General Operation; Operation In Sub-Freezing Conditions; Unit Maintenance And Shutdown In Sub-Freezing Conditions - York YVAA Installation, Operation & Maintenance Instructions Manual

SECTION 6 - COMMISSIONING

GENERAL OPERATION

After completion of the above checks for System 1,
switch OFF the SYS 1 switch on the keypad and repeat
the process for each subsequent system. When all run
correctly, stop the unit, switch all applicable switches
to the 'ON' position and restart the unit.
Assure all checks are completed in the Equipment
Pre - Startup and Startup Checklist. The chiller is then
ready to be placed into operation.

Operation in Sub-freezing Conditions

The YVAA may be operated in sub-freezing conditions
if the following freeze protections are taken:
A. A suction service valve electric actuator is in-
stalled. Chiller software will operate the actuator
in order to protect against freezing due to evapo-
rator refrigerant migration.
B. No suction service valve is installed but the water
circuit valves are kept open, there is continuous
power to the chiller and pump for chilled water
pump control, and the pump will operate and
circulate water through the evaporator whenever
commanded by the chiller.
The above operation is only advised if
uninterrupted power can be ensured. Un-
foreseen power interruptions can damage
the evaporator in a very short time frame
if the temperature falls below freezing.
If there is potential for power loss, Johnson Con-
trols recommends the water in the chilled water cir-
cuit be replaced with an appropriate water-to-glycol
concentration.
100
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Unit Maintenance and Shutdown in
Sub-freezing Conditions
If the YVAA is maintained or shut down and will be
subjected to sub-freezing conditions, it is critical to
protect against evaporator and waterbox freeze dam-
age. Johnson Controls recommends the following
options (in order of freeze protection level) be
performed on each circuit.
A. Glycol: Replace water with an appropriate water
to glycol concentration of antifreeze.
B. Drain: Remove power to the waterbox heaters.
Close the water valves, drain the evaporator, and
leave the evaporator drain valves open.
C. Refrigerant Valve - Off: Close the water valves,
close flash tank drain valves, close the suction
service valves and leave power to the chiller
for evaporator heater mat and waterbox heater
operation. For units without a suction service
valve, close the discharge and compressor oil
valves.
D. Pump Control: Keep power to the chiller in or-
der to have control over chilled water pumps and
heater operation and leave the water circuit valves
open. This will enable water to circulate through
the evaporator to avoid freezing.
Options A and B are the recommended
processes for unit maintenance and
shutdown. Unforeseen power interrup-
tions can damage the evaporator in a very
short time frame if the temperature falls
below freezing.
Failure to follow Johnson Controls freeze
protection recommendations can void the
warranty.
FORM 201.28-NM1.1
ISSUE DATE: 1/31/2018
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JOHNSON CONTROLS