Carrier 38GNA - Manual (Page 3)

Table 2—Tubing Data
REFRIGERANT LINE LENGTH
UNIT SIZE
10 to 50 ft 51 to 100 ft
Diameter (In.)
Suction Liquid Suction Liquid
018, 024 5/8 3/8 3/4 3/8
1. Maximum vertical separation for evaporator over condensing unit is 50 ft.
2. Over 50 ft of vertical separation, the condensing unit must be located above
the evaporator. For requirements beyond 50 ft, obtain information from
distributor or consult Long-Line Application Guideline.
3. Charge adjustment is required when using more than 25 ft of tubing. See
Refrigerant Charging information on unit rating plate.
4. Do not use larger than 3/4-in. suction line.
If accessory tubing package or evaporator coil has been open for
more than 5 minutes, evacuate evaporator coil and tubing system.
Always evacuate if field-supplied tubing is used. See Evacuation
section.
Ensure field-supplied tubing is of refrigerant grade. Insulate the
suction line with insulation that has an adequate vapor barrier.
Evacuate tubing.
1. Run refrigerant lines as directly as possible, avoiding any
unnecessary turns and bends.
2. Tape the liquid line to the top of the insulated suction line for
support.
3. Suspend the refrigerant lines so they do not damage the
insulation on the suction line and do not transmit vibration to
the structure.
4. If the refrigerant lines are too long, the excess may be cut off.
5. Connect tubing to the condensing unit. The refrigerant tubing
and evaporator coil should be leak tested upon completion.
When making piping connections, be sure to provide clearance at
unit for electrical connection.
Connect suction and liquid refrigerant lines to condensing unit.
(See Fig. 1.) Make suction line connection first.
Two grommets are provided to seal the gap between refrigerant
lines and unit casing. Cut small grommet, slip it over liquid line
and push it into casing opening. Gap around suction line is sealed
in same manner except that suction line insulation must be cut and
pushed back before grommet can be slipped into place. (See Fig.
4.)
FIELD TUBING CONNECTIONS - All models are equipped
with 3/8-in. liquid and 5/8-in. suction back seated service valves
with mechanical flare field connections. Factory-supplied 3/8-in.
to 3/8- in. and 5/8-in. to 5/8-in. flare-to-sweat adaptor tubes are
provided. Field-supplied couplings are required for tubing pack­
ages exceeding 50-ft long-line applications.
LEAK TESTING — No installation is complete until all field and
factory joints have been checked for leaks.
1. Remove valve stem caps from both service valves and check
to be sure valves are front seated (turned clockwise). Remove
service port caps.
2. Attach gage manifold to service ports of service valves and
purge hoses.
3. Pressurize evaporator coil and interconnecting refrigerant
tubing with vapor from an external refrigerant cylinder of
R-22 until the system and cylinder pressure are equalized.
NOTE: NEVER USE A UNIT CHARGE FOR LEAK TEST­
ING.
4. Leak test with an electronic detector, a halide torch, or a liquid
soap solution.
5. Recover refrigerant and repair any leaks.
6. If system is free of leaks, prepare unit for operation.
EVACUATION
1. Connect evacuation equipment to system gage manifold.
2. Evacuate system following appropriate steps for type of
evacuation equipment used.
3. Pressurize system with refrigerant to 10 psig and open (turn
counter-clockwise) both service valves.
4. Remove gage manifold. Replace valve stem and service port
caps on both service valves.
Step 4 —Make Electrical Connection
Field wiring must comply with local and national fire, safety and
electrical codes. Voltage to unit must be within range of 253v to
187v. Refer to nameplate for other electrical data. Contact local
power company for correction of improper line voltage.
Step 3—^Test Unit
A WARNING
According to NEC, ANSI/NFPA 70, and local codes, the
cabinet must have an uninterrupted or unbroken ground, to
minimize personal injury if an electrical fault should occur.
The ground may consist of electrical wire or metal conduit
when installed in accordance with existing electrical codes.
Failure to follow this warning could result in an electric
shock, fire, or death.
See unit’s rating plate for recommended fuse size. When making
electrical connections, provide clearance at unit for refrigerant
piping connections.
BRANCH CIRCUIT DISCONNECT - Install a branch circuit
disconnect per NEC of adequate size to handle unit starting
current. Locate disconnect within sight from and readily accessible
from unit, per Section 440-14 of the NEC.
LINE POWER LEADS
Extend leads from disconnect per NEC into unit through hole
provided in service panel. (See Fig. 1.) Connect ground lead to
ground lug in control box for safety. Connect line power leads to
contactor screw terminals LI and L2. (See Fig. 5 or 6.) Contactor
terminals are approved for use with copper field wiring.
CONTROL POWER (24V) — Use furnace or fan coil trans­
former as 24v supply for system. Transformer must have a
minimum capacity of 30 va. Bring control wiring through hole in
unit service panel and connect to pigtails from unit contactor.
Contactor pigtails are labeled Y and C. Refer to Fig. 5 or 6 for
system control circuit connections.