Carrier 48MA-50ME016-040 User Manual

48MA/50ME016-040

Combination Multizone Heating/Cooling Units

Gas, Electric, or Glycol Heat

Installation, Start-Up

and Service Instructions

CONTENTS

Page

SAFETY CONSIDERATIONS ...................2

INSTALLATION .............................2-34

General ......................................2

Unit Clearances ..............................2

Roof Curb ...................................2

Roof Openings ...............................2

Rigging Unit .................................5

Unit Positioning ..............................5

Removing Shipping Shields ..................5

Field-Fabricated Ductwork ....................5

Condensate Drains ...........................9

Gas Piping (48MA) ...........................9

Optional Glycol Connections (50ME) .........10

Field Power Supply Wiring ..................10

• UNIT COMMON FEED MINIMUM CIRCUIT AMPS

Field Control Wiring .........................14

• ZONE THERMOSTATS

• ZONE MODULE CONNECTIONS

• ACCESSORY REMOTE CONTROL PANEL

Reheat Humidity Control ....................34

Optional Economizer ........................34

Optional Exhaust Damper ...................34

START-UP ................................34-39

Evaporator Fan .............................34

Compressor Rail Shipping Bolts .............34

Refrigerant Valves ..........................34

Zone Module Gas Valves (48MA) .............34

Gas Heat Lighting Procedure (48MA) .........35

• TO SHUT OFF GAS HEAT

Intermittant Pilots (48MA) ...................35

• ADJUSTMENT

• PRESSURE ADJUSTMENT (NATURAL GAS)

Main Burner Adjustment (48MA) .............36

• ORIFICE ALIGNMENT

• PRIMARY AIR ADJUSTMENT

Outdoor-Air Thermostat Adjustment

(50ME With Electric Heat) ..................36

• UNITS WITH 2-ELEMENT HEATERS

• UNITS WITH 3-ELEMENT HEATERS

Optional Glycol Heating Coils ................38

Zone Airflow Adjustment ....................38

Sequence of Operation .....................38

• COOLING

• HEATING (48MA)

• HEATING (50ME WITH ELECTRIC HEAT)

• HEATING (50ME WITH GLYCOL HEATING COILS)

• OUTDOOR-AIR DAMPER

SERVICE ..................................39-43

Cabinet Panels and Grilles ..................39

• SIDE PANELS

• TOP PANELS

• HEATER ACCESS PANELS

Cleaning ....................................39

• EVAPORATOR COILS (ZONE COOLING COILS)
AND GLYCOL HEATING COILS

• CONDENSER AND OUTDOOR-AIR COOLING
COILS

• CONDENSATE DRAINS

• INDOOR-AIR FILTERS

• OUTDOOR-AIR INLET SCREENS

• GAS HEATING SECTION

• COMBUSTION AIR FAN

Airflow Switches ............................39

• INDOOR AIRFLOW SWITCH (AFS1)

• COMBUSTION AIRFLOW SWITCH (AFS2)

Service Switch ..............................39

Time GuardT Control Circuit .................39

Capacity Control Pressure Switches (CCP)

(2-Compressor Units Only) ................39

Compressor Oil .............................39

• TO ADD OR REMOVE OIL

Compressor Capacity Control Unloader(s) ....40

• CONTROL SET POINT

• PRESSURE DIFFERENTIAL

Crankcase Heater(s) .........................40

Refrigerant Charge ..........................40

• NO CHARGE

• LOW CHARGE

Head Pressure Control ......................40

• MOTORMASTERt HEAD PRESSURE CONTROL

DEVICE

• FAN CYCLING PRESSURESTAT

Condenser Fans ............................41

• ADJUSTMENT

• FAN MOTOR REMOVAL

• LUBRICATION

Evaporator Fans and Motor ..................41

• MOTOR REMOVAL

• FAN SHAFT BEARING REMOVAL

• FAN SPEED ADJUSTMENT

• PULLEY REMOVAL

• PULLEY ALIGNMENT

• BELT TENSION ADJUSTMENT

• LUBRICATION

Forced-Draft Blower (48MA) .................42

• LUBRICATION

• AIR SHUTTER ADJUSTMENT

Zone Module Transformers ..................42

Optional Economizer ........................42

• THERMOSTAT SETTINGS

• DAMPER POSITION

• OPERATION

Optional Exhaust Damper ...................42

Replacement Parts ..........................42

START-UP CHECKLIST .....................CL-1

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.

Book 1 1
Tab 1c 1d

PC 111 Catalog No. 564-840 Printed in U.S.A. Form 48MA/50ME-3SI Pg 1 4-96 Replaces: 48MA/50ME-1SI

SAFETY CONSIDERATIONS

Installation and servicing of air-conditioning equipment
can be hazardous due to system pressure and electrical com­ponents. Only trained and qualified service personnel should
install, repair, or service air-conditioning equipment.

Untrained personnel can perform basic maintenance func­tions of cleaning coils and filters and replacing filters. All
other operations should be performed by trained service per­sonnel. When working on air-conditioning equipment, ob­serve precautions in the literature, tags and labels attached
to the unit, and other safety precautions that may apply.

Follow all safety codes, including ANSI (American
National Standards Institute) Z223.1. Wear safety glasses and
work gloves. Use quenching cloth for unbrazing operations.
Have fire extinguisher available for all brazing operations.

INSTALLATION

General —

stall unit, electrical wiring, gas supply line (48MA) and con­densate drain lines in accordance with all applicable codes.

Install unit on rooftop, outdoor site only. In-

Unit Clearances — See Fig. 1 and 2 for service and

airflow clearances. For 48MA gas-fired units, provide not
less than 36-in. clearance to combustibles from top and all
sides. Keep burner end free from any obstruction.

Locate exit terminals of mechanical draft system (48MA

flue outlet) as follows:

• Not less than 12 in. from any opening through which com­bustion products could enter the building.

• Not less than 2 ft from any adjacent building.

• Not less than 7 ft above grade when unit is adjacent to
public walkways.

Before performing service or maintenance operations on
unit, turn offmain power switch to unit. Electrical shock
could cause personal injury.

Do not try to light any appliance. Do not touch any elec­trical switch; do not use any phone in your building.
Immediately call your gas supplier from a neighbor’s
phone. Follow the gas supplier’s instructions. If you can­not reach your gas supplier, call the fire department.

Do not store or use gasoline or other flammable vapors
and liquids in the vicinity of the 48MA unit or any other
gas-fired appliance.

Improper installation, adjustment, alteration, service, or
maintenance can cause injury or property damage. Re­fer to this manual. For assistance or additional infor­mation, consult a qualified installer, service agency, or
the gas supplier.

Disconnect gas piping from 48MA unit when leak test­ing at pressures greater than 0.5 psig. Pressures greater
than 0.5 psig will cause gas valve damage resulting in
a hazardous condition. If gas valve is subjected to pres­sure greater than 0.5 psig, it must be replaced. When
pressure testing field-supplied gas piping at pressures of

0.5 psig or less, the unit connected to such piping must
be isolated by manually closing the gas valve.

RoofCurb — Assemble and install per instructions shipped

with this accessory. Information required to field fabricate a
roof curb and other curb data are shown in Fig. 3-5.

Install field-supplied insulation, cant strips, roofing and
counter flashing as required. Seal all curb joints with mastic
or other suitable roof cement to keep out moisture. Be sure
that run-offpan at compressor end of curb is completely flashed
and sealed.

Seal strip (Fig. 3) is shipped with accessory roof curb. In­stall as described in the roof curb installation instructions.
The seal strip compresses under unit weight so that an air­tight seal and vibration isolation are provided between unit
base and curb.

Roof Openings — Except for the compressor and con-

denser section, roof area under the unit need not be filled in
as the curb-mounted unit encloses this space. Leaving this
roof section open provides ample clearance for ductwork,
piping, and power and control wiring.

If the roof area inside curb is to be filled in so that roof
deck and bottom of base unit can be used as a return-air ple­num, any spaces under the curb flanges caused by corru­gated roofing or roof irregularities must be sealed to prevent
water seepage. If spaces are not sealed, the negative pres­sure of return air may draw water under the unit and into the
building structure.

If openings are cut in a finished roof, provide at least 6-in.
space on each of the longer sides of the supply and return air
openings. Due to interference from the roof curb structure,
this additional clearance may not be possible on the short
sides.

2

CONDENSER SECTION AIRFLOW

CONN — Connection

NOTES:

1. Space required for service and airflow all
around and above unit is 36 inches.

2. For additional information see Fig. 4.

3. Centerof gravity is within 6in. radius of geo­metric center of unit.

4. Maximum allowable pitch of unit is
10 ft in any direction.

1

⁄2in. per

Certified dimension drawings available on request.

UNIT

48MA

016-030 7- 2

AB C DEFGHJKL

3

⁄43-05⁄

8

17-115⁄162-215⁄1613-51⁄20- 91⁄162-10 7-33⁄160-31⁄80-31⁄

034,040 7-11 3-915⁄16* 21- 91⁄164-25⁄

*Overall height; includes 13⁄4-in. for fan guards.

Fig. 1 — Base Unit Physical Data and Dimensions; 48MA Units

DIMENSIONS (ft-in.)

8

13-51⁄20-111⁄163- 45⁄168-63⁄40-31⁄320-215⁄160-71⁄

3

8

0-31⁄

8
4

CONDENSER SECTION AIRFLOW

CONN — Connection

NOTES:

1. Space required for service and airflow all
around and above unit is 36 inches.

2. For additional information see Fig. 5.

3. Centerof gravity is within 6in. radius of geo­metric center of unit.

4. Maximum allowable pitch of unit is
10 ft in any direction.

1

⁄2in. per

Certified dimension drawings available on request.

UNIT

50ME

016-030 7- 2

A B C D EFGHJ

3

⁄

4

3-09⁄

16

17-115⁄

034,040 7-11 3-915⁄16* 21-91⁄

*Overall height; includes 13⁄4-in. for fan guards.

Fig. 2 — Base Unit Physical Data and Dimensions; 50ME Units

DIMENSIONS (ft-in.)

16

2-215⁄

16

13-51⁄

2

3-71⁄

16

7-33⁄

16

0-31⁄

8

0-31⁄

16

4-25⁄

8

13-51⁄

2

4-4 8-63⁄

4

0-215⁄

16

0-71⁄

8
4

4

AIRFLOW

*Factory supplied (with accessory roof curb).
†Field supplied (when using accessory roof curb).

NOTE: Dimensions are in inches.

Fig. 3 — Roof Curb Detail

Rigging Unit — Inspect unit for shipping damage, and

file any damage claim immediately with transportation
company.

Lift unit with cables and spreader bars, using lifting brack­ets provided (Fig. 1 and 2). Lift one unit at a time, keep unit
upright, and do not drop. Unit weights are given in Table 1.
Unit center of gravity is within 6 in. of unit’s geometric cen­ter. Eyebolts may be removed after unit is in final position.

IMPORTANT: Do not drill or punch holes in unit frame
or panels; damage to internal components or wiring
may result.

UnitPositioning — When lowering unit onto roof curb,

do not exceed the out-of-symmetry tolerances given in
Fig. 4 and 5. Be sure unit is level or is pitched within speci­fied tolerances. Units have drains on both sides and may be
pitched to either side.

Removing Shipping Shields (Fig. 6)

1. Remove shield over flue outlet grille (48MA only).

2. Remove shields (sheet metal covers) located in the outdoor-

air inlet screen tracks behind the louvers. If the screens
are removed for this procedure, be sure to replace them
before replacing the louvered assembly.

Field-Fabricated Ductwork — Supply- and return-

air openings are shown in Fig. 4 and 5. To simplify supply­air connection, a zone duct plenum may be field fabricated
as shown in Fig. 7. It is recommended that this plenum be
installed prior to unit positioning.

It is recommended that the unit be supported on blocks
temporarily while the duct plenum is installed, rather than
installing the plenum while the unit is suspended. The duct
plenum may be installed once the unit is located in its final
position, but it is much easier to install the plenum prior to
unit final placement.

Zone supply-air duct openings on the base unit have tab
slot connections similar to those shown in Fig. 7 except that
the end partitions are hemmed. Hem is positioned so that the
1-in. flange at entering end of field-fabricated plenum will
force-fit between hem and adjacent unit frame.

Standard flexible duct connections between duct plenum
and duct system may be used. Follow applicable codes.

Insulate any supply-air ducts passing through uncondi­tioned spaces and cover with a vapor barrier. Separate ducts
with insulation if they run parallel for more than 5 ft. This
will prevent heat transfer between zones.

Install a manual balancing damper in each zone duct to
provide the required zone airflow.

The return-air duct connection consists of 4 sheet metal
flanges as shown in Fig. 1, 2, 4, and 5.

5

Table 1 — Physical Data

UNIT 48MA/50ME 016 024 028 030 034 040

Zone Modules (Quantity) 8 8 10 10 12 12
Nominal Cooling Capacity (tons) 15 20 25 28 30 37

OPERATING WEIGHT (lb)

Base Unit 48MA 3395 3815 4075 4080 5340 5710
Base Unit 50ME (with electric heat) 2995 3415 3675 3680 4900 5270

Roof Curb 506 506 506 506 630 630
REFRIGERANT CHARGE — R-22 (lb) 28 32 43 43 57 66.1
COMPRESSOR Reciprocating Hermetic, 1725 Rpm

No. 1 Type 06DE537 06DE824 06DE537 06DE537 06DE537 06EE250

Cylinders...Unloaders 6...2 6...2 6...2 6...2 6...2 4...1

No. 2 Type — 06DA824 06DA824 06DA537 06DA537 06EA250

Cylinders (have no unloaders) —66664

System Oil Charge (pints) 11 18 18 18 18 31

Unloader Settings (psig) Compressor No. 1 Only

Unloader No. 2

Unloader No. 1

Capacity Steps (%) 100,67,33
CONDENSER FANS Propeller, Direct Drive

Motor Hp...Rpm...Frame (NEMA)

Nominal Cfm 16,500 15,000 15,000 15,000 24,000 23,000
EVAPORATOR FANS* Centrifugal, Belt Drive

Number...Size (in.) 2...15 × 15 2...15 × 15 2...15 × 15 2...15 × 15 3...15 × 9 3...15 × 9

Cfm (Nominal) 6000 8000 10,000 10,000 12,000 12,000

Motor Hp...Rpm

Fan Pulley

Outside Diameter (in.) 10.6 10.6 8.0 8.0 8.0 8.0
Bore (in.) 1

Fan Belt Number...Size

Motor Pulley Factory Installed

Outside Diameter (in.)
Bore (in.) 1
Resulting Fan Rpm
Shaft Center Line Distance (in.) 18 ± 2.5 18 ± 2.5 18 ± 2.5 18 ± 2.5 21 ± 2.5 21 ± 2.5

Maximum Fan Rpm 1300 1300 1300 1300 1550 1550

CONDENSER COOLING COIL Thermostatic Expansion Valve, Hot Gas Bypass

Face Area (sq ft) 6.8 6.8 6.8 6.8 10.2 10.2

Corrugated Fins/in. ...Rows 13...2 13...2 13...2 13...2 13...2 13...3

EVAPORATOR COILS (zone) Solenoid Valve and Capillary Tube for each

Number...Face Area (sq ft/ea) 8...2.12 8...2.12 10...2.12 10...2.12 12...2.01 12...2.01

Corrugated Fins/in. ...Rows 13...3 13...3 13...3 13...3 12...3 15...3

HEATING SECTION (48MA) One Heat Assembly in Each Zone Module

Rise Range 25 F to 55 F at 0.75 in. wg ESP

Input (1000 Btuh)

Bonnet Cap.† (1000 Btuh)

Burner Spud Qty...Size 2...38 2...38 2...38 2...38 2...38 2...38
OPTIONAL HEATING SECTION (50ME Electric)

Electric Heaters Nichrome, Open-Wire Resistance Element in Each Zone Module

Qty...Elements (each)** 8...2 or 3 8...2 or 3 10...2 or 3 10...2 or 3 12...2 or 3 12...2 or 3
OPTIONAL HEATING SECTION

(50ME Glycol Coil)

Maximum Allowable Inlet Temperature (F) 200

Maximum Allowable Flow, Each Coil (Gpm) 6

Solution Mixture 20% Glycol

Maximum Allowable Working Pressure (Psig) 30

Total Internal Volume (Gal) 2.61 2.61 3.15 3.15 3.76 3.76
PRESSURE SWITCHES

Low-Pressure (Psig)

High-Pressure (Psig)

Indoor Airflow Switch (AFS1)

Factory Setting (cfm) 6000 9000
Adjustment Range (cfm) 4000-6000 6000-9000

INDOOR AIR FILTERS

Standard Qty...Size (in.) 12...20 × 25 × 2

High Efficiency (optional)

Qty...Size (in.)

OUTDOOR AIR FILTERS

Qty...Size (in.) 2...20 × 25 × 1 2...32 × 35 × 1

LEGEND

ESP — External Static Pressure
NEMA — National Electrical Manufacturers Association

*Standard unit shipped with standard motor, pulley, and belt(s); alternate unit shipped with alternate motor, pulley, and belt(s).

†The heating efficiency rating is a product thermal efficiency rating determined under continuous operating conditions independent of any installed system.

**See Field Power Supply Wiring section on page 10 and Table 4 for details.

Loads 71.0 ± 1.5 —
Unloads 57.5 ± 2.5 —
Loads 75.0 ± 1.5 75.5 ± 1.5
Unloads 62.5 ± 2.5 58.0 ± 2.5

No. 1 1...1075...56 (Single phase)
No. 2 1...1140...56 (3 phase)
No. 3 ————1...1140...56 (3 phase)

Std 5...1725 7
Alt ————20...1725 20...1725

3

⁄

Std 1...3V630 1...3V630 2...3V560 2...3V560 2...3V630 2...3V630
Alt ————3...3V670 3...3V670

Std 5.3 6.0 5.0 5.0 5.0 5.0
Alt ————6.06.0

Std 880 995 1095 1095 1095 1095
Alt ————1320 1320

Total 432 432 540 540 648 648
Each Module 54 54 54 54 54 54
Total 324 324 405 405 486 486
Each Module 40.5 40.5 40.5 40.5 40.5 40.5

16

1

⁄

8

100,83,67

50,33,17

1

⁄2...1725 10...1725 10...1725 15...1725 15...1725

13⁄

16

13⁄

8

100,80,60

40,20

13⁄

16

13⁄

8

100,80,60

40,20

13⁄

16

13⁄

8

100,83,67

50,33,17

111⁄

16

15⁄

8

One Heating Coil in Each Zone Module

Cutout 29±5
Cut-in 39±5
Cutout 400±5
Cut-in 300±5

12...20 × 25 × 2 (36.5% Efficient)

100,75,

50,25

111⁄

16

15⁄

8

6

EVAPORATOR (ZONE MODULE) AIRFLOW

CONN — Connection
*Not used on 48MA016,024 (8 zone module units).

NOTES:

1. For additional information, see Table 1 and Fig. 1.

2. Maximum allowable unit pitch is

3. Remove shipping brace before assembling curb section (location
shown).

1

⁄2in. per 10 ft in any direction.

UNIT

48MA

ABCDE F GHJ

016-030 18-2
034,040 21-97⁄

Fig. 4 — Roof Curb Physical Data and Dimensions; 48MA Units

1

⁄

8

7- 3 11-9 5-61⁄

8

7-113⁄

4

14-13⁄

DIMENSIONS (ft-in.)

4

7-27⁄

8

1-109⁄

16

2-29⁄

16

6-03⁄

8

0- 71⁄

4

6-77⁄

16

8-43⁄

16

2- 91⁄

8

3-1 6-81⁄

2

0-105⁄

2
16

7

(034,044 12-ZONE MODULES)

END DETAIL

EVAPORATOR (ZONE MODULE) AIRFLOW

CONN — Connection
*Not used on 50ME016,024 (8 zone module units).

NOTES:

1. For additional information, see Table 1 and Fig. 2.

2. Maximum allowable unit pitch is

3. Remove shipping brace before assembling curb section (location
shown).

1

⁄2in. per 10 ft in any direction.

UNIT

50ME

ABCDE F GHJ

016-030 18-2
034,040 21-97⁄

Fig. 5 — Roof Curb Physical Data and Dimensions; 50ME Units

1

⁄

8

7- 3 11-9 5-61⁄

8

7-113⁄

4

14-13⁄

DIMENSIONS (ft-in.)

4

7-27⁄

8

1-109⁄

16

2-29⁄

16

6-03⁄

8

0- 71⁄

4

6-77⁄

16

8-43⁄

16

2- 91⁄

8

3-1 6-81⁄

2

0-105⁄

2
16

8

CondensateDrains — Pipe nipples covered with foam

rubber insulation are shipped in unit return air filter section
(6 nipples in units 48MA, 4 nipples in units 50ME). Install
a nipple in each drain connection on both sides of unit. See
Fig. 1 and 2 for drain locations. Be sure foam rubber seals
space between nipple and base rail opening to prevent rain
leaks.

Connect a drain line to drain connection under outdoor air
inlet grilles on both sides of unit. These drains need not be
trapped.

Install a trapped drain line on remaining connections on
lowest side of unit depending on unit pitch. If unit is level,
a trapped drain may be installed at each connection if de­sired. Cap or plug unused connections on high side of unit
to prevent airflow between unit interior and outdoors.

OUTDOOR AIR INLET
(ONE ON EACH SIDE OF UNIT)
SHIPPING SHIELD
(BEHIND LOUVERS)

FLUE OUTLET
COVER
(48MA ONLY)

Do not interconnect drains. Make each trap a minimum of
4 in. deep. Insulate trap against freeze-up or use flexible
material.

Gas Piping (48MA) — Unit is equipped for use with

type of gas shown on nameplate. Refer to latest edition of
ANSI Z223.1. Unit main gas connection and alternate gas
connection locations are shown in Fig. 1, 4, and 8. Do not
use gas supply pipe smaller than unit gas connection. Maxi­mum allowable natural gas supply pressure is 10.0 in. wg;
minimum allowable natural gas supply pressure for full rate
input is 5.0 in. wg.

1

Pitch pipe
upward to risers and from risers upward to meter. Install a
dirt and moisture pocket (drip leg) at each section of vertical
pipe run. Use only ground joint unions to ensure leakfree
joints. Use only pipe joint compounds that are resistant to
the action of liquefied petroleum gases.

⁄4in. per 15 ft. Pitch all horizontal pipe runs

Fig. 6 — Shipping Shield Locations

(016-030 Units Shown)

NOTE: Dimension to suit job requirements. Twelve inches will bring
duct plenum to bottom of roof curb.

Fig. 7 — Field-Fabricated Zone Duct Plenum Detail

*Typical; both ends.

9

UNIT

48MA,50ME

A* 7
B* 75⁄

DIMENSIONS (in.)

016,024 028,030 034,040

5

⁄

8
8

75⁄

8

73⁄

4

75⁄

53⁄

16

4

*Shutoff valve not used except where required by code.

All units have a main power supply terminal board in the
power and condensing control box. The electric resistance
heater power supply terminal board(s) (if unit is so equipped)
on 50ME units is located in the heater control box at front
of unit. See Fig. 2, 5, and 9.

All terminal boards are suitable for use with copper or
aluminum wire.

Connect electrical conduit (a threaded pipe nipple) shipped
with unit to threaded fitting in roof curb and bottom of main
power and condensing section control box. Route main power
wires through conduit to terminal board in box as shown on
unit label wiring diagram and in Fig. 9.

When installing 48MA,50ME040 units with optional 20-hp
motor,the electrical conduit interconnecting the curb and con­trol box power wire openings will not accommodate alumi­num wire of the size that may be required. If aluminum wire
cannot be accommodated, an external transition box and short
lengths of no. 300 kcmil, 75 C copper wire from the tran­sition box to the unit main power connection are
recommended.

Voltage to compressor terminals during compressor op­eration must be within voltage range indicated on unit name­plate. Phases must be balanced within 2%.

Properly cap any gas connection not being used.

Fig. 8 — Suggested Gas Piping (48MA)

Unit has factory-installed gas shutoff valves. Install gas
shutoff valve external to unit if required by code (Fig. 8).
After piping is complete, pressurize gas line and check for
leaks with soap and water solution.

Do not use an open flame when checking for gas leaks.

OptionalGlycol Connections (50ME) — Each zone

module has its own glycol heating coil and 115-v solenoid
valve. Heating coils are connected in parallel to common sup­ply and return manifolds. Supply manifolds are equipped with
bleed cocks. Supply and return connections are shown in
Fig. 2 and 5. Unit does not have internal pressure relief for

part-load operation. Maximum allowable system working pres­sure is 30 psig. Unit ratings are based on 20% glycol solu-

tions. Install solution supply apparatus in accordance with
application requirements, and mix glycol solution percent­age in accordance with glycol manufacturer’s recommenda­tions. Freeze-up protection is not factory installed.

Field Power Supply Wiring — When installed, unit

must be electrically grounded in accordance with local codes
or,in the absence of local codes, with the National Electrical
Code (NEC).

Unit has a circuit breaker for each compressor, each fan
motor, and for each 50ME electric resistance heater assem­bly (if unit is so equipped). If required by local code, pro­vide an additional disconnect switch in accordance with code
being followed.

LEGEND

EQUIP — Equipment
GND — Ground
TB — Terminal Board

*208/230 v units only.

Fig. 9 — Field Power Supply Details

10

Use the following formula to determine the percent volt-

age imbalance.
% Voltage Imbalance:

= 100 ×

max voltage deviation from average voltage

average voltage

EXAMPLE: Supply voltage is 460-3-60.

AB = 452 v
BC = 464 v
AC = 455 v

Average Voltage =

452 + 464 + 455

3

1371

=

3

= 457

Determine maximum deviation from average voltage.
(AB) 457 − 452=5v

(BC) 464 − 457=7v
(AC) 457 − 455=2v

Maximum deviation is 7 v.
Determine percent voltage imbalance:

% Voltage Imbalance = 100 x

7

457

= 1.53%

This amount of phase imbalance is satisfactory as it is below
the maximum allowable 2%.

IMPORTANT: If the supply voltage phase imbalance
is more than 2%, contact your local electric utility com­pany immediately.

Unit failure as a result of operation on improper line volt­age or excessive phase imbalance constitutes abuse and may
cause damage to electrical components. See Tables 2-5 for
unit, electric heater, and 50ME electrical application elec­trical data.

Each 50ME electric heat unit is fitted with a heating lock­out circuit (if equipped with optional heat). If any zone mod­ule is operating on mechanical cooling (compressor is op­erating), the heating element in each zone module is locked
out and cannot be energized.

On 50ME units, cooling power supply wires and electric
heater power supply wires (if applicable) must be sized ac­cording to the cooling MCA (Minimum Circuit Amps) val­ues and heating MCA values shown on unit nameplate and
in Tables 3-5. These wires may be powered by a common
power supply (i.e., a pull-box junction), if desired. The com­mon power supply wires from the main power source to the
junction must be sized according to the common MCA val­ues shown in Table 5.

UNIT COMMON FEED MINIMUM CIRCUIT AMPS —
The unit common feed MCA is calculated on the basis of
either: the sum of the cooling MCA plus

1

⁄2heating MCA on
units with 2 heating elements per zone module (or2⁄3heat­ing MCA on units with 3 heating elements per zone module)
or the sum of the evaporator fan motor full load amps, per
NEC, plus the full heating MCA, whichever is larger. Field
wiring must conform to NEC limitations for Type T wire.

UNIT

48MA

016

024

028

030

034

040

COMP — Compressor
FLA — Full Load Amps
IFM — Indoor (Evaporator) Fan Motor
LRA — Locked Rotor Amps
MCA — Minimum Circuit Amps

Voltage

(3 Ph, 60 Hz)

208/230 187 254 63.6 266

460 414 508 28.6 120 3.0 6.6 49.8 60
575 518 632 22.8 96 2.4 5.6 39.8 45

208/230 187 254 44.4 170 44.4 170

460 414 508 19.9 77 19.9 77 3.0 11.0 62.2 70
575 518 632 15.7 62 15.7 62 2.4 9.0 49.4 60

208/230 187 254 63.6 266 44.4 170

460 414 508 28.6 120 19.9 77 3.0 13.0 76.1 90
575 518 632 22.8 96 15.7 62 2.4 10.5 60.4 70

208/230 187 254 63.6 266 63.6 266

460 414 508 28.6 120 28.6 120 3.0 13.0 84.5 100
575 518 632 22.8 96 22.8 96 2.4 10.5 67.5 90

208/230 187 254 63.6 266 63.6 266

460 414 508 28.6 120 28.6 120 3.0 3.0

575 518 632 22.8 96 22.8 96 2.4 2.4

208/230 187 254 80.0 345 80.0 345

460 414 508 38.5 150 38.5 150 3.0 3.0

575 518 632 31.4 120 31.4 120 2.4 2.4

LEGEND

VOLTAGE

RANGE

Min Max RLA LRA RLA LRA No. 1 No. 2 No. 3 FLA Hp FLA MCA MOCP

Table 2 — Unit 48MA Electrical Data

COMP

NO. 1

COMP

NO. 2

— — 6.2

6.2

6.2

6.2

6.2

6.2

OFM

FLA

6.6

6.6

6.6

6.6

6.6 6.6

6.6 6.6

MOCP — Maximum Overcurrent Protection
OFM — Outdoor (Condenser) Fan Motor
RLA — Rated Load Amps

NOTES:

1. Combustion air fan is a 115-1-60 motor on all units.

2. Condenser fan motor no. 1 is a 208/230-1-60 speed control motor

on all units.

COMBUSTION

FAN MOTOR

— 1.8 5

— 1.8 7.5

— 1.8 10

— 1.8 10

15 46.2 210.8 225
20 61.0 224.6 250

1.8

1.8

15 21.0 94.5 100
20 26.6 100.5 125
15 16.0 75.6 90
20 21.3 80.6 100
15 46.2 247.7 300
20 61.0 261.5 300
15 21.0 116.7 150
20 27.0 122.7 150
15 16.0 95 125
20 21.3 100 125

IFM

16.2 109.6 125

24.2 137.5 150

30.8 168.1 200

30.8 187.3 200

POWER
SUPPLY

11

Table 3 — Unit 50ME Electrical Data

UNIT

50ME

016

024

028

030

034

040

COMP — Compressor
FLA — Full Load Amps
IFM — Indoor (Evaporator) Fan Motor
LRA — Locked Rotor Amps
MCA — Minimum Circuit Amps
MOCP — Maximum Overcurrent Protection
OFM — Outdoor (Condenser) Fan Motor
RLA — Rated Load Amps

VOLTAGE

(3 Ph, 60 Hz)

208/230 187 254 63.6 266

460 414 508 28.6 120 3.0 6.6 49.5 60
575 518 632 22.8 96 2.4 5.6 39.6 45

208/230 187 254 44.4 170 44.4 170

460 414 508 19.9 77 19.9 77 3.0 11.0 61.9 70
575 518 632 15.7 62 15.7 62 2.4 9.0 49.2 60

208/230 187 254 63.6 266 44.4 170

460 414 508 28.6 120 19.9 77 3.0 13.0 75.8 90
575 518 632 22.8 96 15.7 62 2.4 10.5 60.2 70

208/230 187 254 63.6 266 63.6 266

460 414 508 28.6 120 28.6 120 3.0 13.0 84.5 100
575 518 632 22.8 96 22.8 96 2.4 10.5 67.3 90

208/230 187 254 63.6 266 63.6 266

460 414 508 28.6 120 28.6 120 3.0 3.0

575 518 632 22.8 96 22.8 96 2.4 2.4

208/230 187 254 80.0 345 80.0 345

460 414 508 39.3 150 39.3 150 3.0 3.0

575 518 632 31.4 120 31.4 120 2.4 2.4

LEGEND

VOLTAGE

RANGE

Min Max RLA LRA RLA LRA No. 1 No. 2 No. 3 Hp FLA MCA MOCP

COMP

NO. 1

COMP

NO. 2

— — 6.2

6.2

6.2

6.2

6.2

6.2

NOTE: Condenser fan motor no. 1 is a 208/230-1-60 speed control
motor on all units.

OFM

FLA

6.6

6.6

6.6

6.6

6.6 6.6

6.6 6.6

IFM

16.2 109.6 125

—5

24.2 138.0 150

— 7.5

30.8 168.9 200

—10

30.8 188.0 200

—10

15 46.0 210.8 225
20 61.0 224.6 250
15 19.8 94.5 100
20 26.6 100.5 125
15 16.0 75.6 90
20 21.3 80.6 100
15 46.2 247.7 300
20 61.0 261.5 300
15 19.8 118.5 150
20 26.6 124.5 150
15 16.0 95 125
20 21.3 100 125

POWER
SUPPLY

UNIT

50ME

016,024

028,030

034,040

FLA — Full Load Amps
MCA — Minimum Circuit Amps
MOCP — Maximum Overcurrent Protection

NOMINAL
VOLTAGE

(3 Ph, 60 Hz)

208/230

460
575 106 3 7.7 133 150

208/230

460
575 132 3 7.7 166 175

208/230

460
575 158 3 7.7 199 200

LEGEND

ELECTRIC

HEAT kW

(Unit Total)

43/ 53
57/ 70
87/106

53
70

106

54/ 66
72/ 88

108/132

66
88

132

65/ 79
87/106

129/158

79
106
158

Table 4 — Electric Resistance Heater Data

HEATING ELEMENTS

PER ZONE MODULE

2
2
3

2
2
3

2
2
3

2
2
3

2
2
3

2
2
3

NOTES:

1. Heaters are rated at 230 v, 460 v, and 575 v.

2. Terminal boards provided for heater power wire connections are

FLA PER

HEATING ELEMENT

13.0/14.4

17.3/19.2

17.3/19.2

7.2

9.6

9.6

13.0/14.4

17.3/19.2

17.3/19.2

7.2

9.6

9.6

13.0/14.4

17.3/19.2

17.3/19.2

7.2

9.6

9.6

suitable for use with copper or aluminum wire.

MCA

(Each Circuit)

150/166
200/221
150/166

83
111
166

188/207
250/276
188/207

103
138
207

225/249
150/165
225/249

124
166
249

MOCP

(Each Circuit)

175/175
225/225
175/175

90
125
175

200/225
275/300
200/225

110
150
225

250/250
175/175
250/250

125
175
250

12

Table 5 — Unit 50ME Electrical Application Data

UNIT

50ME

Size

016 5

024 7.5

028 10

030 10

034

040

IFM — Indoor (Evaporator) Fan Motor
MCA — Minimum Circuit Amps

IFM

Hp

15

20

15

20

LEGEND

NOMINAL
VOLTAGE

208/230

460
575 106 39.6 132.5 — 138.1

208/230

460
575 106 49.2 132.5 — 141.5

208/230

460
575 132 60.2 165.6 — 176.1

208/230

460
575 132 67.3 165.6 — 177.7

208/230

460
575 158 75.6 198.8 — 214.8

208/230

460
575 158 80.6 198.8 — 220.1

208/230

460
575 158 95.0 198.8 — 227.5

208/230

460
575 158 100.0 198.8 — 232.5

kW

(Unit

Total)

43/ 53
57/ 70
87/106

53
70

106

43/ 53
57/ 70
87/106

53
70

106

54/ 66
72/ 88

108/132

66
88

132

54/ 66
72/ 88

108/132

66
88

132

65/ 79
87/106

129/158

79
106
158

65/ 79
87/106

129/158

79
106
158

65/ 79
87/106

129/158

79
106
158

65/ 79
87/106

129/158

79
106
158

Cooling

109.8/109.8

49.5

138.0/138.0

61.9

168.9

75.8

188.0

84.5

210.8

94.5

224.6

100.5

247.7

116.7

261.5

122.7

MCA

Heating

Circuit

12

150.0/165.6

200.0/220.9

150.0/165.8

82.9

110.5

165.8

150.0/160.6

200.0/220.9

150.0/165.8

82.9

110.5

165.8

188.0/207.1

250.0/276.1

188.0/207.1

102.8

138.0

207.1

188.0/207.1

250.0/276.1

188.0/207.1

102.8

138.0

207.1

225.0/248.5

150.0/165.6

225.0/248.5

124.3

165.1

248.5

225.0/248.5

150.0/165.1

225.0/248.5

124.3

165.6

248.5

225.0/248.5

150.0/165.1

225.0/248.5

124.3

165.6

248.5

225.0/248.5

150.0/165.1

225.0/248.5

124.3

165.6

248.5

—
—

150.0/165.8
—

—
—

150.0/165.8
—

—
—

188.0/207.1
—

—
—

188.0/207.1
—

—

150.0/165.1

225.0/248.5
—

—

150.0/165.1

225.0/248.5
—

—

150.0/165.1

225.0/248.5
—

—

150.0/165.1

225.0/248.5
—

Unit

Common

Feed

184.8/192.6

216.7/237.6

316.7/348.3

90.9

117.1

172.4

213.0/220.8

238.0/248.5

342.2/359.0

103.4

121.5

176.8

262.9/272.5

293.9/307.0

419.6/445.0

127.2

151.0

220.1

282.0/291.6

313.0/326.0

438.7/464.0

135.9

153.5

222.6

323.3/335.1

360.8/376.4

510.9/543.2

156.7

185.4

268.3

337.1/348.9

374.6/391.2

524.6/558.0

162.7

192.2

275.1

360.2/372.0

397.7/412.8

547.7/579.0

178.9

199.5

282.4

374.0/385.8

411.5/426.6

561.5/592.8

148.9

205.5

288.4

13

Field Control Wiring

ZONE THERMOSTATS — Install a Carrier approved ac­cessory zone thermostat assembly in each zone according to
installation instructions included in the accessory.Locate each
thermostat assembly in the space where it will sense average
zone temperature.

Route thermostat cable or equivalent single leads of no.
18 AWG (American Wire Gage) colored wire from thermo­stat subbase terminals through opening on base unit
(Fig. 1, 2, 4, and 5) to low-voltage thermostat connections
on zone control board (Fig. 10). Use no. 16 AWG wire for
lengths exceeding 50 ft.

ZONE MODULE CONNECTIONS — Any module may be
controlled independently or jointly with another module or
modules. Modules are combined into nests that form indi­vidual Class II circuits (40 va) as follows:

Modules no. 1 and 2, 3 and 4, 5 and 6, 7 and 8, 9 and 10
(028-040 units), 11 and 12 (034,040 units).

The control signal can be transferred from one nest
to another nest by using factory-supplied jumpers on

quick-connect type multiplexing terminals. This prevents over­loading the nest control transformers. Factory-supplied jump­ers with quick-connect terminals are shipped in the zone con­trol and thermostat panel compartment.

Under no circumstances shall the transformer power from

one Class II circuit be interconnected with any other circuit.

Thermostat heat anticipator settings are indicated for each
permitted zone module connection arrangement illustrated
in Fig. 11-28.

To Join Modules of the Same Nest Into the Same Zone (i.e.,
modules no. 1 and 2) — Install field-supplied jumpers on
thermostat connections (screw terminals) Y to Y and W2 to
W2 as shown in Fig. 11. Connect thermostat wires to ter­minal connections of first module in zone (for consistency).
Two-stage cooling may be obtained in this example as shown
in Fig. 12 (using a 2-stage thermostat).

To Join Modules Not of the Same Nest Into the Same Zone
(i.e., modules no. 2 and 3) — Install the factory-supplied jump­ers on quick-connect terminals 6 to 1, 7 to 2, and 8 to 3 as
shown in Fig. 13. Note that module no. 1 is independently
controlled by its own thermostat (in Fig. 13).

LEGEND

AFS — Airflow Switch
CR — Control Relay
ECR — Economizer Relay
ECT — Economizer Outdoor-Air Thermostat
GV — Gas Valve (not used on 50ME units)
HC — Heater Contactor
HR — Heater Relay
IFC — Indoor (Evaporator) Fan Contactor
LLS — Liquid Line Solenoid
MC — Master Cooling
MCR — Master Cooling Relay
MH — Master Heating
MHR — Master Heating Relay
MU — Master Unit
MUR — Master Unit Relay
NC — Normally Closed
NO — Normally Open
NS — Night Setback
SW — Switch
TRAN — Transformer

Quick-Connect Type Terminals (for multiplexing)
Screw-Type Terminals

NOTE: Twelve-zone unit shown. Eight-zone units have modules
1-8 only. Ten-zone units have modules 1-10 only.

Fig. 10 — Zone Control Board Component Location

14

Fig. 10 — Zone Control Board Component Location (cont)

15