How to prepare an FAHU for testing

How to Prepare an FAHU for Testing

A Fresh Air Handling Unit (FAHU) plays a vital role in HVAC systems by supplying treated fresh air into a building, improving indoor air quality and comfort. Before commissioning, it is essential to properly prepare the FAHU for testing to ensure it operates efficiently and complies with design and safety standards.

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 Steps to Prepare an FAHU for Testing:

1. Physical Inspection:

   • Check that the FAHU is installed securely on vibration isolators or a concrete pad.

   • Ensure all duct connections (supply and return) are properly sealed and insulated.

   • Verify that the condensate drain is connected and sloped correctly for drainage.

2. Check Filters and Components:

   • Confirm that pre-filters, fine filters, and HEPA filters (if applicable) are installed, clean, and properly seated.

   • Inspect the cooling/heating coils for cleanliness and correct piping connections.

   • Ensure that dampers, mixing box, and access doors operate freely and are airtight.

3. Electrical and Control System Check:

   • Verify that the power supply is connected and that all electrical components (fans, motors, sensors) are properly wired.

   • Check the control panel, thermostats, and BMS communication for correct configuration and labeling.

   • Confirm emergency stop buttons and safety interlocks are functional.

4. Fan and Motor Preparation:

   • Ensure the blower fan and motor alignment are correct.

   • Check the rotation direction of the fan using manual jogging before full start-up.

   • Inspect for any unusual noise or imbalance during operation.

5. Airflow and Damper Adjustment:

   • Make sure volume control dampers are installed and accessible for balancing.

   • Confirm that motorized dampers are functioning and responding to control signals.

6. Leak and Pressure Test:

   • Perform a duct leakage test if required.

   • Check the static pressure and airflow rate match the design requirements using a manometer or airflow hood.

7. Safety Measures:

   • Confirm the FAHU area is clean and safe for testing.

   • Keep test documentation and tools ready, including datasheets, testing forms, and calibration certificates.

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Proper preparation of the FAHU before testing ensures a smooth commissioning process, helps avoid delays, and guarantees the system performs as intended. Attention to detail in inspection, connections, and functionality checks lays the foundation for reliable, long-term operation of the unit.