1. 💨 Air Balancing Procedures

A. Fan Coil Units (FCU) Balancing Steps

• Ensure automatic control systems are fully commissioned.
• Perform all pre-commissioning checks.
• Set FCU to specified fan speed.
• Open all diffuser/grille dampers fully.
• Measure initial airflow from all outlets using a flow hood.
• Calculate total measured flow and compare with design flow.
• Identify the index outlet (lowest percentage of flow).
• Keep index outlet damper fully open.
• Adjust other outlets to proportionally match design flow using bolometer.
• As you adjust each outlet, monitor the index outlet for airflow changes.
• Finalize proportional balance at all outlets and record all values.

B. Ventilation / Exhaust Fan Balancing

• Confirm pre-commissioning checks are complete.
• Record fan motor amperage and RPM.
• Ensure fan settings are within manufacturer limits.
• Open all duct dampers (main and branches).
• Measure total airflow using the duct traverse method (target: 105% of design flow).
• Identify the index branch (lowest reading).
• Balance all other branches proportionally, keeping index branch damper open.
• Monitor and measure airflow after each adjustment.
• Finalize the balance and record results.

C. Air Handling Unit (AHU) Balancing

• Set fan speed to deliver total design air quantity.
• Ensure speed does not exceed manufacturer’s limits.
• Open all main, branch, and terminal dampers.
• Measure total fan airflow using duct traverse (target: 105% of design flow).
• Identify index branch and keep damper fully open.
• Balance other branches and terminals proportionally.
• Ensure motor amperage stays within limits.
• Record final measurements:
  • Fan RPM
  • Motor voltage and current
  • Static pressure (entering and leaving the fan)

D. Air Terminal Balancing Procedure

• Use flow hood or bolometer where access is available.
• Use anemometer and calculate velocity × free area if access is restricted.
• Begin balancing at the most remote branch or terminal.
• Identify index terminal (lowest percentage of design flow).
• Adjust adjacent terminals to match the index terminal percentage.
• Continue this process progressively.
• Record all terminal flow rates and ensure totals match sub-branch flow.
• Follow CIBSE Application Guide 3/89 for standards.

E. Stairwell Pressurization Fan Balancing

• Complete all pre-commissioning and interfacing checks.
• Ensure fire alarm integration is functional.
• Open all outlet dampers.
• Measure initial airflow from all terminals (Initial Scan).
• Identify the index outlet (least airflow).
• Keep index damper open and throttle other dampers proportionally.
• Use anemometer to monitor index flow as others are adjusted.
• Record balanced values for all outlets.
• Measure and record pressure difference between floors and stairwells.

2. ❄️ Chilled Water System Balancing

F. Secondary Pump Shut-Off Head Test

• Use a differential pressure gauge to test across suction/discharge points.
• Set all valves (supply, return, and control) to fully open.
• Run pump and temporarily close discharge valve (<1 minute).
• Measure shut-off head and compare with manufacturer data.
• If not matching, create a parallel curve from test data.
• Re-open valve slowly and proceed to full-flow pressure check.

G. Preliminary Flow Rate Check

• With all valves open, measure total actual flow.
• Compare with system design flow.
• Adjust main regulating valve to achieve ~110% of design flow if needed.

H. Proportional Chilled Water Balancing (Main to Terminal)

• Keep DRVs and isolation valves fully open.
• Measure initial flow across heat exchangers and risers.
• Identify index riser (lowest flow).
• Keep index DRV open and throttle other risers proportionally.
• Monitor index percentage rise after each riser adjustment.
• Finalize balance and record flow across all risers.

I. Final Witnessing & Reporting

• Upon successful TAB completion:
  • Submit the test report to the consultant.
  • Schedule witnessing inspection.
  • Ensure documentation includes all final readings and compliance with design specs.

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