58
AC-SVX003A-EN
Freeze Protection
One or more of the ambient freeze avoidance methods in
the table below must be used to protect the chiller from
ambient freeze damage. See RF-PRB002*-EN for more
information.
Method
Protects to
ambient
temperature
Notes
Water Pump
Control AND
Heaters
Down to -20°F
• Heaters alone will provide low ambient protection down to -20°F (-29°C), but will NOT protect the
evaporator from freezing as a result of charge migration. Therefore, it is required that water pump control
be used in conjunction with heaters.
• The optional factory installed pump package includes -20°F (-29°C) ambient freeze protection for water.
• Heaters are factory-installed on the evaporator and will protect it from freezing.
• Install heat tape on all water piping, pumps, and other components that may be damaged if exposed to freezing
temperatures. Heat tape must be designed for low ambient temperature applications. Heat tape selection should be
based on the lowest expected ambient temperature.
• The controller can start the pump when freezing conditions are detected. For this option the pump must to be
controlled by the Stealth unit and this function must be validated.
• Water circuit valves need to stay open at all times.
• Water pump control and heater combination will protect the evaporator down to any ambient temperature
provided power is available to the pump and the controller. This option will NOT protect the evaporator in
the event of a power failure to the chiller unless backup power is supplied to the necessary components.
• When no chiller operation is possible and the pump is already off, controller pump control function for freeze
protection will command the pump to turn:
– ON if average of the evaporator entering water temperature, the evaporator leaving water temperature, and
the evaporator refrigerant pool temperature is less than Low Evaporator Refrigerant Temperature Cutout
(LERTC) + 4°F for a period of time.
– OFF again if the evaporator refrigerant pool temperature rises above the LERTC + 6°F for a period of time.
Note: Time period referenced for ON and Off conditions above is dependent on past running conditions and
present temperatures measured.
– ON if entering OR leaving water temperature LWTC for 30°F-sec (17°C-sec)
– OFF again if water temperature > LWTC for 30 min
Freeze
Inhibitor
Varies. See Low
Evaporator
Refrigerant Cutout,
Glycol Requirements.
• Freeze protection can be accomplished by adding sufficient glycol to protect against freezing below the lowest
ambient expected.
• Use of glycol type antifreeze reduces the cooling capacity of the unit and must be considered in the design
of the system specifications.
• For units with free-cooling option, glycol solution is REQUIRED. See Free-Cooling Fluid Management section.
Drain Water
Circuit
Below -20°F
• Shut off the power supply to the unit and to all heaters.
• Purge the water circuit.
• Blow out the evaporator to ensure no liquid is left in the evaporator.
Installation Mechanical
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