York YK-EP B Operation & Maintenance Manual page 176

SECTION 3 - DISPLAY MESSAGES
The total count is incremented once for every second
the Evaporator Refrigerant Temperature is below the
freeze threshold (but is never decremented below zero).
The number of seconds it will take the chilled liquid to
freeze is based on how far the Evaporator Refrigerant
Temperature is below the freeze threshold as follows:
number of seconds
=
to freezing
freeze threshold – evap.
Smart Freeze is activated only if the feature has been
enabled by a Service Technician (following instruc-
tions in OptiView Control Center – Service Instruc-
tions (Form 160.54-M1)) and the Leaving Chilled Liq-
uid Temperature Setpoint is less than 38.0°F.
Evaporator – Transducer Or Leaving Liquid
Probe
A possible defective Evaporator Pressure transducer
or Leaving Chilled Liquid temperature transmitter has
been detected. The pressure and temperature that these
devices are indicating are not in the correct relationship
to each other. The Control Center converts the Evapo-
rator Pressure to a Saturated Temperature value and
compares this value to the Leaving Chilled Liquid tem-
perature (difference equals chilled liquid temp minus
evaporator saturated temp). The difference should not be
outside the range of –2.5°F to +25.0°F. If the transducer
and transmitter are accurate, the Evaporator Saturated
temperature should not be greater than 2.5°F warmer
nor greater than 25.0°F colder than the Leaving Chilled
Liquid Temperature. In order to initiate a shutdown, the
difference must be outside the acceptable range continu-
ously for 10 minutes. The chiller can be started after the
Operator presses the WARNING RESET button.
Evaporator – Transducer Or Temperature Sensor
A possible defective Evaporator Pressure transducer or
Refrigerant Temperature Sensor has been detected. The
Control Center converts the Evaporator Pressure to a
Saturated Temperature value and compares this value
to the optional Evaporator Refrigerant Temperature
Sensor. If the difference between these temperatures
is greater than 3.0°F, continuously for 1 minute, this
shutdown is performed. This check is only performed
under the following conditions:
• Chiller has been running for at least 10 minutes
• Evaporator Refrigerant Temperature (RT7) has
been enabled by a Service Technician using in-
structions in OptiView Control Center – Service
Instructions (Form 160.54-M1)
176
(4053.7)
refrigerant temp.
• Not in Brine Cooling mode
• Smart Freeze is enabled.
• Evaporator Temperature Sensor (RT7) or Evapo-
rator Saturation Temperature is indicating a tem-
perature of less than 32.0°F
The chiller can be started after the temperatures are
within 3.0°F of one another and the Operator presses
the WARNING RESET button.
Condenser – High Pressure Contacts Open
The contacts of the electro-mechanical high pressure
safety device, located on the condenser shell, have
opened because this device has detected a pressure:
• more than 204 PSIG (R134a)
The contacts will automatically close when the con-
denser pressure decreases to:
• less than 160 PSIG (R134a
The chiller can be started after the contacts close and
the Operator presses the WARNING RESET button.
Condenser – High Pressure
The condenser pressure, as sensed by the Condenser
transducer, has increased to:
• more than 180.0 PSIG (R134a)
• more than 265.0 PSIG (R22).
The chiller can be started after the pressure decreases to:
• less than 120.0 PSIG (R134a)
• less than 205 PSIG (R22) and the Operator press-
es the WARNING RESET button.
For special order R134a high condenser temperature
chiller applications, the Condenser Temperature Range
Setpoint is set to Extended. The trip/reset threshold is
then 200/140 PSIG.
Condenser – High Pressure – Stopped
The condenser pressure exceeded 160.0 PSIG (R134a),
240.0 PSIG (R22) while the chiller was stopped. High
temperature condenser water flowing through the
condenser while the chiller is shutdown can cause a
condenser high pressure condition resulting in loss of
refrigerant. This safety fault anticipates this problem
by annunciating the condenser high pressure condition.
The chiller can be restarted after a Service Technician
performs a special reset preset procedure contained in
FORM 160.87-OM1
ISSUE DATE: 8/24/2018
JOHNSON CONTROLS