30
compressor discharge piping and waterbox
heads because of high temperature.
F. Refrigeration Components:
Refrigerant circuit components shall include oil sep-
arator, high and low side pressure relief devices, dis-
charge and liquid line shutoff valves, filter drier,
moisture indicating sight glass, expansion valve,
refrigerant economizer (unit sizes 350, 400), and
complete charge of compressor oil. The units shall
have a complete operating charge of refrigerant
HFC-134a.
G. Controls:
1. Unit controls shall include the following mini-
mum components:
a. Microprocessor with non-volatile memory.
Battery backup system shall not be accepted.
b. Separate terminal block for power and
controls.
c. Separate 115-v power supply to serve all
controllers, relays, and control components.
d. ON/OFF control switch.
e. Replaceable solid-state controllers.
f. Pressure sensors installed to measure
suction, oil, economizer, and discharge
pressure. Thermistors installed to measure
evaporator entering and leaving fluid
temperatures.
2. Unit controls shall include the following
functions:
a. Automatic circuit lead/lag.
b. Capacity control based on leaving chilled
fluid temperature and compensated by rate
of change of return-fluid temperature with
temperature set point accuracy to 0.1° F
(0.05° C).
c. Limiting the chilled fluid temperature
pulldown rate at start-up to an adjustable
range of 0.2° F to 2° F (0.1 to 1.1° C) per
minute to prevent excessive demand spikes
at start-up.
d. Seven-day time schedule.
e. Leaving chilled fluid temperature reset from
return fluid and outside air temperature.
f. Chilled water and condenser water pump
start/stop control.
g. Chiller control for parallel chiller applications
without addition of hardware modules and
control panels (requires thermistors).
h. Timed maintenance scheduling to signal
maintenance activities for strainer
maintenance and user-defined maintenance
activities.
i. Single step demand limit control activated by
remote contact closure.
H. Safeties:
Unit shall be equipped with thermistors and all nec-
essary components in conjunction with the control
system to provide the unit with the following
protections:
1. Loss of refrigerant charge.
2. Reverse rotation.
3. Low chilled fluid temperature.
4. Motor overtemperature.
5. High pressure.
6. Electrical overload.
7. Loss of phase.
8. Loss of chilled water flow
I. Diagnostics:
1. The control panel shall include, as standard, a
display:
a. Touch screen display consisting of ¼ VGA
LCD (liquid crystal display) with adjustable
contrast and backlighting.
b. Display shall allow a user to navigate
through menus, select desired options and
modify data.
2. Features of the display shall include:
a. Display shall be customizable and allow up to
72 data points.
b. Display shall support both local equipment
or network made for remote mount.
c. Display shall allow access to configuration,
maintenance, service, set point, time sched-
ules, alarm history and status data.
d. Display shall have one button for chiller on/
off.
e. Display shall include three levels of password
protection against unauthorized access to
configuration and maintenance informa-
tion, and display set up parameters.
f. Display shall allow for easy connection of a
portable hand held technician tool to access
information and upload and/or download
chiller settings.
g. Display shall be compatible with the Carrier
Comfort Network
®
(CCN) system and pro-
vide network alarm acknowledgement or
indication and provide capability to fully
monitor and control chiller.
h. Display alarms and parameters shall be
capable of being displayed in full text.
i. Display shall be capable of displaying the last
50 alarms and will store a snapshot of a
minimum of 20 status data parameters for
each alarm.
j. Compressor run hours.
k. Compressor number of starts.
l. Compressor current.
Guide specifications (cont)
