This checklist identifies Key Commissioning Test Requirements and Key Preparations and Cautions for testing the cooling section of an air handler. 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
General: All Systems
- ___ 1. During design review, the following items were addressed to avoid issues during functional testing:
- a) The control element range matches the requirements of the control sequence and does not overlap the range of other elements served by the same signal to prevent unintentional simultaneous heating and cooling.
- b) The cooling element design temperatures and configuration, and the cooling control, ensure adequate dehumidification under all operating modes (if applicable).
- c) The cooling element is protected from freezing.
- d) The quality of the evaporative media and heat exchangers will not be compromised by accumulations of dust or dirt, and filters have been included if necessary.
- e) Proper operation of the pump down cycle (if specified or provided) has been verified.
- ___ 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) The cooling element is configured to prevent IAQ problems and water damage. Condensate can drain satisfactorily and does not carry over into the air stream.
- b) For air handling units, the freezestat shuts the fan down when tripped and the fan restarts upon manual reset.
- c) The control valve closes completely and there is no leak-through.
- d) The cooling coil has been flushed and pressure tested.
- e) The performance of any freeze protection associated with evaporative cooling equipment has been verified.
- f) The water quality is suitable or the water quality control performance has been verified.
- g) Installation and proper connection of the refrigeration piping to the DX coil including sight glasses, dryers, service valves, solenoid valves, and wells for expansion bulbs and testing superheat has been verified.
- h) Evacuation and subsequent charging of the refrigerant circuit has been verified.
- a) The cooling element is configured to prevent IAQ problems and water damage. Condensate can drain satisfactorily and does not carry over into the air stream.
- ___ 3. The cooling element (coil, heat exchanger, etc.) capacity is verified, if required by the specification, taking into account the accuracy of in instrumentation and the actual conditions at the time of the test.
- ___ 4. Mechanical cooling is properly sequenced with the economizer to minimize the potential for cooling and dehumidifying unnecessary volumes of outdoor air.
- ___ 5. Cooling is properly sequenced with heat transfer elements in the air handling system to minimize the potential for simultaneous heating and cooling.
- ___ 6. Proper operation of the cooling equipment is verified per the design sequence of operations.
Evaporative Cooling Systems
- ___ 7. The spray pumps and spray system performance have been verified.
- ___ 8. The evaporative cooling effectiveness has been verified.
- ___ 9. The level control and blow down system performance has been verified.
DX Cooling Systems
- ___ 10. Adjustment and performance of the refrigeration control devices such as the expansion valve, the hot gas bypass system, the compressor unloading system, and the head pressure regulating system has been verified.
Key Preparations and Cautions
- 1. In most states, a license is required to perform any work that might release refrigerant to the atmosphere.
- 2. Poorly installed, operated, and maintained evaporative coolers can be a source of infection.
- 3. Some tests can cause discharge temperatures significantly above or below normal, leading to discomfort, potential damage, and/or activation of fire dampers.
- 4. Rapid stroking of valves and dampers can cause air or water hammer.
- 5. Testing can cause electrical loads that exceed design and switch gear ratings, and/or demand peaks well in excess of those encountered during normal operation, especially if testing during winter in buildings with electric heat.
- 6. Rapid adjustment of superheat can cause liquid slugging and compressor damage.
- 7. Be prepared to manually shutdown if rapid compressor cycling is encountered.
- 8. Test sequences that subject cool surfaces (ducts, interiors) to large volumes of untreated air should be avoided to preclude condensation problems.
- 9. Note that the system must be protected against freezing at the extreme temperatures, which will typically be even colder than the design heating temperature.
- 10. Testing for valve leak-by and proper valve operation should be conducted with the pumping system operating at its peak differential pressure. The differential pressure across the valve plug can have a significant impact on the close-off rating and shift the operating spring range of the valve.
Page last updated: September 12, 2006