B456 - 230993.11 - Sequence of Operations for HVAC DDC.pdf

Repair HVAC Building 456 Services ANG Project #GJKZ152865

Fairchild Airforce Base, Spokane, WA 100% B-3 Submission

Washington Air National Guard

SEQUENCE OF OPERATIONS FOR HVAC DDC 230993.11 - 1

SECTION 230993.11 - SEQUENCE OF OPERATIONS FOR HVAC DDC

PART 1 - GENERAL

1.1 RELATED DOCUMENTS

A. Drawings and general provisions of the Contract, including General and Supplementary

Conditions and Division 01 Specification Sections, apply to this Section.

1.2 SUMMARY

A. Section includes control sequences for DDC for HVAC systems, subsystems, and equipment.

B. Related Requirements:

1. Section 230923 "DDC Systems for HVAC" for control equipment.

1.3 DEFINITIONS

A. Analog Output: Proportional output signal (zero- to 10-V dc, 4 to 20 mA).

B. Binary Output: On/off output signal or contact closure.

C. DDC: Direct digital control.

D. Digital Output: Data output that must be interpreted digitally.

1.4 ACTION SUBMITTALS

A. Product Data:

1. An instrumentation list for each controlled system. Label each element of the controlled system in table format. Show, in the table element name, type of device, manufacturer, model number, and control device product data sheet number.

2. A complete description of the operation of the control system, including sequences of operation. Include and reference a schematic diagram of the controlled system.

B. Shop Drawings:

1. Riser diagrams showing control network layout, communication protocol, and wire types.

2. Schematic diagram of each controlled system. Include all control points labeled with point names shown or listed. Show the location of control elements in the system.

3. Wiring diagram for each controlled system. Show all control elements labels. Where a control element is the same as that shown on the control system schematic, label with the same name. Label all terminals.

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1.5 AIR-HANDLING-UNIT CONTROL SEQUENCES

A. Air-Handling Unit Time Schedule:

1. Occupied Time Schedule:

a. Input:

1) Device: DDC controller.

2) Location: Time schedule.

3) Transference: DDC controller.

b. Output:

1) Device: DDC controller.

c. Action:

1) Enable startup, initiation, and control.

2) Energize unit on occupied/unoccupied cycle.

3) Energize unit on day/night cycle.

4) Energize unit on duty cycle.

5) Energize return-air fans 30 seconds after supply fans are energized.

6) Do not enable mixed-air control during morning warm-up period.

a) Unoccupied: Position outdoor-air and relief-air dampers closed and return-air dampers open.

7) Do not enable humidifier control during morning warm-up period.

8) Enable control of heating coil(s) during morning warm-up period.

9) Energize coil circulating pump(s).

10) Return heating control valves to normal position when unit is cycled on.

11) Do not enable cooling-coil control during morning warm-up period.

B. Start and Stop Supply Fan(s):

1. Enable:

a. Input:

1) Device: Low limit temperature switch with automatic reset.

2) Location: Upstream of cooling coil.

3) Transference: Starter relay.

b. Output:

1) Device: Hard wired to motor controller and DDC controller.

2) Location: Motor controller.

3) Transference: Starter relay.

SEQUENCE OF OPERATIONS FOR HVAC DDC 230993.11 - 3

c. Action:

1) Allow start if temperature is above 37 deg F.

2) Signal alarm if fan fails to start as commanded.

2. Enable:

a. Input:

1) Device: Low limit temperature switch with automatic reset.

2) Location: Supply airstream.

3) Transference: Starter relay.

b. Output:

1) Device: Hard wired to motor controller and DDC controller.

2) Location: Motor controller.

3) Input Transference: Starter relay.

c. Action:

1) Allow start if temperature is below 120 deg F.

2) Signal alarm if fan fails to start as commanded.

3. Enable:

a. Input:

1) Device: Smoke detector with auxiliary contact automatic reset.

2) Location: Duct mounted after supply fan.or mounted in air-handling unit.

3) Transference: Starter relay.

b. Output:

1) Device: Hard wired.

2) Location: Motor controller.

3) Transference: Starter relay.

c. Output Device: Hard wired through motor controller; DDC controller alarm.

d. Action:

1) Allow start if airstream is free of products of combustion.

2) Signal alarm if fan fails to start as commanded.

C. Supply Fan(s) Variable-Volume Control:

1. Fan Speed Control:

a. Input:

1) Device: Air pressure transmitter.

SEQUENCE OF OPERATIONS FOR HVAC DDC 230993.11 - 4

2) Location: Supply-duct static pressure referenced to ambient-space static pressure.

3) Transference: DDC controller.

b. Output:

1) Device: Analog output.

2) Transference: Variable-frequency motor controller.

c. Action:

1) Maintain constant supply-duct static-pressure set point.

2) Set-Point Reset (for Systems with DDC of Individual Zone Terminals):

Reset static-pressure set point based on the zone requiring the most pressure;

reset set point lower until one zone damper is nearly wide open.

3) Set variable-frequency drive to minimum speed when fan is stopped.

2. Fan Airflow:

a. Input:

1) Device: Airflow sensor or transmitter.

2) Location: Supply duct.

3) Transference: DDC controller.

b. Output:

1) Device: DDC controller.

c. Action: Report supply-duct airflow.

3. High Pressure:

a. Input:

1) Device: Air pressure switch.

2) Location: Supply duct referenced to outside the duct.

3) Transference: DDC controller.

b. Output:

1) Device: Binary output; DDC controller.

2) Transference: Starter relay; operator's workstation.

c. Action: When static pressure rises above excessive-static-pressure set point.

1) Stop fan.

2) Signal alarm.

D. Return Fan(s) Variable-Volume Control:

SEQUENCE OF OPERATIONS FOR HVAC DDC 230993.11 - 5

1. Fan Speed Control:

a. Input:

1) Device: Airflow sensor or transmitter.

2) Location: Supply airstream and return airstream.

3) Transference: DDC controller.

b. Output:

1) Device: Analog output.

2) Location: Variable-frequency drive.

3) Transference: Variable-frequency drive controller.

c. Action:

1) Maintain constant airflow offset between supply- and return-air fans.

2) Set variable-frequency drive to minimum speed when fan is stopped.

2. Fan Speed Control:

a. Input:

1) Device: Air pressure sensor or differential transmitter.

2) Location: Indoor space static pressure referenced to outdoor static pressure.

3) Transference: DDC controller.

b. Output:

1) Device: Analog output.

2) Transference: Variable-frequency motor controller.

c. Action:

1) Maintain constant indoor static-pressure set point of 0.02-inch wg positive for outdoors.

2) Set variable-frequency drive to minimum speed when fan is stopped.

d. Action: Maintain constant indoor static pressure.

E. Mixed-Air Control:

1. Minimum Position:

a. Input:

1) Device: DDC controller.

2) Location: Time schedule.

3) Transference: DDC controller.

b. Input:

SEQUENCE OF OPERATIONS FOR HVAC DDC 230993.11 - 6

1) Device: Flow measuring station.

2) Location: Outdoor-air intake.

3) Transference: DDC controller.

c. Output:

1) Device: Analog output.

2) Location: Outdoor damper.

3) Transference: Damper actuator(s).

d. Action:

1) Open outdoor-air dampers to minimum position.

2) Modulate outdoor-air dampers to maintain minimum airflow at set point.

2. Heating Reset:

a. Input:

1) Device: DDC controller.

2) Location: Software.

3) Transference: DDC controller.

b. Output:

1) Device: Analog output.

2) Location: Outdoor dampers.

3) Transference: Damper actuator(s).

c. Action: Set outdoor-air dampers to minimum position.

3. Carbon Dioxide Reset:

a. Input:

1) Device: Carbon dioxide transmitter.

2) Location: Space.

3) Transference: DDC controller.

b. Output:

1) Device: Analog output.

2) Location: Dampers.

3) Transference: Damper actuator(s).

c. Action: Reset minimum outdoor-air damper position to maintain carbon dioxide set point.

4. Supply-Air Temperature:

SEQUENCE OF OPERATIONS FOR HVAC DDC 230993.11 - 7

a. Input:

1) Device: Air-temperature sensor or air-temperature sensor with air-temperature RTD transmitter.

2) Location: Supply-airstream.

3) Transference: DDC controller.

b. Output:

1) Device: Analog output.

2) Location: Damper section.

3) Transference: Damper actuator(s).

c. Action:

1) Modulate outdoor-, return-, and relief-air dampers to maintain air-temperature set point of 55 deg F.

2) Do not enable control during morning warm-up period.

5. Cooling Reset:

a. Input:

1) Device: Air-temperature sensor or air-temperature sensor with air-temperature RTD transmitter.

2) Location: Outdoor- and return-air ducts.

3) Input Transference: DDC controller.

b. Output:

1) Device: Analog output.

2) Location: Outdoor- and return-air ducts.

3) Transference: Damper actuator(s).

c. Action: Set outdoor-air dampers to minimum position when outdoor-air temperature exceeds return-air temperature.

F. Filters:

1. Differential Pressure:

a. Input:

1) Device: Pressure differential switch or transmitter.

2) Location: Filter bank.

3) Transference: DDC controller.

b. Output:

1) Device: DDC controller.

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2) Location: DDC controller.

3) Transference: Operator's workstation.

c. Action: Signal alarm on low- and high-pressure conditions.

G. Coordination of Air-Handling Unit Sequences: Ensure that preheat, mixed-air, heating-coil, and cooling-coil controls have common inputs and do not overlap in function.

H. Indicate the following on the operator's workstation display terminal:

1. DDC system graphic.

2. DDC system on-off indication (operating or not operating).

3. DDC system occupied/unoccupied mode.

4. Outdoor-air-temperature indication.

5. Supply-fan on-off indication (operating or not operating).

6. Supply duct static-pressure indication.

7. Supply duct static-pressure set point.

8. Supply-fan airflow rate.

9. Supply-fan speed.

10. Return-fan on-off indication (operating or not operating).

11. Space static-pressure indication.

12. Space static-pressure set point.

13. Return-fan airflow rate.

14. Return-fan speed.

15. Preheat-coil air-temperature indication.

16. Preheat-coil air-temperature set point.

17. Mixed-air-temperature indication.

18. Mixed-air-temperature set point.

19. Mixed-air damper position.

20. Relative humidity indication.

21. Relative humidity set point.

22. Relative humidity control-valve position.

23. Filter air-pressure-drop indication.

24. Filter low-air-pressure drop set point.

25. Filter high-air-pressure drop set point.

26. Supply-air-temperature indication.

27. Supply-air-temperature set point.

28. Cooling-coil leaving-air-temperature indication.

29. Cooling-coil leaving-air-temperature set point.

30. Cooling-coil control-valve position.

31. Space temperature indication.

32. Space temperature set point.

1.6 DEDICATED OUTSIDE AIR SYSTEM UNIT CONTROL SEQUENCE

A. Run Conditions - Scheduled:

1. The unit shall run based upon an operator adjustable schedule.

B. Emergency Shutdown:

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1. The unit shall shut down and generate an alarm upon receiving an emergency shutdown signal.

C. ATFP Emergency Shutdown:

1. The unit shall shut down and generate an alarm upon receiving an emergency shutdown signal from the building ATFP shutdown.

D. Supply Air Smoke Detection:

1. The unit shall shut down and generate an alarm upon receiving a supply air smoke detector status.

E. Outside Air Dampers:

1. The outside air damper shall open anytime the unit runs and shall close anytime the unit stops. The supply fan shall start only after the corresponding damper status has proven the damper is open. The outside air damper shall close 4 sec (adj.) after the fan stop.

2. Alarms shall be provided as follows:

a. Outside air damper failure: commanded open, but the status is closed.

b. Outside air damper in hand: commanded closed, but the status is open.

F. Supply Fan:

1. The supply fan shall run anytime the unit is commanded to run. To prevent short cycling, the supply fan shall have a user definable (adj.) minimum runtime, unless shutdown on safeties.

2. Alarms shall be provided as follows:

a. Supply fan failure: commanded on, but the status is off.

b. Supply fan in hand: commanded off, but the status is on.

c. Supply fan runtime exceeded: status runtime exceeds a user definable limit (adj.).

G. Supply Air Temperature and Supply Air Setpoint:

1. The controller shall monitor the supply air temperature and shall maintain:

a. A 78°F (adj.) Cooling setpoint.

b. A 68°F (adj.) Heating setpoint.

H. Dx Cooling Coil Valve:

1. The controller shall measure the cooling air temperature and modulate the dx cooling coil valve to maintain a cooling setpoint of 55°F (adj.) for dehumidification the cooling shall be enabled whenever:

a. The supply air temperature is above cooling setpoint.

b. And the supply fan status is on.

2. Alarms shall be provided as follows:

a. High supply air temp: if the supply air temperature is greater than 20°F (adj.)

above setpoint.

I. Gas Heating Valve:

1. The controller shall measure the supply air temperature and modulate the gas heating valve to maintain the supply air temperature setpoint (above).

2. The heating shall be enabled whenever:

a. The outdoor air temperature is below heating setpoint.

b. Or the supply air temperature is below the cooling setpoint.

c. And the supply fan status is on.

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3. The gas heating valve shall open to 100% (adj.) whenever:

a. Supply air temperature drops below 41°F (adj.).

4. Alarms shall be provided as follows:

a. Low supply air temp: If the supply air temperature is less than 10°F (adj.) below setpoint.

J. Filter Differential Pressure Monitor:

1. The controller shall monitor the differential pressure across the filter.

2. Alarms shall be provided as follows:

a. Filter change required: Filter differential pressure exceeds a user definable limit

(adj.).

K. Alarms Shall Be Provided as Follows:

1. High supply air temp: If the supply air temperature is greater than 118°F (adj.).

2. Low supply air temp: If the supply air temperature is less than 44°F (adj.).

PART 2 - PRODUCTS (Not Applicable)

PART 3 - EXECUTION (Not Applicable)

END OF SECTION 230993.11