Standard Operating Procedure (SOP)

Here’s a detailed Standard Operating Procedure (SOP) for an Air Handling Unit (AHU), typically used in HVAC systems. This SOP ensures proper operation, maintenance, and safety procedures for handling AHUs.

1. Purpose:

To outline the standard procedure for the operation, inspection, and maintenance of the Air Handling Unit to ensure optimal performance and air quality.

2. Scope:

Applicable to all AHUs installed in the facility, covering startup, normal operation, shutdown, and routine maintenance.

3. Responsibilities:

• HVAC Technician / Operator: Daily checks and basic operations

• Maintenance Team: Preventive and corrective maintenance

• Facility Manager: Overall compliance and scheduling

4. Safety Precautions:

• Wear PPE: gloves, safety goggles, mask

• Lockout/tagout electrical supply before maintenance

• Ensure proper ventilation when using cleaning chemicals

• Do not bypass safety interlocks

5. Equipment/Tools Required:

• Multimeter

• Filter pressure gauge

• Cleaning supplies

• Lubricants (if applicable)

• PPE

6. Procedure:

6.1. Start-Up Procedure:

1. Ensure power supply is available.

2. Check the condition of air filters; replace if dirty.

3. Inspect dampers for proper operation.

4. Confirm the fan/motor area is free from obstructions.

5. Switch on the main power.

6. Start the AHU from the control panel.

7. Monitor for abnormal noise or vibration.

8. Check airflow and supply air temperature.

9. Record readings (ampere, voltage, temperature, pressure drop).

6.2. Normal Operation Monitoring:

• Check and record:

  • Return and supply air temperature

  • Fan motor current

  • Differential pressure across filters

  • Vibration or noise from fan/motor

• Ensure condensate drain is not clogged

• Verify damper positions and actuator response

6.3. Shutdown Procedure:

1. Turn off the unit from the control panel.

2. Allow motor to come to a complete stop.

3. Switch off the power supply.

4. Perform post-operation inspection if needed.

7. Preventive Maintenance (Monthly or as per schedule):

• Clean or replace air filters

• Inspect and clean blower assembly

• Check and tighten electrical connections

• Lubricate motor bearings (if not sealed type)

• Clean cooling/heating coils

• Inspect insulation and ductwork

• Test operation of safety and control devices

8. Emergency Handling:

• In case of fire or smoke, shut down the AHU immediately.

• If unusual vibration, noise, or burning smell is detected, switch off power and inform maintenance.

• Log the incident and corrective action taken.

9. Documentation:

• Maintain a logbook for each AHU with:

  • Daily operating data

  • Maintenance records

  • Fault reports and corrective actions

10. References:

• Manufacturer’s operation and maintenance manual

• Local HVAC codes and standards

• Facility-specific safety guidelines.

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