Sequence of Operations (SOO)
Pilot Pre-Flight Checklist
Before a pilot takes off — they do not just push the throttle:
Engine check
Flaps to position
Runway clearance confirmed
Speed check at V1
Rotate at V2
Gear up at safe altitudeEvery step in order. Miss one — safety is compromised.
AHU Sequence of Operations:
START SEQUENCE:
Step 1: Confirm no fire alarm active
Step 2: Open outside air damper → wait 30 seconds
Step 3: Start supply air fan → confirm run feedback within 5 seconds
If no feedback in 5 seconds → raise fault alarm, do not proceed
Step 4: Enable chilled water valve PID control
Step 5: Enable heating valve PID control
Step 6: Start return air fan
RUNNING:
Control supply air temperature at 16°C via CHW valve PID
Control space temperature at 24°C
Monitor CO2 → adjust fresh air damper via DCV logic
Monitor filter DP → alarm if above limit
STOP SEQUENCE:
Step 1: Close chilled water valve fully
Step 2: Stop supply air fan
Step 3: Stop return air fan
Step 4: Close outside air damper after 60 seconds
FIRE MODE:
Immediate stop on fire alarm signal
All dampers close
Manual restart required — no auto restart on fire
SOO is the English language description.
FBD is the visual drawing of the same logic.
Controller is the machine that runs it.
SOO is written by the BMS design engineer. FBD is programmed from the SOO. Commissioning verifies both match reality.
Related Topics
- What is BMS integration? — how a BMS connects with VFDs, energy meters, BACnet/Modbus devices and other building systems
- How to design a BMS system step by step — the complete BMS design methodology covering site survey, IO list, controller selection, sequence of operations
- What is a Building Management System (BMS)? — fundamentals of BMS controls and architecture for HVAC, lighting, energy and access
- What is BMS commissioning? — the disciplined commissioning process that turns a BMS install into a working building brain
- Browse all Control Loops & FBD topics — more from this section of the EnSmart BMS Library