Relief Devices; High-Side Protection; Pressure Relief Valves; Other Safeties - Carrier Air Conditioner Operation And Service Manual

Relief Devices —
Fusible plugs are located in each cir-
cuit to protect against damage from excessive pressures.
HIGH-SIDE PROTECTION — One
between 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 replaced, 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 48.

PRE-START-UP

IMPORTANT: Before beginning Pre-Start-Up or Start-
Up, complete Start-Up Checklist for ComfortLink™
Chiller Systems at end of this publication (page CL-1).
The Checklist assures proper start-up of a unit, and
provides a record of unit condition, application require-
ments, system information, and operation 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 equipment to which the chiller supplies liquid.
Consult manufacturer's instructions. If the unit
has field-installed accessories, 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 flu-
id to be cooled. Bleed all air out of high points of system.
An air vent is included with the cooler. If outdoor temper-
atures are expected to be below 32 F (0° C), sufficient in-
hibited ethylene glycol or other suitable corrosion-inhibit-
ed 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. 35. An acceptable oil level in the compressor is from
1 3
/ in. to / in. of sight glass. Adjust the oil level as re-
8 8
quired. No oil should be removed unless the crankcase
device is located
3
/ -in. SAE
8
65
heater has been energized for at least 24 hours. See Oil
Charge section on page 53 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 chillers,
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. 35 — Compressor Connections
(Lead Compressor Shown)