Relief Devices; High-Side Protection; Low-Side Protection; Pressure Relief Valves - Carrier 30GTN Service And Troubleshooting Manual

Relief Devices —
Fusible plugs are located in each cir-
cuit to protect against damage from excessive pressures.
HIGH-SIDE PROTECTION — One device is located be-
tween condenser and filter drier; a second is on filter drier.
These are both designed to relieve pressure on a temperature
rise to approximately 210 F (99 C).
LOW-SIDE PROTECTION — A device is located on suc-
tion line and is designed to relieve pressure on a temperature
rise to approximately 170 F (77 C).
PRESSURE RELIEF VALVES (208/230, 460, 575 v;
60 Hz Units Only) — Valves are installed in each circuit
(one per circuit). The valves are designed to relieve at
450 psig (3103 kPa). These valves should not be capped. If
a valve relieves, it should be replaced. If valve is not re-
placed, it may relieve at a lower pressure, or leak due to trapped
dirt from the system which may prevent resealing.
The pressure relief valves are equipped with a
flare for field connection. Some local building codes require
that relieved gases be removed. This connection will allow
conformance to this requirement.
Other Safeties —
There are several other safeties that
are provided by microprocessor control. For details refer to
Alarms and Alerts section on page 47.

PRE-START-UP

IMPORTANT: Before beginning Pre-Start-Up or
Start-Up, complete
ComfortLink™ Chiller Systems at end of this publi-
cation (page CL-1). The Checklist assures proper start-up
of a unit, and provides a record of unit condition, ap-
plication requirements, system information, and op-
eration at initial start-up.
Do not attempt to start the chiller until following checks
have been completed.

System Check

1. Check all auxiliary components, such as the chilled fluid
circulating pump, air-handling equipment, or other equip-
ment to which the chiller supplies liquid. Consult manu-
facturer's instructions. If the unit has field-installed ac-
cessories, be sure all are properly installed and wired
correctly. Refer to unit wiring diagrams.
2. Backseat (open) compressor suction and discharge shut-
off valves. Close valves one turn to allow refrigerant pres-
sure to reach the test gages.
3. Open liquid line service valves.
4. Fill the chiller fluid circuit with clean water (with
recommended inhibitor added) or other noncorrosive
fluid to be cooled. Bleed all air out of high points of
system. An air vent is included with the cooler. If out-
door temperatures are expected to be below 32 F
3 ⁄ -in. SAE
8
Start-Up Checklist for
(0° C), sufficient inhibited ethylene glycol or other suit-
able corrosion-inhibited antifreeze should be added to
the chiller water circuit to prevent possible freeze-up.
5. Check tightness of all electrical connections.
6. Oil should be visible in the compressor sight glass. See
Fig. 31. An acceptable oil level in the compressor is from
⁄ to ⁄ of sight glass. Adjust the oil level as required.
1 3
8 8
No oil should be removed unless the crankcase heater
has been energized for at least 24 hours. See Oil Charge
section on page 52 for Carrier-approved oils.
7. Electrical power source must agree with unit
nameplate.
8. Crankcase heaters must be firmly locked into compres-
sors, and must be on for 24 hours prior to start-up.
9. Fan motors are 3 phase. Check rotation of fans during
the service test. Fan rotation is clockwise as viewed from
top of unit. If fan is not turning clockwise, reverse 2 of
the power wires. For low noise fan option on 50 Hz chill-
ers, fans rotate counterclockwise as viewed from top of
unit. If fan is not turning counterclockwise, reverse 2 of
the power wires.
10. Check compressor suspension. Mounting rails must be
floating freely on the springs.
11. Perform service test to verify proper settings.
*Lead compressor only.
Fig. 33 — Compressor Connections
(Lead Compressor Shown)
64