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38GP
User Manual
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Carrier 38GP User Manual

Carrier International

Corporation

Installation, Operation,
and Maintenance Instructions
Important—Read Before Installing
The Model 38GP Condensing Unit does not have a trans former; therefore, the fan-coil or blower package trans former (or another source) must be used as a low-voltage supply. The low-voltage supply must have an additional capacity of 15VA to handle the load imposed by this equipment.
The compressor motor is equipped with em internal protec tor. Excessive current or temperature wiU cause the protec tor to open, giving the indication of an open circuit in the motor winding. Sufi&cient time should be allowed for the overload to reset before assuming the compressor has an open winding.
Each condensing unit is shipped with a refrigerant charge that is adequate for most systems using matching coils and refrigerant tubing kits. This charge is adequate for up to 25 feet of interconnecting tubing. For tube lengths greater or less than 25 feet, the refrigerant charge must be adjusted. See Table II for charge quantity and refer to refrigerant­tube sizing. Tables IV through VII, for the adjustment re quirements.
NOTE: If additional refrigerant is needed, a crankcase heater
wül probably be required. (Refer to the appropriate refriger ant-tube sizing table.) When a crankcase heater is used, inform the homeowner that power must be turned on to the air conditioning unit at least 12 hours before the thermostat is turned to the COOLING position for spring startup.
A filter-drier is not normally required in the system when a complete system is used (condensing unit, refrigerant tub ing, and evaporator coil). For exceptions to this rule, see Section II, “Installing Refrigerant Tubing,” of the Stand ard Installation Practices booklet packaged with the unit.
To obtain optimum performance and efficiency with match ing or mix-matched evaporator coils, it may be necessary to change the metering device. See Table IX for necessary changes.
^Carrier International Corporation 1984
38GP

(50-HZ)

Figure 1—Model 38GP
GENERAL
The condensing unit, as shipped from the factory, includes: a compressor, a condenser fan and motor, hquid and suction service valves, an air-cooled condenser coil, and all neces sary electriceil controls.
The condensing unit is designed for use with matching evaporator coils. An expansion valve is not required. How ever, the unit can be used with a suitable evaporator coil that uses an expansion valve with a pressure equalization feature during the off cycle. Expansion valves with this fea ture.are available from your Distributor.
Installation comprises the following steps (sections):
I. Locating the Unit
II. InstaUing Refrigerant Tubing
III. Leak Testing
IV. Purging (if required)
V. Evacuation (if required)
VI. Electrical Connections
VII. Checking Charge
VIII. Adjusting Charge
38GP-C12SI-CIC
AIR IN
NOTE: Fan position on motor shaft should be as close to motor as possible without touching.
Figure 2—Dimensional Drawing
TABLE I—DIMENSIONS (In Inches)
Size
025
040, 047 & 054
----------X---------­27-3/8 24-9/16 6-3/8 1-7/8 3/8 27-3/8 30-9/16 6-3/8 1-7/8 3/8
----------C----------
D
----------1----------
F G
11-9/16 11-9/16
H 11-3/4 11 -3/4
11/32 3/4 11/32
3/4
K
TABLE II—SPECIFICATIONS
Refrigerant Type R-22
Size 025
Factory Refrigerant Charge Lbs-oz 4-8
040
R-22 R-22
6-8 7-2 Refrigerant Tube^ Liquid 3/8 3/8 Connection Size (Compatible) Vapor 3/4 3/4 Approx Shipping Weight Lbs 155 200
♦Refer to appropriate refrigerant tube sizing table to determine correct liquid- and suction-tube diameters.
047
3/8 3/4
230
054 R-22 6-11
3/8 3/4
232
TABLE III—ELECTRIC CONNECTIONS
Nameplate
Size 025 040
Volts—Phase (60-Hertz) 230—1—50 Operating Voltage Range
207-253 360-440 360-440 360-440 360-440
400—3—50
400—3—50
Unit Ampacity for Elec trical Conductor Sizing. 18.5 6.7 9.2 14.1 Total Unit Amps 15.1 5.6 7.6 Min Branch Circuit Wire Size Copper Conductor^
AWG No.
Max Length
In Ftt
12 14 14 14
94 321 236 156 228
Largest Wire Size Terminal Will
, Accommodate
Type Conn
AWG No. 6
Screw Screw
6 6 6 6
Screw
Max Branch. Circuit Fuse Sizet
Amps 25
10
15
NOTE: Use copper wire only between disconnect switch and unit.
♦If other than 75° C copper conductor is used, determine size from unit-ampacity and the National Electric Code. Voltage drop of wire must be less
than 2% of unit rated voltage. fLength shown is as measured one way along the wire path between the unit and service panel-for minimum 2% voltage drop. $Sing)e-phase units may use fuses or HACFI-type circuit breakers of same size as noted.
047 054
400—3—50 400—3—50
15.4
11.5 12.5
12
Screw Lug
20 20
All of the above steps are covered in general by the like­numbered sections of the Standard Installation Practices in the back of this manual; therefore, this Installation Instruc tion will contain only supplementary information applicable to installing the condensing unit. It should be noted that evacuation and purging are not normally required when a
complete matching system is installed. However, if any of the component parts are subject to contamination, or if tub ing kits and matching coUs are not used, the system must be purged or evacuated.
NOTE; Be sure to adjust system airflow per requirements of
the fan-coil, evaporator coil, and condensing unit combination.
In addition, the following sections should be reviewed by the equipment owner;
IX. Sequence of Operation
X. Care and Maintenance
I. LOCATING THE UNIT
(Supplementary Instructions)
Select a location for the unit where water, ice, emd snow will not fall from an overhang and damage the unit top or fan blade. Care must be exercised to maintain the clearance requirements listed on page 2 to assure proper access for servicing and to avoid recirculation of condenser air.
II. INSTALLING REFRIGERANT TUBES (Supplementary Instructions)
A. Determining Liquid-Tube Diameter
The correct liquid-tube diameter cem be determined by using the appropriate table as described in steps 1 through 7 which follow. Be certain to use only the hquid-tube table that matches the size unit being installed. (See Tables IV thru VII.)
1. Measure total one-way horizontal distance for intended tubing path.
2. Measure total one-way vertical distance for intended tubing path.
3. At left-hand end of table, select value that matches measured vertical length. Be sure to note that upper section of table is used if coohng coü is above unit, whereas lower section is used if cooUng coil is below
unit.
4. Move across this Une towards right-hand side until cor
rect vertical column is reached for measured horizontal length.
5. Correct diameter will be indicated at intersection of
these lines.
6. If point of intersection falls within shaded area, crank case heater must be added.
7. For apphcations where coohng coil is to be placed more than 50 feet below unit, see your Distributor for spe cific recommendations.
Here is an example; Unit is size 025. Coohng coil is located 43 feet above unit. Horizontal distance is 72 feet.
First, in the section marked “Coü Above Unit,” find the hne showing measurement of 41-50 feet. Follow this line towards the right until it intersects the vertical colunrn marked 71-80 feet. The correct tube size is 5/16-inch OD, and the fact that the 5/16-inch size falls in the shaded area
means that the unit wih require a crankcase heater.
B. Instructions for Total System Charge
The total system refrigerant charge includes the condensing unit, the evaporator coü, and the interconnecting tubing. The factory charge is sufficient for a system using 25 feet of
interconnecting tubing and a matching evaporator coil. For systems using tubing lengths other than 25 feet, adjust the charge in accordance with the notes under the proper table (IV through VII).

TABLE IV—UNIT SIZE 025

Vertical
Distance to to to
(Ft) 10 20 30 40
Coil
Above 21 to 30 1/4 1/4
Unit
Coil
Below
Unit
41 to 50
31 to 40, 1/4
11 to 20 1/4 1
Oto 10 Oto 10
11 to 20 21 to 30 31 to 40 1/4 41 to 50 1/4 1/4 51«; /3«,
D 11 21 31
5/16 5/16 5/46 5/16
Horizontal Distance- -Feet
to to to
5/16 5/-16 5/16
t
t
4,/4,<
41 51
50 60 70 80 90 100
61 to to
5/16
71 81 91
to to
5/16 3/8
5/16
1/4
1
5/16
5/J6
5/16
5/16

TABLE V—UNIT SIZE 040

Horizontal Distance— Feet
Vertical a
Distance to to to to to to to to to to
(Ft)
Coil 31 to 40
Above 21 to 30 1./4
Unit 11 to 20 1/4
Coil 11 to 20
Below
Unit
41 to 50 1/4 5/16 5/16 5/16 5/16 5/16 5,'16 5/16 5/16 5/16
Oto 10 1/4 Oto 10 1/4
21 to 30 1/4 31 to 40 41 to 50 1/4 1/4 1/4 1/4 1/4 1,-4
11 21 31 41 51 61 71 81
10 20 30 40 50 60 70 80 90 100
1/4
t
t
1/4
Î
5/16
5/16
5./16
91
5/16

TABLE VI—UNIT SIZE 047

Horizontal Distance— Feet
Vertical 11 21 31
Distance to to to to to to to to to to
(Ft)
41 to 50 5/16 5/16 3/8 3/8
Coil 31 to 40 5/16 5/16
Above 21 to 30 5/16
Unit 11 to 20 5/16 5/16
Oto 10 Oto 10
Coil 11 to 20
Below 21 to 30
Unit 31 to 40
41 to 50 5/16 5/16 5/16 5/16 5/16 5/16 5/16 5/16 5/16
10 20 30 40 50 60 70 80 90 100
41
51 61 71 81 91
3/8 3/8 3/8
3/8
m/§
.t
5/16
t
5/16 5/16
5/16

TABLE VII—UNIT SIZE 054

Vertical 11 21 31 41 51 61 71 81 91
Distance to to to to to to to to to to
(Ft)
Coil 31 to 40
Above 21 to 30
Unit 11 to 20 5/ 5.'16
Coil
Below
Unit
(1) Unit charge adequate for 3/8-in. OD tube lengths up to 25 ft. For lengths
(2) Unit charge adequate for 1/4-in. OD tube lengths up to 75 ft. For lengths
(3) Unit charge adequate for 5/16-in. OD tube lengths up to 40 ft. For lengths
(4) If tube size falls within shaded area, add crankcase heater.
41 to 50
Oto 10 Oto 10
11 to 20 21 to 30 31 to 40 41 to 50 5/16
below or above 25 ft, adjust charge at rate of 0.6 oz/ft. This may be done by using superheat charging label.
above 75 ft, adjust charge at rate of 0.2 oz/ft.
above 40 ft, adjust charge at rate of 0.4 oz/ft.
10
3/8 3/8 3/8 3/8
5/ 16
' ’
Horizontal Distance— Feet
30 40 50
20
t
5.'16] 5/ 1 6
5/16|5/16|5/16|5/16|5/16 3/8 3/8 3/8 3/8
3 5
1'
i J
70 80 90
60
3./8 3/8 3/8 3,'8 3/8
5/16
5 1 6
1
i
6
...
4
100
—3—
TABLE Vili—RECOMMENDED
SUCTION-TUBE DIAMETERS
Suction-Tube
Size
025 0 to 120 5/8
040 Oto 60
047
054 0 to 65 1-1/8
NOTE: The above table is based on a tube loss of 2°F. Longer lengths
can be used in each diameter listed, or smaller diameters may be used, but the result will be larger tube losses with a lower unit capacity and efficiency rating. Refer to your Distributor for specific details.
Length (Feet)
120 to 150 7/8
60 to 135 7/8
Oto 85 7/8
85 to 150 1-1/8
65 to 150 1-3/8
Recommended
Diameter (inches)
3/4
TABLE IX—REQUIRED PISTON SIZE FOR
INDOOR COIL
Condensing
Unit Size
025 040 76 047 054 88
NOTE: The piston sizes listed in this table are for systems where the
vertical separations between indoor and outdoor units do not exceed 10 feet. For vertical separations exceeding 10 feet, consult the factory for the proper piston sizes.
Piston
identification No.
59
82
If other than matching interconnecting tubing or evapora tor coU is being used, use an accurate scale or volumetric charging cylinder (such as a Dial-A-Charge) and weigh in the refrigerant until the desired superheat temperature is obtained. See the superheat charging label attached to each condensing unit.
When system charging has been completed, stamp the total
amount of refrigerant in the block provided on the condens ing unit rating plate. The total system charge is the same as the field charge.
C. Determining Suction-Tube Diameter
The correct suction-tube diameter can be determined by using Table VIII as follows:
1. Measure total length (vertical and horizontal) of intended tubing path.
2. Find correct unit size at left of table. The tube lengths are shown in the center of the table
with the appropriate diameters on the right.
iX. SEQUENCE OF OPERATiON
When the thermostat “calls for cooling,” the thermostat contacts close, energizing contactor holding coil 2D or 2M from a 24-volt external power source. The contactor closes, energizing compressor motor 3F or 3J and condenser fan motor 3C or 3D with supply voltage.
When the thermostat is satisfied, the contacts open, deenergizing contactor holding coil 2D or 2M and, in turn, breaking the supply voltage circuit. AH motors should stop.
Optional Start Assist (When Used)
Start thermistor 4K is wired in parallel to run capacitor 4G on single-phase units. Its purpose is to provide additional start assist. When compressor 3J starts, start thermistor 4K builds its internal resistance to a level where it effec
tively removes itself electrically from circuit. When contac tor 2D or 2M is deenergized, start thermistor 4K will auto matically reset itself in approximately 3 to 5 minutes.
Start Kit 2K and 4D
The start kit consists of start relay 2K and start capacitor 4D. Start capacitor 4D helps compressor 3J start. When the compressor starts, start relay 2K disconnects start capaci tor 4D from the circuit, allowing compressor 3J to run on run capacitor 4A or 4G. When contactor 2D or 2M deener gizes, start relay 2K reconnects the start capacitor in the circuit, making it ready for the next compressor start.
X. CARE AND MAINTENANCE
For continuing high performance, and to rnmirnize possible equipment failure, it is essential that periodic maintenance be performed on this equipment. Consult your local Dealer for the proper frequency or maintenance and the availability of a maintenance contract.
The air for the condenser coil is drawn into the unit on four sides and discharged out the top. Keep the air inlet and out let grilles unplugged and clear of any obstructions at all times. Never cover the unit or lean anything against it which might restrict airflow or cause hot air from the top grille to recirculate into the sides. Keep trash and debris away from the uiut at all times. Never stand on the unit or use it as a support for ladders, etc.
The refrigerant tubing connecting this unit with the coohng coil is easily crushed or crimped. Therefore, do not hang or stand anything on it. Do not move the unit after it has been installed, as this may crimp the tubing and cause the unit to malfunction.
The ability to properly perform maintenance on this equip ment requires certain mechanical skills and tools. If you do not possess these, contact your Distributor for maintenance.
The minimum maintenance that should be performed on this equipment is as follows:
1. Check condenser coü for cleanliness each month during cooling season. Clean as necessary, but at least once at the beginning of each cooling season. To insure reliable performance in sea coast or contaminated atmosphere installations, the unit must be kept free of debris and the condenser coil flushed with fresh water at least once a month. See Section X, item A, for proper procedures.
—4—
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