Daikin EWWD320, Installation, Operation And Maintenance Manual

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3. BAS, BAS input is field-wired into a communication module that is factory-installed on the unit controller.
4. Control Panel Switches Three On/Off switches are located in the main Control Panel and have the following
function:

UNIT shuts down the chiller through the normal shutdown cycle of unloading the compressors.

COMPRESSOR one switch for each compressor on the unit, executes an immediate shutdown without the
normal shutdown cycle.

CIRCUIT BREAKER disconnects optional external power to system pumps and tower fans.
A fourth switch located on the left outside of the Unit Control Panel and labeled EMERGENCY STOP SWITCH stops the
compressor immediately. It is wired in series with the COMPRESSOR On/Off switches.
Annual Unit Startup/Shutdown
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. 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.
3. Open the compressor disconnect switch . Set the manual COMPRESSOR and UNIT ON/OFF switches in the Unit
Control Panel to the OFF position.
4. Check for corrosion and clean and paint rusted surfaces.
5. Clean and flush water tower for all units operating on a water tower.
6. Remove condenser heads at least once a year to inspect the condenser tubes and clean if required.
Annual Startup
1. Check and tighten all electrical connections.
2. Replace the drain plug in the cooling tower pump if it was removed at shutdown time the previous season.
3. Install fuses in main disconnect switch (if removed).
4. Reconnect water lines and turn on supply water. Flush condenser and check for leaks.
Operating parameters
It is a responsibility of the technicial executing the first or annual startup, to check chiller operating parameters to assure
the correct operation of the chiller (e.g. to be sure there was no refrigerant leak during transportation, installation or long
shutdown period).
Main operating parameters to be checked are:
1.
Evaporating pressure.
2. Condensing pressure.
3. Refrigerant superheat at compressor suction
4. Refrigerant superheat at compressor discharge
5. Subcooling of liquid coming out of the condenser banks
All these parameters can be read directly on the operator interface panel
Correct values for these parameters at any allowed operating condition have be obtained using the chiller selection tool.
For reference only, for chiller at full load at standard conditions with no specific reference to chiller size, the allowable
range operating parameters is:
Table 5 - Typical working conditions with unit at 100%
(Evap Water Temp 12/7°C
– Cond Water Temp 30/35°C)
Evaporating pressure 350 ÷ 360 kPa
Condensing pressure 915 ÷ 935 kPa
Suction superheat 0.5 ÷ 1.0 °C
Discharge superheat 9 ÷ 12 °C
Liquid subcooling 4 ÷ 6 °C