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If pressure should be present, STOP, retighten the bolts and determine why pressure is present.
8.2.7
Cleaning and Preserving
A common cause of service calls and equipment malfunction is dirt. This can be prevented with normal maintenance. The
system components most subject to dirt are:
1. Permanent or cleanable filters in the air handling equipment must be cleaned in accordance with the manufacturer
’s
instructions; throwaway filters should be replaced. The frequency of this service will vary with each installation.
2. Remove and clean strainers in chilled water system, oil cooler line and condenser water system at every inspection.
8.3
Annual Shutdown
Where the chiller can be subject to freezing temperatures, the condenser and chiller must be drained of all water. Dry air
blown through the condenser will aid in forcing all water out. Removal of condenser heads is also recommended. The
condenser and evaporator are not self-draining and tubes must be blown out. Water permitted to remain in the piping and
vessels can rupture these parts if subjected to freezing temperature.
Forced circulation of antifreeze through the water circuits is one method of avoiding freeze up.
1. Take measures to prevent the shutoff valve in the water supply line from being accidentally turned on.
2. Make sure that all the shutoff valves of the unit oil line are closed.
3. If a cooling tower is used, and if the water pump will be exposed to freezing temperatures, be sure to remove the pump
drain plug and leave it out so any water that can accumulate will drain away.
4. Open the compressor disconnect switch, and remove the fuses
. If the transformer is used for control voltage, the
disconnect must remain on to provide power to the oil heater.
Set the manual UNIT ON/OFF switch in the Unit
Control Panel to the OFF position.
5. Check for corrosion and clean and paint rusted surfaces.
6. Clean and flush water tower for all units operating on a water tower. Make sure tower blowdown or bleed-off is
operating. Set up and use a good maintenance program to prevent
“liming up” of both tower and condenser. It should
be recognized that atmospheric air contains many contaminants that increase the need for proper water treatment.
The use of untreated water can result in corrosion, erosion, sliming, scaling or algae formation. It is recommended
that the service of a reliable water treatment company be used. Daikin assumes no responsibility for the results of
untreated or improperly treated water.
7. Remove condenser heads at least once a year to inspect the condenser tubes and clean if required.
8.4
Annual Startup
A dangerous condition can exist if power is applied to a faulty compressor motor starter that has been burned out. This
condition can exist without the knowledge of the person starting the equipment.
This is a good time to check all the motor winding resistance to ground. Semi-annual checking and recording of this
resistance will provide a record of any deterioration of the winding insulation. All new units have well over 100 megohms
resistance between any motor terminal and ground.
Whenever great discrepancies in readings occur, or uniform readings of less than 50 megoh ms are obtained, the motor
cover must be removed for inspection of the winding prior to starting the unit. Uniform readings of less than 5 megohms
indicate motor failure is imminent and the motor should be replaced or repaired. Repair before failure occurs can save a
great deal of time and labor spent in the cleanup of a system after a motor burnout.
1. Make sure that all the shutoff valves of the unit oil line are open.
2. The control circuit must be energized at all times, except during service. If the control circuit has been off and oil is
cool, energize oil heaters and allow 24 hours for heater to remove refrigerant from the oil before starting.
3. Check and tighten all electrical connections.
4. Replace the drain plug in the cooling tower pump if it was removed at shutdown time the previous season.
5. Install fuses in main disconnect switch (if removed).
6. Reconnect water lines and turn on supply water. Flush condenser and check for leaks.
7. Refer to the Operating Manual before energizing the compressor circuit.
8.5
Repair of System
8.5.1
Pressure Relief Valve Replacement
Current condenser designs use two relief valves separated by a three-way shutoff valve (one set). This three-way valve
allows either relief valve to be shut off, but at no time can both be shut off. In the event one of the relief valves are leaking
in the two valve set, these procedures must be followed:
•
If the valve closest to the valve stem is leaking, back seat the three-way valve all the way, closing the port to the
leaking pressure relief valve. Remove and replace the faulty relief valve. The three-way shutoff valve must remain
either fully back seated or fully forward to normal operation. If the relief valve farthest from the valve stem is leaking,
front seat the three-way valve and replace the relief valve as stated above.
•
The refrigerant must be pumped down into the condenser before the evaporator relief valve can be removed.
8.5.2
Pumping Down
If it becomes necessary to pump the system down, extreme care must be used to avoid damage to the evaporator from
freezing. Always make sure that full water flow is maintained through the chiller and condenser while pumping down. To