Carrier Heat Pump 38BYC User Manual

38BYC, 38BYG

12 SEER Split System

Heat Pump

Visit www.carrier.com

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

PC 101

Catalog No. 533-80078

Printed in U.S.A.

Form 38BYC-3SI

Pg 1

11-02

Replaces: 38BYC-2SI

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

⁷⁄₈IN. OD & SMALLER

4 O'CLOCK

following:

•Use a brazing shield.

•Wrap service valves with wet cloth or use a heat-sink

material.

LARGER THAN ⁷⁄₈IN. 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.

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

018

024

3/8

5/8

3/4

7/8

5/8

3/4

5/8

3/4

7/8

3/4

030, 036

042

3/4

7/8

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

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.

Table 2—Accessory Usage

REQUIRED FOR

LOW-AMBIENT

APPLICATIONS

(BELOW 55°F)

REQUIRED FOR

BURIED LINE

APPLICATIONS†

(OVER 3 FT)

LONG-LINE

APPLICATIONS*

(OVER 50 FT)

ACCESSORY

Crankcase Heater

Evaporator Freeze Thermostat

Accumulator

Yes

Compressor Start-Assist

Capacitor and Relay

Yes

MotorMaster® Control,

Yes

Low-Ambient Pressure Switch

See low-ambient

Instructions

Wind Baffle

Unit Risers

Recommended

Liquid-Line Solenoid Valve

See Long-Line

Application

Guideline

Yes

Hard-Shutoff TXV

Ball-Bearing Fan Motor

Yes‡

* 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.

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

24 VAC HOT

24 VAC COM

HEAT STAGE 2

COOL/HEAT

STAGE 1

INDOOR FAN

RVS COOLING

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.)

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.

TI DFT

TEST 30 50 90

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.

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.

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

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

30–minute cycle

50–minute cycle

90–minute cycle

10–minute cycle

5 minutes

5.5

7 sec

12 sec

21 sec

2 sec

4.5

1 sec

Fig. 10—Defrost Control

6. When you hear reversing valve change position, remove

screwdriver immediately; otherwise, control will terminate

normal 10-minute defrost cycle in approximately 2 sec.

101

104

107

110

113

116

119

122

125

128

131

134

137

140

102

105

108

111

114

117

120

123

126

129

132

135

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

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.

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.

38byc3si