Below is detailed method statement for T&C of Chillers as a standard template.
SCOPE OF WORK
Testing and Commissioning of Chillers for Al Ahli Hospital, Doha as per specification clause 2.71, and in accordance with the manufacturer’s instructions.
Part I Mechanical Systems
Part II Electrical Systems
Testing Tools / Equipment
- Clamp on Meter
- Megger Tester
- Amp Meter
- Electronic Leak detector
- Electronic Thermometer
(All test equipment should be with valid calibration certificates)
Part I Mechanical Systems:
- Inspect all water piping for flow direction and correct connections at the evaporator.
- See that all auxiliary control equipment is operative and that an adequate cooling load is available for initial start-up.
- Check all compressor valve connections for tightness to avoid refrigerant loss at start-up. Open the compressor suction and discharge shut off valves until back seated. Open the liquid line shut off valves until back seated. Always replace valve seal caps.
- Make sure system switch S1 is in the “Stop” position and pump-down switches PS1, PS2, PS3 and PS4 are set to “Pump-down and Stop”, throw the main power and control disconnect switches to “ON”. This will energize crankcase heaters. Wait a minimum of 12 hours before starting up unit. Turn compressor unit breakers to ”OFF” position until ready to start unit.
- Vent the air from the evaporator as well as from the system piping. Open all water flow valves and start the chilled water pump. Check all piping for leaks. Flush the evaporator and system piping to obtain clean / non-corrosive water in the evaporator unit.
- Double check that the compressor suction and discharge shut off valves is backseated. Always replace valve seal caps.
- Ensure that the ball valves are open on the lines entering the evaporator.
- Ensure that the manual liquid line shut off valve at the outlet of the subcooler is open.
- Adjust the leaving chilled water temperature set point on the MicroTech Controller to the desired chilled water temperature.
- Start the auxiliary equipment for the installation by turning on the time clock, and/or remote ON/OFF switch, and chilled water pump after checking that all procedures mentioned in Part II Electrical sitemaps are completed.
- Check to see that pumpdown switches PS1, PS2,PS3 and PS4 are in the “Pumpdown and Stop” (open) position. Throw the S1 switch to the “Auto” position.
- Under the “Control Mode” menu of the keypad place the unit into the automatic cool mode.
- Start the system by moving pumpdown switch PS1 to the “Auto” position.
- After running circuit 1 for a short time, check the rotation of the condenser fans. (Proper rotation will have air being drawn into the vertical coils and discharged out from the top of the unit). Check for flashing in the refrigerant sight glass under stable conditions.
- Repeat steps 8 and 9 for PS2, PS3 and PS4 and the second, third and fourth refrigerant circuits.
- Check the superheat should be between 8o and 12oF, with the liquid line sightglass full, once the system temperatures have stabilized at the Micro Tech set point temperatures.
Part II Electrical Systems:
- To assure correct compressor rotation, field power supply leads must be properly phased prior to start-up.
- With all electric disconnects open, check all screw or lug type electrical connections to be sure they are tight for good electrical contact.
- Using a phase tester, check that electrical phasing to each compressor circuit is A-B-C for phases L1, L2 & L3 respectively.
- Check the voltage of the unit power supply and see that it is within the ± 10% tolerance that is allowed. Voltage unbalance between phases must be within ± 3%.
- Verify that all mechanical and electrical inspection has been completed as per local codes.
These sections are covered under Method Statement for Building Management system.
MANUFACTURER’S/OTHER’S SPECIAL RECOMMENDATIONS:
For further recommendations, please refer to the manufacturer’s manual.
RECORD AND REPORT DATA
- Prepare report of recommendations for correcting unsatisfactory performance, if any.
- All test data to be recorded in forms, which are enclosed for reference.
Only competent personnel will be present in vicinity of the testing area while carrying out the test.
Train the Owner’s maintenance personnel for Operation and Preventative maintenance as per specification clauses.
The procedure will take 1 day per chiller.
Prior to starting the Chiller all electrical works related to supply of power to the equipment should be tested and energized.
Furthermore, chemical treatment of chilled water pipes and circulating pumps should be commissioned.
In addition, all AHUs should be operational to provide load for the Chiller.
Checklist For Testing & Commissioning Of Chillers:
|MECHANICAL SYSTEMS :|
|1||Check water piping connections at the evaporator.|
|2||See that all auxiliary control equipment is operative and that an adequate cooling load|
|is available for initial start-up.|
|3||Check all compressor valve connections for tightness. Open suction & discharge shutt|
|off valves and liquid line shut off valve.|
|4||Make sure that system switch S1 is in the “stop” position and pumpdown switches are|
|set to “pumpdown and stop” and control disconnect switches to “on”. Wait a minimum of|
|12 hours before starting up of unit. Turn compressor unit breakers to “off” position until|
|ready to start the unit.|
|5||Vent the air from the evaporator as well as from the system. Start the chilled water pump|
|after opening all water flow valves.|
|6||Ensure that the ball valves are open on the refrigerant lines entering the evaporator.|
|7||Ensure that liquid line shut off valve at the outlet of the subcooler is open.|
|8||Adjust the leaving chilled water temperature set point on the MicroTech controller to the|
|desired chilled water temperature.|
|9||Start the auxiliary equipment for the installation by turning on the time clock, and/or remote|
|ON/OFF switch and chilled water pump after completing all Electrical check-ups.|
|10||Throw the S1 switch to the auto position.|
|11||Under the “control mode” menu of the keypad place the unit into the automatic cool mode.|
|12||Start the system by moving pumpdown switch to PS1 to the “auto” position.|
|13||After running circuit 1 for a short time, check the rotation of the condenser fans. Check for|
|flashing in the refrigerant sight glass under stable conditions.|
|14||Repeat steps 12 & 13 for PS2, PS3 and PS4 and the second, third and fourth refreigerant|
|15||Check that the superheat should be between 8 and 12 deg. F, with the liquid line sight glass|
|full, once the system temperatures have stabilized at the MicroTech set point temperatures.|
|ELECTRICAL SYSTEMS :|
|1||With the electric disconnects open, check all screw or lug type electrical connections to be|
|sure that they are tight for good electrical contact.|
|2||Using a phase tester, check that electrical phasing to each compressor circuit is A-B-C|
|for phases L1, L2 & L3 respectively.|
|3||Check the voltage of the unit power supply and see that it is within the +/- 10% tolerance|
|that is allowed. Voltage unbalance between phases must be within +/- 3%.|
|4||Verify that all mechanical and electrical inspections have been completed as per local codes|