This checklist identifies Key Commissioning Test Requirements and Key Preparations and Cautions for an air handling system’s warm-up process. 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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Key Commissioning Test Requirements
- ___ 1. During design review, the following items were addressed to avoid issues during functional testing:
- a) The water temperature available for warm-up minimizes the cycle length without sacrificing energy efficiency.
- b) Different requirements for interior and perimeter zones, or other zoning requirements have been accounted for.
- c) Coil capacities adequate to satisfy load
- d) Warm-up cycle sequence of operations is optimized. For example, the following strategies may be employed:
- Turn off all make-up air, ventilation air, and exhaust fans during warm-up. Note that some jurisdictions may require a pre-occupancy purge, in which case ventilation air may be required. But it may be better to warm up the building first and then start to slowly ventilate over an extended period of time to minimize energy usage.
- Prevent system from going to maximum output unless load is not being met within a reasonable amount of time.
- To prevent overheating and creating a false cooling load, command VAV box dampers closed on units serving interior zones if these zones do not require warm-up.
- Ensure warm-up mode cannot be enabled when the building is occupied, especially if ventilation air and exhaust fans are turned OFF as part of the sequence of operation.
- a) The water temperature available for warm-up minimizes the cycle length without sacrificing energy efficiency.
- ___ 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) All air handling unit prefunctional checks are complete and system is ready for continued operation.
- b) All terminal unit prefunctional checks are complete and system is ready for continued operation.
- c) All heating plant prefunctional checks are complete and system is ready for continued operation.
- ___ 3. The proper warm-up control sequence and its integration with both the air handling unit and terminal equipment is verified.
- ___ 4. The flow rate used by the terminal unit maximizes the heat available for warm-up and minimizes the cycle length without sacrificing energy efficiency (if terminal unit reheat coils are used for warm-up).
- ___ 5. Verify make up air, ventilation air, and exhaust systems are not operated during the warm-up cycle (typical sequence of operations).
- ___ 6. Heating control valves close off completely with no leakage past the valve.
- ___ 7. The warm-up cycle length is not too long during extreme cold weather. This is best verified through trending. If the warm-up cycle is too long, the night setback control sequence and setpoints may need to be adjusted.
- ___ 8. Heat is available for warm-up during moderate weather (i.e., heating plant is locked out based on atmospheric conditions). May need to override the lockout setpoint during testing.
Key Preparations and Cautions
- 1. It is important that the design and test plan recognize the difference between preheat, reheat, heating and warm-up elements and functions.
- 2. Some test procedures, either by design or by failure of the element under test to perform as intended, can cause air handling system discharge temperatures to become significantly elevated above normal. These high discharge temperatures can pose the following problems:
- a. Occupant discomfort
- b. Disruption of the process served by the system and potential damage to product
- c. Inadvertent activation of fire dampers
- d. Inadvertent activation of heat detectors and rate of rise detectors and subsequent false fire alarm and building evacuation
- Test plans should provide for these contingencies by taking steps such as disabling key fire detection elements for the test and ensuring that fusible links have been selected to tolerate any temperature that can be produced in the system.
- 3. Overly rapid stroking of valves and dampers during a test process can cause air, water, and steam hammer problems in the duct and piping systems serving the warm-up heating system.
- 4. Functionally testing an electric warm-up system during the summer months while the cooling plant is in operation can cause significant problems including:
- a. Distribution system load conditions that exceed design that can trigger trips in the primary switchgear resulting in unscheduled and unanticipated outages.
- b. Demand peaks well in excess of those that would normally be encountered during the normal operation of the building due to the demand that the warm-up coils place on the system concurrently with the refrigeration equipment.
Page last updated: September 11, 2006