Operation In Sub-Freezing Conditions; Unit Maintenance And Shutdown In Sub-Freezing Conditions - Quantech QTC4 STYLE A Series Installation Operation & Maintenance

SECTION 6 - COMMISSIONING

Operation in Sub-freezing Conditions

The QTC4 may be operated in sub-freezing conditions
if the following freeze protections are taken:
A. A suction service valve electric actuator is
installed. Chiller software will operate the
actuator in order to protect against freezing due to
evaporator 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 cir-
culate water through the evaporator whenever
commanded by the chiller.
The above operation is only advised if
uninterrupted power can be ensured.
Unforeseen 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, Quantech recom-
mends the water in the chilled water circuit be replaced
with an appropriate water-to-glycol concentration.
Failure to follow Quantech freeze pro-
tection recommendations can void the
warranty.
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Unit Maintenance and Shutdown in Sub-
freezing Conditions
If the QTC4 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. Quantech 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 op-
eration. 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.
FORM QTC4-NM1
ISSUE DATE: 4/2/2018
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QUANTECH