Below is a precise HVAC method statement that briefly explains testing and commissioning of split unit ac air conditioner.
The test will be commenced after Split Unit installation and power supply panel T&C activities completed. All areas and fan inlet & outlet should be cleared of waste materials and any other obstruction.
The purpose of this procedure is to define the step by step method to implement the correct practices for the pre-commissioning & commissioning of “Split Unit” through the guidelines contained herein so as to ensure that the job execution complies with the project requirements and serves the intended function to satisfactory level.
Project manager in coordination with site engineers and supervisors is overall responsible for implementation of this procedure and to make sure that all works are performed as per contract specifications, approved shop drawings, approved material submittals and split unit manufacturer’s operation instructions.
Commissioning Engineer; will be responsible for the day to day activities on site, for the test report and design information approval and the onsite testing and balancing.
TAB technician; will be responsible for the day to day systems balancing at site as instructed by the commissioning engineer.
Referenced Codes:
- CIBSE Guide Commissioning Code A – Air Distribution System
- CIBSE Guide Commissioning Code R – Refrigeration System
- CIBSE Guide Commissioning Code M – Commissioning Management
- BSRIA Application Guide AG 3/89.3. – Commissioning Air
- BSRIA Technical Notes TN 1/78. Air System Balancing, Regulating Variable Flow Rate Systems.
Quality Control Requirements
In general, it shall be ensured by site mechanical engineer that product manufacturer’s recommendations are followed and split unit testing and commissioning shall be monitored by project engineer.
The Project Engineer shall further oversee the Pre-commissioning and commissioning activity as per the approved method statement for Start-up and Commissioning of Split Units.
Split Unit shall be tested under direct supervision of manufacturer / local dealer’s representatives.
Tools / Equipment /Testing Instruments
Arrange below tools and instruments for smooth testing activities:
- Digital Multimeter
- Clamp Meter
- Tachometer
- Anemometer
- Flow Hood Kit
- Digital Thermometer
- Psychrometer
Split Unit Commissioning Sequence
Before commencing commissioning works, the following information/items will be made available:
Full set of up-to-date installation drawings and specification detailing all systems to be commissioned.
Full set of up-to-date plant schedules which include details of Split Unit volumes (supply and return), model and electrical data, voltage, current, power, power control system logic statement and diagrams.
Any special operating keys, tools etc.
Access to all areas; equipment’s etc. through doors, risers, false ceilings etc.
Mechanical Checks
Carefully inspect the unit for any physical damages / dents.
Check and ensure the shipping bolts / clamps are removed.
Check tightness of all nuts / bolts, screws, fasteners, rubber vibration isolators etc. as applicable
Check the piping connections as per approved drawings.
Check the fan rotation freely by hand and the direction of rotations on initial startup.
Align the Unit in the direction of drain to maintain the gravity slope.
Electrical Checks
Ensure the connected cables have been tested and verify the test reports.
Check all terminations are complete and tightened as required.
Check the cabling / wiring including grounding is completed and dressed neatly for thermostat.
Ensure all identification and labeling is completed.
Check the isolator is fixed close to the Split Units for emergency power shut-down.
Start Up and Test Preparation
Check the line voltage before energizing the power
Switch ON the power.
Verify for the proper operation of the Split Units motor.
Measure the current drawn (amperage) by Split Units and record the same.
Verify proper operation of the thermostat, supply air temperature.
Check for any abnormal noise and vibration on startup. Rectify as / if required.
After about an hour’s operation, check that all nuts / bolts, screws, clamps etc. are tight and secure for external units.
Record the Split Unit/External Unit name plate data in the commissioning format.
Record the ampere / voltage drawn by the compressor / fan of the outdoor unit.
Record the refrigerant pressure of the outdoor unit.
Ensure it is within the limits as per the Ambient temperature.
Ensure compliance to the manufacturer’s instruction as applicable.
COMMISSIONING PROCEDURE
Ensure to follow manufacturer’s recommendations and instructions received with material.
As the unit is Pre-commissioned, it shall be started.
Check the evaporator motor running current and make sure it is below the full load current.
Check the air flow direction.
Check condenser unit running current and make sure its below FLC.
Check the voltage when compressor is running.
Measure ON coil and OFF coil temperatures.
Check the condensate drain through without stagnation.
For ducted units terminals design air flow can be achieved by adjusting the VCD /OBD, wherever applicable.
Record the ampere / voltage drawn by the fan of the outdoor unit as well as its full load ampere.
DEMONSTRATION PROCEDURES
The Commissioning Engineer will ensure that the following works are carried out:
a) Record and submit reading for 100% of the test requirement. Witnessing shall be carried out and signed off once the readings are recorded and that repeatability of readings is proven within the accepted tolerance.
b) Submittal of all records of data obtained during Pre-Commissioning, Commissioning and Performance testing in accordance with, and on, the approved forms.
c) Preparation of report of recommendations for correcting any unsatisfactory mechanical performances when system cannot be successfully balanced.
Health & Safety Requirements
- All safety precautions shall be followed as per the established Project Safety Plan.
- Only experienced and skilled technicians shall be engaged for carrying out Start-up and Commissioning of Split Units.
- Safety Guards shall be in place and secured prior to start-up.
- Cable test reports shall be verified prior to energization.
- Appropriate Warning signs and tapes shall be placed during start-up and commissioning as required.
- All PPE shall be worn as appropriate according to the nature of the job.
- Work area shall be maintained neat and clean.
Split unit ac testing and commissioning report / checklist
