218
FORM 160.54-M1
ISSUE DATE: 10/25/2019
SECTION 24 - SMART FREEZE PROTECTION
JCI COMPANY CONFIDENTIAL JOHNSON CONTROLS
in normal operation, loading will be allowed when the
pressure increases to 57.5 psig (R22) and 28.0 psig
(R-134a).
The following is a summary of the operation with
Smart Freeze disabled and enabled.
SMART FREEZE DISABLED
• Minimum Leaving Chilled Liquid setpoint - 38.0°F
• Low Chilled Liquid Temp cycling shutdown
threshold - 1° to 34.0°F below the Leaving Chilled
Liquid Temperature setpoint, as programmed, or a
minimum of 36.0°F.
• Low Evaporator Pressure safety shutdown threshold
R22 - 54.3 psig (29.6°F)
R-134a – 25.0 psig (28.7°F)
• PRV Load Inhibit
R22 – 56.2 psig
R-134a – 27.0 psig
• Load Inhibit disable
R22 – 57.5 psig
R-134a – 28.0 psig
SMART FREEZE ENABLED
• Minimum Leaving Chilled Liquid setpoint - 36.0°F
• If the Leaving Chilled Liquid Temperature
setpoint is greater than or equal to 38.0°F:
1. The Low Leaving Chilled Liquid Tem-
perature cycling shutdown threshold is 1 to
34.0°F below the Leaving Chilled Liquid
Temperature setpoint, as programmed, or a
minimum of 36.0°F.
2. The Low Evaporator Pressure safety shut-
down threshold is the same as Smart Freeze
disabled above.
• If the Leaving Chilled Liquid Temperature
setpoint is less than 38.0°F:
1. The Low Leaving Chilled Liquid Tempera-
ture cycling shutdown threshold is 1 to 3.0°F
below the Leaving Chilled Liquid Tempera-
ture setpoint, as programmed, or a minimum
of 34.0°F.
2. Low Evaporator Pressure shutdown thresh-
old is determined by how far the Evaporator
Refrigerant Temperature is below the freeze
threshold of 32.8°F (refrigerant temperature
sensor RT7) or 34.0°F (Evaporator Satura-
tion Temperature. See Note 1 below.) and the
total number of seconds it remains there. See
explanation above.
• PRV Load Inhibit is the same as Smart Freeze
Disabled above.
• Load Inhibit Disable is the same as Smart Freeze
Disable above.
Note 1: The freeze threshold evaporation saturation
temperature is 32.0°F on Flash memory card version
C.MLM.01.01 (and earlier).
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