as long as the damper actuator is operating
between a preset low and high value (thresholds). For example, the relevant
authorities may mandate a damper opening of over 80% for increased ventilation
to
27
Date Recue/Date Received 2022-04-13
address COVID-19 concerns. Configuring the clipped output mode low and high
parameter values at 80% and 100% means that whenever the existing economizer's
optimization algorithm opens the damper between 80% and 100% the signal is
passed thru. However, when the existing economizer tries to position the
damper to
less than 80%, the EBC maintains (or forces) the 80% minimum. The EBC operates
similarly to address smokey conditions. Here the low and high limits may be
set for
0% and 10%. As long as the existing economizer tries to position the damper
between those limits the signal is passed through but the EBC will not let the
damper
open more that the specified 10%. If this clipped mode condition is not
present, the
EBC logic continues to block 530.
[0092] In block 530, the EBC logic determines whether to enter increased
ventilation
temperature mode. If so, the logic continues in block 531 to execute logic for
increasing ventilation using information from the temperature sensors, and
then
ends. This mode implements an algorithm inspired by the ASHRAE Increased
Ventilation algorithm. The EBC version has increased flexibility, but the
general idea
is to automate a process somewhat similar to the centuries-old process of
"open the
window a little more if the temperature inside is OK, otherwise, close it a
bit." This
logic is described further with reference to Figure 6. If this increased
ventilation
temperature mode is not set, the EBC logic continues to block 532.
[0093] In block 532, the EBC logic determines whether to enter increased
ventilation
CO2 mode. If so, the logic continues in block 531 to execute logic for
increasing
ventilation using information from the sensors, and then ends. This logic is
described further with reference to Figure 7. If this increased ventilation
CO2 mode
is not set, the EBC logic continues to block 534.
[0094] In block 534, the EBC logic determines whether to enter
passthrough pulse
mode. If so, the logic continues in block 535 to execute logic for increasing
ventilation using information from the temperature sensors, and then ends.
This
logic is described further with reference to Figure 8. If this passthrough
pulse mode
is not set, the EBC logic ends.
28
Date Recue/Date Received 2022-04-13
[0095]
Figure 6 is an example flow diagram of an increased ventilation mode routine
of an example Economizer Bypass Controller using a temperature sensor to
modulate increased damper ventilation. In overview, this logic automates a
process
somewhat similar to the centuries-old process of "open the window a little
more if
the temperature inside is OK, otherwise, close it a bit." Starting in block
601, the
logic sends the existing economizer's signal plus a damper delta value to the
damper
actuator and measures the space air temperature using the proxy of return air
temperature (e.g., the sensor connected via cable 204 in Fig. 2) for "T"
minutes. At
the end of this time, in block 602 the logic determines whether the space air
temperature has stayed relatively unchanged. If it has not remained relatively
unchanged, it continues to block 607 to decrease the extra damper opening
value
(damper delta) a preset amount, being sure this amount doesn't go below zero
(block 608), adds this damper delta to the input signal percent (block 611)
and sends
this sum to the damper actuator (block 612-613). On the other hand, in block
602 if
the space air temperature has been stable for the "T" minutes, the logic
continues
to block 603-604 to measure the space air temperature for another "T" minutes
(block 603) and check for stability again (block 604). If the space air
temperature
wasn't stable for this time, then the logic continues to blocks 607-613 to
lower the
damper delta again and continue to measure in block 601. On the other hand, in
block 604 if the space air temperature continues to be stable measure for an
additional "T" minutes, then the logic continues to block 605-606 to measure
the
space air temperature for another "T" minutes (block 605) and check for
stability
again (block 606). If the space air temperature wasn't stable for this final
time,
decrease the damper delta as before (blocks 607-613). However, if the space
air
temperature has continued to be stable for three measurement periods (blocks
601-
606), then the logic proceeds to block 609 to increase the damper delta, and
continues to block 610 to ensure that the amount doesn't grow to more than
100%,
adds this damper delta to the input signal percent (block 611) and sends this
sum to
the damper actuator (block 612-613) to calculate the new damper actuator
position.
29
Date Recue/Date Received 2022-04-13
[0096] The logic shown in Fig. 6 is intended to be more conceptual than
formulaic.
The damper actuator output value is constantly being calculated as the input
from
the existing economizer controller plus the damper delta rather than as the
conceptual one-time-per-stability-measurement shown. The increased ventilation
mode logic's goal is to calculate the damper delta as space air temperature
stability
allows. As long as the existing HVAC system's economizer and mechanical
temperature system can maintain the space air temperature, the logic will open
the
damper a bit more and more than the existing economizer is directing. However,
when the HVAC system starts to reach the limits of its capacity to keep the
temperature constant, and the measured space air temperature becomes unstable,
the increased ventilation mode logic then reduces the damper delta. Over time,
this
algorithm will increase the damper opening to the point where the existing
HVAC
system capacity is maximized but no further.
[0097] Figure 7 is an example flow diagram of an increased ventilation
mode routine
of an example Economizer Bypass Controller using a CO2 sensor to modulate
increased damper ventilation. This logic implements similar logic to that
described
with respect to Figure 6, except that rather than monitoring space air
temperature
stability, this mode and logic monitors space Air CO2 level. The logic shown
in blocks
701-713 determines whether the CO2 level is above the threshold the damper
delta
will increase to increase ventilation and bring the CO2 level down. When the
CO2
level is below the threshold value, the damper delta will drop returning the
control
bias towards the existing economizer. As this mode monitors CO2, the
temperature
is not taken into consideration. This means that as the ventilation level
increases,
the temperature will likely change depending on the HVAC system's capacity to
maintain it. Thus, it is also possible for both logic flows to operate to
complement
each other.
[0098] Figure 8 is an example flow diagram of a passthrough pulse mode
routine of
an example Economizer Bypass Controller that provides increased ventilation
for
set cycles of time (pulsed increased ventilation). This mode implements a
Date Recue/Date Received 2022-04-13
passthrough mode with a regular pulse of overridden damper opening time that
persists until that opening time is satisfied or the space air temperature
becomes
unstable. This mode may be useful, for example, to address COVID-19 conditions
to force a building flush pulse for a specific length of time or a specific
cycle time.
Also, this mode can be used for smoke conditions to continue to circulate
inside air
for a period of time with minimum damper opening to mitigate smoke ingress.
[0099] Specifically, in block 801, the EBC logic operates as if in
passthrough mode
for a time "T" (which may be configurable). At the end of the preset time
cycle "T," in
block 802 the damper actuator is set to a preset value and in block 803 the
logic
starts to monitor the space air temperature for a preset "P" time (which may
be
configurable). In block 804, if at any time the temperature become unstable
beyond
a preset limit, then the logic continues to block 806 to return the damper
actuator
from the preset value back to tracking the existing economizer input value as
if in
passthrough mode, and continues back to block 801. If the temperature never
becomes unstable eventually in block 805 the preset pulse time expires, and
the
logic continues to block 806 to return the damper actuator from the preset
value
back to tracking the existing economizer input value as if in passthrough
mode, and
continues to block 801. In some implementations, the EBC logic after executing
block 806 ends.
[00100] Figure 9 is an example flow diagram illustrating handling of
floating controller
economizer adaptation. This logic describes a mechanism to convert from
floating
control inputs to a percentage and back as used in the prior flow diagrams
(Fig. 5A-
8).
[00101] Floating control devices are relatively simple and inexpensive
devices, at
least compared to the proportional percentage control devices. One reason for
this
simplicity is there is no feedback between the controller and the actuator: in
the
case of using an EBC, there is no feedback between the existing damper
actuator
and the existing economizer and the EBC. This means that the existing
economizer
and the EBC do not know where the damper actuator is situated at any given
time.
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Date Recue/Date Received 2022-04-13
For example, at startup, the existing economizer and EBC do know the last
position
of the damper actuator. It could be fully open, fully closed, or somewhere in
the
middle. Gusts of wind, grade school children with sticks, maintenance
procedures,
and malfunctions can change the actuator position from where the EBC expects
it.
[00102] Therefore, periodically, the existing economizer and the EBC
preferably re-
index the floating control actuator to force it into a known position by
traveling to
either a fully closed or a fully open position for longer than the maximum
travel time
of the actuator. Opening or closing for longer than the maximum travel time
ensures
that the actuator is in the extreme position no matter where it started. The
challenge
is that the damper actuator is a slow device and one of common actuators
requires
95 seconds to travel from fully closed to fully open. The same for the return
trip.
[00103] As described above, a goal of the EBC is to disassociate the
existing
economizer from the existing damper actuator. The only way the EBC "knows"
that
the existing economizer is doing a re-indexing maneuver is that the close or
open
signal stays activated for longer than a full actuator travel time. Therefore,
not only
does the EBC need to integrate the existing economizer's floating control
signals,
but it must also monitor those signals for a re-indexing operation and
schedule a
matching pre-programmed maneuver so that the existing damper actuator performs
that action, even if the EBC mode output doesn't match the existing economizer
output at all.
[00104] The logic of Figure 9 buries these details to conceptually show
that when
floating control devices are being used there is a pre-processing step to
convert the
two floating control signals into the single percentage signal (blocks 901 and
902).
After the EBC calculates the desired output (as part of processing the mode ¨
block
903) block 904 executes a post-processing step to convert the single
percentage
signal back into two floating control signals. Then in block 905, the floating
controller
signals are sent to the existing damper actuator. Using this technique, the
only user-
supplied data needed for these operations is the fully closed to open travel
time of
the actuator.
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Date Recue/Date Received 2022-04-13
[00105] The pre-processing logic of block 902 is the easiest of the two. In
one EBC
example, the microcontroller counts up the time the input floating control
"Open"
signal is active and counts down the time the "Close" input signal is active,
a simple
integration of the two signals. This count value is then divided by the travel
time of
the actuator and the percentage of opening is the result. Because the re-
indexing
maneuvers must exceed the maximum travel time to be sure the actuator is fully
closed or open, a constraint function is used to keep the percentage between
0%
and 100%.
[00106] The post-processing logic of block 904 is only slightly more
complex as the
microcontroller must keep track of what percentage it calculates itself to be
at and
use that to determine which, if any, output floating control "Open" or "Close"
signals
must be activated to achieve the desired output position. The process is
similar to
the counting, dividing, and constraining in the pre-processor logic of block
902.
[00107] Figure 10 an example block diagram of an example Economizer Bypass
Controller as a computing system used to communicate in a networked
environment.
It is meant to generally illustrate how a microprocessor controlled EBC can
interact
with other environments and devices. It is to be understood, as described
above,
that not all implementations of an EBC contain a microprocessor or the other
components described here.
[00108] Note that one or more general purpose virtual or physical computing
systems
suitably instructed or a special purpose computing system may be used to
implement an EBC. Further, the EBC may be implemented in software, hardware,
firmware, or in some combination to achieve the capabilities described herein.
[00109] Note that one or more general purpose or special purpose computing
systems/devices may be used to implement the described techniques. However,
just because it is possible to implement the EBC techniques on or using a
general
purpose computing system does not mean that the techniques themselves or the
operations required to implement the techniques are conventional or well
known.
33
Date Recue/Date Received 2022-04-13
[00110] The economizer bypass controller 1000 may comprise one or more
server
and/or client computing systems and may span distributed locations. In
addition,
each block shown may represent one or more such blocks as appropriate to a
specific embodiment or may be combined with other blocks. Moreover, the
various
blocks of the Economizer Bypass Controller 1010 may physically reside on one
or
more machines, which use standard (e.g., TCP/IP) or proprietary interprocess
communication mechanisms to communicate with each other.
[00111] In the embodiment shown, economizer bypass controller 1000
comprises a
computer memory ("memory") 1001õ one or more Central Processing Units ("CPU")
1003, Input/Output devices 1004 (e.g., keyboard, mouse, CRT or LCD display,
etc.),
other computer-readable media 1005, and one or more network connections 1006.
In some embodiments, the EBC is headless ¨ in others display 1002 is present.
The
EBC 1000 is shown residing in memory 1001.
[00112] In other embodiments, some portion of the contents, some of, or all
of the
components of the EBC 1000 may be stored on and/or transmitted over the other
computer-readable media 1005. The components of the EBC 1000 preferably
execute on one or more CPUs 1003 and manage the bypass control of a damper
unit in an HVAC rooftop unit, as described herein. Of note, one or more of the
components in Figure 10 may not be present in any specific implementation. For
example, some embodiments embedded in other software may not provide means
for user input or display.
[00113] In a typical embodiment, the EBC 1000 includes one or more bypass
controller logic modules 1011, and one or more configuration data and
parameter
data repositories 1020 (which may also include logging information). In at
least
some embodiments, some portions are all of repository 1020 are provided
external
to the EBC and are available, potentially, over one or more networks 1050.
Other
and /or different modules may be implemented. In addition, the EBC may
interact
via a network 1050 with application or client code 1055 that uses output
results
computed by the bypass controller logic 1011, one or more external control
systems
34
Date Recue/Date Received 2022-04-13
1060, and/or one or more third-party information provider systems 1065, such
as
other types of input relating to weather forecasts, emergencies, and the like.
[00114] In an example embodiment, components/modules of the EBC 1000
such as
logic 1020 are implemented using standard programming techniques. For example,
the logic 1020 may be implemented as a "native" executable running on the CPU
1003, along with one or more static or dynamic libraries. In other
embodiments, the
logic 1020 may be implemented as instructions processed by a virtual machine.
A
range of programming languages known in the art may be employed for
implementing such example embodiments, including representative
implementations of various programming language paradigms, including but not
limited to, object-oriented, functional,
procedural, scripting, declarative, and
component-oriented.
[00115] The embodiments described above may also use well-known or
proprietary,
synchronous or asynchronous client-server computing techniques. Also, the
various
components may be implemented using more monolithic programming techniques,
for example, as an executable running on a single CPU computer system, or
alternatively decomposed using a variety of structuring techniques known in
the art,
including but not limited to, multiprogramming, multithreading, client-server,
or peer-
to-peer, running on one or more computer systems each having one or more CPUs.
Some embodiments may execute concurrently and asynchronously and
communicate using message passing techniques.
Equivalent synchronous
embodiments are also supported.
[00116] In addition, programming interfaces to the data stored as part
of the EBC
1000 (e.g., in the data repository 1020) can be available by standard
mechanisms
such as through C, C++, C#, and Java APIs; libraries for accessing files,
databases,
or other data repositories; through scripting languages such as XML; or
through Web
servers, FTP servers, or other types of servers providing access to stored
data. The
data repository may be implemented as one or more database systems, file
Date Recue/Date Received 2022-04-13
systems, or any other technique for storing such information, or any
combination of
the above, including implementations using distributed computing techniques.
[00117] Also the example EBC 1000 may be implemented in a distributed
environment comprising multiple, even heterogeneous, computer systems and
networks. Different configurations and locations of programs and data are
contemplated for use with techniques of described herein. In addition, the
[server
and/or client] may be physical or virtual computing systems and may reside on
the
same physical system. Also, one or more of the modules may themselves be
distributed, pooled or otherwise grouped, such as for load balancing,
reliability or
security reasons. A variety of distributed computing techniques are
appropriate for
implementing the components of the illustrated embodiments in a distributed
manner
including but not limited to TCP/IP sockets, RPC, RMI, HTTP, Web Services (XML-
RPC, JA)(-RPC, SOAP, etc.) and the like. Other variations are possible. Also,
other
functionality could be provided by each component/module, or existing
functionality
could be distributed amongst the components/modules in different ways, yet
still
achieve the functions of an EBC.
[00118] Furthermore, in some embodiments, some or all of the components of
the
EBC 1000 may be implemented or provided in other manners, such as at least
partially in firmware and/or hardware, including, but not limited to one or
more
application-specific integrated circuits (ASICs), standard integrated
circuits,
controllers executing appropriate instructions, and including microcontrollers
and/or
embedded controllers, field-programmable gate arrays (FPGAs), complex
programmable logic devices (CPLDs), and the like. Some or all of the system
components and/or data structures may also be stored as contents (e.g., as
executable or other machine-readable software instructions or structured data)
on a
computer-readable medium (e.g., a hard disk; memory; network; other computer-
readable medium; or other portable media article to be read by an appropriate
drive
or via an appropriate connection, such as a DVD or flash memory device) to
enable
the computer-readable medium to execute or otherwise use or provide the
contents
36
Date Recue/Date Received 2022-04-13
to perform at least some of the described techniques. Some or all of the
components
and/or data structures may be stored on tangible, non-transitory storage
mediums.
Some or all of the system components and data structures may also be stored as
data signals (e.g., by being encoded as part of a carrier wave or included as
part of
an analog or digital propagated signal) on a variety of computer-readable
transmission mediums, which are then transmitted, including across wireless-
based
and wired/cable-based mediums, and may take a variety of forms (e.g., as part
of a
single or multiplexed analog signal, or as multiple discrete digital packets
or frames).
Such computer program products may also take other forms in other embodiments.
Accordingly, embodiments of this disclosure may be practiced with other
computing
system configurations.
[00119]
From the foregoing it will be appreciated that, although specific embodiments
have been described herein for purposes of illustration, various modifications
may
be made without deviating from the spirit and scope of the invention. For
example,
the methods and systems for performing bypass ventilation modes discussed
herein
are applicable to other architectures. Also, the methods and systems discussed
herein are applicable to differing protocols, communication media (optical,
wireless,
cable, etc.) and devices (such as wireless handsets, electronic organizers,
personal
digital assistants, portable email machines, game machines, pagers, navigation
devices such as GPS receivers, etc.).
37
Date Recue/Date Received 2022-04-13
