Distribution

This checklist identifies Key Commissioning Test Requirements and Key Preparations and Cautions for testing an air handler’s distribution system. 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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Test Guidance

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Typical Problems

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Control System Design Guide

Key Commissioning Test Requirements

Note that many of the following test requirements pertain to issues that should be addressed and checked during design, submittals, construction, or initial start-up in order to successfully test each system.

• ___ 1. During design review, the following items were addressed to avoid issues during functional testing:
  • a) Low pressure drop designs are used for fire and smoke dampers. (Example)
  • b) The unique requirements of underfloor plenums have been addressed.
  • c) The system is designed to handle pressures created by the rapid closing of dampers.
  • d) For manual balancing dampers, locking mechanisms are robust.
  • e) Life safety equipment and systems are viable and reliable, including smoke and fire control systems. Proper operation of smoke and fire dampers should be verified prior to performing any functional tests on the distribution system.
• ___ 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) Construction and installation changes from design do not increase the distribution system pressure drop:
    • Duct sizes and aspect ratios are appropriate to minimize pressure drop.
    • Duct fittings are designed and installed to minimize pressure drop.
    • Fan inlet and outlet are designed and installed to minimize pressure drop.
    • Flex duct is limited.
  • b) Ducts are appropriately insulated to avoid condensation and save energy.
  • c) During construction, ducts are not contaminated with water, construction dust, or debris prior to installation.
  • d) Seismic restraint requirements have been fulfilled.
• ___ 3. Distribution system pressure drops do not exceed design expectations.
• ___ 4. Leakage requirements have been met.
• ___ 5. Pressure relief doors are installed and operate correctly to protect the ductwork if fire/smoke dampers shut quickly but fans are still slowing down.
• ___ 6. Access doors are appropriately sized and located close enough to specific devices to facilitate maintenance and inspection. For example, the access door near a smoke/fire damper should be large enough and close enough so that the fusible link can be reached for testing and replacement as necessary by maintenance personnel.

Key Preparations and Cautions

• 1. General cautions as outlined in Functional Testing Basics, Section 12: General Precautions and Preparations should be observed. In particular, testing fire and smoke dampers in active systems places the system at risk for failure due to air hammer and related effects and proper precautions should be taken to minimize this risk.
• 2. Releasing and resetting any fire damper should be undertaken with caution due to the sharp sheet metal edges that can be encountered and the high spring forces associated with the closure mechanisms.
• 3. Opening access doors on active systems can expose personnel to significant forces created by the operating pressures on the doors, and they should proceed with caution when opening, closing, or going through these doors. They are also at risk for being trapped inside an active unit if the pressures pull the doors closed behind them. Personnel should take appropriate precautions to prevent this and should including working in teams, and making sure that someone on the site knows where they will be working and when they expect to be finished.
• 4. Testing safety systems such as permissive interlocks, static switches, and pressure relief doors can place the operating system at risk, the exact level of which is determined by the rigor of the test. Appropriate cautions and controls should be in place when performing these tests to thwart any problems and limit the exposure of the system to damage in the event that the component under test was to fail to perform its intended function.
• 5. Ensure all smoke and fire dampers are in the open position prior to performing any functional tests on the distribution system.

Page last updated: September 11, 2006