38BYC, 38BYG
12 SEER Split System
Heat Pump
Installation and Start-Up Instructions
NOTE: Read the entire instruction manual before starting the
installation.
This symbol → indicates a change since the last issue.
SAFETY CONSIDERATIONS
Improper installation, adjustment, alteration, service, maintenance,
or use can cause explosion, fire, electrical shock, or other
conditions which may cause death, personal injury, or property
damage. Consult a qualified installer, service agency, or your
distributor or branch for information or assistance. The qualified
installer or agency must use factory-authorized kits or accessories
when modifying this product. Refer to the individual instructions
packaged with the kits or accessories when installing.
Follow all safety codes. Wear safety glasses, protective clothing,
and work gloves. Use quenching cloth for brazing operations.
Have fire extinguisher available. Read these instructions thor-
oughly and follow all warnings or cautions included in literature
and attached to the unit. Consult local building codes and National
Electrical Code (NEC) for special requirements.
A98525
Fig. 1—Model 38BYG
Recognize safety information. This is the safety-alert symbol
When you see this symbol on the unit and in instructions or
manuals, be alert to the potential for personal injury.
.
4. Leave some slack between structure and unit to absorb
vibration.
5. When passing refrigerant tubes through the wall, seal opening
with RTV or other pliable silicon based caulk. (See Fig. 2.)
Understand the signal words DANGER, WARNING, and CAU-
TION. These words are used with the safety-alert symbol. DAN-
GER identifies the most serious hazards which will result in severe
personal injury or death. WARNING signifies hazards which
could result in personal injury or death. CAUTION is used to
identify unsafe practices which would result in minor personal
injury or product and property damage. NOTE is used to highlight
suggestions which will result in enhanced installation, reliability,
or operation.
6. Avoid direct tubing contact with water pipes, duct work, floor
joists, wall studs, floors, and walls.
7. Do not suspend refrigerant tubing from joists and studs with a
rigid wire or strap that comes in direct contact with tubing.
(See Fig. 2.)
8. Ensure that tubing insulation is pliable and completely sur-
rounds vapor tube.
9. When necessary, use hanger straps which are 1 in. wide and
conform to shape of tubing insulation. (See Fig. 2.)
Before installing, modifying, or servicing system, main elec-
trical disconnect switch must be in the OFF position. There
may be more than 1 disconnect switch. Lock out and tag
switch with a suitable warning label. Electrical shock can
cause personal injury or death.
10. Isolate hanger straps from insulation by using metal sleeves
bent to conform to shape of insulation.
When outdoor unit is connected to factory-approved indoor unit,
outdoor unit contains system refrigerant charge for operation with
indoor unit of the same size when connected by 15 ft of
field-supplied or factory-accessory tubing. For proper unit opera-
tion, check refrigerant charge using charging information located
on control box cover.
INSTALLATION RECOMMENDATIONS
NOTE: In some cases noise in the living area has been traced to
gas pulsations from improper installation of equipment.
1. Locate unit away from windows, patios, decks, and so forth
where unit operation sounds may disturb customer.
IMPORTANT: Maximum liquid line size is 3/8-in. O.D. for all
residential applications including long line.
2. Ensure that vapor- and liquid-tube diameters are appropriate to
capacity of unit.
IMPORTANT: Always install a liquid line filter drier on any
system using existing field service line sets and or existing indoor
coil or fan coil units. Always use a filter direr on burnout unit
replacements.
3. Run refrigerant tubes as directly as possible by avoiding
unnecessary turns and bends.
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book
Tab 5a 5a
1
4
PC 101
Catalog No. 533-80078
Printed in U.S.A.
Form 38BYC-3SI
Pg 1
11-02
Replaces: 38BYC-2SI
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If TXV installation is required, remove existing AccuRater® from
indoor coil. Refer to Figs. 4 and 5 and install TXV kit as follows:
feeder tubes, there is a 3/8-in. O.D. stub tube approximately 2 in.
long. (See Fig. 6.) The defrost thermostat should be located on stub
tube. Note that there is only 1 stub tube used with liquid header,
and on most units it is the bottom circuit.
1. Install suction tube adapter.
2. Install liquid flare-to-sweat adapter.
FEEDER TUBE
STUB TUBE
3. Connect external equalizer tube to fitting on suction tube
adapter.
4. Position sensing bulb on horizontal portion of suction tube
adapter. Secure using supplied hardware.
5. Insulate bulb after installation. (See Fig. 5.)
6. Leak check all connections.
DEFROST
THERMOSTAT
COIL
SENSING
BULB
A97517
Fig. 6—Defrost Thermostat Location
Step 9—Make Piping Connections
EQUALIZER
TUBE
Relieve pressure and recover all refrigerant before system
repair or final unit disposal to avoid personal injury or death.
Use all service ports and open all flow control devices,
including solenoid valves.
THERMOSTATIC
EXPANSION
VALVE
A88382
Fig. 4—Typical TXV Installation
If ANY refrigerant tubing is buried, provide a 6 in. vertical
rise at service valve. Refrigerant tubing lengths up to 36 in.
may be buried without further special consideration. For
lengths longer than 36 in., refer to Application Guideline and
Service Manual — Residential Split System Air Conditioners
and Heat Pumps.
10 O'CLOCK
2 O'CLOCK
SENSING BULB
STRAP
SUCTION TUBE
To prevent damage to unit or service valves observe the
8 O'CLOCK
7⁄8 IN. OD & SMALLER
4 O'CLOCK
following:
•Use a brazing shield.
•Wrap service valves with wet cloth or use a heat-sink
material.
LARGER THAN 7⁄8 IN. OD
A81032
Outdoor units may be connected to indoor section using accessory-
tubing package or field-supplied refrigerant grade tubing of correct
size and condition. For tubing requirements beyond 50 ft, substan-
tial capacity and performance losses can occur. Following the
recommendations in the Residential Split System Long-Line
Application Guideline will reduce these losses. Refer to Table 1
for field tubing equivalent line length. Refer to Table 2 for
accessory requirements.
Fig. 5—Positioning of Sensing Bulb
Step 7—Check Outdoor AccuRater® Piston
Check outdoor unit piston. Remove retainer on liquid service valve
and check piston size with matching number listed on outdoor unit
rating plate.
For buried line applications greater than 36 in., refer to Table 2 and
Residential Split System Buried Line Application Guideline.
Buried line applications may not exceed 100 ft.
Step 8—Check Defrost Thermostat
Check defrost thermostat to ensure it is properly located and
securely attached. There is a liquid header with a brass distributor
and feeder tube going into outdoor coil. At the end of 1 of the
If refrigerant tubes or indoor coil are exposed to atmosphere, they
must be evacuated to 500 microns to eliminate contamination and
moisture in the system.
3
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Table 1—Refrigerant Connections And Recommended Liquid- And Vapor-Tube Diameters (In.)
LIQUID
Connection Diameter
VAPOR
Connection Diameter
VAPOR (LONG LINE)
Connection Diameter Tube Diameter
UNIT
SIZE
Tube Diameter
Tube Diameter
018
024
3/8
3/8
3/8
3/8
3/8
3/8
3/8
3/8
3/8
3/8
5/8
3/4
3/4
7/8
7/8
5/8
3/4
5/8
3/4
3/4
7/8
7/8
3/4
3/4
030, 036
042
3/4
7/8
7/8
1-1/8
1-1/8
048, 060
1-1/8
NOTES:
1. Tube diameters are for lengths up to 50 ft. For tubing lengths greater than 50 ft horizontal, or greater than 20 ft vertical differential, consult the Application Guideline
and Service Manual — Air Conditioners and Heat Pumps.
2. Do not apply capillary tube indoor coils to these units.
OUTDOOR UNIT CONNECTED TO FACTORY APPROVED
INDOOR UNIT
attention to feeder tubes, making sure wire ties on feeder tubes are
secure and tight.
Outdoor unit contains correct system refrigerant charge for opera-
tion with indoor unit of same size when connected by 15 ft of
field-supplied or factory accessory tubing. Check refrigerant
charge for maximum efficiency.
Step 10—Make Electrical Connections
To avoid personal injury or death, do not supply power to unit
with compressor terminal box cover removed.
REFRIGERANT TUBING
Connect tubing to fittings on outdoor unit vapor- and liquid-
service valves. (See Table 1.) Use refrigerant grade tubing.
Be sure field wiring complies with local and national fire, safety,
and electrical codes, and voltage to system is within limits shown
on unit rating plate. Contact local power company for correction of
improper voltage. See unit rating plate for recommended circuit-
protection device.
SWEAT CONNECTION
NOTE: Operation of unit on improper line voltage constitutes
abuse and could affect unit reliability. See unit rating plate. Do not
install unit in system where voltage may fluctuate above or below
permissible limits.
To avoid valve damage while brazing, service valves must be
wrapped in a heat sink material such as a wet cloth.
Remove plastic retainer holding outdoor piston in liquid service
valve and connect sweat/flare adapter provided to valve. (See Fig.
7.) Connect refrigerant tubing to fittings on outdoor unit vapor-
and liquid-service valves. Service valves are closed from factory
and ready for brazing. After wrapping service valve with a wet
cloth, tubing set can be brazed to service valve using either silver
bearing or non-silver bearing brazing material. Consult local code
requirements. Refrigerant tubing and indoor coil are now ready for
leak testing. This check should include all field and factory joints.
NOTE: Use copper wire only between disconnect switch and
unit.
NOTE: Install branch circuit disconnect of adequate size per
NEC to handle unit starting current. Locate disconnect within sight
from and readily accessible from unit, per Section 440-14 of NEC.
ROUTE GROUND AND POWER WIRES
Remove access panel to gain access to unit wiring. Extend wires
from disconnect through power wiring hole provided and into unit
control box.
PISTON BODY
The unit 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 can result in an
electric shock, fire, or death.
PISTON
PISTON
RETAINER
CONNECT GROUND AND POWER WIRES
STRAINER
Connect ground wire to ground connection in control box for
safety. Connect power wiring to contactor as shown in Fig. 8.
CONNECT CONTROL WIRING
Route 24v control wires through control wiring grommet and
connect leads to control wiring. See Thermostat Installation
Instructions for wiring specific unit combinations. (See Fig. 9.)
SWEAT/FLARE ADAPTER
Use No. 18 AWG color coded, insulated (35°C minimum) wire. If
thermostat is located more than 100 ft from unit, as measured
along the control voltage wires, use No. 16 AWG color coded wire
to avoid excessive voltage drop.
A97512
Fig. 7—Liquid-Service Valve
IMPORTANT: Check to be certain factory tubing on both indoor
and outdoor unit has not shifted during shipment. Ensure tubes are
not rubbing against each other or any sheet metal. Pay close
All wiring must be NEC Class 1 and must be separated from
incoming power leads.
4
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Table 2—Accessory Usage
REQUIRED FOR
LOW-AMBIENT
APPLICATIONS
(BELOW 55°F)
REQUIRED FOR
REQUIRED FOR
BURIED LINE
APPLICATIONS†
(OVER 3 FT)
LONG-LINE
APPLICATIONS*
(OVER 50 FT)
ACCESSORY
Crankcase Heater
Evaporator Freeze Thermostat
Accumulator
Yes
Yes
No
Yes
No
Yes
No
No
Yes
Compressor Start-Assist
Capacitor and Relay
Yes
Yes
Yes
MotorMaster® Control,
or
Yes
No
No
Low-Ambient Pressure Switch
See low-ambient
Instructions
Wind Baffle
No
No
No
No
Unit Risers
Recommended
Liquid-Line Solenoid Valve
See Long-Line
Application
Guideline
or
No
Yes
No
Hard-Shutoff TXV
Ball-Bearing Fan Motor
Yes‡
No
* For tubing line sets between 50 and 175 ft, refer to Application Guideline and Service Manual — Air Conditioners and Heat Pumps.
† For buried line applications, refer to Application Guideline and Service Manual — Air Conditioners and Heat Pumps.
‡ Required for low-ambient controller (full-modulation feature) and MotorMaster® Control only.
Step 13—Start-Up
DISCONNECT
PER N. E. C. AND/OR
LOCAL CODES
CONTACTOR
To prevent compressor damage or personal injury, observe
the following:
FIELD POWER
WIRING
•Do not overcharge system with refrigerant.
•Do not operate unit in a vacuum or at negative pressure.
•Do not disable low-pressure switch.
In scroll compressor applications:
FIELD GROUND
WIRING
•Dome temperatures may be hot.
GROUND
LUG
A91056
To prevent personal injury wear safety glasses, protective
clothing, and gloves when handling refrigerant and observe
the following:
•Back-seating service valves are not equipped with Schrader
valves. Fully back seat (counterclockwise) valve stem before
removing gage-port cap.
Fig. 8—Line Power Connections
Use furnace transformer, fan coil transformer, or accessory trans-
former for control power, 24v/40va minimum.
NOTE: Use of available 24v accessories may exceed the mini-
mum 40va power requirement. Determine total transformer load-
ing and increase the transformer capacity or split the load with an
accessory transformer as required.
•Front-seating service valves are equipped with Schrader
valves.
IMPORTANT: Check factory wiring and wire connections to
ensure terminations are secured properly. Check wire routing to
ensure wires are not in contact with tubing, sheet metal, and so
forth.
Federal Regulations require that you do not vent refrigerant to
atmosphere. Recover during system repair or final unit
disposal.
Step 11—Compressor Crankcase Heater
Follow these steps to properly pumpdown a system and avoid
negative suction pressure.
When equipped with a crankcase heater, furnish power to heater a
minimum of 24 hr before starting unit. To furnish power to heater
only, set thermostat to OFF and close electrical disconnect to
outdoor unit. A crankcase heater is required if refrigerant tubing is
longer than 50 ft.
1. Fully back seat (open) liquid- and vapor-tube service valves.
2. Unit is shipped with valve stem(s) front seated (closed) and
caps installed. Replace stem caps after system is opened to
refrigerant flow. Replace caps finger-tight and tighten with
wrench an additional 1/12 turn.
Step 12—Install Electrical Accessories
Refer to the individual instructions packaged with kits or acces-
sories when installing.
3. Close electrical disconnects to energize system.
5
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4. Set room thermostat to desired temperature. Be sure set point
is below indoor-ambient temperature.
outdoor temperature falls below setting of outdoor thermostat
(field-installed option), contacts close to complete circuit and bring
on second bank of supplemental electric heat.
5. Set room thermostat to HEAT or COOL and fan control to ON
or AUTO mode, as desired. Operate unit for 15 minutes.
Check system-refrigerant charge.
When thermostat is satisfied, its contacts open, de-energizing
contactor and relay. All heaters and motors should stop.
SEQUENCE OF OPERATION
DEFROST
NOTE: Defrost-control board may be equipped with 5-minute
lockout timer that may be initiated upon any interruption of power.
The defrost control is a time/temperature control which includes a
field-selectable (quick-connects located at board edge) time period
between defrost cycles (30, 60, or 90 minutes), factory set at 90
minutes.
With power supplied to indoor and outdoor units, transformer is
energized.
The electronic timer and defrost cycle start only when contactor is
energized and defrost thermostat is closed.
COOLING
On a call for cooling, thermostat makes circuits R-O, R-Y, and
R-G. Circuit R-O energizes reversing valve, switching it to cooling
position. Circuit R-Y energizes contactor, starting outdoor-fan
motor and compressor circuit. R-G energizes indoor unit-blower
relay, starting indoor-blower motor on high speed.
Defrost mode is identical to cooling mode except that outdoor-fan
motor stops and second-stage heat is turned on to continue
warming conditioned space.
To initiate defrost, the defrost thermostat must be closed. This can
be accomplished as follows:
When thermostat is satisfied, its contacts open, de-energizing the
contactor and blower relay. Compressor and motors should stop.
1. Turn off power to outdoor unit.
NOTE: If indoor unit is equipped with a time-delay relay circuit,
the blower runs an additional 90 sec to increase system efficiency.
2. Disconnect outdoor-fan motor lead from OF2 on control
board. (See Fig. 10.) Tape lead to prevent grounding.
HEAT
PUMP
TYPICAL
FAN COIL
HP THERMOSTAT
R
C
R
R
C
24 VAC HOT
24 VAC COM
HEAT STAGE 2
C
*
W2
W2
W2
*
*
E
W3
G
COOL/HEAT
STAGE 1
Y
Y
G
INDOOR FAN
O
E
RVS COOLING
O
EMERGENCY
HEAT
IF AVAILABLE
*
A02325
Fig. 9—Generic Wiring Diagram
(See Thermostat Installation Instructions for wiring specific unit combinations.)
LEGEND
24-V FACTORY WIRING
24-V FIELD WIRING
FIELD SPLICE CONNECTION
ODT
OUTDOOR THERMOSTAT
EHR
EMERGENCY HEAT RELAY
SHR
SUPPLEMENTAL HEAT RELAY
A97413
HEATING
3. Restart unit in heating mode, allowing frost to accumulate on
outdoor coil.
On a call for heating, thermostat makes circuits R-Y and R-G.
Circuit R-Y energizes contactor, starting outdoor-fan motor and
compressor. Circuit R-G energizes indoor-blower relay, starting
blower motor on high speed.
4. After a few minutes in heating mode, liquid-line temperature
should drop below closing point of defrost thermostat (ap-
proximately 30°F).
Should temperature continue to fall, R-W2 is made through
second-stage room-thermostat bulb. Circuit R-W2 energizes a
relay, bringing on first bank of supplemental electric heat and
providing electrical potential to second heater relay (if used). If
5. Short between speed-up terminals with a flat-blade screw-
driver. (See Fig. 10.) This reduces the timing sequence to
1/256th of original time. (See Table 3.)
6
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EXAMPLE:
To calculate additional charge required for a 25–ft line set:
25 ft – 15 ft = 10 ft X 0.6 oz/ft = 6 oz of additional charge
OF2
OF1
Units installed with cooling mode TXV require charging with the
subcooling method.
1. Operate unit a minimum of 10 minutes before checking
charge.
2. Measure liquid service-valve pressure by attaching an accurate
gage to service port.
3. Measure liquid-line temperature by attaching an accurate
thermistor type or electronic thermometer to liquid line near
outdoor coil.
O
R
T2
Y
TI DFT
C
TEST 30 50 90
W1
4. Refer to unit rating plate for required subcooling temperature.
5. Refer to Table 4. Find the point where required subcooling
temperature intersects measured liquid service-valve pressure.
O
R
6. To obtain required subcooling temperature at a specific
liquid-line pressure, add refrigerant if liquid-line temperature
is higher than indicated or reclaim refrigerant if temperature is
lower. Allow a tolerance of ± 3°F.
W2
Y
C
CES0110063,
CES0130024
Table 4—Required Liquid-Line Temperature (°F)
A91444
LIQUID
PRESSURE AT
SERVICE VALVE
(PSIG)
REQUIRED SUBCOOLING
TEMPERATURE (°F)
Table 3—Defrost Control Speedup-
Timing Sequence
5
10
15
20
MINIMUM
(MINUTES)
MAXIMUM
(MINUTES)
SPEEDUP
(NOMINAL)
PARAMETER
134
141
148
156
163
171
179
187
196
205
214
223
233
243
253
264
274
285
297
309
321
331
346
359
71
74
66
69
61
64
56
59
30–minute cycle
50–minute cycle
90–minute cycle
10–minute cycle
5 minutes
27
45
81
9
33
55
99
11
5.5
7 sec
77
72
67
62
12 sec
21 sec
2 sec
80
75
70
65
83
78
73
68
86
81
76
71
4.5
1 sec
89
84
79
74
Fig. 10—Defrost Control
92
87
82
77
95
90
85
80
6. When you hear reversing valve change position, remove
screwdriver immediately; otherwise, control will terminate
normal 10-minute defrost cycle in approximately 2 sec.
98
93
88
83
101
104
107
110
113
116
119
122
125
128
131
134
137
140
96
91
86
99
94
89
102
105
108
111
114
117
120
123
126
129
132
135
97
92
NOTE: Length of defrost cycle is dependent upon length of time
it takes to remove screwdriver from test pins after reversing valve
has shifted.
100
103
106
109
112
115
118
121
124
127
130
95
98
101
104
107
110
113
116
119
122
125
7. Unit will remain in defrost for remainder of defrost-cycle time
or until defrost thermostat reopens at approximately 80°F coil
temperature of liquid line.
8. Turn off power to outdoor unit and reconnect fan motor lead
to OF2 on control board. (See Fig. 10.)
Step 14—Check Charge
Factory charge is shown on unit rating plate. To check charge in
cooling mode, refer to Cooling Only Procedure. To check charge
in heating mode, refer to Heating Check Chart Procedure.
HEATING CHECK CHART PROCEDURE
To check system operation during heating cycle, refer to the
Heating Check Chart on outdoor unit. This chart indicates whether
a correct relationship exists between system operating pressure and
air temperature entering indoor and outdoor units. If pressure and
temperature do not match on chart, system refrigerant charge may
not be correct. Do not use chart to adjust refrigerant charge.
COOLING-ONLY PROCEDURE
NOTE: If superheat- or subcooling-charging conditions are not
favorable, charge must be weighed in accordance with unit rating
plate ± 0.6 oz/ft of 3/8-in. liquid line above or below 15 ft
respectively.
7
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NOTE: When charging is necessary during heating season,
charge must be weighed in accordance with unit rating plate ± 0.6
oz/ft of 3/8-in. liquid line above or below 15 ft respectively.
3. Leave User’s Manual with owner. Explain system operation
and periodic maintenance requirements outlined in manual.
4. Fill out Dealer Installation Checklist and place in customer
file.
EXAMPLE:
To calculate additional charge required for a 25–ft line set:
25 ft – 15 ft = 10 ft X 0.6 oz/ft = 6 oz of additional charge
Step 15—Final Checks
CARE AND MAINTENANCE
For continuing high performance and to minimize possible equip-
ment failure, periodic maintenance must be performed on this
equipment.
IMPORTANT: Before leaving job, be sure to do the following:
1. Securely fasten all panels and covers.
Frequency of maintenance may vary depending upon geographic
areas, such as coastal applications.
2. Tighten service valve-stem caps to 1/12-turn past finger-tight.
Copyright 2002 CARRIER Corp. • 7310 W. Morris St. • Indianapolis, IN 46231
38byc3si
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book
Tab 5a 5a
1
4
PC 101
Catalog No. 533-80078
Printed in U.S.A.
Form 38BYC-3SI
Pg 8
11-02
Replaces: 38BYC-2SI
Download from Www.Somanuals.com. All Manuals Search And Download.
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