ADDPENDIX J Sequences of Operation.pdf

AHU 101 SEQUENCE OF OPERATION

a. Supply and Return Fans Hand-Off-Auto Operation: A Hand- Off-Auto switch shall be provided as part of each Graham variable frequency drive. In the Off mode, the respective fan shall be stopped. In the Hand mode, the respective fan shall run continuously. In the Auto mode, the respective fan shall be started and stopped by the DDCP as described below. Upon activation, safeties shall stop both the supply and return fans in Hand, Auto, and Contactor Bypass modes.

b. Supply and Return Fans Local-Remote Speed Control: A local – Remote switch shall be provided as part of each variable speed drive. The local mode is not used on the air handlers at NCT because of the possibility of over pressurizing the duct work. In the Remote mode, the fan speed shall be controlled by the DDCP.

c. Fire/Smoke Damper Auto-Open-Close Control: Provide an Auto-Open-Close switch at the DDCP. When the switch is in the close mode, the supply and return fire dampers shall close.

When the switch is in the Open mode, the supply and return fire dampers shall open. In the Auto mode, the supply and return fire dampers shall be controlled by the DDCP. The Notifier Fire System shall close the supply and return fire dampers upon detecting a smoke/fire condition for the respective unit.

d. Fire Alarm Shutdown: The Notifier Fire Alarm System shall stop the supply and return fans and close the supply and return smoke dampers upon detecting a smoke/fire condition for the respective unit. The Notifier Fire Alarm System shall also send a shutdown signal to the DDCP. Upon receipt of the air handling shutdown signal, the outdoor minimum and maximum and relief dampers shall close. The mixed air damper shall open. The heating and cooling valves shall close. When the fire alarm condition has cleared, and the fire alarm system has been reset, the air handling unit shall be returned to the operating mode.

e. Minimum ventilation rate control: The minimum outside airflow rate set by the mechanical sheets shall be 2000cfm.

This rate is the outside airflow operating set point. The minimum outside airflow is compared to the outside airflow set point by PID module #30 and an error correction value is generated. This value is passed through to Reset buffer module #31. The output of the Reset buffer module #31 is sent to Hi/Low module #32. Hi/Low module #32 will output the highest value to Relay module #33. If the supply return fan start stop is on, Relay module #33 will pass the error correction value to the minimum outside air damper controller. If carbon dioxide levels are O. K., the correction value from the Two-position module #34 generated from Reset buffer module #31 will control the minimum outside air damper to maintain 2000 cfm. At the same time, the return air carbon dioxide level (Co2) is being compared to a constant value of 875 ppm. by Two position module #34. This value is sent to Relay module #35. If the return air Co2 is greater than 900 ppm. the Two-position module #34 causes the Relay module #35 to output an error correction value of 100 percent to Hi/Low module #32. The error correction value of 100 percent coming from the output of Hi/Low module #32 is sent to Relay module #33. If the supply return fan start stop signal is on, Relay module #33 will pass the 100 percent value to the minimum outside air damper and open it to 100 percent. If the output from the Two-position module #34 is less than 850 ppm, it causes the Relay module #35 to output an error correction value of 0 to the Hi/Low module # 32. Since the Hi/Low module #32 takes the highest value as its output; it will ignore the zero value. The Reset buffer module #31 is now controlling the minimum outside air damper.

f. Economizer Mode: PID module #20 compares the mixed air temperature operating set point to the mixed air temperature.

This difference or correction value is sent to Reset buffer module #21. The output of Reset module #21 is passed on to Relay module #22. When the outside air empalthy is less than or equal to the return air empalthy ( empalthy is the amount of energy to cool air expressed as a value), and the outside air temperature is less than the return air temp, and the outside air relative humidity is greater than 40 per cent you will be in economizer mode (economizer is on for Relay module #22).

Since Relay module #22 is selecting economizer on, it will pass the correction value from Reset buffer module #21 to Relay module #23. Relay module #23 will pass the correction value if the mixed air low temperature on alarm is off (mixed air temperature alarms at 45 degrees F.) Relay module #24 will pass the correction value if the supply return start/ stop command is on and this value opens the maximum outdoor air damper. The maximum outside air damper will open enough to satisfy the mixed air temp operating set point. If the mixed air temperature should go below 45 degrees, Relay module #23 shall output a 0 correction value which will close the maximum outdoor air damper. If the freeze limit stat should trigger, Relay #22 will output a 0 value that will close the maximum outdoor damper.

g. Non-Economizer Mode (Cooling and Humidity control):

When the outside air is warmer than the return air, the economizer circuit is off and the maximum outside air damper is closed. The supply air temperature is compared to the supply air temperature set point by PID module #50 and an error correction value is sent to Reset buffer module #51. The error correction value is passed through Reset buffer module #51 to Hi/Low module #52. At the same time, the return air relative humidity is compared to the relative humidity operating set-point by PID module #55 and an error correction value is also sent to Reset buffer module #56. The error correction value is passed through Reset buffer module #56 to Hi/Low module #52. The Hi/Low module #52 takes the highest of the two correction values and outputs it to Relay module #53. Relay module #53 will pass the correction value to the chilled water valve if the supply return fan start stop is on.

h. Heating Mode: The supply air temperature is compared to the supply air heating operating set-point by PID module #60 and an error correction value is sent to Reset buffer module #61.

Reset buffer module #61 passes the error correction value to Relay module #62. If the supply return fan start stop is on, Relay module #62 will pass the correction value to Relay module #63. If the freeze stat limit is normal, Relay module #63 will pass the error correction value to the hot water valve and it will operate to satisfy the supply air temperature heating operational set point.

i. Supply air temperature reset: The supply air temperature set point is a floating set point, and is determined by a calculation.

61 F. – (Range/100) x 100. The Range is equal to set value of 9 which is the specification range (61F- 52F = 9). This calculation was added to account for the average cooling demand for all of the VAVs and FPIBs . shall be reset based on the average demand for cooling. The supply air temperature set point should be reset between 52 and 61 degrees F., to the highest possible value while maintaining all VAV zone temperatures at the required set point.

j. Freeze stat alarm: If the freeze stat limit (38degrees) is reached, Relay module #63 will send a constant of 100 to the hot water valve to open it up to 100 percent. Also, the freeze stat is hardwired to the VFD drive safety relay circuit. When this circuit is activated, it will send a close command to the minimum, maximum, and relief air dampers.

k. Relief and Mixed air damper control: Relief and mixed air damper control is achieved by scaling the minimum outside air damper to 25 percent of its original value. This is done because the minimum outside air damper size is equal to 25 percent of the relief air damper size. Also, the maximum outside air damper is scaled to 75 percent of its original value. This is also done because the maximum outside air damper size is equal to 75 percent of the relief air damper size. Through a calculation, both are added so the combined damper positions equal the relief air damper position. All of this scaling is done to prevent over pressurization or under pressurization of the Administration Area. The calculation input to Reset module #25 is passed through to the relief air damper and the mixed air damper. The relief and mixed air dampers are electronically tied to the same point. This is also done to prevent over and under pressurization of the Administration Area. When the error correction signal from Reset module #25 opens the relief damper 25% it also closes the mixed air damper 25%.

l. Supply return fan start / stop control: Relay module #1 sends a low signal to Relay module #2 if the Notifier fire system is not alarming and is normal. Relay module #2 passes the low signal if the system start / stop command is on. Relay module #3 passes the low signal if the schedule command is on. Relay module #4 passes the low signal if the freeze stat is normal.

Relay #5 passes the low signal if the filter status is normal to Relay module #10 and Relay module #11. Relay module #10 opens the supply air fire damper and Relay module #11 opens the return air damper. Relay module #5 also passes a low signal to Relay module #15 which passes the low signal if the supply air damper position shows open. Relay module #5 passes the low signal to Relay module #16 if the return air fire damper position shows open. Relay module #17 passes the low signal from Relay module #16 if the supply air high static pressure safety is off. Relay module #18 passes the low signal from Relay module #17 to the supply / return fan start stop command. The supply / return fan start stop command signal initiates a start up for the supply and return variable frequency drives.

m. Supply fan variable frequency drive control: The supply fan speed is based on a calculation PO + P1/CO x P2. P1 = Supply air pressure range (1.8 - .8 = 1), CO = 100, P2 = average damper demand defined as per cent of damper position opening, PO = supply air low set point - .8 static pressure sensed by a pressure differential sensor (PD-4) and Relay module #39 passes the supply air pressure operating set point (.8 to 1.8 static pressure) if the supply / return fan start / stop command signal is on. This set point signal (supply air operating set point) is sent to PID module #40 and is compared to the supply air static pressure and an error correction signal is sent to Reset buffer module #41. Reset buffer module #41 passes the error correction signal to Relay module #42. Relay module #42 passes the error correction signal if the supply return fan start / stop command signal is on to the supply fan variable frequency drive.

n. Return fan variable frequency drive control: PID module #45 compares the supply air flow for AHU 101 to the return air flow for AHU 101 and outputs a error correction signal to Reset buffer module #46. Reset module #46 passes the error correction signal to Relay module #47. Relay module #47 passes the error correction signal if the supply return fan start/ stop command signal is on to the return fan variable frequency drive control.

o.

NORTHERN CALIFORNIA TRACON SEQUENCE OF OPERATIONS

AS-BUILT FOR THE CHILLED WATER & HOT WATER REDUNDANCY PROJECT

I. Chilled Water System General:

A. The Chilled Water System consists of 3 chillers, 3 primary chilled water pumps, 3 secondary chilled water pumps, 3 condenser water pumps and 3 cooling towers. The DDC system shall be programmed to control the chiller systems using two scenarios. The first scenario is to control the chiller systems when the CSI LAN system is fully functional. The second scenario is to control the chiller systems when the CSI LAN system is not functional.

The staging of the Chilled Water Systems shall be determined by LEAD / LAG / STANDBY designations. The DDC system operator shall manually determine the LEAD Chilled Water System, the LAG Chilled Water System and the STANDBY Chilled Water System at the front-end computer.

Unit Staging Control

0. OFF unit is assigned Mode 0

1. LEAD unit is assigned Mode 1

2. LAG unit is assigned Mode 2

3. STANDBY unit is assigned Mode 3

4. Failed/Maintenance unit is assigned Mode 4

II. Functional CSI LAN Chiller Control Sequences:

A. Individual Chiller Systems -->

1. The DDC system shall control each chiller and associated equipment using separate DDC controllers. Each DDC controller shall control a chiller, the chiller's associated primary and secondary chilled water pumps, the chiller's associated chilled water and condenser water control valves, and the chiller's associated condenser water pump and cooling tower fan system. The condenser water bypass valve shall be controlled by either the 100 Chiller System DDC controller or the 300 Chiller System DDC controller. The secondary chilled water pumps are equipped with VFD's. The sequencing of the secondary chilled water pumps may, at times, require that another chiller system's secondary chilled water pump run to maintain the system differential pressure setpoint when only one chiller is running.

B. LEAD Chilled Water System Control -->

1. The LEAD Chilled Water System shall run continuously. The DDC system shall signal the DDC system operator to switch the LEAD Chilled Water System whenever the running time exceeds 336 hours (adjustable) more than the average run time of all three chilled water systems, or when there is a hard failure of the LEAD Chilled Water System, or when there is a request for maintenance from the LEAD Chilled Water System.

C. LEAD Chilled Water System Start-Up -->

1. During the start-up of the LEAD Chilled Water System, the DDC system shall go through a start-up sequence.

2. If the DDC system registers that all three of the valves have opened fully, then the DDC system shall start the LEAD chiller system's primary chilled water pump and the LEAD chiller system's condenser water pump. The DDC system shall monitor the status of these pumps using current switches. If the DDC system does not register a RUN status from either of the pumps after a 6 second (adjustable) time delay, then the DDC system shall stop both pumps, close the LEAD chiller's three valves, disable the start-up of the LEAD chiller and send an alarm message to the DDC system operator.

3. The DDC system shall open the LEAD chiller's chilled water valve, the LEAD chiller's condenser water valve and the LEAD chiller's cooling tower isolation valve. The DDC system shall then check the status of all three of the valves to verify that all three valves have opened fully. If any of the three valves have not opened fully, then the DDC system shall close all three of the valves, disable the start-up of the LEAD chiller system and send an alarm message to the DDC system operator.

4. If the DDC system registers that both pumps are running after the 20 second (adjustable) time delay and the DDC system registers flow through the LEAD chiller's chilled water flow meter and the LEAD chiller's condenser water flow meter, then the DDC system shall start the LEAD chiller. A differential flow switch piped across the chiller evaporator and a differential flow switch piped across the chiller condenser shall be hardwired to the chiller's self contained control package to prevent chiller operation in the event of a no-flow condition. The DDC system shall monitor the status of the LEAD chiller. If the DDC system does not register a RUN status from the LEAD chiller after a 5-minute (adjustable) time delay, then the DDC system shall stop the LEAD chiller, stop both of the LEAD chiller system's pumps, close the LEAD chiller's three valves and send an alarm message (Mode 4) to the DDC system operator.

5. If the DDC system registers that the LEAD chiller is running after the 5-minute (adjustable) time delay, then the DDC system shall control its panel run relay to signal that its chilled water system is operational. The other two chilled water systems shall monitor this run relay.

6. If the DDC system registers that the LEAD chiller is running after the 5-minute (adjustable) time delay, then the DDC system shall modulate the LEAD chiller's chilled water valve to maintain a flow setpoint of 576 GPM (adjustable) through the LEAD chiller's chilled water flow meter. At the same time, the DDC system shall modulate the LEAD chiller's condenser water valve to maintain a flow setpoint of 720 GPM (adjustable) through the LEAD chiller's condenser water flow meter.

D. LAG Chilled Water System Start-Up -->

1. The DDC system shall monitor two primary chilled water flow meters and two secondary chilled water flow meters. The 100 Chiller DDC control panel shall monitor an UltraSonic type flow meter on the primary chilled water system and an UltraSonic type flow meter on the secondary chilled water system. The 300 Chiller DDC control panel shall monitor an Impeller type flow meter on the primary chilled water system and an Impeller type flow meter on the secondary chilled water system. The 100 Chiller DDC control panel Ultrasonic type flow meters shall be used as the primary source of flow information and the Impeller type flow meters shall be used for backup.

2. If the LEAD chiller's amperage exceeds 95% (adjustable) of the rated amperage for the chiller for 10 minutes (adjustable), then the LEAD chiller system DDC controller shall control its panel LAG DEMAND relay to signal that a LAG chiller is needed to meet the system load. If the c.chws supply temp is 2 degrees F higher than the York chilled water liquid setpoint for 10 minutes then a LAG chiller is commanded ON. The LAG DEMAND relay shall remain ON until the LAG chiller system is no longer needed.

a. The DDC system shall open the LAG chiller's chilled water valve, the LAG chiller's condenser water valve and the LAG chiller's cooling tower isolation valve. When the LAG chiller system is operating, the LAG chiller systems cooling tower isolation valve shall remain open. The DDC system shall then check the status of all three of the valves to verify that all three valves have opened fully. If any of the three valves have not opened fully, then the DDC system shall close the LAG chiller's chilled water and condenser water valves, disable the start-up of the LAG chiller and send an alarm message to the DDC system operator.

b. The DDC system shall start the LAG chiller system's primary chilled water pump and the LAG chiller system's condenser water pump. The DDC system shall monitor the status of these pumps using current switches. If the DDC system does not register a RUN status from either of the pumps after a 20 second (adjustable) time delay, then the DDC system shall stop both pumps, close the LAG chiller's chilled water and condenser water valves, disable the start-up of the LAG chiller and send an alarm message to the DDC system operator. The control the LAG chiller system's cooling tower isolation valve shall revert back to control by the DDC system to maintain the cooling tower condenser water supply temperature setpoint (see Cooling Tower System Control section).

c. If the DDC system registers that both pumps are running after the 20 second (adjustable) time delay and the DDC system registers flow through the LAG chiller's dp switches, then the DDC system shall start the LAG chiller. A differential flow switch piped across the chiller evaporator and a differential flow switch piped across the chiller condenser shall be hardwired to the chiller's self contained control package to prevent chiller operation in the event of a no-flow condition. The DDC system shall monitor the status of the LAG chiller. If the DDC system does not register a RUN status from the LAG chiller after a 5-minute (adjustable) time delay, then the DDC system shall stop the LAG chiller, stop both of the LAG chiller system's pumps, close the LAG chiller's chilled water and condenser water valves and send an alarm message to the DDC system operator.

d. If the DDC system registers that the LAG chiller is running after the 5-minute (adjustable) time delay, then the DDC system shall control its panel run relay to signal that its chilled water system is operational. The other two chilled water systems shall monitor this run relay.

e. If the DDC system registers that the LAG chiller is running after the 5-minute (adjustable) time delay, then the DDC system shall modulate the LAG chiller's chilled water valve to maintain a flow setpoint of 576 GPM (adjustable) through the LAG chiller's chilled water flow meter. At the same time, the DDC system shall modulate the LAG chiller's condenser water valve to maintain a flow setpoint of 720 GPM (adjustable) through the LAG chiller's condenser water flow meter.

E. LAG Chilled Water System Shut-Down -->

1. If the the total amperage for the LEAD and LAG chillers is less than 45% (adjustable) of the total rated amperage of the two chillers then the LAG chiller system shall be disabled.

2. When the DDC system disables the LAG chiller system, the DDC system shall first stop the LAG chiller.

3. When the DDC system registers a STOP status from the chiller, the DDC system shall stop the LAG chiller system's primary chilled water pump and the condenser water pump after a 20 second time delay (adjustable) to allow for heat dissipation from the chiller

4. After the DDC system registers that the LAG chiller system's primary chilled water pump is not running, the DDC system shall close the LAG chiller's chilled water valve. The DDC system shall keep the LAG chiller's chilled water valve open until the LAG chiller system's primary chilled water pump registers a STOP status.

5. The DDC system shall not re-enable the LAG chiller system for a minimum time delay of 10 minutes (adjustable).

F. Secondary Chilled Water Pump Control -->

1. Once the LEAD chiller is running, the DDC system shall control the secondary chilled water pumps to maintain the secondary chilled water system differential pressure setpoint of 8 PSI (adjustable). The DDC system shall monitor a secondary chilled water system differential pressure sensor in the penthouse and secondary chilled water system differential pressure sensors in the electronics wing. The differential pressure sensors in the electronics wing shall be monitored by the 100 Chiller System DDC panel and the other differential pressure sensor in the electronics wing shall be monitored by the 300 Chiller System DDC panel. The differential pressure sensor monitored by the 100 Chiller System DDC panel shall be used for normal control of the secondary chilled water pumps and the differential pressure sensor monitored by the 300 Chiller System DDC panel shall be used as a backup. The DDC system shall use the lower of the two readings to control the secondary chilled water pumping system to maintain the secondary chilled water system’s differential pressure setpoint of 8 PSI (adjustable).

2. When the DDC system registers that the LEAD chiller is running, the DDC system shall start the LEAD chiller system's secondary chilled water pump to run at 10% (adjustable).

The DDC system shall monitor the status of the LEAD chiller system's secondary chilled water pump by monitoring the secondary pump's VFD status (dry contacts in the VFD). If the DDC system does not register a RUN status from the LEAD chiller system's secondary chilled water pump after a 6 second (adjustable) time delay, then the DDC system shall switch the lead.

3. If the DDC system registers that the LEAD chiller system’s secondary chilled water pump is running after the 6 second (adjustable) time delay, then the DDC system shall control the pump’s VFD to maintain the secondary chilled water system differential pressure setpoint of 8 PSI (adjustable).

4. If the LEAD chiller's secondary chilled water pump speed exceeds 95%, then the DDC system shall start the LAG chiller system's secondary chilled water pump to run at the same speed. The DDC system shall monitor the status of the LAG chiller system's secondary chilled water pump by monitoring the secondary pump's VFD status (dry contacts in the VFD). If the DDC system registers that the LAG chiller system's secondary chilled water pump is running after the 6 second (adjustable) time delay. then the DDC system shall control both pumps together, at the same speed, to maintain the secondary chilled water system differential pressure setpoint of 8 PSI (adjustable).

5. If the DDC system does not register a RUN status from the LAG chiller system's secondary chilled water pump after a 6 second (adjustable) time delay, then the DDC system shall stop the LAG chiller system's secondary chilled water pump, send an alarm to the DDC system operator and start the STANDBY chiller system's secondary chilled water pump. The DDC system shall monitor the status of the STANDBY chiller system's secondary chilled water pump by monitoring the secondary pump's VFD status (dry contacts in the VFD). If the DDC system registers that the STANDBY chiller system's secondary chilled water pump is running after the 6 second (adjustable) time delay. The DDC system shall control both pumps together, at the same speed, to maintain the secondary chilled water system differential pressure setpoint of 8 PSI (adjustable). If the DDC system does not register a RUN status from the STANDBY chiller system's secondary chilled water pump after a 6 second (adjustable) time delay, then the DDC system shall stop the STANDBY chiller system's secondary chilled water pump and send an alarm to the DDC system operator.

6. When the DDC system is controlling the LEAD chiller system's secondary chilled water pump in tandem with another chiller system's secondary chilled water pump and the speed of both pumps drops below 40% (adjustable), then the DDC system shall stop the non- LEAD chiller system's secondary chilled water pump and return to controlling the LEAD chiller system's secondary chilled water pump to maintain the secondary chilled water system differential pressure setpoint. When the LEAD chiller system's secondary chilled water pump speed exceeds 95%, the DDC system shall revert back to the tandem pump control sequence.

G. Cooling Tower System Control -->

1. Once the LEAD chiller is running, the DDC system shall control the LEAD chiller system’s cooling tower fan in conjunction with the condenser water system’s bypass valve.

The speed of the cooling tower fans shall be controlled to maintain a cooling tower condenser water supply temperature setpoint. The condenser water bypass valve shall be controlled to maintain a bypass valve condenser water supply temperature setpoint of 5 deg F less than the lowest condenser water setpoint Each Chiller System DDC control panel shall monitor the condenser water supply and return temperature sensors.

2. When the DDC system registers that the LEAD chiller is running, the DDC system shall modulate the condenser water bypass valve to maintain the bypass valve condenser water supply temperature setpoint 5 deg F less than lowest condenser water setpoint . When the condenser water supply temperature rises 5 deg F more than lowest condenser water setpoint , the condenser water bypass valve shall be positioned for full condenser water flow to the cooling towers.

3. After the condenser water bypass valve has been positioned for full condenser water flow to the cooling towers, the DDC system shall start the LEAD chiller system's cooling tower fan to run at 20% (adjustable). The DDC system shall monitor the status of the LEAD chiller system's cooling tower fan by monitoring the cooling tower fan's VFD status (dry contacts in the VFD). If the DDC system does not register a RUN status from the LEAD chiller system's cooling tower fan after a 6 second (adjustable) time delay, then the DDC system shall stop the LEAD chiller system's cooling tower fan, the LEAD chiller system's secondary chilled water pump, disable the LEAD chiller system and send an alarm to the DDC system operator.

Chillers that fail during operation shall automatically be assigned a Mode 4 status. Any chiller taken out of service for maintenance shall be assigned a Mode 4 status. The DDCP shall not attempt to start any chiller system assigned a Mode 4 status.

4. If the DDC system registers that the LEAD chiller system’s cooling tower fan is running after the 6 second (adjustable) time delay, then the DDC system shall control the fan’s VFD to maintain the cooling tower condenser water supply temperature setpoint.

H. Chiller Alarm Sequencing -->

1. If a chiller system goes into an alarm condition that necessitates the shutdown of the chiller system, the DDC system shall adjust to keep the chiller plant operating to meet the load of the facility.

2. If the LEAD chiller system fails during startup or during normal operation, then the DDC system shall switch the chiller system to run as the LEAD chiller and the STANDBY chiller system shall assume the LAG chiller system responsibility. The DDC system shall send an alarm to the DDC system operator.

3. If the LAG chiller system fails during startup or during normal operation, then the DDC system shall shutdown the LAG chiller system and the STANDBY chiller system shall assume the LAG chiller system responsibility. The DDC system shall send an alarm message to the system operator.

4. If the LEAD and the LAG chiller systems fail during startup or normal operation, then the STANDBY chiller system shall assume the LEAD chiller responsibility. The DDC system shall send an alarm message to the system operator.

III. Non - Functional CSI LAN Chiller Control Sequences:

A. LEAD Chilled Water System Control (100 Chiller System)

1. When the DDC control system senses a degraded LAN situation, the DDC system shall shutdown the entire chilled water system. After the entire chilled water system has been shut down for a minimum time delay of 10 minutes (adjustable), the DDC system shall enable the LEAD Chilled Water System (100 Chiller System) which shall run continuously.

B. LEAD Chilled Water System Start-Up --> During the start-up of the LEAD Chilled Water System, the DDC system shall go through a start-up sequence.

1. The DDC system shall check the status of the LAG and STANDBY chilled water systems by monitoring run relays controlled by those system's DDC control panels. If either of the run relays indicates that another chilled water system is running, then the DDC system shall disable the start-up of the LEAD Chilled Water System.

2. If both chilled water systems are not running, then the DDC system shall open the

LEAD chiller's chilled water valve, the LEAD chiller's condenser water valve and the LEAD chiller's cooling tower isolation valve. The DDC system shall then check the status of all three of the valves to verify that all three valves have opened fully. If any of the three valves have not opened fully, then the DDC system shall close all three of the valves, disable the start-up of the LEAD chiller system and control its panel LAG DEMAND relay to signal that a LAG chiller system (300 Chiller System) is needed. The LAG DEMAND relay shall remain ON until the LEAD chiller system fault has been corrected. The other two chilled water systems shall monitor this LAG DEMAND relay.

3. If the DDC system registers that all three of the valves have opened fully, then the DDC system shall start the LEAD chiller system's primary chilled water pump and the LEAD chiller system's condenser water pump. The DDC system shall monitor the status of these pumps using current switches. If the DDC system does not register a RUN status from either of the pumps after a 20 second (adjustable) time delay, then the DDC system shall stop both pumps, close the LEAD chiller's three valves, disable the start-up of the LEAD chiller and control its panel LAG DEMAND relay to signal that a LAG chiller system (300 Chiller System) is needed. The LAG DEMAND relay shall remain ON until the LEAD chiller system fault has been corrected. The other two chilled water systems shall monitor this LAG DEMAND relay.

4. If the DDC system registers that both pumps are running after the 20 second (adjustable) time delay and the DDC system registers flow through the LEAD chiller's chilled water flow meter and the LEAD chiller's condenser water flow meter, then the DDC system shall start the LEAD chiller. A differential flow switch piped across the chiller evaporator and a differential flow switch piped across the chiller condenser shall be hardwired to the chiller's self contained control package to prevent chiller operation in the event of a no-flow condition. The DDC system shall monitor the status of the LEAD chiller. If the DDC system does not register a RUN status from the LEAD chiller after a 2-minute (adjustable) time delay, then the DDC system shall stop the LEAD chiller, stop both of the LEAD chiller system's pumps, close the LEAD chiller's three valves and control its panel LAG DEMAND relay to signal that a LAG chiller system (200 Chiller System) is needed. The LAG DEMAND relay shall remain ON until the LEAD chiller system fault has been corrected. The other two chilled water systems shall monitor this LAG DEMAND relay.

5. If the DDC system registers that the LEAD chiller is running after the 2-minute (adjustable) time delay, then the DDC system shall control its panel run relay to signal that its chilled water system is operational. The other two chilled water systems shall monitor this run relay

6. If the DDC system registers that the LEAD chiller is running after the 2-minute (adjustable) time delay, then the DDC system shall modulate the LEAD chiller's chilled water valve to maintain a flow setpoint of 576 GPM (adjustable) through the LEAD chiller's chilled water flow meter. At the same time, the DDC system shall modulate the LEAD chiller's condenser water valve to maintain a flow setpoint of 720 GPM (adjustable) through the LEAD chiller's condenser water flow meter.

C. LAG Chilled Water System Start-Up -->

1. The 100 Chiller DDC control panel shall monitor an UltraSonic type flow meter on the primary chilled water system and an UltraSonic type flow meter on the secondary chilled water system. The 300 Chiller DDC control panel shall monitor an Impeller type flow meter on the primary chilled water system and an Impeller type flow meter on the secondary chilled water system. The 100 Chiller DDC control panel Ultrasonic type flow meters shall be used as the primary source of flow information and the Impeller type flow meters shall be used for backup.

2. If the secondary chilled water flow exceeds the primary chilled water flow by more than 75 GPM (adjustable) for 5 minutes (adjustable), then the LEAD chiller system's DDC panel LAG DEMAND relay shall be controlled ON. The LAG chiller system DDC control panel shall register the ON status of the LEAD chiller system's DDC panel LAG DEMAND relay and shall enable the LAG chiller system. During the start-up of the LAG Chilled Water System, the DDC system shall go through the following start-up sequence:

a. The DDC system shall check the status of the STANDBY chilled water system by monitoring run relay controlled by that system's DDC control panel. If the run relay indicates that the STANDBY chilled water system is running, then the DDC system shall disable the start-up of the LAG Chilled Water System.

b. If the STANDBY chilled water system is not running, then the DDC system shall open the LAG chiller's chilled water valve, the LAG chiller's condenser water valve and the LAG chiller's cooling tower isolation valve. When the LAG chiller system is operating, the LAG chiller systems cooling tower isolation valve shall remain open. The DDC system shall then check the status of all three of the valves to verify that all three valves have opened fully. If any of the three valves have not opened fully, then the DDC system shall close the LAG chiller's chilled water and condenser water valves and disable the start-up of the LAG chiller.

c. If the DDC system registers that all three of the valves have opened fully, then the DDC system shall start the LAG chiller system's primary chilled water pump and the LAG chiller system's condenser water pump. The DDC system shall monitor the status of these pumps using current switches. If the DDC system does not register a RUN status from either of the pumps after a 20 second (adjustable) time delay, then the DDC system shall stop both pumps, close the LAG chiller's chilled water and condenser water valves and disable the start-up of the LAG chiller. The control the LAG chiller system's cooling tower isolation valve shall revert back to the control sequence used to maintain the cooling tower condenser water supply temperature setpoint (see Cooling Tower System Control section).

d. If the DDC system registers that both pumps are running after the 20 second (adjustable) time delay and the DDC system registers flow through the LAG chiller's chilled water flow meter and the LEAD chiller's condenser water flow meter, then the DDC system shall start the LAG chiller. A differential flow switch piped across the chiller evaporator and a differential flow switch piped across the chiller condenser shall be hardwired to the chiller's self contained control package to prevent chiller operation in the event of a no-flow condition. The DDC system shall monitor the status of the LAG chiller. If the DDC system does not register a RUN status from the LAG chiller after a 4-minute (adjustable) time delay, then the DDC system shall stop the LAG chiller, stop both of the LAG chiller system's pumps and close the LAG chiller's chilled water and condenser water valves. The control the LAG chiller system's cooling tower isolation valve shall revert back to the control sequence used to maintain the cooling tower condenser water supply temperature setpoint (see Cooling Tower System Control section).

e. If the DDC system registers that the LAG chiller is running after the 4-minute (adjustable) time delay, then the DDC system shall control its panel run relay to signal that its chilled water system is operational. The other two chilled water systems shall monitor this run relay.

f. If the DDC system registers that the LAG chiller is running after the 4-minute (adjustable) time delay, then the DDC system shall modulate the LAG chiller's chilled water valve to maintain a flow setpoint of 576 GPM (adjustable) through the LAG chiller's chilled water flow meter. At the same time, the DDC system shall modulate the LAG chiller's condenser water valve to maintain a flow setpoint of 720 GPM (adjustable) through the LAG chiller's condenser water flow meter.

D. LAG Chilled Water System Shut-Down -->

1. If the primary chilled water flow exceeds the secondary chilled water flow by 625 GPM (adjustable) for more than 5 minutes (adjustable), then the LEAD chiller system's DDC panel LAG DEMAND relay shall be controlled OFF. The LAG chiller system DDC control panel shall register the OFF status of the LEAD chiller system's DDC panel LAG DEMAND relay and shall disable the LAG chiller system.

2. When the DDC system disables the LAG chiller system, the DDC system shall first stop the LAG chiller.

3. When the DDC system registers a STOP status from the chiller, the DDC system shall stop the LAG chiller system's primary chilled water pump and the condenser water pump after a 2 minute time delay to allow for heat dissipation from the chiller. (adjustable)

4. After the DDC system registers that the LAG chiller system's primary chilled water pump is not running, the DDC system shall close the LAG chiller's chilled water valve. The DDC system shall keep the LAG chiller's chilled water valve open until the LAG chiller system's primary chilled water pump registers a STOP status.

5. After the DDC system registers that the LAG chiller system's condenser water pump is not running, the DDC system shall close the LAG chiller's condenser water valve. The DDC system shall keep the LAG chiller's condenser water valve open until the LAG chiller system's condenser water pump registers a STOP status.

6. After the DDC system registers that the LAG chiller is not running, the LAG chilled water system primary chilled water pump has stopped, the LAG chilled water system's condenser water pump has stopped, and both the LAG chiller's chilled water and condenser water valves are closed, then the DDC system shall control its panel run relay to signal that its chilled water system is no longer operational. The other two chilled water systems shall monitor this run relay.

7. The DDC system shall not re-enable the LAG chiller system for a minimum time delay of 20 minutes (adjustable).

E. Chiller Alarm Sequencing -->

1. If LEAD chiller system goes into an alarm condition that necessitates the shutdown of the chiller system, then DDC system shall adjust to keep the chiller plant operating to meet the load of the facility.

IV. Miscellaneous Chilled Water Systems General:

A. The Miscellaneous Chilled Water Systems consist of the refrigerant alarm system, the emergency ventilation system, the cooling tower sump level control system, the cooling tower tank level control system, the condenser water filter system and the condenser water chemical treatment system. A redundant DDC controller shall be used to control the refrigerant alarm system, the emergency ventilation system, the cooling tower sump level control system and the cooling tower tank level control system in the event of a LAN or DDC controller failure.

B. Refrigerant Alarm System -->

1. The Refrigerant Alarm System shall normally be controlled using the Miscellaneous Chilled Water System DDC Controller #1 Panel. When the Miscellaneous Chilled Water System DDC Controller #2 Panel registers that the Miscellaneous Chilled Water System DDC Controller Panel #1 is no longer functional via a panel run status relay, the Miscellaneous Chilled Water System DDC Controller Panel #2 shall assume control of the Refrigerant Alarm System.

2. The active DDC Controller shall monitor the chiller room Refrigerant Level Monitor.

When the DDC controller registers a refrigerant level alarm or when a chiller room emergency ventilation switch is activated, the DDC system shall start the chiller room exhaust fan EF-503 and open the chiller room emergency OA dampers. After the refrigerant alarm is reset at the refrigerant monitor and the DDC system operator issues a manual reset command, the DDC system shall stop the chiller room exhaust fan EF-503 and close the chiller room emergency OA dampers. When the CSI LAN system is not functional, the DDC system shall stop the chiller room exhaust fan EF-503 and close the chiller room emergency OA dampers after the refrigerant alarm is reset.

3. The DDC system shall monitor Refrigerant Level Monitor audible alarm silence switches. When the DDC system registers that an alarm silence switch has been activated, the DDC system shall silence the Refrigerant Level Monitor audible alarm. The DDC system operator may also silence the Refrigerant Level Monitor audible alarm via a manual operator command at the DDC front-end (if LAN system is operational). After the refrigerant alarm is reset at the refrigerant monitor, the audible alarms shall be reactivated until the alarm silence switches and alarm silence relay are returned to their normal positions.

C. Cooling Tower Make-Up Water Control -->

1. The Cooling Tower water system shall be provided with make-up water directly from the city water main by opening a make-up water valve, or through the cooling tower water system water storage tank by starting the tank water pump. The DDC system operator shall designate which of the two sources is to be used by the DDC system as the primary (LEAD) source of make-up water and which source will be the secondary (LAG) source of make-up water. When the CSI LAN is not operational, the tank water make-up valve shall automatically be selected as the primary (LEAD) source of make-up water and the cooling tower water system city water makeup shall be selected as the secondary (LAG) source of make-up water.

D. Cooling Tower Water Level Control -->

1. The Miscellaneous Chilled Water System DDC Controller #1 Panel shall monitor a Cooling Tower Sump level monitor and shall control one of the two sump make-up water valves. The Miscellaneous Chilled Water System DDC Controller #2 Panel shall monitor another separate Cooling Tower Sump level monitor and shall control the other of the two sump make-up water valves. The Miscellaneous Chilled Water System DDC Controller #1 shall be the primary controller for the sump level monitoring and the sump make-up water valve. The Miscellaneous Chilled Water System DDC Controller #1 shall maintain the status as the primary controller for the sump level monitoring and the sump make-up water valve. If the Miscellaneous Chilled Water System DDC Controller #1 panel is not operating when the CSI LAN system is not operational, then the Miscellaneous Chilled Water System DDC Controller #2 panel shall become the primary controller for the sump level monitoring and the sump make-up water valve. The DDC system shall control the sump water level by starting and stopping the cooling tower water tank pump CTP-1 and opening and closing the city water make-up water valve at lead and lag levels. The setpoints are adjustable through the DDC system. In addition, the low water level switches LS-1, LS-2 and LS-3 shall be interlocked to stop their respective cooling tower water pumps P-3A, P-3B, and P-3C when the sump water level drops below their setting. Low and High water level alarms shall be transmitted to the DDC control system front-end.

E. Cooling Tower Water System Water Tank Level Control

1. The Miscellaneous Chilled Water System DDC Controller #1 Panel shall monitor a Cooling Tower Water System Water Tank level monitor and shall control one of the two tank make-up water valves. The Miscellaneous Chilled Water System DDC Controller #2 Panel shall control the other of the two tank make-up water valves. When the CSI LAN system is operational, the Miscellaneous Chilled Water System DDC Controller #1 shall be the primary controller for the tank level monitoring and the tank make-up water valve. When the CSI LAN system is not operational, the Miscellaneous Chilled Water System DDC Controller #1 shall maintain the status as the primary controller for the tank level monitoring and the tank make-up water valve. If the Miscellaneous Chilled Water System DDC Controller #1 panel is not operating when the CSI LAN system is not operational, then the Miscellaneous Chilled Water System DDC Controller #2 panel shall become the primary controller for the tank make-up water valve. The Miscellaneous Chilled Water System DDC Controller #2 shall not monitor the level of the Cooling Tower Water System Water Tank. The DDC system shall control the tank water level by opening and closing the tank water make-up water valve at lead and lag levels.

The setpoints are adjustable through the DDC system. Low and High water level alarms shall be transmitted to the DDC control system front-end.

F. Cooling Tower Water Filter System Control -->

1. The Miscellaneous Chilled Water System DDC Controller #1 Panel shall control the Cooling Tower Water Filter System only. Whenever a cooling tower water pump P-3A, P-3B or P-3C is started, Filter Pump P-4 shall be started. However, before the DDC system starts Filter Pump P-4, the DDC system shall first open both of the Filter Pump P-4 isolation valves. After the DDC system has opened both of the Filter Pump P-4 isolation valves and verified that both valves have opened, then the DDC system shall start Filter Pump P-4.

V. Hot Water System General:

A. The Hot Water System consists of 2 boilers, 4 primary hot water pumps and 3 secondary hot water pumps. The DDC system shall be programmed to control the boiler systems using two scenarios. The first scenario is to control the boiler systems when the CSI LAN system is fully functional. The second scenario is to control the boiler systems when the CSI LAN system is not functional. The staging of the Boiler Systems shall be determined by LEAD / LAG designations. The DDC system operator shall manually determine the LEAD Boiler System and the LAG Boiler System.

VI. Functional CSI LAN Chiller Control Sequences:

A. Individual Boiler Systems -->

1. The DDC system shall control each boiler and associated equipment using separate DDC controllers. Each DDC controller shall control a boiler, the boiler's associated primary hot water pumps and all three of the secondary hot water pumps. The control of the hot water secondary pumps will be by the Lead Boiler System DDC panel under normal conditions.

B. LEAD Boiler Control -->

1. The LEAD Boiler shall run continuously. The DDC system shall signal the DDC system operator to switch the LEAD Boiler on a weekly basis.

C. LEAD Boiler System Start-Up --> During the start-up of the LEAD Boiler System, the DDC system shall go through a start-up sequence.

1. The DDC system shall start the LEAD Boiler's LEAD primary hot water pump. The DDC system shall monitor the status of this pump using a current sensor. If the DDC system does not register a RUN status from the LEAD Boiler's LEAD primary hot water pump after a 6 second (adjustable) time delay, then the DDC system shall start the LEAD Boiler's LAG hot water pump. If the DDC system does not register a RUN status from the LEAD Boiler's LAG primary hot water pump after a 6 second (adjustable) time delay, then the DDC system shall control its panel BOILER RUN relay to signal that the LEAD boiler system is not functioning correctly and send an alarm message to the DDC system operator. The other boiler system shall monitor this BOILER FAIL relay.

2. If the DDC system registers that either the LEAD or the LAG primary hot water pump is running for the LEAD Boiler after the 2 second (adjustable) time delay, then the DDC system shall enable the LEAD boiler.