23 09 29 BAS Sequence of Operations for HVAC.pdf

X033.01 23 09 29 - 1 BAS Sequence of Operations for HVAC

SECTION 23 09 29

BAS SEQUENCE OF OPERATIONS FOR HVAC

PART 1 - GENERAL

1.01 SECTION INCLUDES

A. Description of Control Sequences.

1.02 WORK INCLUDED

A. The control system will consist of all necessary devices and software to provide the sequences of operation described herein.

B. Provide custom engineered BAS operating software to perform control sequences specified. Sequence of operations describes major control functions but does not limit Contractor's responsibility to provide a fully operational automatic control system.

Contractor shall provide additional control functions not specifically described herein including time delays, control deadbands, equipment interlocks, equipment sequencing, alarm notification, control functions recommended by equipment manufacturers, or as otherwise required.

1.03 SUBMITTALS

A. Provide submittals for products listed in the Product Table below in accordance with Section 23 05 00 – General HVAC Provisions. Submittal requirements indicated by column number designation as follows:

1. Materials List

2. Catalog Data

3. Product Data

4. Performance Data

5. Wiring Diagrams

6. Shop Drawings

7. Installation Instructions

8. Special Requirements listed herein.

PRODUCT TABLE 1 2 3 4 5 6 7 8

All Products This Section X

B. Special Requirements: Provide a complete written sequence of operations for each system or subsystem under all modes of operation. Where Contractor proposes any variation to the sequence of operation described hereunder, the Contractor shall specifically highlight the change and describe the reason for the revision.

1.04 DESIGN REQUIREMENTS

A. All safety control circuits interlocked with motor starters or VFDs shall be hardwired and shall function in all operating modes (Automatic, Hand, and Manual Bypass).

B. Control setpoints and parameters listed in control sequences are initial values. Adjust setpoints and control parameters as directed by Engineer to achieved desired environment conditions, optimum system performance, and as recommended by TAB contractor.

C. Control setpoints shall be adjustable from the Operator Workstation without modification of control programming or use of proprietary software. All setpoints which are necessary for normal operation and optimization of system performance as required by Owner shall be adjustable, and shall include, but not be limited to: time schedules; temperature, pressure, humidity, and CO2 setpoints; time delay settings; safety sequence setpoints; and alarming parameters.

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D. Where BAS network communications are provided to networkable control systems or equipment, Contractor shall configure accessible points for control, monitoring, and alarm as required to provide specified sequences and as directed by the Owner’s Authorized Representative for trending and monitoring.

E. Provide BAS alarm functions and configuration as detailed in plans and specifications, and as directed by Owner’s Authorized Representative. Alarm functions may include:

1. Visual display on workstation graphic.

2. Audible alarm at workstation computer.

3. Listing in workstation alarm log.

4. “Pop-up” alarm notification at workstation computer.

5. Dial-out alarm to Owner’s security staff or alarm monitoring service.

F. BAS Points List

1. Provide all control points required to perform the automatic control sequence described herein, which as a minimum shall include all points listed in BAS Points List scheduled on drawings.

2. Point Communication: All points listed are to be hardwired to BAS controllers, except where point is identified as being communicated over a BAS network.

a. PTP = Hardwired point-to-point

b. C = BAS network communication

3. Point Source: All points shall be connected to field-mounted control devices, except where the point is identified as being obtained from an equipment controller identified. See Drawing Legend or equipment schedules for designation of equipment control panel abbreviations.

PART 2 - PRODUCTS

2.01 SURGE TANK LEVEL CONTROL

A. General: Control make-up water flow to maintain surge tank minimum level. Monitor tank high and low level status and provide alarms to boiler plant operator.

B. Surge Tank Level

1. Modulate make-up water control valve to maintain minimum tank level. Level setpoint determined by equipment manufacturer.

C. Safety Control, Monitoring, and Alarming

1. High Level Alarm: Activate alarm if tank water level is greater than the high level setpoint establish by the unit manufacturer. Maintain alarm until acknowledged by operator.

2. Low Level Alarm: Activate alarm if tank water level is less than 2 inches above the auxiliary low water alarm level. Maintain alarm until acknowledged by operator.

3. Auxiliary Low-Level Alarm: Activate alarm if auxiliary low tank level alarm switch is activated. Stop condensate transfer pumps. Maintain alarm until acknowledged by operator.

2.02 DEAERATOR TANK LEVEL CONTROL

A. General: Control transfer pump operation and flow rate to maintain deaerator tank minimum level. Monitor pump status and tank high and low level status and provide alarms to boiler plant operator.

1. Transfer pump Operation:

2. Lead/Lag Designation

a. Lead and lag designations shall be determined automatically; however, the operator shall have capability to manually changing the lead unit designation.

b. Lead and lag designations shall be alternated weekly.

c. Equipment Operation:

1) Start lead unit when boiler plant is enabled.

2) Start lag unit if lead unit operating status indicates that lead unit has failed, or lag unit operating command is on.

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3) Stop lag unit if lead unit operating status is restored and lag unit operating command is off.

4) Lead pump shall remain in operation for two minutes after the system is disabled.

B. Deaerator Tank Level

1. Modulate transfer pump speed to maintain tank level. Level setpoint determined by equipment manufacturer.

C. Safety Control, Monitoring, and Alarming

1. High Level Alarm: Activate alarm if tank water level is greater than the high level setpoint establish by the unit manufacturer. Maintain alarm until acknowledged by operator.

2. Low Level Alarm: Activate alarm if tank water level is less than 2 inches above the auxiliary low water alarm level. Maintain alarm until acknowledged by operator.

3. Auxiliary Low-Level Alarm: Activate alarm if auxiliary low tank level alarm switch is activated. Stop feedwater pumps. Maintain alarm until acknowledged by operator.

4. Low Deaerator Pressure Alarm: If the deaerator pressure is less than 2 psi for more than 2 minutes, activate Low Deaerator Pressure Alarm. Maintain alarm until acknowledged by operator.

5. Pump Status: If a motor is commanded “on” and the motor status after a 20 second delay indicates that the motor is off, activate status alarm. Maintain alarm until acknowledged by building operator.

2.03 FEEDWATER SUPPLY PRESSURE CONTROL

A. General: Control feedwater pump operation and flow rate to maintain feedwater heat pressure. Monitor pump status and header pressure and provide alarms to boiler plant operator.

B. Feedwater Pump Operation:

1. Unit Stage Designation:

a. Equipment shall be associated with a staging number

1) Stage 1 – Lead unit

2) Stage 2 – Lag unit

3) Stage 3 – Emergency back-up unit

b. Staging designations shall be determined automatically.

1) Staging designations shall be alternated weekly to equalize unit total cumulative runtime.

2) Provide enable/disable switch for each unit to manually disable unit operation.

3) Units that are in alarm or manually disable shall be automatically designated last in staging sequence.

4) Operator shall have capability to manually select lead unit. Programing shall ensure that each stage is associated with only one unit.

c. Staging Operation

1) Start Stage 1 when boiler plant is enabled.

2) Start Stage 2 when either:

a) Steam flow is greater than 10,000 lbs/hr

b) Two boilers are enabled.

3) Stop Stage 2 if both of the following occur.

a) Steam flow is greater than 8,000 lbs/hr for 15 minutes

b) Only one boiler is enabled.

4) Start and stop subsequent stages as stages are enabled and disabled. Start stages in increasing numerical order and stop stages in reverse numerical order. Command stage off if the stage is manually disable or the associated unit is in alarm.

5) A minimum time interval shall occur between enable and disable of stages.

Each stage shall operate for a minimum of 5 minutes prior to next staging event, unless otherwise indicated.

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6) Limit the total number of operating stages where indicated. Refer to individual system control sequences for maximum number of operating stages.

7) For pumping applications, lead pump shall remain in operation for two minutes after the system is disabled.

d. Provide graphic display in tabular format with the following content:

1) Unit tag number as scheduled on drawings

2) Staging designation

3) Manual enable/disable switch

4) Operating command status

5) Number of stages required

6) Staging delay timer

7) Staging delay timer setpoint

8) Staging Operation:

C. Feedwater Header Pressure

1. Modulate feedwater pump speed to maintain a header pressure of 60 psig.

D. Safety Control, Monitoring, and Alarming

1. Pump Status: If a motor is commanded “on” and the motor status after a 20 second delay indicates that the motor is off, activate status alarm. Maintain alarm until acknowledged by building operator.

2. High Feedwater Supply Pressure Alarm: If the supply pressure is more than 75 psi for more than 10 minutes, activate High Feedwater Pressure Alarm. Maintain alarm until acknowledged by operator.

3. Low Feedwater Supply Pressure Alarm: If the supply pressure is less than 50 psi than 10 minutes, activate Low Feedwater Pressure Alarm. Maintain alarm until acknowledged by operator.

2.04 Steam Metering (Alternate No 1)

A. General: Monitor steam flow and totalized steam production.

1. Steam consumption: Provide graphic display screen listing the following data.

a. Current steam flow (lbs/hr).

b. Monthly peak flow (klbs/hr) for current month to date and monthly values for the past 12 months.

c. Annual peak flow (klbs/hr) for previous 12 months.

d. Monthly consumption (klbs) for current month to date and monthly totals for the past 12 months.

e. Annual consumption (klbs) for previous 12 months.

PART 3 - EXECUTION

3.01 INSTALLATION

A. Install complete control system including all components, devices, and accessories required to perform desired sequence of operation.

END OF SECTION