This checklist identifies Key Commissioning Test Requirements and Key Preparations and Cautions for testing an air handling system’s fans and drives. When writing a test, use this checklist to help ensure that these key areas have been covered. The buttons following the checklist items link to supporting information within the Functional Testing Guide and the Control System Design Guide.
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Control System Design Guide |
Key Commissioning Test Requirements
- ___ 1. During design review, the following items were addressed to avoid issues during functional testing:
- a) Variable speed drive installation and operation requirements have been taken into account.
- b) The VFDs and motors are compatible (i.e. inverter-rated motor).
- c) The drive arrangement is suitable for the application.
- d) The unit has good access for control installation, maintenance, and component replacement.
- e) Verify that the fan capacity is properly sized so that the VFD operates near 100% speed at full load (do not use the VFD as a throttling device).
- a) Variable speed drive installation and operation requirements have been taken into account.
- ___ 2. The following "prefunctional" checks were completed and verified prior to performing a functional test (note that this is not a comprehensive list of all prefunctional checks):
- a) Any belt drives have been adjusted and aligned.
- b) All safeties, interlocks, and alarms are programmed (or hard-wired, if applicable) and function correctly, regardless of VFD operating position (i.e., hand, auto, by-pass).
- c) If necessary, the motor shaft is grounded.
- d) Distribution system pressure drops do not exceed design expectations. This is typically performed while conducting construction observation.
- e) Verify all VFD operating parameters are correct for the application, including acceleration and deceleration times and minimum speed setting.
- a) Any belt drives have been adjusted and aligned.
- ___ 3. The fan motor cannot run in the wrong direction, or the system can handle and correct it.
- ___ 4. Fan size and capacity is verified, taking into account the accuracy of in instrumentation and the actual conditions at the time of the test.
- ___ 5. Network failure and recovery does not result in unsafe system operating modes.
- ___ 6. Drive settings and adjustments provide for safe and reliable system operation at peak efficiency in all operating modes.
- ___ 7. For air handling units, the freezestat shuts the fan down when tripped, regardless of VFD operating position (i.e., hand, auto, by-pass).
- ___ 8. The air handling system fan restarts upon manual reset after a freezestat trip.
- ___ 9. Construction and installation changes from design do not increase the distribution system pressure drop. If changes increase distribution system pressure drop, ensure all equipment still receives design flow rate.
- ___ 10. Backdraft dampers need to be tested for proper operation. Non-motorized dampers must open and close freely without binding. Motorized dampers must be connected to the DDC control system and verified that they are commanded open prior to fan operation.
Key Preparations and Cautions
- 1. General cautions as outlined in Section 12: General Precautions and Preparations (in the Functional Testing Basics module) should be observed.
- 2. Safety and interlock testing, verification of some of the drive settings, and loop tuning efforts will place the system at risk. Appropriate precautions and procedures should be in place to protect the personnel and machinery involved in the test process, including plans for quickly aborting the test.
- 3. For variable flow systems, system testing may often involve forcing an individual system into a full flow configuration. This may result in comfort issues and unusual or adverse pressure relationships, especially if adjacent systems are operating under normal conditions.
- 4. Verify that the system can operate in by-pass mode without severely damaging the distribution system or equipment. For example, system pressure may exceed the high static pressure limit switch (or worse rupture the ductwork or equipment) if the fan is operating at a constant speed in by-pass mode but the zone VAV boxes are restricting air flow to meet space temperature setpoint. The case may be that the fan can only operate safely in by-pass mode, if all zone VAV box dampers are commanded 100% open to prevent nuisance trips of the high static pressure switch or damage to the systems.
Page last updated: September 11, 2006