section 23 09 93 sequence of operations for hvac

SECTION 23 09 93
SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
PART 1 - GENERAL
1.1
SUMMARY
A.
This Section includes control sequences for HVAC systems, subsystems, and other equipment.
B.
See Division 23 Section "230923 Direct Digital Control Systems for HVAC" for control
equipment and devices and for submittal requirements.
1.2
SUBMITTALS
A.
Submittals are required and shall include detailed descriptions of the proposed sequence of
operations for all systems specific to the project.
B.
The following information shall be submitted as a very minimum to the Engineer:
1.
2.
3.
1.3
System diagrams denoting the operation of each individual system, folded to an
equivalent 8-1/2 inch by 11 inch bound packet.
DDC logic diagrams.
Written sequences of operation with each specific diagram.
GENERAL
A.
The DDC system shall utilize the existing Automated Logic server located at the exisitng High
School (connected to the Norton School System Ethernet), where all software, graphics, alarms,
and trends shall reside. The DDC System communication protocol shall be BACnet where
indicated on the drawings, and MODBUS where indicated on the drawings. The communication
protocol between a VAV Box controller and room temp sensor or room combination temp/CO2
sensor or room combination temp/relative/relative humidity/CO2 sensor can be the DDC system
communication standard protocol as long as the communication speed is sufficient to perform
all functions described in the Sequence of Operations in a stable manner and must be
demonstrated to the satisfaction of the Architect/Engineer.
B.
DDC System Contractor shall provide temperature differentials and time delays as required to
maintain systems stability.
C.
All Analog Inputs, Analog Outputs, Binary Inputs and Binary Outputs shall be capable of being
manually overridden through the graphic display that shows these types of points, and, the
graphic display shall display the point has been manually overridden by either changing the
color of the point or having text next to the point that states “manually overridden”.
D.
DDC system shall be capable of providing alarms of any point within the system. The DDC
system shall be capable of trending any point within the system, including software control
points calculated by the DDC System, example, heating hot water supply temperature control
point that was calculated based on an outdoor air temperature reset schedule..
E.
Each graphic display that contains an outdoor air airflow rate shall show the following; outdoor
air airflow control point, outdoor air airflow, and shall include on the graphic display; design
outdoor air airflow setpoint. Design outdoor air airflow setpoint is defined as the values shown
on Drawing M701 within the Air Handling Unit Equipment Schedule. If AHU has CO2 demand
control ventilation, design outdoor air airflow setpoint tag shall include value shown on Drawing
M701 and the reduced value described herein.
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F.
For each graphic display that contains a variable frequency drive (VFD) speed control point, the
“speed feedback” value shall also be displayed. This is show the DDC system commanded
speed compared to the actual VFD speed. Speed shall be displayed as percent (%) maximum
motor speed. Graphic display shall include the VFD minimum speed that has been programmed
into the VFD. Example; VFD has been programmed for minimum speed of 25% to maximum
speed of 100%, if graphic display is displaying calculated control point is 10% speed, feedback
will display 25% and operator will know that VFD has been programmed for a minimum speed
of 25%.
G.
All graphic displays that contain a Variable Frequency Drive (VFD), shall include a display of
each VFD with a “hot spot” over said VFD that when hit with the mouse shall go to a text screen
showing the information obtained from the VFD from the BACnet communication. DDC System
Contractor shall provide a list of all points that can be displayed through the communication link
to Norton School, and then Norton School shall determine which points are to be displayed.
Each display, graphic display, or text display, shall include the associated Room Name, Room
Number and Equipment Number. Room Name and Room Number shall be same as displayed
at each room, that is, they shall match the installed Room Labels. Equipment Number shall
match those shown on the drawings.
H.
Run Time Accumulation - A re-settable run time accumulation for each Binary Output Object
connected to mechanical loads greater than 1 HP, electrical loads greater than 10 KW, or
wherever else specified or requested by Norton school shall be provided.
I.
DDC System Graphics shall consist as a minimum of :
1.
Cover Graphic Display showing entire floor plan, with hot spots over descriptions to move
to floor plans, heating hot water plant, chilled water plant or the displays screens
described below.
2.
The first floor plan shall show the entire first and second floor with hot spots to move to
individual floor plans that match the drawing floor plans, and each floor plan shall display
the room temperature, room relative humidity, CO2 level, status of lighting control
occupancy sensor as “occupied or unoccupied”, and has a “hot spot” at the room
temperature or room relative humidity or CO2 level such that the cursor can be brought to
this “hot spot” and then the graphic display of the FPVAV or VAV box is then displayed.
3.
Display of the heating hot water plant.
4.
Display of the chilled water plant.
5.
Display of each Air Handling Unit, 9 graphic displays, and, all sub-displays (text screens)
described herein. Each display shall include the status of the duct smoke detector, and is
obtained via the BACnet communication to the Fire alarm Panel. Each display shall also
include an “off-automatic” point so that Norton Maintenance can easily stop the unit.
6.
Display of each single duct shutoff type VAV box.
7.
Display showing all Desrtatification fans, one display for all Destratification fans.
8.
Display of cabinet unit heaters, one display for all cabinet unit heaters.
9.
Display of status of all exhaust fans (one or two simple display for all fans) controlled
and/or monitored by the DDC system.
10.
Display of Cross-Connect Room Temperature, Kitchen Freezer and Kitchen Cooler
temperature, all Technology Closet Room Temperature (quantity 6) and Elevator
Machine Temperature (quantity 2).
11.
Display of Electricity Meter data, include status of surge protector alarm, and all subdisplays (text screens) described herein.
12.
Display of main Domestic Water Meter data
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1.4
13.
Display of Natural Gas Meter data
14.
Display of Domestic Hot Water supply temperature, domestic hot water heaters, recirc
pumps, domestic hot water meter, and all sub-displays (text screens) described herein.
15.
Display of Domestic Water Booster Pump.
16.
Display of Emergency Generator
17.
Display of Fire Alarm System.
18.
Display for Scheduling “Snow Day” or “Delay Start of School”.
19.
Display showing all current unacknowledged alarms and past unacknowledged alarms.
20.
Provide screens displaying the written out full sequence of operation for each piece of
HVAC equipment. Provide a link to the sequence of operation displays on their respective
equipment graphics.
HEATING HOT WATER BOILERS AND ASSOCIATED PUMPS
A.
The heating hot water boiler system consists of two heating hot water boilers and two circulating
pumps (lead/standby)
B.
One heating hot water pump shall be designated, through the DDC System, as the lead pump
(adj.) and other shall be the standby pump. The standby pump shall automatically start on a
lead pump failure. The DDC system shall rotate the lead pump and standby pump on a weekly
(adj.) basis.
C.
The DDC System shall enable and disable each boiler and control the firing rate of each boiler.
Each boiler controller communicates with the DDC System via MODBUS communication
protocol. One heating hot boiler shall be designated as the lead boiler (adj.) and other shall
then be the lag boiler. The lag boiler shall automatically start on a lead boiler failure, and the
lag boiler shall also operate when the DDC system requires two boilers to operate. The DDC
system shall rotate the lead boiler and lag boiler on a weekly basis.
D.
The DDC System, shall reset the boiler plant heating hot water discharge temperature setpoint,
and each boiler controller shall control the operation of the boiler to maintain this setpoint.
When the outdoor temperature is between 70F (adj) and 40F (adj), reset shall be based on
outdoor air temperature, and shall be linear between setpoints and do not go below or above
setpoint limits when the outdoor temperature is above or below the values in the reset schedule;
40F outdoors - 140F heating hot water supply temperature, 70F outdoors - 110F heating hot
water supply temperature. When the outdoor air temperature is above 70F (adj), the heating hot
water supply temperature shall be maintained at 110F (adj). When the outdoor air temperature
is below 40F (adj), the heating hot water supply temperature shall be maintained at 140F (adj).
E.
When the outdoor temperature is below 35F (adj.), the DDC system shall energize the lead hot
water pump to run continuously and enable the boiler plant. When the outdoor temperature is
below 55F (adj.) the DDC system shall energize the lead hot water pump to run continuously
during occupied periods and during the heating optimal start period (see AHU sequence of
operation) and enable the boiler plant. During unoccupied periods when the outdoor air
temperature is above 35F (adj) the DDC system shall energize the lead hot water pump to run
continuously and enable the boiler plant when there is a demand for heat from any heating coil
(AHU, VAV Box, Cabinet Unit Heater, Etc) on the DDC system, and the pump and boiler plant
shall be energized/enabled for a minimum 30 minute period. During occupied periods when the
outdoor air temperature is above 55F the DDC system shall energize the lead hot water pump
to run continuously and enable the boiler plant when there is a demand for heat from any
heating coil (AHU, VAV Box, Cabinet Unit Heater, etc) on the DDC system, and the pump and
boiler shall be energized/enabled for a minimum 30 minute period.
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F.
When the lead boiler is energized by the DDC System, the DDC System shall open the boiler
water isolation valve and the boiler shall not be allowed to be enabled until the boiler controller
verifies proof of water flow through the boiler by the factor furnished and mounted flow switch
located in the boiler water discharge pipe. When a lag boiler is enabled by the DDC System, the
DDC System shall open the boiler water isolation valve and the boiler shall not be allowed to be
enabled until the boiler controller verifies proof of water flow through the boiler by the factory
furnished and mounted flow switch located in the boiler water discharge pipe.
G.
The DDC System shall sequence and determine the quantity of boilers required to operate to
maintain heating hot water supply temperature control point. When a boiler is disabled by the
DDC System, the water isolation valve shall remain open for 5 minutes (adj.) to allow the
exchanger to cool down, and then this isolation valve shall close. When the DDC System
disables the boiler plant, boilers are disabled and the pump is going to be de-energized, the
pump shall operate a minimum of 5 minutes (adj.) to allow the boiler heat exchanger to cool
down.
H.
Each heating hot water pump is variable speed and the DDC system shall vary the speed of the
pump motor as required to maintain differential pressure setpoint (adj) at both differential
pressure sensors. The pump variable speed drive shall be set such that minimum speed is 15
Hz (25%) and maximum speed is 60 Hz (100%). The TAB Contractor shall inform the DDC
System Contractor of the differential pressure setpoints required to maintain design flow rate.
I.
Heating hot water flow is monitored through a flow meter located upstream of the pumps intake.
Each boiler requires 25 gpm minimum water flow. The DDC System shall maintain minimum
water flow by modulating the bypass valve, when one boiler is energized the minimum water
flow is 25 gpm, and when two boilers are energized the minimum water flow is 50 gpm. If
minimum water flow falls below setpoint for more than 1 minute, the DDC system shall initiate
an alarm. The modulating bypass valve shall be spring return fail open flow through boilers.
J.
Each boiler has 350 gpm maximum water flow, therefore when one boiler is operating the
maximum water flow is 350 gpm through it. When the water flow exceeds 350 gpm (bypass
valve fully closed) the DDC System shall override the boiler plant controller and enable a lag
boiler and minimum water flow shall be maintained at 50 gpm. If minimum water flow falls
below setpoint for more than 2 minutes, the DDC system shall initiate an alarm. The modulating
bypass valve shall be spring return fail open flow through boilers.
K.
Each boiler can be operated in manual mode. Whenever a boiler is to be operated in manual
mode, the heating hot water pump must be operating.
L.
Each heating hot water pump can be operated in manual mode, and the operator must select
the pump speed at which the pump is to operate. Note, the pump variable frequency drives do
not have a bypass contactor, that is, this variable frequency drive only contains an inverter
section which will control the speed of the motor.
M.
The boilers’ individual operating and safety controls shall be in place for proper boiler firing.
The DDC system shall monitor boiler and pump failures. Should a boiler or pump failure occur,
the DDC system shall provide an alarm and indicate the specific alarm.
N.
Boilers Emergency Shutdown Switch – Two manual mushroom style pushbutton switches
mounted under plexiglass cover when pushed shall immediately shutdowns boilers B-1 and B-2
burners. Switches are located in Mechanical Room next to man doors leading to North and
South Corridors. Reset shall be manual by pulling pushbutton. This is a hardwired interlock.
Switch, wiring, conduit, relays, etc. are all furnished and installed by DDC System Contractor.
Switch position is also monitored by the DDC System and when either switch is depressed the
DDC System shall indicate an alarm. Each switch status shall be displayed on the heating hot
water plant graphic display.
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23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
O.
The DDC System shall monitor the building heating hot water supply and return temperatures.
P.
The DDC System shall monitor the each boiler discharge water temperature.
Q.
The DDC System shall monitor heating hot water supply pressure through a pressure sensor
located between the air separator and pump suction, and shall provide an alarm if the suction
pressure falls below 10 psig (adj).
R.
The DDC System shall monitor the heating hot water make-up water meter and display current
flow (gpm) and cumulative flow (gallons), and shall provide an alarm if the flow exceeds 25
gallons (adj) in a 5 minute (adj) period.
S.
Graphic display shall include additional information obtained from each boiler from the
MODBUS communication. As a minimum, each boiler status, each boiler supply and return
water temperature shall be displayed, each boiler firing rate, and each boiler alarm condition,
DDC System Contractor shall provide a list of all points to Norton School that can be displayed
through the communication link, and then Norton School shall determine which additional points
are to be displayed.
T.
Heating hot water boiler system (boilers, pumps, global outdoor air sensor, etc.) and all DDC
System controls associated with it are on emergency power, powered by the emergency
generator, and remain fully operational during an electrical power failure. See electrical
drawings for emergency power sources. The direct Digital Control Panels(s) serving the
heating hot water boiler system shall also be powered through an uninterruptible power supply
(UPS) that can provide backup power for 30 minutes. This is to prevent this (these) Direct
Digital Control Panels from going down on a loss of power while waiting for the emergency
generator to power it (them).
1.5
AIR COOLED CHILLER AND CHILLED WATER PUMP SEQUENCE OF OPERATION
A.
The chilled water system consists of one air cooled chiller and two circulating pumps. The air
cooled chiller provides chilled water when the outdoor temperature is above 55F. The standalone microprocessor based air cooled chiller control panel shall monitor and control the air
cooled chiller as directed by its chiller control software. The air cooled chiller control software
shall perform control strategies described herein.
B.
The Controls Contractor shall be responsible to provide any and all BACnet interface equipment
in order to achieve the degree of interface and control as required by these sequences of
operation. These interfaces shall include the hardware and software of the temperature control
system and the chiller manufacturer as well.
C.
The DDC system shall energize the chilled water pump and enable the chiller whenever the
outdoor air temperature is above 55F and the time schedule indicates occupied period. The
DDC system shall enable the chiller whenever there is a call for cooling from any Air Handling
Unit and the outdoor air temperature is above 55F during unoccupied periods and during the
optimal start period. When the chiller is disabled by the DDC system, the chilled water pump
shall operate for 5 minutes before shutting down to remove energy from the evaporator and
sufficient chilled water valves shall remain open to aid in removing energy from the evaporator.
D.
The chiller shall be enabled after chilled water pump flow has been proven. When the chiller is
enabled, the DDC system shall reset the chiller discharge temperature based on outdoor air
temperature according to the following schedule:
Outdoor Air Temp
At 55°F (adj.)
13-032
Chilled Water Supply
Temp
50°F (adj.)
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Above 75°F (adj.)
44°F (adj.)
E.
Chiller Soft Start and Demand Limit. The chiller control software shall provide a user-adjustable
loading time or a chilled water pull down delay program at system start-up. This prevents the
unnecessary full load operation of chiller and limits system electrical demand during chilled
water loop pulldown. The DDC system shall also demand limit the chiller according to the
following schedule;
Outdoor Air Temp
Chiller Demand Limit
At 55°F (adj.)
60% (adj.)
Above 75°F (adj.)
100% (adj.)
F.
The chilled water pump is variable speed and the DDC system shall vary the speed of the pump
motor as required to maintain differential pressure at both differential pressure sensors. The
pump variable speed drive shall be set such that minimum speed is 15 Hz (25%) and maximum
speed is 60 Hz (100%).
G.
One chilled water pump shall be designated, through the DDC System, as the lead pump (adj.)
and other shall be the standby pump. The standby pump shall automatically start on a lead
pump failure. The DDC system shall rotate the lead pump and standby pump on a weekly (adj.)
basis. However, when the lead pump speed exceeds 60% (adj) the lag pump shall be started
and both pumps shall operate in unison until the pumps speed has decreased to 40% (adj),
then operation reverts back to one pump.
H.
Chilled water flow is monitored through a flow meter located upstream of the pump intake.
Chiller requires 325 gpm minimum waterflow, and shall be accomplished by utilizing 3-way
chilled water control valves on AHU-2, AHU-4 and AHU-6. If water flow falls below 325 gpm for
more than 2 minutes, the DDC system shall initiate an alarm. During morning cool-down, the
DDC system shall limit the pump speed so that chilled water flow does not exceed 460 GPM,
I.
The chiller can be operated in manual mode, and each chilled water pump can be operated in
manual mode, and the operator must select the pump speed at which the pump is to operate.
The pump must be operating before manually starting the chiller and must operate for at least
five minutes after the chiller is manually disabled.
J.
The chiller has an integral outdoor thermostat that senses outdoor air temperature, and when it
is below 50F (adj.) outdoors, this outdoor thermostat shall prevent the chiller from operating.
This is to prevent chiller operation if the DDC system global outdoor temperature sensor has
failed.
K.
Chiller Status Report. Provide an operating status report for the chiller. The report shall provide
the present status of all binary information and for analog information present value, today’s
average, and the month-to-date average for the following information to provide the operator
with critical chiller operating data:
1.
2.
3.
4.
5.
6.
7.
8.
9.
L.
Compressor On/Off Status.
Compressor Starts/Run hours – Compressor A, B.
Phase 1/2/3 percent RLA – Compressor A, B.
Active chiller diagnostics or alarms.
Leaving chilled water temperature.
Entering chilled water temperature.
Chilled water supply temperature setpoint.
Percent RLA/Percent current limit.
Outdoor air temperature.
Diagnostic/Protection. The DDC system shall be able to alarm from all sensed points and
diagnostic alarms sensed by the chiller controller.
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M.
All points and diagnostics shall be made available throughout the building control system. The
Controls Contractor shall coordinate with the chiller manufacturer to furnish and install the
required hardware and software for the information to be relayed through the building control
system. The system shall utilize the industry standard BACnet protocol for all information
exchange.
N.
If the fire alarm system is activated for any reason, such as; smoke detector, pull station, flow
switch, etc., the DDC system shall disable the air cooled chiller, and de-energize the chilled
water pump, with the time delays described above to remove energy from the chiller exchanger.
When the fire alarm system is reset, the DDC system shall automatically restart the chilled
water system.
O.
The chilled water lines located outdoors are electrically heat traced (field installed) and the
chiller barrel is electrically heat traced (factory installed) to prevent water within the pipes and
barrel from freezing during winter. When the outdoor air temperature is below 38F (adj), the
chilled water pump shall be cycled every 1 hour (adj) by operating the pump at minimum speed
for 5 minutes (adj), or, continuously run the chilled water pump at minimum speed if the water
temperature sensed at the chiller barrel is below 38F (adj), this is an additional means to
prevent any chilled water located outdoors from freezing. The heat trace shall be active
whenever the outdoor temperature is below 40F (adj). The DDC System shall monitor the
chilled water supply and return temperatures at the chiller barrel inlet/outlet through the BACnet
communication to the chiller and provide an alarm if water temperature falls below 37F (adj).
The pipe heat trace and chiller barrel heat trace are on emergency power through the
emergency generator.
1.6
MECHANICAL ROOM EXHAUST FAN
A.
1.7
DDC System shall monitor Mechanical Room temperature and start exhaust fan EF-XX at
speed when room temperature rises above 85F (adj), and open the associated outdoor air
intake. Exhaust fan shall not operate for temperature control when the outdoor air temperature
is below 35F (adj).
AIR HANDLING UNIT AHU-1 – MAIN GYM
A.
B.
13-032
General Operation
1.
The AHU operates as a single zone variable air volume system and consists of; a supply
fan with variable frequency drive, exhaust fan with variable frequency drive, variable
speed enthalpy energy recovery wheel with outdoor air and exhaust air bypasses, air
filters, UVc lights, chilled water cooling coil and pre-heat and reheat heating hot water
coils. Note, exhaust fan the variable frequency drive does not have a bypass contactor,
that is, this variable frequency drive only contains an inverter section which will control
the speed of the motor.
2.
If the supply fan variable frequency drive is to be operated in manual mode or bypass
mode, then sufficient number of VAV box supply air dampers must be manually
overridden to allow sufficient supply airflow to prevent activating the high pressure static
safety switch.
3.
The AHU is scheduled for automatic operation through the DDC system on a time of day
basis for occupied and unoccupied modes.
Occupied Mode
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1.
The supply and exhaust fans run continuously, the outdoor air dampers, return air
dampers and supply fan modulate as required to maintain minimum outdoor air control
point, The unit is controlled as follows
2.
The DDC system shall determine the discharge air temperature control point. On a call
for cooling, the discharge air temperature shall be maintained at 55F (adj) and the supply
fan speed shall vary between 100% (adj) speed and 50% (adj) speed. As the call for
cooling diminishes, the supply fan shall slow down to 50% (adj) speed with the supply air
temperature maintained at 55F (adj). When the room temperature is between the room
cooling temperature setpoint and heating temperature setpoint, the supply fan operate at
50% (adj) speed with the supply air temperature maintained at 55F (adj). When the room
temperature falls below the heating temperature setpoint, the supply fan shall operate at
50% (adj) speed and the discharge air temperature shall reset between 55F (adj) and
90F (adj) as required to maintain room temperature heating setpoint. If additional heating
is required, the supply air temperature shall be maintained at 90F (adj) and the supply fan
speed shall slowly increase (5% speed per minute up to 100% (adj) speed), and then the
reverse occurs when less heating is required. See dehumidification cycle below for
additional information.
3.
The pre-heat coil shall prevent discharge air from this coil falling below 50F (adj) by
modulating the heating hot water control serving this coil.
4.
Dehumidification cycle – If room relative humidity exceeds 60% (adj) (as sensed by the
room sensor) and the outdoor air temperature is above 60F (adj), the system enters
dehumidification mode. The AHU cooling coil discharge temperature shall be maintained
at 55F (adj.) and the reheat coil shall provide reheat to maintain room temperature. If
dehumidification is required while the AHU supply fan is operating between 100% (adj)
and 50% (adj) speed, the DDC system shall slowly increase supply fan speed (5% speed
per minute up to 100% (adj) speed) and reset discharge air temperature between 55F
(adj) and 90F (adj) as required to maintain room temperature cooling temperature
setpoint. The system stops dehumidification mode when the room relative humidity falls
below 55%.
5.
Exhaust fan operation – The DDC system shall operate the exhaust fan variable
frequency drive. The exhaust fan is interlocked with the supply fan and exhaust damper
end switch and shall not operate until supply fan status is proven and the exhaust
damper is fully open. Exhaust air airflow is measured and controlled by the DDC system.
The exhaust fan speed shall be based on maintaining a 2000 CFM positive differential
between outdoor air airflow and exhaust airflow, and the exhaust fan does not start until
outdoor air airflow exceeds 3000 CFM. Exhaust fan motor speed shall not fall below 25%
rated speed, and shall not exceed 100% rated speed.
6.
Energy Recovery Section Operation
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a.
The DDC system shall operate the energy recovery section as required to
maximize energy recovery, including varying the speed of the energy recovery
wheel to control AHU discharge air temperature. The energy recovery section shall
maximize energy recovery prior to allowing the heating coil to operate. The energy
recovery section shall maximize energy recovery during mechanical cooling by
allowing the cooling coil to operate during economizer.
b.
Between 65F (adj) and 55F (adj) outdoor air temperature, the energy recovery
wheel outdoor air bypass and exhaust air bypass dampers are 100% open and the
return air bypass dampers are 100% closed, and, the chilled water coil shall
provide cooling as required. Above 65F (adj) outdoor air temperature, the energy
recovery wheel outdoor air bypass and exhaust air bypass dampers are 100%
closed, the AHU operates on minimum outdoor air, and the energy recovery wheel
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operates at 100% speed when the return air temperature exceeds the outdoor air
temperature by more than 2F DB (adj). Between 55F (adj) and 38F (adj) outdoor
air temperature, the energy recovery wheel outdoor air bypass and exhaust air
bypass dampers are 100% open, the energy recovery wheel, operates at 100%
speed and the return air bypass dampers modulate to maintain unit discharge air
temperature and prevent minimum outdoor air from falling below control point, and
the heating water coil shall provide additional heat as required. Below 38F (adj)
outdoor air temperature, the energy recovery wheel outdoor air bypass and
exhaust air bypass dampers are 100% closed, the AHU operates on minimum
outdoor air, the energy recovery wheel speed varies as required to maintain
discharge air temperature, and the heating coil operates to provide additional heat
when the energy recovery wheel cannot provide sufficient heat..
13-032
c.
Self Cleaning - When the rotor has been still for 30 minutes (adj) the self cleaning
function begins by rotating the rotor for 10 seconds (adj) at minimum speed, then
stopping the rotor.
d.
The energy recovery section shall include a “frost control” mode when the outdoor
temperature is below 20F (adj), to prevent the energy recovery wheel from
accumulating too much frost. The unit monitors the wheel exhaust side discharge
air temperature and prevent it from falling below 15F (adj) by varying the speed of
the energy recovery wheel to reduce energy recovery to remove frost from the
wheel. when the unit is in "frost control", the graphic display shall indicate that is in
"frost control" mode.
e.
Rotation monitoring - The Variable Frequency Drive monitors the rotation of the
rotor. If the rotor is not rotating while being commanded to rotate, the DDC
System shall provide an alarm.
f.
During frost control the mixed air temperature sensor shall control the outdoor air
and return air dampers to maintain 40F (adj) mixed air temperature, minimum
outdoor air control is overridden during “frost control”. If the DDC system detects
the energy recovery wheel is not operating when it should be operating when the
outdoor air temperature is below 35F (adj), then the mixed air temperature sensor
shall control the outdoor air damper and return air damper to maintain 40F (adj)
mixed air temperature.
7.
Economizer operation – When the outdoor air temperature is below 65F (adj.)
economizer operation “free cooling” shall be allowed. The DDC system shall operate the
outdoor air and return air dampers, energy recovery section, heating hot water coil
control valve and cooling coil control valve in sequence and without overlap to maintain
discharge air temperature, that is, if the energy recovery section cannot provide sufficient
energy transfer then heating hot water coil control valve shall modulate as required to
provide additional heat to maintain discharge air control point, and if the energy recovery
wheel is providing too much heat then the exhaust air bypass damper shall modulate and
when this damper is fully open and if the energy recovery wheel still provides too much
heat then the outside air bypass dampers shall modulate open as required to maintain
discharge air temperature. When the outdoor air temperature is above 65F (adj.),
economizer is disabled. During economizer operation, outdoor air airflow rate shall not
fall below minimum outdoor air airflow control point.
8.
Minimum outdoor air airflow. Outdoor air airflow is measured and controlled by the DDC
system. Minimum outdoor airflow setpoint adjustment is through the DDC System. If the
room CO2 sensor is reading below 1000 ppm (adj) setpoint, then the outdoor air airflow
shall be 25% of the value shown on drawing M-701. If the room CO2 sensor is reading
above setpoint, then the DDC controller shall modulate the outdoor air airflow up to 100%
of the value shown on Drawing M-701, and the DDC controller shall increase supply fan
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23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
speed as required to maintain outdoor air airflow control point. If the room CO2 sensor
continues to read above setpoint for 10 minutes, the DDC system shall issue an alarm.
When the outdoor air is below 5F (ajd) the outdoor air shall be 10% of the value shown
on drawing M-701.
9.
C.
The UVc lights downstream of the cooling coil are energized only when the AHU supply
fan is energized by the DDC System. There is a manual “On-Off” switch and access door
switch on the AHU, and if the access door is opened, the door switch shall de-energize
the UVc lights.
Unoccupied Mode
1.
When the AHU is “off”, the supply fan is off, the exhaust fan is off, the cooling coil control
valve if closed, the heating coil control valve modulates to maintain 70F interior
temperature as sensed by the discharge air stat, the outdoor air dampers are closed, the
return air dampers are open, and the exhaust air dampers are closed.
2.
Unoccupied heating - The DDC system shall monitor the room temperature. When the
room temperature falls below 60F (adj.), the AHU shall activate to provide heat to the
room. When the AHU is activated, the supply fan shall operate at 100% (adj) speed and
the AHU discharge air temperature shall be maintained at 90F (adj.), the exhaust fan
remains off, the outdoor air dampers remain closed, the return air dampers remain open
and the exhaust dampers remain closed. The AHU shall stop when the room temperature
rises to 65F (adj).
3.
Unoccupied cooling - The DDC system shall monitor the room temperature. When the
room temperature rises above 85F (adj.), the AHU shall start, the supply fan shall operate
at 100% speed and discharge 55F supply air, the exhaust fan remains off, the outdoor air
dampers remain closed, the return air dampers remain open, the exhaust air dampers
remain closed. When the room temperature falls below 80F, the AHU shall stop. Note;
Economizer operation shall be utilized if the outdoor air temperature is less than the
economizer changeover setpoint, see “Economizer Operation” in Occupied Mode above.
4.
Morning warm-up - The DDC system shall monitor the room temperature and outdoor air
temperature and automatically start the AHU prior to the occupancy schedule start time
based on “optimal start time” to get the room up to occupied setpoint temperature by
occupied start time, and during this period of operation the outdoor air dampers remain
closed, the return air dampers remain open, the exhaust fan remains off, and exhaust
dampers remain closed. During morning warm-up, the AHU supply fan shall operate at
100% speed and discharge 90F (adj.) supply air. The AHU shall enter occupied mode at
occupied period start time.
5.
Morning cool-down - The DDC system shall monitor the room temperature and outdoor
air temperature and automatically start the AHU prior to the occupancy schedule start
time based on “optimal start time” to get the room down to occupied setpoint temperature
by occupied start time, and during this period of operation the outdoor air dampers
remain closed, the return air dampers remain open, the exhaust fan remains off, and the
exhaust dampers remain closed. During morning cool-down, the AHU supply fan shall
operate at 100% speed and shall discharge 55F (adj.) supply air. The AHU shall enter
occupied mode at occupied period start time. Note; Economizer operation shall be
utilized if the outside air temperature is less than the economizer changeover setpoint,
see “Economizer Operation” in Occupied Mode above.
6.
Area relative humidity check - When the outdoor air temperature is above 70F (adj), if the
room relative humidity rises above 65% (adj) the AHU supply fan shall operate at 100%
speed, the cooling coil shall discharge 55F (adj.) air, the outdoor air dampers remain
closed, return air dampers remain open, the exhaust fan remains off, the exhaust air
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13-032
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
dampers remain closed, and the reheat coil provides reheat as required to maintain
unoccupied room temperature setpoint. The AHU stops when the room relative humidity
falls below 60%.
D.
1.8
External Safeties
1.
Duct smoke detector, supplied by others, installed in the return air duct shall
automatically shut-down the AHU when activated. The AHU shall automatically restart
after the fire alarm system has been reset.
2.
Activation of any fire alarm pull station or fire sprinkler system water flow switch shall
automatically shut-down the AHU when activated. The AHU shall automatically restart
after the fire alarm system has been reset.
3.
The low temperature cutout stat shall activate if a temperature of less than 38F is sensed
at any one foot of the sensing element. When the low temperature cutout stat actives, the
AHU immediately shuts down, the pre-heat and re-heat heating coils control valves fully
opens, and the DDC system provides an alarm that the low temperature cutout stat has
activated. The low temperature cutout stat requires a manual reset.
4.
Supply fan and exhaust fan status shall be monitored through the current sensor. If
supply fan state changes to “off” when it should be operating, the exhaust fan shall be
stopped and the AHU shall go to an “off” state and the DDC system shall generate an
alarm. If the exhaust fan state changes to “off” when it should be operating, the DDC
system generates an alarm and the AHU continues to operate.
5.
The DDC system shall monitor the AHU discharge temperature. If the supply air
temperature falls below 50F (adj.) the DDC system shall generate an alarm, and if the
supply air temperature falls below 45F (adj.) the DDC system shall stop the AHU,
generate an alarm and not allow the AHU to restart until the alarm is acknowledged and
the unit is manually restarted. If during occupied mode, the supply air temperature rises
above 100F (adj.) the DDC system shall generate an alarm, and if during any mode of
operation the supply air temperature rises above 110F (adj.) for 5 minutes the DDC
system shall stop the AHU, generate an alarm and not allow the AHU to restart until the
alarm is acknowledged and the unit is manually restarted.
AIR HANDLING UNIT AHU-2 (LOCKERS, TOILETS AND GYM CLASSROOMS)
A.
B.
13-032
General Operation
1.
The AHU operates as a variable air volume system supplying 100% outdoor air and
consists of; a supply fan with variable frequency drive, exhaust fan with variable
frequency drive, enthalpy energy recovery wheel with outdoor air and exhaust air
bypasses, air filters, UVc lights, heating hot water coil, and chilled water cooling coil.
Note, these variable frequency drives have a bypass contactor.
2.
The AHU is scheduled for automatic operation through the DDC system on a time of day
basis for occupied and unoccupied modes.
Occupied Mode
1.
The supply and exhaust fans run continuously. The unit is controlled as follows
2.
The DDC system shall determine the discharge air temperature control point. When the
outdoor air temperature is above 55F (adj.), the supply air temperature will be maintained
23 09 93 - 11
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
at 55F (adj.). When the outdoor air temperature is below 55F (adj.), reset between 55F
(adj.) to 62F (adj.) based on the zone with the greatest cooling demand.
3.
The DDC system shall determine the supply air duct static pressure control point and
shall operate the supply fan variable frequency drive. The DDC system shall monitor the
damper position of each terminal unit associated with the AHU and shall reset the supply
air duct static pressure control point based on the zone requiring the most pressure, that
is, the static pressure control point shall be reset lower until one zone damper is nearly
wide open, and the duct static pressure shall be limited to operate between 1.5” WC
(adj.) and 3.0” WC (adj.) measured 2/3 downstream of the supply fan discharge. Supply
fan motor speed shall not fall below 25% rated speed, and shall not exceed 100% rated
speed.
4.
Heating coil operation note – The heating coil has a temperature sensor on the
downstream side, and its purpose is to prevent the heating coil discharge temperature
from falling below 50F (adj.).
5.
Energy Recovery Section Operation
23 09 93 - 12
a.
The DDC system shall operate the energy recovery section as required to
maximize energy recovery, including varying the speed of the energy recovery
wheel to control AHU discharge air temperature. The energy recovery section shall
maximize energy recovery prior to allowing the heating coil to operate. The energy
recovery section shall maximize energy recovery during mechanical cooling by
allowing the cooling coil to operate during economizer.
b.
Between 65F (adj) and 55F (adj) outdoor air temperature, the energy recovery
wheel outdoor air bypass and exhaust air bypass dampers are 100%, and, the
chilled water coil shall provide cooling as required. Above 65F (adj) outdoor air
temperature, the energy recovery wheel outdoor air bypass and exhaust air
bypass dampers are 100% closed, and the energy recovery wheel operates at
100% speed when the return air temperature exceeds the outdoor air temperature
by more than 2F DB (adj). Below 55F (adj) outdoor air temperature, the energy
recovery wheel outdoor air bypass and exhaust air bypass dampers are 100%
closed, the energy recovery wheel speed varies as required to maintain discharge
air temperature, and the heating coil operates to provide additional heat when the
energy recovery wheel cannot provide sufficient heat..
c.
Self Cleaning - When the rotor has been still for 30 minutes (adj) the self cleaning
function begins by rotating the rotor for 10 seconds (adj) at minimum speed, then
stopping the rotor.
d.
The energy recovery section shall include a “frost control” mode when the outdoor
temperature is below 20F (adj), to prevent the energy recovery wheel from
accumulating too much frost. The unit monitors the wheel exhaust side discharge
air temperature and prevent it from falling below 15F (adj) by varying the speed of
the energy recovery wheel to reduce energy recovery to remove frost from the
wheel. when the unit is in "frost control", the graphic display shall indicate that is in
"frost control" mode.
e.
Rotation monitoring - The Variable Frequency Drive monitors the rotation of the
rotor. If the rotor is not rotating while being commanded to rotate, the DDC
System shall provide an alarm.
f.
During frost control the mixed air temperature sensor shall control the outdoor air
and return air dampers to maintain 40F (adj) mixed air temperature, minimum
outdoor air control is overridden during “frost control”. If the DDC system detects
13-032
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
the energy recovery wheel is not operating when it should be operating when the
outdoor air temperature is below 35F (adj), then the mixed air temperature sensor
shall control the outdoor air damper and return air damper to maintain 40F (adj)
mixed air temperature.
6.
C.
D.
13-032
The UVc lights downstream of the cooling coil are energized only when the AHU supply
fan is energized by the DDC System. There is a manual “On-Off” switch and access door
switch on the AHU, and if the access door is opened, the door switch shall de-energize
the UVc lights.
Unoccupied Mode
1.
When the AHU is “off”, the supply fan is off, the exhaust fan is off, the cooling coil control
valve if closed, the heating coil control modulates to maintain 70F interior temperature as
sensed by the discharge air stat, the outdoor air dampers are closed, the exhaust
dampers are closed, the energy recovery wheel bypass dampers are closed.
2.
Unoccupied heating – When the space temperature falls below 60F (adj.), the AHU shall
activate and the supply fan and exhaust fan shall operate, the unit shall operate on 100%
return air, and the unit shall operate as described in “occupied mode” until the space
temperature rises above 63F.
3.
Unoccupied cooling - When the space temperature rises above 85F (adj.), the AHU shall
activate and the supply fan and exhaust fan shall operate, the unit shall operate on 100%
return air, and the unit shall operate as described in “occupied mode” until the space
temperature falls below 80F.
4.
Morning warm-up and morning cool-down – The supply fan and exhaust fan shall
operate, the unit shall operate on 100% return air, and the unit shall operate as described
in “occupied mode” until the occupied start time. The unit shall utilize optimum start to
determine when to energize to bring the space to occupied setpoint by the occupied start
time.
5.
Area relative humidity check. If relative humidity sensed by the room sensor (see plans
for location) rise above 65% and the outdoor air temperature is above 55F, the AHU shall
start and supply 55F supply air until the relative humidity falls below 60%. The supply fan
and exhaust fan shall operate, the unit shall operate on 100% return air, and the unit shall
operate as described in “occupied mode”.
External Safeties
1.
Duct smoke detector, supplied by others, installed in the exhaust air duct shall
automatically shut-down the AHU when activated. The AHU shall automatically restart
after the fire alarm system has been reset.
2.
Activation of any fire alarm pull station or fire sprinkler system water flow switch shall
automatically shut-down the AHU when activated. The AHU shall automatically restart
after the fire alarm system has been reset.
3.
The low temperature cutout stat shall activate if a temperature of less than 38F is sensed
at any one foot of the sensing element. When the low temperature cutout stat actives,
the AHU immediately shuts down, the heating coil control valve fully opens, and the DDC
system provides an alarm that the low temperature cutout stat has activated. The low
temperature cutout stat requires a manual reset.
4.
Supply fan and exhaust fan status shall be monitored through the current sensor. If
supply fan state changes to “off” when it should be operating, the exhaust fan shall be
23 09 93 - 13
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
stopped and the AHU shall go to an “off” state and the DDC system shall generate an
alarm. If the exhaust fan state changes to “off” when it should be operating the DDC
system generate an alarm, the exhaust damper shall close and the AHU continues to
operate.
5.
E.
1.9
The DDC system shall monitor the AHU discharge temperature. If the supply air
temperature falls below 50F (adj.) the DDC system shall generate an alarm, and if the
supply air temperature falls below 45F (adj.) the DDC system shall stop the AHU,
generate an alarm and not allow the AHU to restart until the alarm is acknowledged and
the unit is manually restarted. If during occupied mode, the supply air temperature rises
above 75F (adj.) the DDC system shall generate an alarm, and if during any mode of
operation the supply air temperature rises above 100F (adj.) for 5 minutes the DDC
system shall stop the AHU, generate an alarm and not allow the AHU to restart until the
alarm is acknowledged and the unit is manually restarted.
Other
1.
The DDC system shall directly monitor; mixed air temperature, exhaust air temperature,
return air temperature, and return air relative humidity.
2.
The DDC system shall monitor and display outside air airflow and exhaust air airflow.
3.
The DDC system shall directly monitor outside air temperature and relative humidity
globally.
4.
All safeties shall be wired such that the unit will not start in “auto”, “manual” or “hand”.
AIR HANDLING UNITS;
AHU-3 (CLASSROOMS)
AHU-6 (CLASSROOMS)
AHU-7 (CLASSROOMS)
AHU-8 (CLASSROOMS)
AHU-9 (AUDITORIUM)
A.
General Operation
1.
The AHU operates as a variable air volume system and consists of; a supply fan with
variable frequency drive, exhaust fan with variable frequency drive, variable speed
enthalpy energy recovery wheel with outdoor air and exhaust air bypasses, air filters,
heating hot water coils, chilled water cooling coil, and UVc lights. Note, the exhaust fan
variable frequency drive does not have a bypass contactor, that is, this variable
frequency drive only contains an inverter section which will control the speed of the
motor.
2.
If the supply fan variable frequency drive is to be operated in manual mode or bypass
mode, then sufficient number of VAV box supply air dampers must be manually
overridden to allow sufficient supply airflow to prevent activating the high pressure static
safety switch.
3.
The AHU is scheduled for automatic operation through the DDC system on a time of day
basis for occupied and unoccupied modes.
4.
Heating coil operation note – The heating coil has a temperature sensor on the
downstream side, and its purpose is to prevent the heating coil discharge temperature
from falling below 50F (adj.).
23 09 93 - 14
13-032
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
B.
13-032
Occupied Mode
1.
The supply and exhaust fans run continuously, the outdoor air dampers and return air
dampers modulate as required to maintain minimum outdoor air setpoint. The unit is
controlled as follows
2.
The DDC system shall determine the discharge air temperature control point. When the
outdoor air temperature is above 55F (adj.), the supply air temperature will be maintained
at 55F (adj.). When the outdoor air temperature is below 55F (adj.), reset between 55F
(adj.) to 62F (adj.) based on the zone with the greatest cooling demand.
3.
The DDC system shall determine the supply air duct static pressure control point and
shall operate the supply fan variable frequency drive. The DDC system shall monitor the
damper position of each terminal unit associated with the AHU and shall reset the supply
air duct static pressure control point based on the zone requiring the most pressure, that
is, the static pressure control point shall be reset lower until one zone damper is nearly
wide open, and the duct static pressure shall be limited to operate between 1.5” WC
(adj.) and 3.0” WC (adj.) measured 2/3 downstream of the supply fan discharge. Supply
fan motor speed shall not fall below 25% rated speed, and shall not exceed 100% rated
speed.
4.
Economizer operation – When the outdoor air temperature is below 65F (adj.)
economizer operation “free cooling” shall be allowed. The DDC system shall operate the
outdoor air and return air dampers, energy recovery section, heating hot water coil
control valve and cooling coil control valve in sequence and without overlap to maintain
discharge air temperature, that is, if the energy recovery section cannot provide sufficient
energy transfer then heating hot water coil control valve shall modulate as required to
provide additional heat to maintain discharge air control point, and if the energy recovery
wheel is providing too much heat then the exhaust air bypass damper shall modulate and
when this damper is fully open and if the energy recovery wheel still provides too much
heat then the outside air bypass dampers shall modulate open as required to maintain
discharge air temperature. When the outdoor air temperature is above 65F (adj.),
economizer is disabled. During economizer operation, outdoor air airflow rate shall not
fall below minimum outdoor air airflow control point.
5.
Energy Recovery Section Operation
a.
The DDC system shall operate the energy recovery section as required to
maximize energy recovery, including varying the speed of the energy recovery
wheel to control AHU discharge air temperature. The energy recovery section shall
maximize energy recovery prior to allowing the heating coil to operate. The energy
recovery section shall maximize energy recovery during mechanical cooling by
allowing the cooling coil to operate during economizer.
b.
Between 65F (adj) and 55F (adj) outdoor air temperature, the energy recovery
wheel outdoor air bypass and exhaust air bypass dampers are 100% open and the
return air bypass dampers are 100% closed, and, the chilled water coil shall
provide cooling as required. Above 65F (adj) outdoor air temperature, the energy
recovery wheel outdoor air bypass and exhaust air bypass dampers are 100%
closed, the AHU operates on minimum outdoor air, and the energy recovery wheel
operates at 100% speed when the return air temperature exceeds the outdoor air
temperature by more than 2F DB (adj). Between 55F (adj) and 38F (adj) outdoor
air temperature, the energy recovery wheel outdoor air bypass and exhaust air
bypass dampers are 100% open, the energy recovery wheel, operates at 100%
speed and the return air bypass dampers modulate to maintain unit discharge air
temperature and prevent minimum outdoor air from falling below control point, and
the heating water coil shall provide additional heat as required. Below 38F (adj)
23 09 93 - 15
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
outdoor air temperature, the energy recovery wheel outdoor air bypass and
exhaust air bypass dampers are 100% closed, the AHU operates on minimum
outdoor air, the energy recovery wheel speed varies as required to maintain
discharge air temperature, and the heating coil operates to provide additional heat
when the energy recovery wheel cannot provide sufficient heat.
c.
Self Cleaning - When the rotor has been still for 30 minutes (adj) the self cleaning
function begins by rotating the rotor for 10 seconds (adj) at minimum speed, then
stopping the rotor.
d.
The energy recovery section shall include a “frost control” mode when the outdoor
temperature is below 20F (adj), to prevent the energy recovery wheel from
accumulating too much frost. The unit monitors the wheel exhaust side discharge
air temperature and prevent it from falling below 15F (adj) by varying the speed of
the energy recovery wheel to reduce energy recovery to remove frost from the
wheel. when the unit is in "frost control", the graphic display shall indicate that is in
"frost control" mode.
e.
Rotation monitoring - The Variable Frequency Drive monitors the rotation of the
rotor. If the rotor is not rotating while being commanded to rotate, the DDC
System shall provide an alarm.
f.
During frost control the mixed air temperature sensor shall control the outdoor air
and return air dampers to maintain 40F (adj) mixed air temperature, minimum
outdoor air control is overridden during “frost control”. If the DDC system detects
the energy recovery wheel is not operating when it should be operating when the
outdoor air temperature is below 35F (adj), then the mixed air temperature sensor
shall control the outdoor air damper and return air damper to maintain 40F (adj)
mixed air temperature.
6.
Exhaust fan operation – The DDC system shall operate the exhaust fan variable
frequency drive. The exhaust fan is interlocked with the supply fan and exhaust damper
end switch and shall not operate until supply fan status is proven and the exhaust
damper is fully open. Exhaust air airflow is measured and controlled by the DDC system.
The exhaust fan speed shall be based on maintaining a 1000 CFM positive differential
between outdoor air airflow and exhaust airflow, and the exhaust fan does not start until
outdoor air airflow exceeds 1500 CFM for AHU units X and X. For AHU-X, the exhaust
fan speed shall be based on maintaining a 500 CFM positive differential between outdoor
air airflow and exhaust airflow, and the exhaust fan does not start until outdoor air airflow
exceeds 1000 CFM. Exhaust fan motor speed shall not fall below 25% rated speed, and
shall not exceed 100% rated speed.
7.
Minimum outdoor air airflow. Outdoor air airflow is measured and controlled by the DDC
system. Minimum outdoor airflow setpoint adjustment is through the DDC System. If all
associated space CO2 sensors are reading CO2 below setpoint, then the outdoor air
shall be 25% of the value shown on drawing M-701. If any space CO2 sensor is reading
above setpoint and the associated VAV box primary air damper has operated at VAV box
maximum cooling CFM setpoint for 5 minutes, then the Air Handling Unit controller shall
modulate the outdoor air airflow to the design value scheduled on drawing M-701. If that
space CO2 sensor continues to read above setpoint for 10 minutes, the Air Handling Unit
outdoor air airflow shall be increased an additional 10% of the design value scheduled on
drawing M-701, and, if that space CO2 stills reads above setpoint for 10 minutes the
DDC system shall issue an alarm and reset the Air Handling Unit outdoor air airflow to
the design value scheduled on drawing M-701. When the outdoor air is below 5F (ajd) the
outdoor air shall be 10% of the value shown on drawing M-701. See Single Duct Shutoff
VAV Box Sequence of Operation for additional information.
23 09 93 - 16
13-032
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
8.
C.
13-032
The UVc lights downstream of the cooling coil are energized only when the AHU supply
fan is energized by the DDC System. There is a manual “On-Off” switch and access door
switch on the AHU, and if the access door is opened, the door switch shall de-energize
the UVc lights.
Unoccupied Mode
1.
When the AHU is “off”, the supply fan is off, the exhaust fan is off, the cooling coil control
valve if closed, the heating coil control modulates to maintain 70F interior temperature as
sensed by the discharge air stat, the outdoor air dampers are closed, the return air
dampers are open, the return air dampers upstream of the energy recovery wheel are
closed, the exhaust dampers are closed, the energy recovery wheel bypass dampers are
closed, and, all terminal units associated with the AHU enter unoccupied mode.
2.
Unoccupied heating – The DDC system shall monitor each space temperature
associated with each terminal unit associated with the AHU. When a space temperature
falls below 60F (adj.), fan powered terminal units shall activate their fan and heat the
space, and, terminal units without fans shall activate the air handling unit and heat the
space, and the terminal unit heating coil shall be utilized to provide heat to the space.
When the AHU is activated, the AHU shall maintain 75F (adj.) discharge air temperature
and the DDC system shall open the primary air damper in sufficient terminal units to allow
the AHU to exceed minimum supply CFM operation.
3.
Unoccupied cooling - The DDC system shall monitor each space temperature associated
with each terminal unit associated with the AHU. When a space temperature rises above
85F (adj.), the AHU shall start and discharge 55F supply air, the outdoor air dampers
remain closed, the return air dampers remain open, the return air dampers upstream of
the energy recovery wheel are closed, the exhaust dampers are closed, and the terminal
unit serving that space shall go to full cooling mode, and, other terminal units shall go to
occupied mode as required to allow the AHU to exceed minimum supply CFM operation.
When the critical zone space temperature falls below 80F, the AHU shall stop. Note;
Economizer operation shall be utilized if the outside air temperature is less than the
economizer changeover setpoint, see “Economizer Operation” in Occupied Mode above.
4.
Morning warm-up – The DDC system shall monitor each zone temperature and outdoor
air temperature and automatically start the AHU prior to the occupancy schedule start
time based on “optimal start time” to get all the spaces up to occupied setpoint
temperature by occupied start time, and during this period of operation the outdoor air
dampers remain closed, the return air dampers are open, the return air dampers
upstream of the energy recovery wheel are closed, the exhaust dampers are closed.
During morning warm-up, the AHU shall discharge 75F (adj.) supply air, all terminal units
shall operate at maximum cooling CFM setpoint, and all terminal units heating hot water
control valve shall modulate as required to maintain room temperature setpoint. This is
to allow the AHU to provide additional heat for morning warm-up. When a room
temperature rises above the occupied heating setpoint, the FPVAV shall enter occupied
mode, and all FPVAV’s shall enter occupied mode at occupied period start time.
5.
Morning cool-down - The DDC system shall monitor each zone temperature and outdoor
air temperature and automatically start the AHU prior to the occupancy schedule start
time based on “optimal start time” to get all the spaces down to occupied setpoint
temperature by occupied start time, and during this period of operation the outdoor air
dampers remain closed, the return air dampers are open, the return air dampers
upstream of the energy recovery wheel are closed, the exhaust dampers are closed.
During morning cool-down, the AHU shall discharge 55F (adj.) supply air and each
terminal unit shall operate in occupied mode. Note; Economizer operation shall be
utilized if the outside air temperature is less than the economizer changeover setpoint,
see “Economizer Operation” in Occupied Mode above.
23 09 93 - 17
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
6.
D.
E.
Area relative humidity check. If relative humidity sensed by the room sensor (see plans
for location) rise above 65% and the outdoor air temperature is above 55F, the AHU shall
start and supply 55F supply air until the relative humidity falls below 60%. The AHU
outdoor air damper is closed, the exhaust air dampers are closed, and all associated
terminal units are at maximum cooling CFM.
External Safeties
1.
Duct smoke detector, supplied by others, installed in the return air duct shall
automatically shut-down the AHU when activated. The AHU shall automatically restart
after the fire alarm system has been reset.
2.
Activation of any fire alarm pull station or fire sprinkler system water flow switch shall
automatically shut-down the AHU when activated. The AHU shall automatically restart
after the fire alarm system has been reset.
3.
The low temperature cutout stat shall activate if a temperature of less than 38F is sensed
at any one foot of the sensing element. When the low temperature cutout stat actives,
the AHU immediately shuts down, the heating coil control valve fully opens, and the DDC
system provides an alarm that the low temperature cutout stat has activated. The low
temperature cutout stat requires a manual reset.
4.
A high static pressure cutout switch measures supply air duct static pressure and shall
automatically shut-down the AHU when activated and the DDC system shall provide an
alarm that the unit has shut-down. The high static cutout switch shall require a manual
reset and the AHU shall require a manual restart after the high static pressure cutout
switch has reset. The high static cutout switch static pressure setpoint shall be 4.0” WC
(adj.).
5.
Supply fan and exhaust fan status shall be monitored through the current sensor. If
supply fan state changes to “off” when it should be operating, the exhaust fan shall be
stopped and the AHU shall go to an “off” state and the DDC system shall generate an
alarm. If the exhaust fan state changes to “off” when it should be operating the DDC
system generate an alarm, the exhaust damper shall close and the AHU continues to
operate.
6.
The DDC system shall monitor the AHU discharge temperature. If the supply air
temperature falls below 50F (adj.) the DDC system shall generate an alarm, and if the
supply air temperature falls below 45F (adj.) the DDC system shall stop the AHU,
generate an alarm and not allow the AHU to restart until the alarm is acknowledged and
the unit is manually restarted. If during occupied mode, the supply air temperature rises
above 75F (adj.) the DDC system shall generate an alarm, and if during any mode of
operation the supply air temperature rises above 100F (adj.) for 5 minutes the DDC
system shall stop the AHU, generate an alarm and not allow the AHU to restart until the
alarm is acknowledged and the unit is manually restarted.
7.
Exhaust air volume – The DDC system shall monitor exhaust air airflow rate and not
allow the exhaust air airflow rate to exceed the quantity indicated on the drawings in the
equipment schedule.
Other
1.
The DDC system shall directly monitor; mixed air temperature, exhaust air temperature,
return air temperature, and return air relative humidity.
2.
The DDC system shall directly monitor outside air temperature and relative humidity
globally.
23 09 93 - 18
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23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
1.10
A.
B.
13-032
3.
All safeties shall be wired such that the unit will not start in “auto”, “manual” or “hand”.
4.
All points on the DDC system shall be capable of providing a user adjustable alarm and
being trended.
AIR HANDLING UNITS;
AHU-4 AND KITCHEN HOOD EXHAUST FAN, STUDENT DINING AND KITCHEN
General Operation
1.
The AHU operates as a variable air volume system and consists of; a supply fan with
variable frequency drive, air filters, UVc lights, pre-heat heating hot water coil, chilled
water cooling coil, pre-heat heating coil run-a-round pump, and associated relief air
dampers. Note, the variable frequency drive has a bypass contactor.
2.
If the supply fan variable frequency drive is to be operated in manual mode or bypass
mode, then sufficient number of VAV box supply air dampers must be manually
overridden to allow sufficient supply airflow to prevent activating the high pressure static
safety switch.
3.
The AHU is scheduled for automatic operation through the DDC system on a time of day
basis for occupied and unoccupied modes.
4.
The heating coil shall have a run-a round pump that operates whenever the outdoor
temperature is below 38F or the freeze stat activates. And the heating coil has a
temperature sensor on the downstream side, its purpose is to prevent the heating coil
discharge temperature from falling below 50F (adj.).
Occupied Mode
1.
The supply and exhaust fans run continuously, the outdoor air dampers and return air
dampers modulate as required to maintain minimum outdoor air setpoint. The unit is
controlled as follows
2.
The DDC system shall determine the discharge air temperature control point. When the
outdoor air temperature is above 55F (adj.), the supply air temperature will be maintained
at 55F (adj.). When the outdoor air temperature is below 55F (adj.), reset between 55F
(adj.) to 62F (adj.) based on the zone with the greatest cooling demand. The pre-heat coil
shall prevent discharge air from this coil falling below 50F (adj) by modulating the heating
hot water control serving this coil. The run-a-round pump serving this coil shall operate
whenever the unit is operating and the outdoor air temperature is below 40F (adj). See
external safeties below for additional information.
3.
The DDC system shall determine the supply air duct static pressure control point and
shall operate the supply fan variable frequency drive. The DDC system shall monitor the
damper position of each terminal unit associated with the AHU and shall reset the supply
air duct static pressure control point based on the zone requiring the most pressure, that
is, the static pressure control point shall be reset lower until one zone damper is nearly
wide open, and the duct static pressure shall be limited to operate between 1.5” WC
(adj.) and 3.0” WC (adj.) measured 2/3 downstream of the supply fan discharge. Supply
fan motor speed shall not fall below 25% rated speed, and shall not exceed 100% rated
speed.
4.
Economizer operation – When the outdoor air temperature is below 65F (adj.)
economizer operation “free cooling” shall be allowed. The DDC system shall operate the
outdoor air and return air dampers, heating hot water coil control valve and cooling coil
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control valve in sequence and without overlap to maintain discharge air temperature.
When the outdoor air temperature is above 65F (adj.), economizer is disabled. During
economizer operation, outdoor air airflow rate shall not fall below minimum outdoor air
airflow control point.
5.
Minimum outdoor air airflow. Outdoor air airflow is measured and controlled by the DDC
system. Minimum outdoor airflow setpoint adjustment is through the DDC System. If all
associated space CO2 sensors are reading CO2 below setpoint, then the outdoor air
shall be 25% of the value shown on drawing M-701. If any space CO2 sensor is reading
above setpoint and the associated VAV box primary air damper has operated at VAV box
maximum cooling CFM setpoint for 5 minutes, then the Air Handling Unit controller shall
modulate the outdoor air airflow to the design value scheduled on drawing M-701. If that
space CO2 sensor continues to read above setpoint for 10 minutes, the Air Handling Unit
outdoor air airflow shall be increased an additional 10% of the design value scheduled on
drawing M-701, and, if that space CO2 stills reads above setpoint for 10 minutes the
DDC system shall issue an alarm and reset the Air Handling Unit outdoor air airflow to
the design value scheduled on drawing M-701. If the See FPVAV and Single Duct
Shutoff VAV Box Sequence of Operation for additional information.
a.
The DDC system, through a current sensor, shall monitor Exhaust Fan EF-XX
which serves the kitchen exhaust hood. Whenever the Kitchen hood exhaust fan
is operating, the minimum outdoor air airflow control point shall be determined by
the speed of the Kitchen exhaust fan as this exhaust fan is controlled through a
variable frequency drive that provides an analog fan motor speed feedback signal
to the Air Handling Unit controller. With exhaust fan EF-XX operating at 100%
exhaust fan motor speed, AHU-4 shall provide a minimum of XXXX CFM outdoor
air.
b.
When a Kitchen Hood fire suppression system is activated, the associated exhaust
fan shall energize through the Kitchen Hood Control System, if not already
energized, and go to 100% speed, and, the DDC system shall stop Air Handling
Unit AHU-4, and initiate an alarm.
Relief Air Damper Operation – The DDC system shall operate the relief air damper motor,
and it shall not operate until supply fan status is proven. Room differential pressure with
respect to the Corridor is measured and controlled by the DDC system. The relief air
damper position shall be based on maintaining the room at 0.05 inch WC (adj) positive
with respect to the Corridor.
6.
C.
The UVc lights downstream of the cooling coil are energized only when the AHU supply
fan is energized by the DDC System. There is a manual “On-Off” switch and access door
switch on the AHU, and if the access door is opened, the door switch shall de-energize
the UVc lights.
Unoccupied Mode
1.
When the AHU is “off”, the supply fan is off, the cooling coil control valve if closed, the
heating coil control modulates to maintain 70F interior temperature as sensed by the
discharge air stat, the outdoor air dampers are closed, and the relief air dampers are
closed, and, all terminal units associated with the AHU enter unoccupied mode.
2.
Unoccupied heating – The DDC system shall monitor each space temperature
associated with each terminal unit associated with the AHU. When a space temperature
falls below 60F (adj.), fan powered terminal units shall activate their fan and heat the
space, and, terminal units without fans shall activate the air handling unit and heat the
space, and the terminal unit heating coil shall be utilized to provide heat to the space.
When the AHU is activated, the AHU shall maintain 75F (adj.) discharge air temperature
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23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
and the DDC system shall open the primary air damper in sufficient terminal units to allow
the AHU to exceed minimum supply CFM operation.
D.
13-032
3.
Unoccupied cooling - The DDC system shall monitor each space temperature associated
with each terminal unit associated with the AHU. When a space temperature rises above
85F (adj.), the AHU shall start and discharge 55F supply air, the outdoor air dampers
remain closed, the return air dampers are open, the relief air dampers are closed, and the
terminal unit serving that space shall go to full cooling mode, and, other terminal units
shall go to occupied mode as required to allow the AHU to exceed minimum supply CFM
operation. When the critical zone space temperature falls below 80F, the AHU shall stop.
Note; Economizer operation shall be utilized if the outside air temperature is less than the
economizer changeover setpoint, see “Economizer Operation” in Occupied Mode above.
4.
Morning warm-up – The DDC system shall monitor each zone temperature and outdoor
air temperature and automatically start the AHU prior to the occupancy schedule start
time based on “optimal start time” to get all the spaces up to occupied setpoint
temperature by occupied start time, and during this period of operation the outdoor air
dampers remain closed, the return air dampers are open, the relief air dampers are
closed. During morning warm-up, the AHU shall discharge 75F (adj.) supply air, all
terminal units shall operate at maximum cooling CFM setpoint, and all terminal units
heating hot water control valve shall modulate as required to maintain room temperature
setpoint. This is to allow the AHU to provide additional heat for morning warm-up. When
a room temperature rises above the occupied heating setpoint, the FPVAV shall enter
occupied mode, and all FPVAV’s shall enter occupied mode at occupied period start
time.
5.
Morning cool-down - The DDC system shall monitor each zone temperature and outdoor
air temperature and automatically start the AHU prior to the occupancy schedule start
time based on “optimal start time” to get all the spaces down to occupied setpoint
temperature by occupied start time, and during this period of operation the outdoor air
dampers remain closed, the return air dampers are open, the relief air dampers are
closed. During morning cool-down, the AHU shall discharge 55F (adj.) supply air and
each terminal unit shall operate in occupied mode. Note; Economizer operation shall be
utilized if the outside air temperature is less than the economizer changeover setpoint,
see “Economizer Operation” in Occupied Mode above.
6.
Area relative humidity check. If relative humidity sensed by the room sensor (see plans
for location) rise above 65% and the outdoor air temperature is above 55F, the AHU shall
start and supply 55F supply air until the relative humidity falls below 60%. The AHU
outdoor air damper is closed, the exhaust air dampers are closed, and all associated
terminal units are at maximum cooling CFM.
External Safeties
1.
Duct smoke detector, supplied by others, installed in the return air duct shall
automatically shut-down the AHU when activated. The AHU shall automatically restart
after the fire alarm system has been reset.
2.
Activation of any fire alarm pull station or fire sprinkler system water flow switch shall
automatically shut-down the AHU when activated. The AHU shall automatically restart
after the fire alarm system has been reset.
3.
The low temperature cutout stat shall activate if a temperature of less than 38F is sensed
at any one foot of the sensing element. When the low temperature cutout stat actives,
the AHU immediately shuts down, the pre-heat heating coil heating control valve fully
opens, the re-heat heating coil control valve fully opens, the pre-heat heating coil run-around pump energizes (if not energized), and the DDC system provides an alarm that the
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low temperature cutout stat has activated. The low temperature cutout stat requires a
manual reset.
E.
4.
A high static pressure cutout switch measures supply air duct static pressure and shall
automatically shut-down the AHU when activated and the DDC system shall provide an
alarm that the unit has shut-down. The high static cutout switch shall require a manual
reset and the AHU shall require a manual restart after the high static pressure cutout
switch has reset. The high static cutout switch static pressure setpoint shall be 4.0” WC
(adj.).
5.
Supply fan and exhaust fan status shall be monitored through the current sensor. If
supply fan state changes to “off” when it should be operating, the exhaust fan shall be
stopped and the AHU shall go to an “off” state and the DDC system shall generate an
alarm. If the exhaust fan state changes to “off” when it should be operating the DDC
system generate an alarm, the exhaust damper shall close and the AHU continues to
operate.
6.
The DDC system shall monitor the AHU discharge temperature. If the supply air
temperature falls below 50F (adj.) the DDC system shall generate an alarm, and if the
supply air temperature falls below 45F (adj.) the DDC system shall stop the AHU,
generate an alarm and not allow the AHU to restart until the alarm is acknowledged and
the unit is manually restarted. If during occupied mode, the supply air temperature rises
above 75F (adj.) the DDC system shall generate an alarm, and if during any mode of
operation the supply air temperature rises above 100F (adj.) for 5 minutes the DDC
system shall stop the AHU, generate an alarm and not allow the AHU to restart until the
alarm is acknowledged and the unit is manually restarted.
7.
Exhaust air volume – The DDC system shall monitor exhaust air airflow rate and not
allow the exhaust air airflow rate to exceed the quantity indicated on the drawings in the
equipment schedule.
Other
1.
The DDC system shall directly monitor; mixed air temperature, exhaust air temperature,
return air temperature, and return air relative humidity.
2.
The DDC system shall directly monitor outside air temperature and relative humidity
globally.
3.
All points on the DDC system shall be capable of providing a user adjustable alarm and
being trended.
All safeties shall be wired such that the unit will not start in “auto”, “manual” or “hand”.
4.
1.11
A.
AIR HANDLING UNIT AHU-5 SERVES ADMINISTRATION AREA
General Operation
1.
The AHU operates as a variable air volume system and consists of; a supply fan with
variable frequency drive, return fan with variable frequency drive, relief air section,
outdoor air section, air filters, UVc lights, heating hot water coil, and chilled water cooling
coil. Note, these variable frequency drives have a bypass contactor.
2.
If the supply fan variable frequency drive is to be operated in manual mode or bypass
mode, then sufficient number of VAV box supply air dampers must be manually
overridden to allow sufficient supply airflow to prevent activating the high pressure static
safety switch.
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23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
B.
13-032
3.
The AHU is scheduled for automatic operation through the DDC system on a time of day
basis for occupied and unoccupied modes.
4.
Heating coil operation note – The heating coil has a temperature sensor on the
downstream side, and its purpose is to prevent the heating coil discharge temperature
from falling below 50F (adj.).
Occupied Mode
1.
The supply and return fans run continuously, the outdoor air dampers and relief air
dampers modulate as required to maintain minimum outdoor air setpoint, The unit is
controlled as follows
2.
The DDC system shall determine the discharge air temperature control point. When the
outdoor air temperature is above 55F (adj.), the supply air temperature will be maintained
at 55F (adj.). When the outdoor air temperature is below 55F (adj.), reset between 55F
(adj.) to 62F (adj.) based on the zone with the greatest cooling demand.
3.
The DDC system shall determine the supply air duct static pressure control point and
shall operate the supply fan variable frequency drive. The DDC system shall monitor the
damper position of each terminal unit associated with the AHU and shall reset the supply
air duct static pressure control point based on the zone requiring the most pressure, that
is, the static pressure control point shall be reset lower until one zone damper is nearly
wide open, and the duct static pressure shall be limited to operate between 1.5” WC
(adj.) and 3.0” WC (adj.) measured 2/3 downstream of the supply fan discharge. Supply
fan motor speed shall not fall below 25% rated speed, and shall not exceed 100% rated
speed.
4.
Return fan operation – The DDC system shall operate the return fan variable frequency
drive. The return fan is interlocked with the supply fan. The return fan speed shall track
the supply fan speed. When the AHU is operating in occupied mode, the return fan shall
track the supply fan at a rate 10% less (adj.) than the supply fan, that is, when the supply
fan is at 100% speed the return fan is at 90% speed. When the AHU is operating in unoccupied mode, the return fan shall track the supply fan, that is, when the supply fan is at
100% speed the return fan is at 100% speed. Return fan motor speed shall not fall below
25% rated speed, and shall not exceed 100% rated speed.
5.
Economizer operation – When the outdoor air temperature is below 65 degree F (adj.)
economizer operation “free cooling” shall be allowed. The DDC system shall operate the
outdoor air and relief air dampers, heating hot water coil control valve and cooling coil
control valve in sequence and without overlap to maintain discharge air temperature.
The unit shall maximize economizer operation by allowing the cooling coil to operate
during economizer. When the outdoor air temperature is above 65F (adj.), economizer is
disabled. During economizer operation, outdoor air airflow rate shall not fall below
minimum outdoor air airflow setpoint.
6.
Minimum outdoor air airflow (as scheduled on drawings). Outdoor air airflow is measured
and controlled by the DDC system. Minimum outdoor airflow setpoint adjustment is
through the DDC System and is set to maintain the value shown on Drawing M-701.
When the outdoor air is below 5F (ajd) the outdoor air shall be 10% of the value shown
on drawing M-701.
7.
The UVc lights downstream of the cooling coil are energized only when the AHU supply
fan is energized by the DDC System. There is a manual “On-Off” switch and access door
switch on the AHU, and if the access door is opened, the door switch shall de-energize
the UVc lights.
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23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
C.
Unoccupied Mode
1.
When the AHU is “off”, the supply fan is off, the return fan is off, the cooling coil control
valve if closed, the heating coil control modulates to maintain 70F interior temperature as
sensed by the discharge air temperature sensor, the outdoor air dampers are closed, the
exhaust air dampers are closed, and, all terminal units associated with the AHU enter
unoccupied mode.
2.
Unoccupied heating – The DDC system shall monitor each space temperature
associated with each terminal unit associated with the AHU. When a space temperature
falls below 60F (adj.), fan powered terminal units shall activate their fan and heat the
space, and, terminal units without fans shall activate the air handling unit and heat the
space, and the terminal unit heating coil shall be utilized to provide heat to the space.
When the AHU is activated, the AHU shall maintain 75F (adj.) discharge air temperature
and the DDC system shall open the primary air damper in sufficient terminal units to allow
the AHU to exceed minimum supply CFM operation.
3.
Unoccupied cooling - The DDC system shall monitor each space temperature associated
with each terminal unit associated with the AHU. When a space temperature rises above
85F (adj.), the AHU shall start and discharge 55F supply air, the outdoor air dampers
remain closed, the exhaust air dampers remain closed, and the terminal unit serving that
space shall go to full cooling mode, and, the DDC system shall open the primary air
damper in sufficient terminal units to allow the AHU to exceed minimum supply CFM
operation. When the critical zone space temperature falls below 80F, the AHU shall stop.
Note; Economizer operation shall be utilized if the outdoor air temperature is less than
the economizer changeover setpoint, see “Economizer Operation” in Occupied Mode
above.
4.
Unoccupied override – There shall be an override pushbutton located in the Admin Area
Secretary Room A104 which when depressed during unoccupied periods causes the
associated AHU and all terminal units to enter occupied mode for 2 hours to allow the
space to be ventilated, cooled or heated.
5.
Morning warm-up – The DDC system shall monitor each zone temperature and outdoor
air temperature and automatically start the AHU prior to the occupancy schedule start
time based on “optimal start time” to get all the spaces up to occupied setpoint
temperature by occupied start time, and during this period of operation the outdoor air
dampers remain closed and the exhaust dampers are closed. During morning warm-up,
the AHU shall discharge 75F (adj.) supply air, all terminal units shall operate at maximum
cooling CFM setpoint, and all terminal units heating hot water control valve shall
modulate as required to maintain room temperature setpoint. When a room temperature
rises above the occupied heating setpoint, the terminal unit shall enter occupied mode,
and all terminal units shall enter occupied mode at occupied period start time.
6.
Morning cool-down - The DDC system shall monitor each zone temperature and outdoor
air temperature and automatically start the AHU prior to the occupancy schedule start
time based on “optimal start time” to get all the spaces down to occupied setpoint
temperature by occupied start time, and during this period of operation the outdoor air
dampers remain closed and the exhaust dampers are closed. During morning cooldown, the AHU shall discharge 55F (adj.) supply air and each terminal unit shall operate
in occupied mode. Note; Economizer operation shall be utilized if the outside air
temperature is less than the economizer changeover setpoint, see “Economizer
Operation” in Occupied Mode above.
7.
Area relative humidity check. If relative humidity sensed by the room sensor (see plans
for location) rise above 65% and the outdoor air temperature is above 55F, the AHU shall
start and supply 55F supply air until the relative humidity falls below 60%. The AHU
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23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
outdoor air damper is closed, the exhaust air dampers are closed, and all associated
terminal units are at maximum cooling CFM.
D.
E.
13-032
External Safeties
1.
Duct smoke detector, supplied by others, installed in the return air duct shall
automatically shut-down the AHU when activated. The AHU shall automatically restart
after the fire alarm system has been reset.
2.
Activation of any fire alarm pull station or fire sprinkler system water flow switch shall
automatically shut-down the AHU when activated. The AHU shall automatically restart
after the fire alarm system has been reset.
3.
The low temperature cutout stat shall activate if a temperature of less than 38F is sensed
at any one foot of the sensing element. When the low temperature cutout stat actives,
the AHU immediately shuts down, the heating coil control valve fully opens, and the DDC
system provides an alarm that the low temperature cutout stat has activated. The low
temperature cutout stat requires a manual reset.
4.
A high static pressure cutout switch measures supply air duct static pressure and shall
automatically shut-down the AHU when activated and the DDC system shall provide an
alarm that the unit has shut-down. The high static cutout switch shall require a manual
reset and the AHU shall require a manual restart after the high static pressure cutout
switch has reset. The high static cutout switch static pressure setpoint shall be 4.0” WC
(adj.).
5.
Supply fan and return fan status shall be monitored through the current sensor. If supply
fan state changes to “off” when it should be operating, the return fan shall be stopped and
the AHU shall go to an “off” state and the DDC system shall generate an alarm. If the
return fan state changes to “off” when it should be operating, the DDC system generates
an alarm and the AHU continues to operate.
6.
The DDC system shall monitor the AHU discharge temperature. If the supply air
temperature falls below 50F (adj.) the DDC system shall generate an alarm, and if the
supply air temperature falls below 45F (adj.) the DDC system shall stop the AHU,
generate an alarm and not allow the AHU to restart until the alarm is acknowledged and
the unit is manually restarted. If during occupied mode, the supply air temperature rises
above 75F (adj.) the DDC system shall generate an alarm, and if during any mode of
operation the supply air temperature rises above 100F (adj.) for 5 minutes the DDC
system shall stop the AHU, generate an alarm and not allow the AHU to restart until the
alarm is acknowledged and the unit is manually restarted.
Other
1.
The DDC system shall directly monitor; mixed air temperature, and return air
temperature.
2.
The DDC system shall directly monitor outside air temperature and relative humidity
globally.
3.
All points on the DDC system shall be capable of providing a user adjustable alarm and
being trended.
4.
All safeties shall be wired such that the unit will not start in “auto”, “manual” or “hand”.
23 09 93 - 25
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
1.12
VARIABLE REFRIGERANT FLOW (VRF) SYSTEM
SAHU-1; Serves Gym Classroom 1
SAHU-2; Serves Gym Classroom 2
SAHU-3; Serves Gym Classroom 3
VAV-1; Serves SAHU-1
VAV-2; Serves SAHU-2
VAV-3; Serves SAHU-3
BSB-1 - Branch Selector Box
HP-1; Heat Pump, Serves above Air Handling Units
A.
Controls are furnished with the VRF system and DDC System as shown on the drawings. Each
room thermostat controls the associated VRF air handling unit (SAHU) to provide heating or
cooling to the space. The VRF master controller communicates with equipment as shown and
controls; HP-1 and the refrigerant Branch Selector Box as required per the manufacturer's
programming. The DDC System controls the VAV Boxes that supply outdoor air to the rooms.
B.
Each indoor unit (SAHU) supply fan shall run continuously during occupied periods to maintain
a space temperature setpoint of 75 degrees (adj.) cooling and 70 degrees heating (adj), and
shall energize the auxiliary electric heating coil as required if the refrigerant coil cannot provide
sufficient heat. The integral cooling coil condensate pan pump shall operate as required to
drain cooling coil condensate.
C.
The room CO2 sensor shall control the associated VAV box. The VAV terminal unit controller
monitors the space CO2 sensor and its primary air airflow station, and modulates the primary
air damper between CO2 demand control minimum and maximum CFM settings to maintain
space CO2 setpoint. If space CO2 increases above 1000 ppm (adj.), primary air damper shall
modulate to maximum CFM position. When space CO2 falls below 1000 ppm (adj), primary air
damper modulates to minimum CFM position.
D.
Unoccupied heating – The master controller shall monitor each space temperature associated
with each terminal unit. When a space temperature falls below 60F (adj.), the system shall
operate and heat the space, and the VAV box damper remains closed.
E.
Unoccupied cooling – The master controller shall monitor each space temperature associated
with each terminal unit. When a space temperature rises above 80F (adj.), the system shall
operate and cool the space, and the VAV box damper remains closed.
F.
Morning warm-up – The master controller shall monitor each space temperature and outdoor air
temperature and automatically start the system prior to the occupancy schedule start time
based on “optimal start time” to get all the spaces up to occupied setpoint temperature by
occupied start time.
G.
Morning cool-down – The master controller shall monitor each space temperature and outdoor
air temperature and automatically start the system prior to the occupancy schedule start time
based on “optimal start time” to get all the spaces down to occupied setpoint temperature by
occupied start time.
H.
The DDC system shall monitor the entire system through a BACnet communication protocol.
and display temperature within the rooms and provide an alarms as determined by Norton
School Maintenance staff.
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23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
1.13
VARIABLE REFRIGERANT SYSTEM
SAHU-4; Serves Cross-Connect Room
SAHU-5; Serves Art Room 1
SAHU-6; Serves Art Room 2
SAHU-7; Serves Art Room 3
ERV-1; Energy Recovery Ventilator, Serves Above Air Handling Units
BSB-2 - Branch Selector Box
HP-2; Heat Pump, Serves above Air Handling Units
A.
All controls are furnished with the VRF system and DDC System as shown on the drawings.
Each room thermostat controls the associated VRF air handling unit (SAHU) to provide heating
or cooling to the space. The master controller communicates with equipment as shown and
controls; HP-2 and the refrigerant Branch Selector Box as required per the manufacturer's
programming. The DDC system controls the ERV that exhausts air from the adjacent Toilet
Rooms, supplies outdoor air to the Art Rooms, and performs energy recovery between the
airstreams.
B.
Each indoor unit (SAHU) supply fan shall run continuously during occupied periods to maintain
a space temperature setpoint of 75 degrees (adj.) cooling and 70 degrees heating (adj). and
shall energize the auxiliary electric heating coil as required if the refrigerant coil cannot provide
sufficient heat. The integral cooling coil condensate pan pump shall operate as required to
drain cooling coil condensate.
C.
The ERV operates during occupied periods and remains off during unoccupied periods. The
DDC system monitors each room CO2 sensor. If either CO2 sensor senses above 1000 ppm,
the ERV supply and exhaust fan each operate at 100% speed. When both CO2 sensors sense
below 1000 ppm the ERV supply and exhaust fan each operate at 60% speed. The DDC
system shall provide an alarm if the supply fan or exhaust fan are not operating when
commanded to operate. the DDC System shall monitor ERV supply air and exhaust air
temperatures.
D.
Unoccupied heating – The master controller shall monitor each space temperature associated
with each terminal unit. When a space temperature falls below 60F (adj.), the system shall
operate and heat the space, and the ERV remains off.
E.
Unoccupied cooling – The master controller shall monitor each space temperature associated
with each terminal unit. When a space temperature rises above 80F (adj.), the system shall
operate and cool the space, and the ERV remains off.
F.
Morning warm-up – The master controller shall monitor each space temperature and outdoor air
temperature and automatically start the system prior to the occupancy schedule start time
based on “optimal start time” to get all the spaces up to occupied setpoint temperature by
occupied start time.
G.
Morning cool-down – The master controller shall monitor each space temperature and outdoor
air temperature and automatically start the system prior to the occupancy schedule start time
based on “optimal start time” to get all the spaces down to occupied setpoint temperature by
occupied start time.
H.
The DDC system shall monitor the entire system through a BACnet communication protocol.
and display temperature within the rooms, all ERV points, and provide an alarms as determined
by Norton School Maintenance staff.
13-032
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1.14
SINGLE DUCT SHUTOFF VAV BOX
A.
Each VAV box has a hot water heating coil or electric heating coil. VAV terminal unit operation
is controlled by a controller mounted on the VAV box which communicates to the DDC system.
B.
Hot Water Heating coil operation – The hot water coil output is controlled through a modulating
2-way control valve. VAV box heating coil has a discharge air sensor that prevents the supply
air temperature from exceeding 90F (adj.) during occupied and unoccupied mode. During
morning warm-up mode, supply air temperature shall not exceed 100F (adj.).
C.
Electric Heating coil operation - The electric heating coil output is controlled through an SCR
that modulates the heating output of the coil. VAV box heating coil has a discharge air sensor
that prevents the supply air temperature from exceeding 90F (adj.) during occupied and
unoccupied mode. During morning warm-up mode, supply air temperature shall not exceed
100F (adj.).
D.
Each space temperature sensor (unless noted otherwise) has an adjustable lever that will allow
the temperature setpoint to be increased or decreased by 2F.
E.
The space served by the VAV terminal unit is controlled in occupied and unoccupied modes as
follows;
1.
Occupied mode
The VAV terminal unit is controlled within user defined maximum, minimum cooling and
CO2 demand control minimum primary air airflow settings. The VAV terminal unit controller monitors the space temperature sensor and primary airflow station, and modulates
the primary air damper between CO2 demand control minimum and maximum CFM settings to maintain space temperature setpoint. As the space temperature decreases, the
VAV terminal unit controller closes the primary air damper until it reaches CO2 demand
control minimum CFM (if CO2 demand control has not overridden primary air airflow control point CFM), and upon a further decrease in space temperature the heating hot water
coil control valve or electric heater modulates to maintain space temperature setpoint,
and if the space temperature continues to fall below setpoint, the system shall first verify
the discharge air temperature as heating (above 80°F) and then the primary air damper
modulates open up to maximum airflow setting. Space temperature setpoints are 75F
during cooling and 70F during heating.
The VAV terminal unit controller monitors the space CO2 sensor (if the space has a CO2
sensor) and primary airflow station, and modulates the primary air damper between minimum cooling and maximum cooling CFM settings to maintain space CO2 setpoint. If
VAV box primary air damper is operating between CO2 demand control minimum CFM
and below maximum CFM, and space CO2 increases above 1000 ppm (adj.), primary air
damper shall modulate to maximum CFM position, and, if space overcools then hot water
coil control valve or electric heater modulates to maintain space temperature setpoint.
When space CO2 falls below 1000 ppm, primary air airflow is allowed to fall to CO2 demand control minimum CFM if space does not require cooling or heating.
Space CO2 reading shall be transferred to associated Air Handling Unit controller. See
Air Handling Unit sequence of operation for additional information.
The VAV terminal unit controller also monitors the space relative humidity sensor (if the
space has a relative humidity sensor) and primary air airflow station, and modulates the
primary air damper between minimum and maximum CFM settings to maintain space relative humidity setpoint. If primary air damper is operating between CO2 demand control
minimum CFM and minimum CFM, and space relative humidity increases above 60&
(adj.), primary air damper shall modulate to maximum CFM position, and, if space over-
23 09 93 - 28
13-032
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
cools then hot water coil control valve modulates to maintain space temperature setpoint.
When space relative humidity falls below 55% (adj), primary air airflow is allowed to fall to
CO2 demand control minimum CFM if space does not require cooling.
2.
Unoccupied mode
When the associated Air Handling Unit is in unoccupied mode, the VAV terminal unit is in
unoccupied mode. During the unoccupied mode the primary air damper is fully closed.
When a space temperature falls below 60F (adj.), the associated Air Handling Unit shall
start and the terminal unit shall go to full heating mode and hot water control valve or
electric heating coil shall modulate and heat the space. When the critical zone space
temperature rises above 65F, the Air Handling Unit shall stop, or, the Air Handling Unit
shall operate for a minimum of 30 minutes. When a space temperature rises above 85F
(adj.), the associated Air Handling Unit shall start and the terminal unit shall go to full
cooling mode. When the critical zone space temperature falls below 80F, the Air Handling Unit shall stop, or, the Air Handling Unit shall operate for a minimum of 30 minutes.
Whenever the air handling unit is started, sufficient VAV boxes primary air dampers shall
open to allow air handling unit to operate at minimum supply air CFM.
F.
1.15
A.
1.16
A.
1.17
See Air Handling Unit sequence of operation for unoccupied heating, unoccupied cooling,
morning warm-up and morning cool-down.
LIGHTING CONTROLS OCCUPANCY SENSOR MONITORED BY DDC SYSTEM
Each room that contains a lighting controls occupancy sensor shall have the occupancy sensor
monitored by the DDC System. The Gym occupany sensors are monitored from a single point,
see Electrical drawings. The DDC System shall be capable of displaying the status of the
occupancy sensor as “occupied” or “unoccupied”.
LIGHTING CONTROLS CONTROLLED BY DDC SYSTEM
The DDC System shall provide Form-C relay contacts controlled by the DDC system to operate
Corridor lighting controls. These relay contacts are in parallel with the occupancy sensors. The
DDC system energize-deenergize these contacts on an occupied unoccupied schedule
determined by Norton School. During occupied periods lights remain on. During unoccupied
periods the lights are controlled by occupancy sensor. The DDC System shall be capable of
displaying the status of each relay as “occupied” or “unoccupied”.
SPLIT SYSTEM AIR HANDLING UNIT, SERVES CROSS CONNECT ROOM
A.
The standalone split system controller controls the system. Room thermostat that controls this
system is furnished with the equipment. This system is a backup to the Variable Refrigerant
system.
B.
The indoor unit (SAHU) supply fan shall run continuously and the refrigerant compressor shall
cycle to maintain a space temperature set point of 80 degrees (adj.) year round.
C.
The DDC system shall monitor and display temperature within the Cross-Connect Room, and
provide an alarm if the space temperature exceeds 82F (adj.) or falls below (70F (adj.).
13-032
23 09 93 - 29
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
1.18
A.
1.19
A.
1.20
A.
1.21
THROUGH WALL AC UNIT SEQUENCE OF OPERATION, AC-1 THROUGH AC-X, EACH
SERVE A TECHNOLGY CLOSET OR ELEVATOR MACHINE ROOM
Supply fan shall run continuously and the refrigerant compressor shall cycle to maintain a space
temperature set point of 75 degrees (adj.) year round.
EXHAUST FANS, LOCAL CONTROL EF-XX - SEE EXHUAST FAN SCHEDULE ON
DRAWING M-701
Line voltage space thermostat cycles the exhaust fan to maintain 85F setpoint. DDC system shall
monitor status of each exhaust fan. Exhaust air is directed to ceiling plenum.
EXHAUST FAN LOCAL CONTROL EF-XX - SEE EXHUAST FAN SCHEDULE ON DRAWING
M-701
Line voltage space thermostat cycles the exhaust fan to maintain 85F setpoint. DDC system shall
monitor status of each exhaust fan. Exhaust air is exhausted to outdoors, and when exhaust is
off gravity backdraft damper closes.
EXHAUST FANS CONTROLLED BY DDC SYSTEM - SEE EXHUAST FAN SCHEDULE ON
DRAWING M-701
A.
DDC system shall energize and de-energize Exhaust fans based on an occupied/unoccupied
schedule and as noted herein. DDC system shall monitor status of each exhaust fan.
B.
Exhaust fans that serve Toilet Rooms are also controlled by the DDC System in parallel with the
occupancy sensor and shall energize exhaust fan based on an occupied-unoccupied schedule.
This is to allow the exhaust fan to operate when the toilet room is cleaned in the evening by the
Custodians.
C.
Exhaust air is exhausted to outdoors, and when exhaust is off gravity backdraft damper closes.
1.22
EXHAUST FANS CONTROLLED BY ROOM OCCUPANCY SENSOR - SEE EXHUAST FAN
SCHEDULE ON DRAWING M-701
A.
Exhaust fan shall energize when occupancy sensor energizes light, and shall de-energize when
occupancy sensor turns off light. DDC system shall monitor status of each exhaust fan.
B.
Exhaust fans serving Janitor Closets are also controlled by the DDC System in parallel with the
occupancy sensor and shall energize exhaust fan based on an occupied-unoccupied schedule.
C.
Exhaust air is exhausted to outdoors, and when exhaust is off gravity backdraft damper closes.
1.23
A.
DESTRATIFICTAION FANS - See drawings for quantity and Locations
The DDC System shall start and stop destratification fans during occupied periods these fans
shall operate when the outdoor air temperature is below 45F (adj). During unoccupied periods
these fans remain off. The DDC System does not monitor status of each fan.
23 09 93 - 30
13-032
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
1.24
A.
1.25
A.
1.26
A.
1.27
EXHAUST FAN EF-23, SERVES MAIN ELECTRICAL ROOM
DDC system shall monitor room temperature and cycle exhaust fan as required to maintain 85F
(adj) room temperature. When exhaust fan is energized, motorized wall outdoor air damper
opens. When exhaust fan is de-energized, motorized wall intake air energize closed and gravity
backdraft damper in exhaust fan roof curb close. DDC system shall monitor status of exhaust
fan. DDC System shall provide an alarm if room temperature exceeds 90F.
SCIENCE CLASSROOMS AND ART CLASSROOM – EMERGENCY EXHAUST FANS
Exhaust fan is manually energized through a timer switch located on wall, see drawings for
location. Timer switch is moved to 60 minute position and exhaust fan is energized for 60
minutes. When exhaust fan is de-energized, gravity backdraft damper located a fan discharge
automatically closes to prevent outdoor air from back-drafting into the classroom. DDC system
shall monitor status of each exhaust fan.
ART KILN EXHAUST FAN
Exhaust fan is furnished with Art kiln and is manually started and stopped by switch located on
fan power cord. When exhaust is off, gravity backdraft damper closes.
SCIENCE CLASS ROOM FUME HOOD EXHAUST FANS
A.
Exhaust fan is furnished with fume hood.
B.
Exhaust fan is manually energized and manually de-energized through an “On-Off” switch
located on the fume hood. Motor operated backdraft damper opens when exhaust fan is
energized, and closes when exhaust fan is de-energized.
C.
Fume hood face velocity monitor is wired via a relay contact on the exhaust fan motor starter
such that it's auditable alarm is muted when exhaust fan is de-energized.
1.28
CLASSROOM KITCHEN HOODS, EXHAUST FANS
A
Exhaust fan is furnished with hood.
B
Exhaust fan is manually energized and manually de-energized through an “Off-On” switch
located on the hood, and switch is 3-speed.
C
Exhaust air is exhausted to outdoors, and when exhaust is off gravity backdraft damper closes.
1.29
DISHWASHER HOOD, EXHAUST FAN
A
Exhaust fan is manually energized and manually de-energized through an “Off-On” switch
located on the motor starter. DDC system shall monitor status of each exhaust fan.
B
Exhaust air is exhausted to outdoors, and when exhaust is off gravity backdraft damper closes.
13-032
23 09 93 - 31
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
1.30
A.
1.31
A.
1.32
A.
1.33
A.
1.34
CABINET UNIT HEATERS CUH-X - SEE EQUIPMENT SCHEDULE ON DRAWING M-703
Cabinet unit heater is controlled by a controller mounted within the unit cabinet which
communicates to the DDC system. Cabinet unit heater contains; supply fan, filter, hot water
coil, 2-way control valve and a space temperature sensor that senses return air temperature or
room temperature. Space served by cabinet unit heater shall be maintained at 70F (adj.).
Supply fan operates whenever there is a call for heating, at which time 2-way valve opens full
and cabinet unit heater provides heat until space rises above 70F (adj.). Space temperature
setpoint is through DDC system.
MECHANICAL ROOM UNIT HEATERS UH-X - SEE EQUIPMET SCHEDULE ON DRAWING
M-703
Unit mounted thermostat controls 2-way heating coil valve and unit heater supply fan to
maintain 60F (adj.) space temperature. When the temperature drops below setpoint, the 2-way
heating coil control valve shall fully open and supply fan shall activate.
KITCHEN FREEZER AND KITCHEN COOLER
The DDC system shall monitor the interior temperature of the Kitchen Freezer and Kitchen
Cooler and shall provide and alarm based on upper and lower setpoints determined by Norton
School System Maintenance staff.
ELEVATOR SUMP PUMP
DDC System monitors each sump pump high level switch and provides an alarm.
DOMESTIC WATER BOOSTER PUMP
A.
The DDC system shall monitor the domestic water booster pump through BACnet
communication and display all information provided from the BACnet communication card, and,
shall provide an alarm if an alarm condition exists at the domestic water booster pump.
a.
Graphic display shall include the information obtained from the booster pump from the BACnet
communication. DDC System Contractor shall provide a list of all points to Norton School that
can be displayed through the communication link, and then Norton School shall determine
which points are to be displayed.
1.35
DOMESTIC HOT WATER SYSTEM
A.
The DDC system shall monitor the domestic hot water supply temperature shall provide and
alarm based on upper and lower setpoints determined by Norton School System Maintenance
staff.
B.
The DDC system shall start-stop the domestic hot water recirculation pump, and this pump shall
operate continuously 24/7. The DDC System shall monitor the status of the pump and provide
an alarm when the pump is not operating and has been commended to operate.
C.
The DDC system shall monitor each domestic hot water heater through BACnet communication
and shall provide an alarm if an alarm condition exists at any domestic hot water heater.
23 09 93 - 32
13-032
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
D.
The DDC System shall monitor the domestic hot water meter and display; current consumption
in gallons per minute (gpm) and cumulative consumption in gallons based on current day,
previous day, previous week, previous month and previous year.
E.
DDC System contractor shall setup trends for; domestic hot water supply temperature and
domestic hot water current consumption. Each point shall be trended every 10 minutes (adj),
and, each trend shall be easily displayed by clicking a mouse over the trend description that will
be located on the Domestic Hot Water systems graphic page display.
F.
Graphic display shall include a display of each domestic water heater with a “hot spot” over the
display of the domestic water heater that when hit with the mouse shall go to a text screen
showing the information obtained from the electricity meter from the BACnet communication.
DDC System Contractor shall provide a list of all points to Norton School that can be displayed
through the communication link, and then Norton School shall determine which points are to be
displayed.
1.36
DOMESTIC WATER METER
A
The DDC System shall monitor the domestic water meter and display; current consumtion in
gallons per minute (gpm) and cumulative consumption in gallons based on current day,
previous day, previous week, previous month and previous year.
B
DDC System contractor shall setup trend for; domestic water current consumption. Point shall
be trended every 10 minutes (adj), and, trend shall be easily displayed by clicking a mouse
over the trend description that will be located on the Domestic Water Meter graphic page
display.
1.37
NATURAL GAS METER AND NATURAL GAS PRESSURE SENSOR
A.
The DDC System shall monitor the natural gas meter and display; current consumption in 1000
cubic feet per hour (MCF) and accumulative consumption in thousand cubic feet (MCF) based
on current day, previous day, previous week, previous month and previous year.
B.
DDC System contractor shall setup trend for; natural gas current consumption. Point shall be
trended every 10 minutes (adj), and, trend shall be easily displayed by clicking a mouse over
the trend description that will be located on the Natural Gas Meter graphic page display.
C.
The DDC System shall monitor the natural gas pressure, and provide a user adjustable alarm
point.
1.38
A.
13-032
ELECTRICITY METERS WITHIN MAIN SWITCHBOARDS MSB-A, MSB-B and MSB-C and
ELECTRICAL SURGE PROTECTOR
The Electricity Meters shall communicate to a DDC System controller via Modbus, thus all
points monitored by the Electricity Meters can be viewed, trended and alarmed. The Electricity
meters are located at each main electrical switchboard, and for each electricity meter the DDC
System shall display amperage for each phase, voltage per phase, power factor, power (in kW),
power in KVA, and accumulative consumption in KiloWatt Hours based on current day,
previous day, previous week, previous month and previous year. If a loss of phase is detected
through any electricity meter, all 2-phase (208 volt equipment) and 3-phase HVAC equipment
controlled through the DDC system shall automatically shut down and must be manually
restarted. DDC System contractor shall setup trends for each electricity meter for; amperage of
each phase, voltage, voltage of each phase, power factor, power (in KW), and power (in KVA).
Each point shall be trended every 10 minutes (adj), and, each trend shall be easily displayed by
23 09 93 - 33
23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
clicking a mouse over the trend description that will be located on the Electricity meters graphic
page display.
B.
1.39
Graphic display of each electricity meter shall include a display of each electricity meter with a
“hot spot” over the display of the electricity meter that when hit with the mouse shall go to a text
screen showing the information obtained from the electricity meter from the Modbus
communication. DDC System Contractor shall provide a list of all points to Norton School that
can be displayed through the communication link, and then Norton School shall determine
which points are to be displayed.
EMERGENCY GENERATOR TO DDC SYSTEM INTERFACE
A.
The DDC system shall monitor the emergency generator, and shall provide an alarm if the
emergency generator is activated.
B.
Provide all programming and communication conduit and wiring to the BACNet card serving the
emergency generator. Refer to electrical drawings for location of this BACnet communications
card.
C.
Graphic display shall include the information obtained from the emergency generator from the
BACnet communication. DDC System Contractor shall provide a list of all points to Norton
School that can be displayed through the communication link, and then Norton School shall
determine which points are to be displayed.
1.40
FIRE ALARM PANEL TO DDC SYSTEM INTERFACE
A.
The DDC system shall monitor the Fire Alarm Panel, and perform functions and be provided
with graphic displays as described herein.
B.
Provide all programming and communication conduit and wiring to the BACNet card serving the
Fire Alarm Panel. Refer to electrical drawings for location of this BACnet communications card.
C.
Graphic displays shall include the information obtained from the Fire Alarm Panel from the
BACnet communication. DDC System Contractor shall provide a list of all points to Norton
School that can be displayed through the communication link, and then Norton School shall
determine which points are to be displayed.
1.41
A.
DISPLAY FOR SCHEDULEING “SNOW DAY” OR DELAY START OF SCHOOL
The DDC system shall have a graphic display to be utilized to globally place all the HVAC
equipment in unoccupied mode for a “Snow Day”, or globally delay the start of the occupied
period by a user adjustable time (hours). That is, all occupied start times will be globally
delayed by the user adjustable time period. The display shall contain following;
1
Heading – Snow Day and Delay Start of School Day
2
Snow Day – User Input Field “Date and Year”
3
Delay Start of School Day – User Input Fields “Date and Year” and “Delay Time in Hours”
23 09 93 - 34
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23 09 93.01 – SEQUENCE OF OPERATIONS FOR HVAC CONTROLS
1.42
DISPLAY OF SHOWING CURRENT
UNACKNWOLEDGED ALARMS
A.
UNACKNOWLEDGED
ALARMS
AND
PAST
The DDC system shall have a graphic display that shows al current unacknowledged alarms
in order received and all past unacknowledged alarms in order received.
PART 2 - PRODUCTS (Not Applicable)
PART 3 - EXECUTION (Not Applicable)
END OF SPECIFICATION 23 09 93
13-032
23 09 93 - 35
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