Carrier 48NLT User Manual

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Page 1

48NLT, NMT, NET, NHT AND NVT 018-060

HEATING & COOLING

Packaged Heating/Cooling Units

Installation, Start-Up and Service Instructions

CONTENTS

Page

SAFETY CONSIDERATIONS General

Job Data ..................................

RECEIVING AND INSTALLATION Step 1 — Check Equipment

• IDENTIFY MACHINE

• INSPECT SHIPMENT

Step 2 — Provide Unit Support

• ROOF CURB

• SLAB MOUNT

Step 3 — Provide Ciearances .................................4

Step 4 — Rig and Place Unit....................................4

Step 5 — Connect Condensate Drain Step 6 - instali Venting Step 7 - Instail Gas Piping Step 8 — Instail Duct Connections Step 9 - Instail Electrical Connections

• HIGH VOLTAGE CONNECTIONS

• SPECIAL PROCEDURES FOR 208-V

• CONTROL VOLTAGE CONNECTIONS

• HEAT ANTICIPATOR SETTING

• TRANSFORMER CIRCUIT PROTECTION

PRE-START-UP START-UP MAINTENANCE

NOTE TO INSTALLER — Before the installation, READ THESE INSTRUCTIONS CAREFULLY AND COM

PLETELY. Also, make sure the User’s Manual and Re placement Guide are left with the unit after installation.

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OPERATION

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SAFETY CONSIDERATIONS

Installation and servicing of air conditioning equipment can be hazardous due to system pressure and electrical com ponents. Only trained and qualified personnel should in stall, repair or service air conditioning equipment.

Untrained personnel can perform basic maintenance func tions of cleaning coils and 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. Wear safety glasses and work gloves. Use quenching cloth for unbrazing operations. Have fire extinguisher available for all brazing operations.

A WARNING

Improper installation, adjustment, alteration, service, main

tenance or use can cause carbon monoxide poisoning, fire

or an explosion which can result in personal injury or

unit damage. Consult a qualified installer, service agency

or gas supplier for information or assistance. The quali

fied installer or agency must use only factory-authorized

kits or accessories when modifying this product.

. 1 . 1 . 1

1-10

. 1

6 6

7 8

10,11 11-20

20-26

________

Fig. 1 - Model 48NLT, NMT, NET, NHT and NVT

A WARNING

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

General - The 48NLT, NMT, NET, NHT and NVT

units are fully self-contained, combination gas heating/ cooling units designed for outdoor installation. See Fig. 1. The units are shipped in a vertical configuration and may be installed either on a rooftop or converted to horizontal configuration when placed on a ground-level cement slab.

Job Data — Necessary information consists of:

machine location drawings, piping drawings, field wiring diagrams and rigging guide.

RECEIVING AND INSTALLATION

Step 1 — Check Equipment

IDENTIFY MACHINE — The machine model number and serial number are stamped on machine identification plate. Check this information against shipping papers and job data.

INSPECT SHIPMENT — Inspect for shipping damage while machine is still on shipping pallet. If machine appears to be damaged or is torn loose from its anchorage, have it exam ined by transportation inspectors before removal. Forward claim papers directly to transportation company. Manufac turer is not responsible for any damage incurred in transit.

Check all items against shipping list. Immediately notify the nearest Carrier Air Conditioning office if any item is missing.

To prevent loss or damage, leave all parts in original pack ages until installation.

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

Book|1 |4 PC 111 Catalog No 564-920 Printed in U.S,A. Form 48NT-20SI Pg 1 11-91 Replaces: 48NT-19SI

Tab la la

Page 2

RIGHT SIDE VIEW

LEFT SIDE VIEW

Fig. 2 — 48 Dimensional Drawing, Sizes NLT018 — NET042

Page 3

UNIT

48NHT036 48NVT036 48NHT042 48NVT042 48NLT048 48NMT048 48NHT048 48NVT048 48NLT060 48NMT060 48NHT060 48NVT060

ELECTRICAL CHARACTERISTICS

208/230/1/60, 208/230/3/60, 460/3/60 208/230/1/60, 208/230/3/60, 460/3/60 208/230/1/60, 208/230/3/60, 460/3/60 550 208/230/1/60, 208/230/3/60. 460/3/60 208/230/1/60, 208/230/3/60, 460/3/60 208/230/1/60, 208/230/3/60, 460/3/60 208/230/1/60, 208/230/3/60, 460/3/60

208/230/1/60, 208/230/3/60, 460/3/60,

208/230/1/60, 208/230/3/60, 460/3/60 208/230/1/60, 208/230/3/60, 460/3/60 208/230/1/60, 208/230/3/60, 460/3/60 616 280 139/63 208/230/1/60, 208/230/3/60, 460/3/60 616

NOTE. Clearances must be maintained to prevent recirculation of air from condenser-fan discharge.

REQUIRED CLEARANCES TO COMBUSTIBLE MATERIAL - in. (mm) Maximum Extension of Overhang 48(1219.2)

Unit Top ........................... ■ .36(914.4)

Duct Side of Unit . .... 6 Min. (152.4 Min.)

Side Opposite Ducts .30 (762.0)

Bottom of Unit. .... .0

REQUIRED CLEARANCES FOR SERVICING - in. (mm)

Blower Access Panel Side ... . 30 (762.0)

Control Box Access Side . . 30 (762.0)

UNIT WT LB

530 536 243 119/54 148/67

556 574 580 263 130/59 586 265 131/59 161/73 586 604 610

A B

241 117/53 147/67

249 122/55 152/69 252

124/56 153/69

261 128/58

265

131/59

274

136/62 165/75

277

138/63 166/75

280

139/63

CORNER WT LB/KG

158/72 159/72

161/73

168/76 168/76

148/67 118/54 149/68 120/54 153/69 154/70 125/57 159/72

160/73 162/73 162/73 166/75 167/76 169/77 169/77

123/56

129/59 131/59 132/60 132/60 137/62 139/63 140/64

140/64

Fig. 3 — 48 Dimensional Drawing, Sizes NHT036 — NVT060

Page 4

Table 1 — Physical Data

UNIT SIZE 48 NOMINAL CAPACITY (ton) OPERATING WEIGHT (lb) COMPRESSORS

Quantity REFRIGERANT* REFRIGERANT METERING DEVICE CONDENSER COIL

Rows

FIns/in. CONDENSER FAN

Nominal Airflow (Cfm)

Nominal Speed (Rpm)

Quantlty...Dlameter (in.)

Motor Hp (single-phase)

EVAPORATOR COIL

Rows

Fins/ln.

EVAPORATOR FAN

Nominal Cfm Nominal Speed (Rpm) Diameter x Width (in.) Motor Hp (single-phase)

FURNACE SECTION

Burner Orifice No. (Qty...drlll size) Burner Orifice No. (Qty...drlll size)

Pilot Orifice Diameter (in. ...drill size)

Pilot Orifice Diameter (In.)

RETURN-AIR FILTERS (sq ln.)t

Disposable Cleanable

•Operating charge is iisted on unit namepiate tRequired fieid-suppiied fliter areas are based on the iarger of the ARi-rated (Air Conditioning & Refrigeration institute) cooling airflow or the heating

airflow at a velocity of 300 ft/min for disposable type or 450 ft/min for high-capacity type Air filter pressure drop must not exceed 0.08 in wg

••Single-phase units

ttThree-phase units

(three-phase)

Natural Gas Propane Gas Natural Gas Propane Gas

NLT018 NLT024

IV2

450

1 20 20

600 800

2 44

2. 55 2 55

288 192

NHT024

454

10 X 8

2 44 3 44 2. 44 3 44

NLT030

460 470 476

2000

825

V10

'/3

3 55 2 55 3 55

NMT030 NHT030

2V2

Reciprocating Hermetic. 3500 Rpm

1000

528 352 416

AcouRater® Piston

niR 77

NLT036

480

R-22

1 20

1100

4 44 4 55 3 .55 4 55

NMT036

486

2500 1100

V4 1/4

1200

V2 V2

3 44 4 44 4 42 5.44

624 720

NET036 NHT036

490

10 X 10

490

4 54 5 55 6 55

530

Vio

3/4

480

2500** 3000tt

825** lioott

1200

NVT036

536

6 .44

Step 2 - Provide Unit Support

ROOF CURB — Install accessory roof curb in accordance with instructions shipped with curb. Install insulation, cant strips, roofing and flashing. Ductwork must be attached to curb.

IMPORTANT: The gasketing of the unit to the roof curb is critical for water integrity. Install gasketing material supplied with the roof curb. Improperly ap plied gasketing also can result in air leaks and poor unit performance.

Curb should be level to within */4 inch. This is necessary

for unit drain to function properly. Refer to Accessory Roof Curb Installation Instructions for additional information as required.

SLAB MOUNT — Place the unit on a solid, level concrete pad that is a minimum of 4-in. thick with 2-in. above grade. The slab should extend approximately 2-in. beyond the cas ing on all 4 sides of the unit. Install a gravel apron in front of condenser-air inlets to prevent obstruction of airflow by grass or shrubs. Do not secure the unit to the slab except when required by local codes.

Step 3 — Provide Clearances — The required min

imum operating and service clearances are shown in Fig. 2

and 3. Adequate combustion, ventilation and condenser air must be provided.

The condenser fan discharges through the top of the unit.

Be sure that the fan discharge does not recirculate to the condenser coil. Do not locate the unit in either a corner or under an overhead obstruction. The minimum clearance

under a partial overhang (such as a normal house overhang) is 48-in. above the unit top. The maximum horizontal ex tension of a partial overhang must not exceed 48 inches.

A CAUTION

Do not restrict condenser airflow. An air restriction at either the outdoor-air inlet (the entire surface of the out door coil) or the fan discharge can be detrimental to compressor life.

Do not place the unit where water, ice or snow from an overhang or roof will damage or flood the unit. Do not in stall the unit on carpeting, tile or other combustible mate

rials. The unit may be installed on wood flooring or on Class

A, B or C roof covering materials.

Step 4 — Rig and Place Unit — Use spreader bars

and crate top when rigging the unit. The units must be rigged for lifting as shown in Fig. 4. Refer to Fig. 4 for rigging weight and Table 1 for operating weight. Use extreme cau

tion to prevent damage when moving the unit. Unit must remain in an upright position during all rigging and mov ing operations. The unit must be level for proper conden

sate drainage; therefore, the ground-level pad or accessory roof-mounting curb must be level before setting the unit in place. When a field-fabricated support is used, be sure that the support is level and properly supports the unit.

A CAUTION

When installing the unit on a rooftop, be sure the roof will support the additional weight. Refer to Fig. 4 for corner weight information.

Page 5

Table 1 — Physical Data (cent)

NLT

UNIT SIZE 48 NOMINAL CAPACITY (ton)

OPERATING WEIGHT (lb) 496 500 500 COMPRESSORS

Quantity______

REFRIGERANT* REFRIGERANT METERING

DEVICE

CONDENSER COIL

Rows FIns/ln.

CONDENSER FAN

Nominal Airflow (Cfm) Nominal Speed (Rpm) Quantlty...Dlameter (In.) Motor Hp (single-phase)

EVAPORATOR COIL

Rows Fins/ln.

EVAPORATOR FAN

Nominal Cfm Nominal Speed (Rpm) Diameter x Width (In.)

Motor Hp (single-phase)

FURNACE SECTION

Burner Orifice No. Burner Orifice No. Pilot Orifice Diameter Pilot Orifice Diameter (In.)

RETURN-AIR FILTERS (sq ln.)t

Disposable 720 Cleanable 480

•Operating charge is iisted on unit namepiate tRequired fieid-suppiied fiiter areas are based on the iarger of the ARi-rated (Air Conditioning & Refrigeration institute) cooling airflow or the heating airflow at a velocity of 300 ft/min

for disposable type or 450 ft/min for high-capacity type. Air filter pressure drop must not exceed 0 08 in wg

(three-phase)

_________

(three-phase)

(Qty...drlll size) Natural Gas (Qty...drill size) Propane Gas

(In. ...drill size) Natural Gas

Propane Gas

3 44 3 55

NMT

042

2500 3000 3500

V2 3/4 ’/2 3/4

4. 44 4 55 4 54 5 55

042

NET 042

3Vz

4 42 5 44

NHT

NVT

042

550

6 44

6. 55 3 .55 4 55 5 55 6 54 3 55

NLT

042

556 574 580

Reciprocating Hermetic, 3500 Rpm

3 44 4 44 5 44 6 42 3 44

NMT

048

R-22

AocuRater® Piston

018 77

NHT 048

048

586 586

009

816 544 640

NVT

048

NLT

060

604

NMT

4 44 5 44 4 55 5 55

060

610

2000

960

NHT

060

616

NVT 060

616

I 3450

6 42 6 54

Step 5 — Connect Condensate Drain

NOTE: When installing condensate drain connection be sure to comply with local codes and restrictions.

The unit disposes of condensate water through a %-in.

NPT drain fitting. See Fig. 2 and 3 for location.

Install a 2-in. trap at the drain fitting to ensure proper drainage. See Fig. 5. Make sure the outlet of the trap is at least one-in. lower than the unit drain pan connection to

Fig. 4 - Suggested Rigging

prevent the pan from overflowing. Prime the trap with

water.

If the installation requires draining the condensate water away from the unit, connect a drain tube using a minimum of %-in. OD copper tubing, y4-in. galvanized pipe or %-in. plastic pipe. Do not undersize the tube. Pitch the drain tube

downward at a slope of at least one inch in every 10 ft of

horizontal run. Be sure to check the drain tube for leaks.

UNIT 48 NLT018

NLT024 100 NHT024 NLT030 103 132 132 103 NMT030 105 133 133 105 NHT030 106 134 134 106 NLT036 NMT036 108 NET036 108 137 137 108 NHT036 117 147 148 118 NVT036 119 148 149 120 NLT042 109 139 139 109 NMT042 NET042 110 140 140 110 NHT042 117 NVT042 NLT048 128 NMT048 NHT048 NVT048

NLT060 NMT060 NHT060

NVT060

101

107

110 140

124

130 159 160 131 131 131

136 165 166 137 138 166 167

139 168 169

139 168 169 140

CORNER WT (LB)

B C D

126 126 99 127 129 129 101

136 136 137 137

147 147 117 153 158 159 129

161 161

127

140

154

162 162

100

107 108

110

125

132 132

139 140

Page 6

r MIN

Condensate water can be drained directly onto the roof in rooftop installations (where permitted) or onto a gravel apron in ground-level installations. When using a gravel apron,

make sure it slopes away from the unit.

Step 6 — Install Venting — The vent cap assembly

is shipped in the burner compartment. Remove the access door to locate the assembly.

A CAUTION

The venting system is designed to ensure proper vent

ing. The vent cap assembly must be installed as indi

cated in this section of the unit Installation Instructions.

NOTE; Screw holes in the flue assembly and the unit flue panel are not symmetrically located. Make sure they are oriented properly when installing these components.

Refer to Fig. 6 and install the vent cap as follows:

1. Place vent cap assembly over flue panel. Orient screw holes in vent cap with holes in flue panel.

2. Secure vent cap in place by inserting the single screw on the right side of vent cap.

3. Place the vent cap guard over the vent cap. Orient holes in vent cap guard with holes in vent cap and flue panel.

4. Secure the entire assembly with the remaining 2 screws on the left side of vent cap and vent-cap guard assembly.

Step 7 — Install Gas Piping — The gas supply pipe

enters the unit through the access hole provided. The gas connection to the unit is made to the Vi-in. FPT gas inlet on the manual shutoff or gas valve.

Install a separate gas supply line that runs directly from

the meter to the heating section. Refer to Table 2 and the National Fuel Gas Code (NFGC) for gas pipe sizing. Do

not use cast-iron pipe. It is recommended that black iron

pipe is used. Check the local utility for recommendations concerning existing lines. Choose a supply pipe that is large

enough to keep the pressure loss as low as practical. Never

use pipe smaller than the ‘A-in. FPT gas inlet on the unit

gas valve.

For natural gas applications, the gas pressure at unit gas

connection must not be less than 5 in. wg or greater than

13 in. wg while the unit is operating. For propane applica tions, the gas pressure must not be less than 11 in. wg or greater than 13 in. wg at the unit connection.

When installing the gas supply line, observe local codes pertaining to gas pipe installations. Refer to the NFGC ANSI (American National Standards Institute) Z223.1-1988 NFPA (National Fire Protection Association) 54-1988 (in Canada, CAN/CGA [Canadian Gas Association] B 149.1, (2)-M86). In the absence of local building codes, adhere to the fol lowing pertinent recommendations:

1. Avoid low spots in long runs of pipe. Grade all pipe

V4 inch in every 15 ft to prevent traps. Grade all hori

zontal runs downward to risers. Use risers to connect to

heating section and to meter.

2. Protect all segments of piping system against physical

and thermal damage. Support all piping with appropri ate straps, hangers, etc. Use a minimum of one hanger every 6 ft. For pipe sizes larger than Уг in., follow rec ommendations of national codes.

3. Apply joint compound (pipe dope) sparingly and only to male threads of joint when making pipe connections. Use only pipe dope that is resistant to action of liquefied petroleum gases as specified by local and/or national codes.

Never use Teflon tape.

4. Install sediment trap in riser leading to heating section. This drip leg functions as a trap for dirt and condensate. Install trap where condensate cannot freeze. Install this

sediment trap by connecting a piping tee to riser leading to heating section, so that straight-through section of tee is vertical. See Fig. 7. Then, connect capped nipple into

lower end of tee. Extend capped nipple below level of

gas controls.

Table 2 — Maximum Gas Glow Capacity*

NOMINAL

IRON PIPE,

SIZE

(in.)

1 1.049

VA 1.380 VA

‘Capacity of pipe in cu ft of gas per hr for gas pressure of 0 5 psig or less. Pressure drop of 0.5 in. wg

(based on a 0.60 specific gravity gas) Refer to Table C-4, NFPA 54-1984

fThls length includes an ordinary number of fittings

INTERNAL

DIAMETER

(In.)

.622 175 120 .824 360 250

1.610

10 20 30 40 50

680 1400 950 2100

465 375 320 285 260 240

1460

200

770 600 580

1180 990

82 73

170

151

900 810

LENGTH OF PIPE, FTf

60 70 80

61 57 53 50

125 118

138

530 490 460 430

220

750 690 650 620

90 100 125 150

110 103 93 205 195 175

400 360 325

160 145

550 500

175

—

40 84 77

300 460

200

—

72 135 280 430

Page 7

testing of the piping systems when test pressure in excess of 0.5 psig. Pressure test the gas supply piping system at pressures equal to or less than 0.5 psig. The unit heating section must be isolated from the gas piping system by clos ing the external main manual shutoff valve and slightly open ing the ground-joint union.

A CAUTION

Unstable operation may occur when the gas valve and manifold assembly are forced out of position while con necting improperly-routed rigid gas piping to the gas valve. Use a backup wrench when making connection to avoid strain on, or distortion of, the gas control piping.

A CAUTION

If a flexible conductor is required or allowed by the au thority having jurisdiction, black iron pipe shall be in stalled at the gas valve and shall extend a minimum of 2 in. outside the unit casing.

A WARNING

Never use a match or other open flame when checking for gas leaks. Never purge gas line into combustion chamber. Failure to follow this warning could result in an explosion causing personal injury or death.

Size Small Cabinet Large Cabinet NHT036-NVT060 25V2 in.

NLT018-NET042 20V2 in.

"A"

Fig. 8 — Location of Coii Area Not to be Drilled

5. Install an accessible, external, manual main shutoff valve in gas supply pipe within 6 ft of heating section.

6. Install ground-joint union close to heating section be tween unit manual shutoff and external manual main shut off valve.

7. Pressure-test all gas piping in accordance with local and national plumbing and gas codes before connecting pip ing to unit.

NOTE; Pressure test the gas supply system after the gas supply piping is connected to the gas valve. The supply piping must be disconnected from the gas valve during the

8. Check for gas leaks at the field-installed and factoryinstalled gas lines after all piping connections have been completed. Use soap-and-water solution (or method spec

ified by local codes and/or regulations).

Step 8 — Install Duct Connections — The unit

has duct flanges on the supply- and return-air openings on the side and bottom of the unit. See Fig. 2 and 3 for con nection sizes and locations.

NOTE: The design and installation of the duct system must be in accordance with the standards of the NFPA for instal lation of nonresidence-type air conditioning and ventilating systems, NFPA No. 90A orresidence-type, NFPA No. 90B; and/or local codes and residence-type, NFPA No. 90B; and/ or local codes and ordinances.

Adhere to the following criteria when selecting, sizing

and installing the duct system;

1. The unit is shipped in vertical configuration. To convert unit to horizontal application, remove side duct covers, save screws and install the covers on bottom duct openings.

2. Select and size ductwork, supply-air registers and returnair grilles according to ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers) recommendations.

A CAUTION

When drilling the duct-system fastening holes into the side of the unit instead of the unit duct flanges, use ex treme care to avoid puncturing the coil or coil tubes. See Fig. 8.

Page 8

3. Use flexible transition between rigid ductwork and unit to prevent transmission of vibration. The transition may be screwed or bolted to duct flanges. Use suitable gas kets to ensure weather- and airtight seal.

4. Install external, field-supplied air filter(s) in return-air ductwork where it is easily accessible for service. Rec ommended filter sizes are shown in Table 1,

5. Size all ductwork for maximum required airflow (either heating or cooling) for unit being installed. Avoid abrupt duct size increases or decreases.

6. Adequately insulate and weatherproof all ductwork lo cated outdoors. Insulate ducts passing through uncondi tioned space, and use vapor barrier in accordance with latest issue of SMACNA (Sheet Metal and Air Condi tioning Contractors National Association) and ACCA (Air Conditioning Contractors of America) minimum instal lation standards for heating and air conditioning sys tems. Secure all ducts to building structure,

7. Flash, weatherproof and vibration-isolate all openings in building structure in accordance with local codes and good building practices.

Step 9 — Install Electrical Connections

A WARNING

The unit cabinet must have an uninterrupted, unbroken electrical ground to minimize the possibility of per

sonal injury if an electrical fault should occur. This ground may consist of an electrical wire connected to the unit ground lug in the control compartment, or conduit ap proved for electrical ground when installed in accor dance with NEC (National Electrical Code) ANSI/ NFPA (latest edition) (in Canada, Canadian Electrical

Code CSA C22.1) and local electrical codes. Do not

use gas piping as an electrical ground. Failure to ad

here to this warning could result in personal injury or

death.

A CAUTION

Failure to follow these precautions could result in dam

age to the unit being installed:

1. Make all electrical connections in accordance with NEC ANSI/NFPA (latest edition) and local electrical codes governing such wiring. In Canada, all electrical connec tions must be in accordance with CSA Standard C22.1 Canadian Electrical Code Part 1 and applicable local codes. Refer to unit wiring diagram.

2. Use only copper conductor for connections between field-

supplied electrical disconnect switch and unit. DO NOT

USE ALUMINUM WIRE.

3. Be sure that high-voltage power to unit is within oper ating voltage range indicated on unit rating plate. On 3phase units, ensure that phases are balanced within 2%. Consult local power company for correction of im proper voltage and/or phase balance.

4. Insulate low-voltage wires for highest voltage contained within conduit when low-voltage control wires are run in same conduit as high-voltage wires.

5. Do not damage internal components when drilling through any panel to mount electrical hardware, conduit, etc.

HIGH-VOLTAGE CONNECTIONS - The unit must have a separate electrical service with a field-supplied, water proof, fused disconnect switch mounted at, or within sight from, the unit. Refer to the unit rating plate for maximum fuse/circuit breaker size and minimum circuit amps (ampac ity) for wire sizing. See Table 3 for electrical data.

The field-supplied disconnect switch box may be mounted on the unit over the high-voltage inlet hole in the control corner panel. See Fig. 2 and 3.

Proceed as follows to complete the high-voltage connec tions to the unit;

1. Connect ground lead to chassis ground connection when using separate ground wire.

2. Run high-voltage leads into unit control box and con nect to contactor. See unit wiring label, and Fig. 9.

A CAUTION

TRANSFORMER CONTAINS AUTO RESET OVERCURRENT PROTECTOR.

IT MAY RESET WITHOUT WARNING STARTING HEATING OR COOLING SECTION OF THIS PRODUCT.

DISCONNECT POWER PRIOR TO SERVICING.

THIS COMPARTMENT MUST BE CLOSED EXCEPT WHEN SERVICING.

316056-201 REV A

Fig. 9 — Transformer Label

Page 9

Table 3 — Electrical Data

UNIT

SIZE 01B

024

030

036

042

048

060

AWG FLA LRA MCA MOCP NEC RLA

NOTES: 1

In compliance with NEC requirements for multimotor and combination load and equipment (refer to NEC Articles 430 and 440), the overcurrent pro tective device for the unit shall be fuse or HACR breaker

Unbalanced 3-Phase Supply Voltage

Never operate a motor where a phase imbalance in supply voltage is greater

than 2% Use the following formula to determine the % voltage imbalance.

% Voltage Imbalance

_ y max voltage deviation from average voltage

NOMINAL

V-PH-HZ

208/230-1-60 208/230-1-60

208/230-1-60

208/230-3-60

460-3-60

208/230-1-60

208/230-3-60

460-3-60

208/230-1-60

208/230-3-60

460-3-60

208/230-1-60

208/230-3-60

460-3-60

American Wire Gage Full Load Amps Locked Rotor Amps Minimum Circuit Amps Maximum Overcurrent Protection National Electrical Code Rated Load Amps

Example: Supply voltage is 460-3-60

MODEL NO.

NLT018 187 253 82 49 0 NLT024

NHT024 NLT030

NMT030 NHT030

NLT036 NMT036 NET036 NHT036 NVT036

NLT042 NMT042 NET042 NHT042 NVT042

NLT048 NMT048 NHT048 NVT048

NLT048 NMT048 NHT048

NVT048

NLT060 NMT060 NHT060 NVT060

average voltage

AB = 452 volts BC = 464 volts AC = 455 volts

Average Voltage

VOLTAGE

RANGE

Min Max RLA

187 253

187 253 14.3

187

414

187

414 506 77 41 0 1 2

187 253 26 5

187 253 16.8

187

187 253 30 7

187

414 506 104 55 0 1 2

452 + 464 -r 455

1371

—JT— =457

11.6

253 21 1

14.7

253

506 7 1

23.9 95.4 1 5

253

15.3

253

21 4

COMPR

LRA

61 0

61.0

86.0 08

100 0 1 5

67.0

34 0

82 0

1140

84 0

42 0 1 2

135 0

130 0 22

CONDENSER-

FAN MOTOR

FLA

08 08

1 9

1.9

1.9 22 22

1.2

1.9 1 9 1 9

2.2

2.1

2 1

Determine maximum deviation from average voltage. (AB) 457 - 452 =5 volts (BC) 464 - 457 =7 volts (AC) 457 - 455 =2 volts

Maximum deviation is 7 volts.

Determine % voltage imbalance

% Voltage Imbalance =100 x

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

EVAPORATOR-

FAN MOTOR

FLA

2.5

2.5 12 17 1 25 25

3.0 30

3.0 45 45 45

30 30 45 45 45

1 5 1 5 23 23 23

3.0

45 45

4.5

3.0

4.5

4.5 1 5

1 5 23 23

2.3

4.5 45

4.5

62 45

4.5

62 23

2.3

62 6 46 7

6.2

32 12 17.4 25

AWG MIN

WIRE SIZE

"457

8 6

= 1.53%

POWER SUPPLY

MCA

13 6 20

21 2

21.2 21 7

30.9 30 9

32.4 32 4

32.4

23.3 23 3 24 8 25 1 25 1

11 6 11 6 124 124

12.4 34 3

34 3 35 9

35.9 35 9

24 0

24.0 25 5

25.8 25 8

123

12.3 13 1

13.1 13 1

39 7 39 7

39.7 41 4

27.7 27 7 27 7 29 4

13.8 138 138 147

35 5 50

MOCP

35 35 40 40 40

Page 10

SPECIAL PROCEDURES FOR 208-V OPERATION

Á WARNING

Make sure that the power supply to the unit is switched

OFF before making any wiring changes. Electrical shock

can cause personal injury or death.

1. Disconnect the orange transformer-primary lead from the contactor. See unit wiring label.

2. Remove the tape and cover from the terminal on the end of the red transformer-primary lead.

3. Save the cover.

4. Connect the red lead to the contactor terminal from which the orange lead was disconnected.

5. Using the cover removed from the red lead, insulate the loose terminal on the orange lead.

6. Wrap the cover with electrical tape so that the metal ter minal cannot be seen.

Indoor blower motor speeds should be changed for 208-v operation. In the unit control box, change motor leads on the printed circuit board so that high speed is used for cool ing and medium speed is used for heating. Do not change blower speed setting for 460-v rated units. Refer to StartUp, Indoor Airflow and Airflow Adjustments section.

CONTROL VOLTAGE CONNECTIONS - Locate the room thermostat on an inside wall in the space to be conditioned, where it will not be subjected to either a cooling or heating

source or direct exposure to sunlight. Mount the thermostat

4 to 5 ft above the floor.

Use no. 18 American Wire Gage (AWG) color-coded, insulated (35 C minimum) wires to make the control volt age connections between the thermostat and the unit. If the thermostat is located more than 100 ft from the unit (as

measured along the control voltage wires), use no. 16 AWG

color-coded, insulated (35 C minimum) wires.

A grommeted, control voltage inlet hole is located in the panel adjacent to the control access panel. Run the lowvoltage leads from the thermostat, through the inlet hole, and to the control voltage terminals through a hole in the bottom of the unit control box. Pass control voltage leads through wire ties located under unit control box. Connect the thermostat leads to the terminals as shown in Fig. 10.

HEAT ANTICIPATOR SETTING - The room thermostat heat anticipator must be adjusted properly to ensure proper heating performance. Set the heat anticipator, using an

THERMOSTAT (TYPICAL)

-TERMINAL BOARD

I I I

¿)(y)¿(¿

(U);j~

(L2)i^

(Q)- —

CONTROL BOX

FIELD CONTROL-VOLTAGE WIRING FIELD HIGH-VOLTAGE WIRING

GND

3-PHASE UNITS ONLY

Fig. 10 — High- and Control-Voltage Connections

-CONTACTOR TERMINALS (SEE UNIT WIRING LABEL)

V-*cnKr-—

FIELD SUPPLIED FUSED DISCONNECT

POWER SUPPLY

ammeter between the W and R terminals to determine the exact required setting.

NOTE: For thermostat selection purposes, use 0.6 amp for the approximate required setting.

Failure to make a proper heat anticipator adjustment will

result in improper operation, discomfort to the occupants

of the conditioned space and inefficient energy utilization; however, the required setting may be changed slightly to provide a greater degree of comfort for a particular installation.

TRANSFORMER CIRCUIT PROTECTION - The unit

transformer contains an auto, reset overcurrent protector for control circuit protection. If this device trips, it may reset without warning, starting the heating or cooling section of this product. Use caution when servicing; if overcurrent protector continues to trip, there is a problem in the lowvoltage electrical circuit, such as an electrical short, ground or transformer overload. Disconnect power, correct the con dition, and check for normal unit operation.

PRE-START-UP

A WARNING

Failure to observe the following warnings could result in serious personal injury:

1. Follow recognized safety practices and wear protec tive goggles when checking or servicing refrigerant system.

2. Do not operate compressor or provide any electric power to unit unless compressor terminal cover is in place and secured.

3. Do not remove compressor terminal cover until all electrical sources are disconnected.

4. Relieve all pressure from system before touching or disturbing anything inside terminal box if refriger ant leak is suspected around compressor terminals.

5. Never attempt to repair soldered connection while refrigerant system is under pressure.

6. Do not use torch to remove any component. System contains oil and refrigerant under pressure. To re move a component, wear protective goggles and pro ceed as follows:

a. Shut off gas supply and then electrical power to

unit.

b. Relieve all pressure from system using both high-

and low-pressure ports.

c. Cut component connecting tubing with tubing cut

ter and remove component from unit.

d. Carefully unsweat remaining tubing stubs when

necessary. Oil can ignite when exposed to torch

flame.

Proceed as follows to inspect and prepare the unit for ini

tial start-up:

1. Remove alt access panels.

2. Read and follow instructions on all WARNING, CAU TION and INFORMATION labels attached to, or shipped with, unit.

Make the following inspections: a. Inspect for shipping and handling damages such as

broken lines, loose parts, disconnected wires, etc.

b. Inspect for oil at all refrigerant tubing connections

and on unit base. Detecting oil generally indicates

Page 11

a refrigerant leak. Leak-test all refrigerant tubing con nections using electronic leak detector, or liquidsoap solution. If a refrigerant leak is detected, see Start-Up, Check for Refrigerant Leaks section.

c. Inspect all field- and factory-wiring connections. Be

sure that connections are completed and tight.

d. Inspect coil fins. If damaged during shipping and han

dling, carefully straighten fins with a fin comb.

3. Verify the following conditions:

A WARNING

Do not purge gas supply into the combustion cham ber. Do not use a match or other open flame to

check for gas leaks. Failure to follow this warning could result in an explosion causing personal injury or death.

a. Make sure that gas supply has been purged, and that

all gas piping has been checked for leaks.

b. Make sure that outdoor-fan blade is correctly posi

tioned in fan orifice. Blades should clear fan motor

by no more than V4 inch.

c. Make sure that air filter(s) is in place. d. Make sure that condensate drain pan and trap are filled

with water to ensure proper drainage.

e. Make sure that all tools and miscellaneous loose parts

have been removed.

START-UP

Check for Refrigerant Leaks — Proceed as follows

to locate and repair a refrigerant leak and to charge the unit;

1. Locate leak and make sure that refrigerant system pres sure has been relieved.

2. Repair leak following accepted practices. NOTE; Install a filter drier whenever the system has been

opened for repair.

3. Add a small charge of R-22 refrigerant vapor to system

and leak-test unit.

4. Evacuate refrigerant system if additional leaks are not

found.

5. Charge unit with R-22 refrigerant, using a volumetric-

charging cylinder or accurate scale. Refer to unit rating

plate for required charge. Be sure to add extra refrig

erant to compensate for internal volume of filter drier.

Start-Up Heating Section and Make

Adjustments

A CAUTION

Complete the required procedures given in Start-Up sec tion before starting the unit.

Do not jumper any safety devices when operating the unit.

Make sure that burner orifices are aligned properly. Un stable operation may occur when the burner orifices in the manifold are misaligned.

NOTE: When installing a unit in extremely cold climate areas, a run-in period for the inducer motor is recom mended. After the unit is installed, disconnect the red wire from terminal 2 at the ignition control (IGN) and jumper terminals R-W at the control voltage terminal board. The inducer motor should run but the burner will not ignite. Al low inducer motor to run for 4 to 5 hours. Reconnect red wire to terminal 2 at IGN and remove R-W jumper at the-

control voltage terminal board. Proceed as follows to com

plete heating section start-up.

Follow the lighting instructions on the heating section op eration label (located inside the burner access door) to start the heating section.

When lighting the unit for the first time, perform the following:

If the gas supply pipe was not purged before connecting the unit, it will be full of air. It is recommended that the ground joint union be loosened, and the supply line be al lowed to purge until the odor of gas is detected. Never purge gas lines into a combustion chamber. Immediately upon de tection of gas odor, retighten the union. Allow 5 minutes to elapse, then light unit using the following steps.

CHECK HEATING CONTROL - Start and check the unit for proper heating control operation as follows: (See fur nace lighting instructions located inside burner access panel.)

1. Place the room thermostat SYSTEM switch in the HEAT position and the fan switch in the AUTO, position.

2. Set the heating temperature control of the thermostat above room temperature.

3. Observe that after built-in time delays, the pilot auto

matically lights, the burners light and the blower motor starts.

4. Observe that the burners and pilot go out, and that after a built-in delay the blower motor stops when the heating control setting of the thermostat is satisfied.

NOTE: The 060-size 460-v models are equipped with a 3phase blower motor. Check blower wheel for correct rota tion as indicated by arrow on blower housing. If blower wheel rotates in opposite direction, reverse any 2 blower motor leads or any 2 line voltage leads. Recheck blower wheel rotation if necessary to reverse leads.

CHECK GAS INPUT — Check gas input and manifold pres

sure after unit start-up. (See Table 4.) If adjustment is re

quired, proceed as follows.

The rated gas inputs shown in Table 4 are for altitudes

from sea level up to 2000 ft above sea level. These inputs

are based on natural gas with a heating value of 1050 Btu/

ft^ at 0.65 specific gravity, or propane gas with a heating

value of 2500 Btu/fr at 1.5 specific gravity. For elevations above 2000 ft, reduce input 4% for each 1000 ft above sea level. When the gas supply being used has a different heat ing value or specific gravity, refer to national and local codes, or contact your Distributor or Branch to determine the re quired orifice size.

A CAUTION

These units are designed to consume the rated gas in

puts using the fixed orifices at specified manifold pres sures as shown in Table 4. DO NOT REDRILL THE ORIFICES UNDER ANY CIRCUMSTANCES.

ADJUST GAS INPUT — The gas input to the unit is de termined by measuring the gas flow at the meter or by mea

suring the manifold pressure. Measuring the gas flow at the meter is recommended for natural gas units. The manifold pressure must be measured to determine the input of pro pane gas units.

Measure Gas Flow (Natural Gas Units') — Minor adjust

ment to the gas flow can be made by changing the manifold

pressure. The manifold pressure must be maintained be

tween 3.2 and 3.8 in. wg. If larger adjustments are

required, change main burner orifices following the recom

mendations of national and local codes.

Page 12

Table 4 — Rated Gas Inputs

UNIT 48

NLT018,024,030 NLT036,042; NHT024; NMT030 3 50

NLT048,060; NMT036,042; NHT030

NET036,042

NMT048,060; NHT036.042

NHT048,060; NVT036,042 NVT048,060

‘When a 48N unit is converted to propane, the unit must be modified. See kit instructions.

tBased on altitudes from sea level up to 2000 ft above sea level. For altitudes above 2000 ft, reduce

Input rating 4% for each 1000 ft above sea level In Canada, from 2000 ft above sea level to 4500 ft above sea level, derate the unit 10%.

NUMBER

ORIFICES

GAS SUPPLY PRESSURE

Min Max Min Max

2 5.0

4 5.0 136 11 0 13.6

5 5.0 13.6

6 5.0 13.6 11.0 13.6 6 50 13.6 11.0

5.0 13.6

NOTE; All other appliances that use the same meter must

be turned off when gas flow is measured at the meter.

Proceed as follows:

1. Turn off gas supply to unit.

2. Remove pipe plug on outlet of gas valve, then connect manometer at this point. Turn on gas to unit.

3. Record number of seconds for gas meter test dial to make

(in. wg)

Natural Propane

13.6

13.6 11.0 13.6 3.5

13 6 35

11 0

11.0 13.6 3.5

11.0 13.6 3.5 10.5

136 3.5 10.5

Measure Manifold Pressure (Propane Units') — The main burner orifices on a propane gas unit are sized for the unit rated input when the manifold pressure is 10.5 in. wg.

unit:

1. Turn off gas to unit.

2. Remove pipe plug on outlet of gas valve, then connect

one revolution.

4. Divide number of seconds in Step 3 into 3600 (number

of seconds in one hour).

3. Turn on gas to unit.

4. Remove cover screw over regulator adjustment screw

5. Multiply result of Step 4 by the number of cu ft shown

for one revolution of test dial to obtain cu ft of gas flow

5. Adjust regulator adjustment screw for a manifold pres

per hour.

6. Multiply result of Step 5 by Btu heating value of gas to

obtain total measured input in Btuh. Compare this value with heating input shown in Table 4. (Consult the local gas supplier if the heating value of gas is not known.)

6. Replace cover screw.

7. Turn off gas to unit. Remove manometer from pressure

Example: Assume that the size of test dial is one cu ft, one revolution takes 30 seconds, and the heating value of the gas is 1050 Btu/ft^. Proceed as follows:

1. 30 seconds to complete one revolution.

2. 3600 30 = 120.

3. 120 X 1 = 120 ft^ of gas flow/hr.

4. 120 X 1050 = 126,000 Btuh input.

If the desired gas input is 125,000 Btuh, only a minor

change in the manifold pressure is required.

Observe manifold pressure and proceed as follows to

adjust gas input;

1. Remove cover screw over regulator adjustment screw on gas valve.

2. Turn regulator adjustment screw clockwise to increase gas input, or turn regulator adjustment screw counter clockwise to decrease input. Manifold pressure must be between 3.2 and 3.8 in. wg.

CHECK BURNER FLAME — Observe the unit heating operation, and watch the burner flames through the obser vation port to see if they are light blue and soft in appear ance, and that the flames are approximately the same for each burner. See Fig. 11.

BLOWER HEAT-RELAY OPERATION - Blower relay PCI (see the unit wiring diagram) is located in the control box and adjusts to permit either longer or shorter “off” cy cles. The “on” cycle is factory set for one minute on tim ing. The adjusting dial on the relay (see Fig. 12) is factory

set at the minimum position to provide optimum perfor mance for most installations. On unusual installations, the length of time the blower remains on may need to be increased. To increase blower operation time, rotate the ad

justing dial counterclockwise. To decrease blower opera

tion time, rotate dial clockwise. AIRFLOW AND TEMPERATURE RISE - The heating

MANIFOLD

PRESSURE

(in. wg)

Natural

3.5 10.5

35 10.5

Proceed as follows to adjust gas input on a propane gas

manometer at this point.

on gas valve.

sure reading of 10.5 in. wg. Turn adjusting screw clock wise to increase manifold pressure, or turn adjusting screw counterclockwise to decrease manifold pressure.

tap. Replace pipe plug on gas valve, then turn on gas to unit. Check for leaks.

section for each size unit is designed and approved for heat

A WARNING

Unsafe operation of the unit may result if manifold

pressure is outside this range. Personal injury or unit damage may result.

ing operation within the temperature-rise range stamped on

the unit rating plate.

Table 5 shows the approved temperature-rise range for each unit, and the air delivery cfm at various temperature rises. The heating operation airflow must produce a tem

3. Replace cover screw cap on gas valve.

4. Turn off gas supply to unit. Remove manometer from pressure tap. Replace pipe plug on gas valve. Turn on

perature rise that falls within the approved range.

Refer to Indoor Airflow and Airflow Adjustments sec

tion to adjust heating airflow when required.

gas to unit. Check for leaks.

NATURAL GAS

Orifice

Propane

10.5 44 40,000

10.5 44 60,000 105 44

Heating Orili Size

(Btuh)t

42 96,000 44 100,000 44 120,000 42 144,000

PROPANE*

Input

80,000 55

Orifice

Drill

Size

55 55

Heating

Input

(Btuh)t

40,000 60,000 80,000

96,000 100,000 120,000 144,000

Page 13

PILOT FLAME BURNER FLAME

will close the IFR2 relay 60 seconds after the burners are ignited and the blower motor (IFM) will start. When the thermostat is satisfied, the R and W circuit is opened and power is removed from the PC2 inducer control and the ig nition module (IGN), which causes the MV to close in stantly and the IM is deenergized. The electronic timer PCI will keep the IFM running an additional 60 to 90 seconds. Then the blower stops and the unit is on standby until an other call for heat.

NOTE; If the main limit switch opens due to the unit over heating, the IFM is turned on through the electronic board.

NOTE: When the unit is initially powered, IER2 will close and run the IFM for the duration of the off-delay cycle (60 to 90 seconds).

If the pilot fails to light within a 120-second trial for ig nition period from the initial call for heat, the IGN will go into a Retry mode after a period of approximately 5 min utes (following the 2-minute trial for ignition period). If the pilot again fails to light, IGN will go into Retry mode; this cycle will be repeated until the pilot light ignites. If the pi lot flame has been established but then extinguishes, the IGN will immediately reset as if it were the initial call for heat. If this occurs more than 3 times, the IGN will lock out the system, and the diagnostic LED (located on the IGN) will flash. To reset, open the R-W thermostat circuit for 30 seconds and reclose. If the diagnostic LED glows con stantly, replace control.

LIMIT SWITCHES — Normally closed limit switch LS com pletes the control circuit through the thermostat R circuit. See Fig. 13 and 14. Should the leaving-air temperature rise

above the maximum allowable temperature, the limit switch

opens and the R control circuit “breaks.” Any interruption

in the R control circuit instantly closes the gas valve and stops gas flow to the burners and pilot. The IFM continues

to run until the LS resets.

SAFETY CHECK OF LIMIT CONTROL - The control shuts off the gas supply and energizes the circulating-air blower motor if the furnace overheats.

The recommended method of checking this limit control is to gradually block off the return air after the furnace has been operating for a period of at least 5 minutes. As soon as the limit control functions, the return-air opening should be unblocked to permit normal air circulation. By using this method to check the limit control, it can be established that the limit is functioning properly and the furnace will “fail safe” if there is a restricted circulating air supply or motor failure. If the limit control does not function during this test, the cause must be determined and corrected.

HEATING SEQUENCE OF OPERATION - See Fig. 13 for single-phase operation and Fig. 14 for 3-phase opera tion. Room thermostat calls for heat, closing circuit be

tween R and W 24-V control circuit terminals. (Power to

the R terminal is supplied through LS and ALS safety

switches.) The PC2 inducer control board is energized through the normally closed set of contacts of pressure switches (CPS), which starts the inducer motor (IM). The IM comes up to speed, and the vacuum in the collector box increases, open ing the normally closed and closing the normally open contacts of the pressure switch (PS), energizing the circuit to the ignition control (IGN) and the pilot valve (PV). If theflame sensor proves the presence of the pilot flame, the

internal switching of the ignition control deenergizes the spark generator and energizes the main gas valve (MV) and the IFR2 electronic timer. Gas flows to the main burners and is ignited by the pilot flame. The PCI electronic timer

When the air temperature at the limit switch drops to the low-temperature setting of the limit switch, the switch closes and completes the R control circuit. The electric-spark ig nition system cycles and the unit returns to normal heating operation.

BLOWER AUXILIARY LIMIT SWITCH - Blower aux iliary limit switch ALSl is a temperature-actuated auto, re set switch and is connected in series with the limit switch LS. The function of the switch is to prevent abnormal blower compartment temperatures. The switch is mounted on the blower housing. When the temperature at the auxiliary switch reaches the maximum allowable temperature, the R control circuit “breaks”, closing the gas valve and stopping gas flow to the burners and pilot. The switch will automatically reset when the blower compartment temperature returns to normal. The IFM continues to run until ALSl resets.

ROLLOUT AUXILIARY LIMIT SWITCH - Rollout aux

iliary limit switch ALS2 is a temperature-actuated manual

reset switch connected in series with limit switch LS and

blower auxiliary limit switch ALSl. The function of the switch is to close the main gas valve in the event of flame

rollout. The switch is located above the main burners. When

the temperature at the auxiliary switch reaches the maxi mum allowable temperature, the R control circuit trips, clos ing the gas valve and stopping gas flow to the burners and pilot. To reset the switch, push in the red button. If the switch cycles again, shut down the unit and call for service. The IFM continues to run until ALS2 is reset.

Page 14

SIN6LE STA6E HEAT K SIN6LE STAGE COOL

THERMOSTAT CTYPJ

■@-RED-

BUC KED -

ORN -

TRAN

BRN —

^ ®©<£>

® PCI ®

® I—I I—3 ®

<!> 0 <»> 0 0

♦-0

r^Pi'

IGN o

ALS1 ALS2 C -

CAP. -

1,2

COMP EG GV IFM IFR1

IFR2 IM

IR IGN

NOTES:

1. 230-v operation as shown. For 208-v operation, reverse red and orn leads of transformer.

2. Symbols are an electrical representation only.

3. If any of the original wire, as supplied, must be replaced, use minimum 105° C wiring

4. Use copper wire only for field power supply leads.

5. Compressor and fan motors provided with inherent thermal protection.

Auxiliary Limit Switch (SPST) NC (Blower) Auxiliary Limit Switch (SPST) NC (Rollout) Contactor Capacitors (Run)

Compressor Equipment Ground Gas Valve Indoor Fan Motor Indoor Fan Relay (SPOT) NO (Cooling) Indoor Fan Relay (SPST) NO (Heating) Inducer Motor Inducer Relay (DPST) NO Ignitor Limit Switch (SPST) NC

material.

LEGEND

MV OFM P PCI PC2 PI PS PV ST TRANS

Mam Valve Outdoor Fan Motor Pilot (Flame Sensing) Printed Circuit Board (Blower) Printed Circuit Board (Inducer) Pilot Ignitor Pressure Switch (SPOT) NC Pilot Valve Start Thermistor (024-042 only)

Transformer

Field High-Voltage Wiring Factory High-Voltage Wiring Factory Low-Voltage Wiring Field Low-Voltage Wiring

Marked Connection

Unmarked Connection

internally Connected or

^ Wirenut

Fig. 13 — Typical Single-Phase Wiring Diagram

Page 15

FIELD L3 POWER L2

SUPPLY

BLK-

^5—

{j^ I—@

ilHl—®

■ RSI ORN -

BRN

TRAN

SIN6LE 5TA6E HEAT S SIN6LE STA6E COOL

TfCRMOSTAT CTYPJ

CAPI

1 Co o)

^ CAP2

ICOMPOWB^T arrangement“

ALS1 ALS2 C

CAP. 1,2 CCH COMP

EG GV

IPM IFR1

IFR2 IM

IQN LS

NOTES:

1. 230-v operation as shown. For 208-v operation, reverse red and orn leads of transformer.

2. Symbols are an electnca) representation only.

3. If any of the original wire, as supplied, must be replaced, use minimum 105'^C wiring material.

4. Use copper wire only for field power supply leads.

5. Compressor and fan motors provided with inherent thermal protection.

6. Three-phase motors protected under primary single-phase conditions.

Auxiliary Limit Switch (SPST)

NC (Blower)

Auxiliary Limit Switch (SPST)

NC (Rollout) Contactor Capacitors (Run) Crankcase Heater Compressor Equipment Ground Gas Valve Indoor Fan Motor Indoor Fan Relay (SPOT) NO (Cooling) Indoor Fan Relay (SPST) NO (Heating) Inducer Motor Inducer Relay (DPST) NO Ignitor Limit Switch (SPST) NC

LEGEND

MV OFM p

PC1 PC2

PI PS PV

TRANS

Mam Valve Outdoor Fan Motor Pilot (Flame Sensing) Printed Circuit Board (Blower) Printed Circuit Board (Inducer) Pilot Ignitor Pressure Switch (SPOT) NC Pilot Valve Transformer

Field High-Voltage Wiring Factory High-Voltage Wiring Factory Low-Voltage Wiring Field Low-Voltage Wiring

Marked Connection

Unmarked Connection

Internally Connected or Wirenut

Fig. 14 — Typical 3-Phase Wiring Diagram

Page 16

Start-Up Cooling Section and Make Adjustments

A CAUTION

Complete the required procedures given in the Pre-StartUp section before starting the unit.

Do not jumper any safety devices when operating

the unit.

Do not operate the compressor when the outdoor tem

perature is below 55 F (unless accessory low-temperature

kit is installed).

Do not rapid-cycle the compressor. Allow 5 minutes

between “on” cycles to prevent compressor damage.

CHECKING COOLING CONTROL OPERATION - Start and check the unit for proper cooling control operation as follows:

1. Place room thermostat SYSTEM switch in OFF posi tion. Observe that blower motor starts when FAN switch

is placed in ON position and shuts down when FAN switch is placed in AUTO, position.

2. Place SYSTEM switch in COOL position and FAN switch in AUTO, position. Set cooling control below room tem perature. Observe that compressor, condenser fan and evaporator blower motors start. Observe that cooling cycle shuts down when control setting is satisfied. The blower motor has an off delay of approximately one minute on shutdown.

3. When using an auto.-changeover room thermostat, place both SYSTEM and FAN switches in AUTO, positions. Observe that unit operates in heating mode when tem perature control is set to “call for heating” (above room temperature) and operates in cooling mode when tem perature control is set to “call for cooling” (below room temperature).

CHECKING AND ADJUSTING REFRIGERANT CHARGE

— The refrigerant system is fully charged with R-22 refrig

erant, tested and factory-sealed. NOTE: Adjustment of the refrigerant charge is not required

unless the unit is suspected of not having the proper R-22 charge. Eor all applications, the correct R-22 charge for the best performance is the charge that results in a suction gas superheat of 5 F at the compressor inlet when the unit is operating at the ARI rating conditions of 95 F dry-bulb (db) outdoor and 80 F db/67 F wet-bulb (wb) indoor.

A superheat charging label is attached to the outside of the compressor access door. The label includes a “Super heat Charging Table” and a “Required Suction-Tube Tem

perature (F)” chart.

An accurate superheat thermocouple- or thermistor-type thermometer, a sling psychrometer and a gage manifold are required when using the superheat charging method for eval uating the unit charge. Do not use mercury or small dial-

type thermometers because they are not adequate for this type of measurement.

A CAUTION

When evaluating the refrigerant charge, an indicated adjustment to the specified factory charge must always be very minimal. If a substantial adjustment is indi

cated, an abnormal condition exists somewhere in the

cooling system, such as insufficient airflow across

either coil or both coils.

Proceed as follows:

1. Remove caps from lowfittings.

and high-pressure service

2. Using hoses with valve core depressors, attach low- and high-pressure gage hoses to low- and high-pressure ser vice fittings, respectively.

3. Start unit in cooling mode and let unit run until system pressures stabilize.

4. Measure and record the following. a. Outdoor ambient-air temperature (F db). b. Evaporator inlet-air temperature (F wb). c. Suction-tube temperature (F) at low-side service

fitting.

d. Suction (low-side) pressure (psig).

5. Using “Superheat Charging Table,” compare outdoorair temperature (F db) with evaporator inlet-air temper ature (F wb) to determine desired system operating su perheat temperature. See Table 6.

6. Using “Required Suction-Tube (F)” table, compare de sired superheat temperature with suction (low-side) operating pressure (psig) to determine proper suctiontube temperature. See Table 7.

7. Compare actual suction-tube temperature with proper

suction-tube temperature. Using a tolerance of ± 3 F, add refrigerant if actual temperature is more than 3 F higher than proper suction-tube temperature, or remove

refrigerant if actual temperature is more than 3 F lower

than required suction-tube temperature.

NOTE: If the problem causing the inaccurate readings is a refrigerant leak, refer to Start-Up, Check for Refrigerant Leaks section.

INDOOR AIRFLOW AND AIRFLOW ADJUSTMENTS

A CAUTION

For cooling operation, the recommended airflow is 350 to 450 cfm per each 12,000 Btuh of rated cooling ca pacity. For heating operation, the airflow must pro duce a temperature rise that falls within the range stamped on the unit rating plate.

Direct-drive blower motors are factory connected to de liver the proper heating and cooling airflows at normal ex ternal static pressures (medium speed cooling, low speed heating for 230-v units) and high speed cooling (units with 460-V have medium speed cooling and high speed heating).

For 208-v operation on 208/230-v rated direct drive units, interchange motor leads to high speed for cooling and medium speed for heating operation.

Table 5 shows the temperature rise at various airflow rates. Tables 8 and 9 show both heating and cooling airflows at various external static pressures. Refer to these tables to determine the airflow for the system being installed.

NOTE: Be sure that all supply- and return-air grilles are open, free from obstructions and adjusted properly.

A WARNING

Disconnect electrical power to the unit before changing

blower speed. (Be sure to turn off gas supply before

disconnecting electrical power.) Electrical shock can cause

personal injury or death.

A CAUTION

Do not change the blower-motor lead connections on

460-V units from the factory setting. Damage to unit

may result.

Page 17

Table 5 — Air Delivery (Cfm) at Indicated Temperature Rise and Rated Heating input

NOMINAL SIZE

NLT018,024,030 NHT024; NMT030

NLT036,042 NHT030; NMT036,042 NLT048 NLT060 NET036,042 NHT036,042; NMT048 NMT060 NVT036,042; NHT048 120,000 NHT060 NVT048,060

NOTE: Dashed areas of the table do not fall In the approved temperature rise range of the unit

HEATING

INPUT (Btuh)

40,000 60,000 60,000 - 80,000 - - - - - 1316 80,000 80,000

96,000 - - - 100,000 100,000

120,000 - - - 2539 144,000

- -

- - - - - 987 888

2370

2962 2370

- - - 2116

- -

- - - - - -

- - - -

987

1481 1269

1975 1693 1481 1975 1693 1481

2469

2116

UNIT TEMPERATURE RISE (T)

40 45

740 658

846

1111

1777 1851 1646 1851 1646 1481

2222 1975 1777

1316 1185 1316 1185 1580

2370 2133 1939 1777 1641

50 55

592 538

987

888

1185 1077

1422 1292 1185 1096 1481 1346 1234 1139

1777

60 65

493

808 740 683 634

740

808

987

1077

1346 1234 1616 1616

- - - - -

- - - - - -

1367

1481

1367

1481

70 75

- - 592 -

- - - -

911

846 790 -

1015 - -

- - -

- - - 1269

1185 1111

- - -

1523 1422

Table 6 — Superheat Charging Table*

TEMP (F)

55 9 60 65 70 75 80 85 90

95 100 105 110 115

—

— - —

— — - — -

12 14 17

7 10 12

- - 7

- - - - 5

- - - - - - 8 11 15 19

- - - - - - - 6

- - - - - - - - 8 12 15

- - - - - - - -

- - - - - - - - - 6

- - - - -

54 56 58

10 13 16 19

10 13 16

6 9 12

20 18

60 62

23 26

21 24

21 24 27

19 21 15 12 15

- - -

29 32 35

27 30 33 35

21 24 28

18 21 25

9 13 16 21

10 14

5 9 13

- -

68 70

30 27

33 36 30

18 22

40 38

33 36 39 31 34 37 28 26 30 24 27

15 20

74 76

42 45 40 43 38 41

25 29 23 22 26

18 23

35 33 31

•Superheat at suction service valve. NOTE: Do not attempt to charge system under these conditions; refrigerant slugging may occur

Table 7 — Required Suction-Tube Temperature (F)*

TEMP (F)

61.5 64.2 67.1 70.0 0 35 2 37 4 39 6 8

10 12

41 43 45

43 45 47 49 45 47 47

14 49 51 53 55 16

51 53 55

16 53 20 55 22

24 59 61 26 61 63 65 28 30 32 34

63 65 67 65 67 69 67 69 71 69

36 71 73 38 73 75 40

•Temperature at suction service valve

75 77 79 81

37 39 39 41 43 45 47 49

49 51 53

55 57 59 61 57 59 61 63

71 73 75

43 45

59 61

41 43

51 53

57 59 61

67 69 71

71 73 75

73 75

77 79

73.0 76.0 79.2

47 49 51 53 55

55 57 59

63 65 67 65 67 69 71 69 71 73

77 79 81 83 85 79 81 83

49 51

51 53

55 57 57

81 83 85

83 85

59 61 63 65 67 65 67

69 71

75 77

77 79 81 83

49 51

51 53

53 55 55 57 57 59

63 65

69 71

73 75 77

87 89 89 91

82.4

85.7

59 61 63

73 75

79 81

Page 18

Table 8 — Dry Coil Air Delivery (Cfm)*

at Indicated External Static Pressure and Voltage

— Horizontal Discharge (Without Filter)

V-PH-HZ

NLT018, NLT024, NHT024

208/230-1-60

NLT030, NMT030

208/230-1-60

NHT030, NLT036 NMT036, NLT042 NMT042 208/230-1-60 208/230-3-60,

460-3-60tt

NET036, 042 208/230-1-60 208/230-3-60

460-3-60tt

NHT036, NVT036 NHT042, NVT042 208/230-1-60 208/230-3-60

460-3-60tt

NLT048, NMT048 NHT048 208/230-1-60 208/230-3-60

460-3-60tt

NVT048 208/230-1-60 208/230-3-60

460-3-60tt

NLT060, NMT060

NHT060, NVT060 208/230-1-60 208/230-3-60

460-3-60tt

*Air delivery values are without air filter and are for dry coil. See Table 10 for wet coil pressure drop.

Deduct field-supplied air filter pressure drop and wet coil pressure drop to obtain external static pressure available for ducting.

tFactory blower-motor speed setting for heating operation.

‘'Factory blower-motor speed setting for cooling operation.

ttDo not change blower speed settings for units with 460-v (high speed only).

NOTE: Do not operate the unit at a cooling airflow that is less than 350 cfm per each 12,000 Btuh of rated cooling capacity. Evaporator coil icing may occur at airflows below this point. Water blow-off may occur at airflows above 450 cfm per 12,000 Btuh of rated cooling capacity

MOTOR SPEED

Lowf, Med“

HI Lowf,

Med“ Hi

Lowf, Med“

Hi Lowf,

Med“ Hi

Lowf, Med“

in. wg

Watts Cfm Watts 511 483 464 440 Cfm Watts 519 Cfm 1184 1163 Watts 620 Cfm 1443

Watts Cfm Watts 670 Cfm 1765 1705 1621 1521 1383 Watts

Cfm Watts Cfm Watts 740 700 Cfm 1913 1820 Watts 790 760 720 690 Cfm 2032 Watts 770 730 690 650 Cfm 1945 1880 Watts 850 Cfm 2138 Watts Cfm 1931 1901 1862 1813 Watts 1220 1165

Cfm 2376 2311 2244 Watts 1125 Cfm 2184 2125 Watts Cfm 2380

0.0 0.1

451

1185 1129

1370

560 544 527 505

1515 1452

873 847 814 785 758 1717 1075 1030 2119

985 950

1220 1175

427

1291 1221 1142 1063

507

602

1414

650

1690 1645 1597 1550

2062

1942

810

2045

1055

2307

208 V

0.2 0.3

407 383

1088

1150

1376 1329 1279

1389 1308

2063

1026 979

492

1134 1105

581 559

631

995 960

1995 1913

660

1645 1544

1736

1844 1759 1636

1708 1611

1796

770 730

1943 1846

915

1080

1130

2170

1015 980

2000 1938 1125 1080 2262 2165

0.4 0.5

365 348

420

477 455 431 569

532 493 670

482 461

1227

602 573

930

1863 1793 2135 2066 1998

615 580

650 610

610 575 810 765 730

690

1738

890 860

1768 1703 2183 2125 1035 995

2083

940

1040 2095

0.0

501 477

922

1256 1195

402

1003 1442 1359

1064

1197

1105

542

1254 1857 1795 1708

734 987

1496 1979 1922 1859

900 1121 1087 1046

540 755 725 680

1428

1514

1508 2061 1970 1892 1813

655

1624

2003 2511

1880 2285 2225 2163 2106 1005

2024

561 533 514

1248

1519

610

1597 1530

720 701

1976 1909

850

2086

890 855

2178

820

1095

1300

905

1205 1125

1300 1250 2487

230 V or 460 V

0.1

0.2

0.3

457

1148

1081

1285 1202

557 542

1226 1211 1194 1164

652 631 609 582

1489 1449 1399

593 575 500

1464 1378 1293

680 653 625

1603 1457

911

945

1802 1017 981 1931 1858

1714 1603

1806

820 780

1983 1883

2081

1055 1010

1265 1220 2431

2412 2335 2260 2179

1782 1665

820 780 750

1941 1869 1769

2071 2005 1931 1854

1180 1120 2271 2168

2359 1095 1060 1030

1210 1165 1130 1085

0.4

433

415

1031

490

470

1119

527

505

1347

524

877 850

1734

650 610

750 715

695

655

1704

975 935

2045

0.5

398 971 452

1056

481

1120

543

1261

494

1164

594

1321

809

1667

952

1795

575

1495

675

1545

610

1580

715

1650

890

1085 2087

990

1980

2110

The heating and/or cooling airflow of 208/230-v directdrive blower motors can be changed by changing the lead connections of the blower motor. The motor leads are colorcoded as follows:

black =high speed blue = medium speed

red =low speed

NOTE: For all 208/230-v direct-drive units, the red motor lead connected to the heat relay (L) on PCI blower control determines the heating speed and resulting airflow, and the blue motor lead connected to the cooling relay (H) on PCI blower control determines the cooling speed and resulting airflow. See the unit wiring label.

To change the heating and/or cooling speed of a directdrive motor, connect the appropriate color-coded lead at blower motor connector to speed-tap desired. (See unit wiring label.)

When installing a 208- or 230-v direct-drive unit that is factory connected for heating and cooling speeds that are not the same, and the same speed for both heating and cool ing is required for a particular application, disconnect red lead at terminal L of heat relay and connect to terminal MI on PCI blower control. Connect a field-supplied jumper be tween terminal L on heat relay and terminal H of cooling relay. Connect blue lead at blower motor to appropriate speed tap.

Page 19

Table 9 - Dry Coil Air Delivery (Cfm)*

at Indicated External Static Pressure and Voltage

— Vertical Discharge (Without Filter)

V-PH-HZ

NLT018, NLT024 NHT024 208/230-1-60

NLT030, NI\/1T030 208/230-1-60

NHT030, NLT036

NMT036, NLT042

NMT042 208/230-1-60 208/230-3-60

460-3-60tt

NET036, NET042

208/230-1-60

460-3-60tt

NHT036, NVT036

NHT042, NVT042 208/230-1-60 208/230-3-60

460-3-60tt

NLT048, NHT048

NMT048 208/230-1-60 208/230-3-60

460-3-60tt

NVT048

208/230-1-60

208/230-3-60

460-3-60tt

NLT060, NMT060

NHT060, NVT060

208/230-1-60

208/230-3-60

460-3-60tt

MOTOR

SPEED

Lowf, Med* **

Hi Lowf,

Med** Hi

Lowf, Med**

Hi Lowf,

Med** Hi Lowf,

Med** Hi

in. wg 0.0 0.1

Watts 451 417 Cfm Watts 491 Cfm Watts 509 497 Cfm 1155 Watts 600 582 Cfm 1411 1362

Watts Cfm 1494 Watts 651 Cfm Watts

Cfm Watts Cfm Watts Cfm 1797 Watts 750 715 Cfm 1885 Watts 710 Cfm Watts 785 750 Cfm 1957 1873 Watts Cfm Watts Cfm Watts 1095 1025 Cfm Watts 1190 1145 Cfm 2325 2255

1308 1234

1683 1615

1653 1611

1895 1839

1833 1768

1878 1821 1130 2199 2134

2125 2165

1102

1138

522

1430

833

945 915

680

1709

1779

965

1097

463 454 420 400

504

631

792

645

680

915

208 V

0.2

1045

1162

1120

1326

1358

1536

1569

1803

1620

1704

1700

1786

1767 1026 2095

2005 1095 2187 2120

0.3 0.4

373 355 338 491

397

996 942 889 1196 1161

1084 1020 951

467 445 421

482

1104

561

1249

485

1273

610

1440

765

1518

890

1740 1029 1532 1971 1899 1830 1762 1673

610

680

1608

650

1599 1505 1390

720

1699 1598 1495 1997 1907 1817 1713 1618

875

1716 1654 1584 2060 1996

985

1073 1031 1218 1200

539 512 473 650 632

1195 1133 1493 1457 1412

663 440

1174 1058 1574 1507

575 540 517 695 680 658

1274

725 700 650 880 850 810 790

1473

865

580 545 510 705 670 640 595 570

1547 1448 1315 1855 1707 1684 1574

650 615 585 795 765 735 700 670

1507 1404 1906 1821 1722

600 570 520 740 705 665 635 600

685 650 610 835 805 770 735 705

840 800 770

985 970

1960 2060 1799 2280 2213 2168 2019 1921 1856

950 910

1887

1950 1050 1010 975 1280 1230 1190 1140 Ilio 1065

2050 1975 2437 2365 2390

1153 1763 1700 1619

1373 1805 1748 1692 1650 1582

805 770 1005

1830 2225 2170 2110 2050

0.0 0.1 0.2 0.3 0.4

0.5

382 541

1379

559

422

915

875 1175 1095 1065

600 573 555 523 491 470

1918

1025 985 935

1200

230 V or 460 V

467 447 423

1101

494 470 450 432

513

1301 1225 1143 1075 1002

532

547

1182

611

1431

965

935 900 865 820

1849

1165

1752

1921 1120

0.5

405 388

1050 993 932

517 495 471

1165

1358

1341 1237 1115

1492 1343

1623 1533 1410

1670 1561 1442

1075 1030 995

2220

1132

1088

589 562

1274

624

590 563

745

1498 1361

900 870 830

1075

1030 995

1030 1000 960

1987

2145

523

1218

1215

710

1475

1568

535

640

560

670

1506

1930

2075

*Air delivery values are without air filter and are for dry coil. See Table 10 for wet coil pressure drop

Deduct field-supplied air filter pressure drop and wet coil pressure drop to obtain external static pressure available for ducting.

tFactory blower-motor speed setting for heating operation.

"Factory blower-motor speed setting for cooling operation.

tfDo not change blower speed settings for units with 460-v (high speed only).

NOTE: Do not operate the unit at a cooling airflow that is less than 350 cfm per each 12,000 Btuh of rated cooling capacity. Evapoprator coil icing may occur at airflows below this point. Water blow-off may occur at airflows above 450 cfm per 12,000 Btuh of rated cooling capacity

UNIT CONTROLS —All compressors have the following internal-protection controls:

1. High-Pressure Relief Valve — This valve opens when

the pressure differential between the low and high side becomes excessive.

2. Compressor Overload — This overload interrupts power

to the compressor when either the current or internal tem perature become excessive, and automatically resets when

the internal temperature drops to a safe level.

This overload may require up to 60 minutes (or longer) to reset; therefore, if the internal overload is suspected of being open, disconnect the electrical power to the unit and

check the circuit through the overload with an ohmmeter or continuity tester.

COOLING SEQUENCE OF OPERATION NOTE; Although the actual unit wiring may vary slightly

from that shown in Fig. 13 and 14, the sequence of opera tion will not be affected.

With the room thermostat SYSTEM switch in the COOL position and the FAN switch in the AUTO, position, the cooling sequence of operation is as follows:

When the room temperature rises to a point that is slightly above the cooling control setting of the thermostat, the ther mostat completes the circuit between thermostat terminal R

Page 20

to terminals Y and G. These completed circuits through the thermostat connect contactor coil C (through unit wire Y)

and relay coil IFRl (through unit wire G) across the 24-v secondary of transformer TRAN.

The normally open contacts of energized contactor C close

and complete the circuit through compressor motor COMP and condenser fan motor OFM. Both motors start instantly.

The set of normally open contacts of energized relay IFRl close and complete the circuit through evaporator blower motor IFM. The blower motor starts instantly.

NOTE: The cooling cycle remains “on” until the room tem perature drops to point that is slightly below the cooling control setting of the room thermostat. At this point, the thermostat “breaks” the circuit between thermostat termi nal R to terminals Y and G. These open circuits de energize contactor coil C and relay coil IFRl. The condenser

and compressor motors stop. After a 45-second delay, the

blower motor stops. The unit is in a “standby” condition,

waiting for the next “call for cooling” from the room thermostat.

Table 10 - Wet Coil Pressure Drop

MODEL

018,024

030

036,042

048

060

AIRFLOW

(cfm)

600 700 800 900

900 1000 1200

1000 1200 1400 1600

1400 1600 1800

1700 1900 2100 2300

WET COIL PD

(In. wg)

038 .044 .052

062 .042

.050 .064

.038 .050 .064 .080

050 .060 .072

.100 .120 .140 .160

MAINTENANCE

To ensure continuing high performance, and to minimize the possibility of premature equipment failure, periodic main tenance must be performed on this equipment. This com

bination heating/cooling unit should be inspected at least

once each year by a qualified service person. To trouble shoot heating or cooling of units, refer to Tables 11 and 12.

NOTE TO EQWPMENT OWNER: Consult your local Dealer about the availability of a maintenance contract.

A WARNING

The ability to properly perform maintenance on this equip ment requires certain expertise, mechanical skills, tools

and equipment. If you do not possess these, do not at

tempt to perform any maintenance on this equipment,

other than those procedures recommended in the Us

er’s Manual. FAILURE TO HEED THIS WARNING COULD RESULT IN SERIOUS PERSONAL INJURY AND POSSIBLE DAMAGE TO THIS EQUIPMENT.

The minimum maintenance requirements for this equip

ment are as follows:

1. Inspect air filter(s) each month. Clean or replace when necessary.

2. Inspect cooling coil, drain pan and condensate drain each cooling season for cleanliness. Clean when necessary.

3. Inspect blower motor and wheel for cleanliness and check lubrication each heating and cooling season. Clean and lubricate (if required) when necessary.

4. Check electrical connections for tightness and controls for proper operation each heating and cooling season. Service when necessary.

5. Check and inspect heating section before each heating season. Clean and adjust when necessary.

6. Check and clean vent screen if needed.

A warning

Failure to follow these warnings could result in serious personal injury:

1. Turn off gas supply, then turn off electrical power

to the unit before performing any maintenance or service on the unit.

2. Use extreme caution when removing panels and parts. As with any mechanical equipment, personal injury can result from sharp edges, etc.

3. Never place anything combustible either on, or in contact with, the unit.

4. Should overheating occur, or the gas supply fail to shut off, shut off the external main manual gas valve to the unit, then shut off the electrical supply.

Page 21

Table 11 — Heating Troubleshooting Chart

SYMPTOM

IGN locked out.

Pilot will not light.

Burners will not ignite.

Inadequate heating.

Poor flame characteristics.

CAUSE

LED flashing LED glowing continuously No spark at electrode

Spark shorting out to main burner Realign electrode tip away from main burner but maintain

No gas at pilot burner Clean pilot orifice.

Water in gas line No power to furnace No 24-v power supply to control circuit Miswired or ioose connections Dirty pilot — yellow flame Clean pilot orifice. Pilot burning improperly — sharp blue flame Replace pilot. Burned-out heat anticipator in thermostat No gas at main burners

Broken thermostat wire Dirty air filter Gas input to furnace too low

Unit undersized tor application Restricted airflow Blower speed too low Use faster speed tap

Limit switch cycles main burners

Incomplete combustion results in; Aldehyde odors, CO, sooting flame —

floating flame

Look for problems external to the ignitor module. Replace IGN control. Check air gap between electrode tip and pilot target

Gap should be as shown in Fig. 15. Readjust as necessary.

Clean moisture or dirt accumulation on electrode ceramic with cloth.

Cracked ceramic — replace pilot electrode assembly Check for loose or broken wiring at and between electronic

control head and electrode Replace wire or tighten connection as necessary.

Check fuses or circuit breaker to ensure voltage to unit. Check for 24 v between TH and COM. If you read 24 v and

above steps have been completed, replace electronic ignition control.

spark gap to pilot burner. See Fig. 15.

Check inlet pressure to gas value. Recommended operating pressure 7-in. wg natural gas, 11-in. wg LP gas; 0.5 psig (13.6in. wg) max. pressure

Check for 24 v between terminals PV and COM If you read 24 V and above steps have been completed, replace gas valve.

Drain — install water trap. Check power supply, fuses, wiring or circuit breaker. Check transformer — replace if necessary. Check all wiring and wirenut connections.

Replace thermostat.

1. Check for 24 v between terminals MV and COM on control head If you read 24 v, replace gas valve portion of control head/gas valve assembly.

2. If 24 V is not present, check flame sensor for cracked ce ramic insulator or shorted sensor cable.

Run continuity check to locate break. Clean or replace filter as necessary. Check gas pressure at manifold. Clock gas meter for input. If

loo low, increase manifold pressure, or replace with correct orifices.

Replace with proper unit — or add additional unit

Clean or replace filter — or remove any restriction.

Check temperature rise.

Dirty air filters — clean or replace.

Registers closed, restricted ductwork — open or remove

restriction.

Check temperature rise.

Check heat anticipator setting on thermostat — readjust.

Check all screws around flue outlets and burner compartment

— tighten. LACK OF COMBUSTION AIR. Cracked heat exchanger — replace. Overfired furnace — reduce input, or change orifices. Check vent for restriction — clean as required Check orifice for burner alignment.

REMEDY

GR — Ground LP — Liquid Propane

Page 22

Table 12 — Cooling Troubleshooting Chart

SYMPTOM

Cpmpressor and condenser fan will not start.

Compressor will not start but condenser fan runs.

Compressor cycles (other than normally satisfying thermostat).

Compressor operates continuously.

Excessive head pres-

sure.

Head pressure too low.

Excessive suction pressure.

Suction pressure too low.

CAUSE REMEDY

Power failure Call power company Fuse blown or circuit breaker tripped Replace fuse or reset circuit breaker.

Defective thermostat, contactor, transformer or control relay

Insufficient line voltage Determine cause and correct. Incorrect or faulty wiring Check wiring diagram and rewire correctly. Thermostat setting too high Faulty wiring or loose connections in compres

sor circuit Compressor motor burner out, seized or internal

overload open Defective run/start capacitor, overload, start re

lay One leg of 3-phase power dead Replace fuse or reset circuit breaker.

Refrigerant overcharge or undercharge Blow refrigerant, evacuate system and recharge to nameplate. Defective compressor Replace and determine cause

Insufficient line voltage Determine cause and correct Blocked condenser Defective run/start capacitor, overload or start

relay Defective thermostat Faulty condenser fan motor or capacitor Replace. Restriction in refrigerant system Dirty air filter Replace filter. Unit undersized for load Decrease load or increase unit size. Thermostat set too low Reset thermostat.

Low refrigerant charge Locate leak, repair and recharge. Leaking valves in compressor Air in system Blow refrigerant, evacuate system and recharge. Condenser coil dirty or restricted Dirty air filter Dirty condenser coil Clean coil. Refrigerant overcharged Purge excess refrigerant. Air in system Blow refrigerant, evacuate system and recharge. Condenser air restricted or air short-cycling

Low refrigerant charge Compressor valves leaking

Restriction in liquid tube Remove restriction.

High heat load Check for source and eliminate. Compressor valves leaking

Refrigerant overcharged Purge excess refrigerant.

Dirty air filter

Low refrigerant charge

Metering device or low side restricted

Insufficient evaporator airfiow Increase air quantity. Check filter — replace if

Temperature too low in conditioned area Outdoor ambient below 55 F Install low-ambient kit.

Field-installed filter-drier restricted Replace.

Replace component.

Lower thermostat setting below room temperature Check wiring and repair or replace.

Determine cause. Replace compresor.

Determine cause and replace.

Determine cause.

Determine cause and correct. Determine cause and replace.

Replace thermostat.

Locate restriction and remove.

Replace compressor.

Clean coil or remove restriction.

Replace filter.

Determine cause and correct.

Check for leaks, repair and recharge.

Replace compressor

Replace filter Check for leaks, repair and recharge. Remove source of restriction.

necessary. Reset thermostat.

Page 23

Air Filter

A CAUTION

Never operate the unit without a suitable air filter in

the return-air duct system. Always replace the filter with the same dimensional size and type as originally installed. See Table 1 for recommended filter sizes.

Inspect air filter(s) at least once each month and replace (disposable-type) or clean (cleanable-type) at least twice dur ing each heating and cooling season or whenever the filter(s) becomes clogged with dust and lint.

Replace filters with the same dimensional size and type

as originally provided, when necessary.

Unit Top Removal

A CAUTION

Condenser fan and motor are fastened to the unit top. When removing the top, use extreme care to not pull

the fan motor leads loose.

NOTE; When performing maintenance or service proce dures that require removal of the unit top, be sure to per form all of the routine maintenance procedures that require top removal, including: inspection of the heat exchanger area, coil inspection and cleaning, and condensate drain pan inspection and cleaning.

Only qualified service personnel should perform mainte nance and service procedures that require unit top removal. Refer to the following top removal procedures;

1. Turn off gas supply, then turn off electric power to unit.

2. Remove all screws that secure unit top, including screws

around 4 sides and those on top that screw into internal divider panels. Save all screws.

3. Tape all side panels at each seam near unit top. Use tape

strips that are at least 5-in. long to prevent sides from falling when top is removed.

4. Lift top from unit carefully. Set top on edge and make

sure that top is supported by unit side that is opposite duct (or plenum) side. Use extreme care to prevent dam

age to the fan blades, motor and insulation.

5. Carefully replace and secure unit top to unit, using screws

removed in Step 2, when maintenance and/or service pro

cedures are completed. (Be sure to use original screws that have rubber washers to seal out water when secur ing top to internal divider panels.)

Evaporator Blower and Motor

NOTE: Motors without oilers are prelubricated. Do not at

tempt to lubricate these motors.

For longer life, operating economy and continuing effi

ciency, clean accumulated dirt and grease from the blower

wheel and motor annually.

Lubricate the motor every 5 years if the motor is used

intermittently (thermostat FAN switch in AUTO, position).

or every 2 years if the motor is used continuously (thermo

stat FAN switch in ON position).

A WARNING

Turn off the gas supply, then disconnect and tag elec trical power to the unit before cleaning and lubricating the blower motor and wheel. Failure to adhere to this warning could cause personal injury or death.

To clean and lubricate the blower motor and wheel for

direct-drive models;

1. Remove and disassemble blower assembly as follows: a. Remove blower access door. b. Disconnect blower-motor leads from their termina

tion points at motor. Disconnect yellow lead from control box at capacitor. Disconnect auxiliary limitswitch leads at switch.

c. Remove blower assembly from unit. Be careful not

to tear insulation in blower compartment.

d. Ensure proper reassembly by marking blower wheel

and motor in relation to blower housing before dis assembly.

e. Loosen setscrew(s) that secures wheel to motor shaft,

remove screws that secure motor mount brackets to housing and slide motor and motor mount out of housing.

2. Lubricate motor as follows; a. Thoroughly clean all accumulations of dirt or grease

from motor housing.

b. Remove dust caps or plugs from oil ports located at

each end of motor.

c. Use a good grade of SAE 20 nondetergent motor oil

and put one teaspoon (5 cc, Vie oz., or 16 to 25 drops) in each oil port.

d. Allow time for oil to be absorbed by each bearing,

then wipe excess oil from motor housing.

e. Replace dust caps or plugs in oil ports.

3. Remove and clean blower wheel as follows: a. Ensure proper reassembly by marking wheel orienta

tion and cutoff plate location.

b. Remove screws holding cut-off plate, and remove plate

from housing.

c. Lift wheel from housing. When handling and/or clean

ing blower wheel, be sure not to disturb balance weights

(clips) on blower wheel vanes.

d. Remove caked-on dirt from wheel and housing with

a brush. Remove lint and/or dirt accumulations from wheel and housing with vacuum cleaner, using soft brush attachment. Remove grease and oil with mild

solvent. e. Reassemble wheel and cut-off plate into housing. f. Reassemble motor into housing. Be sure setscrews

are tightened on motor shaft flats and not on round part of shaft.

Page 24

Heating Section — Ensure dependable and efficient

heating operation by inspecting the heating section before each heating season, and cleaning when necessary.

Proceed as follows to inspect and clean heating section:

1. Turn off gas and power to unit.

2. Remove burner access door.

3. Disconnect 2 wires from inducer motor.

4. Remove complete inducer assembly from unit.

5. Remove screws that secure collector box to heat ex changer, exposing flue openings.

6. Remove flue choke.

7. Clean heat exchanger cells using field-provided small

wire brush, steel spring cable, reversible electric drill and vacuum cleaner.

To assemble wire brush and steel spring cable:

NOTE: The items below can be purchased at a local hardware store.

a. Use 4 ft of Vi in. diameter high-grade steel spring

cable (commonly known as drain cleanout or RotoRooter cable).

b. Use Vi-in. diameter wire brush (commonly known

as 25-caliber rifle cleaning bmsh).

c. Insert twisted wire end of brush into end of spring

cable; crimp tight with crimping tool or strike with ball-peen hammer. Tightness is very important.

d. Remove metal sleeve from wire brush to allow proper

brush action.

To clean each heat exchanger cell:

a. Attach variable-speed reversible drill to end of spring

cable (end opposite brush).

b. Insert brush end of cable into upper opening of cell

and slowly rotate with drill. Do not force cable. Gradually insert at least 3 ft of cable into 2 upper passes of cell.

c. Work cable in and out of cell 3 or 4 times to obtain

sufficient cleaning. Do not pull cable with great force.

Reverse drill and gradually work cable out. d. Remove burner assembly. e. Insert brush end of cable in lower opening of cell

and proceed to clean in same manner. f. Repeat above procedures until each cell in unit is

cleaned.

g. Using vacuum cleaner, remove residue from each

cell.

h. Using vacuum cleaner with soft brush attachment,

clean burner assembly.

i. Reinstall burner assembly.

8. After cleaning, check sealant and gaskets to make sure that they have not been damaged. If new sealants or gaskets are needed, contact your Distributor.

9. Reinstall flue choke. Be sure all screws are in and are tight.

10. Clean and replace flue collector assembly, making sure all screws are secure.

11. Replace inducer assembly.

12. Reconnect the 2 wires to inducer motor.

13. Replace burner access door.

14. Turn on power and gas.

15. Set thermostat and check unit for proper operation.

Pilot — Inspect the pilot and clean (when necessary) at

the beginning of each heating season. Remove the accumu lation of soot and carbon from the pilot. The pilot flame must be high enough for proper contact with the flame sen sor. Pilot flame must also come in contact with the pilot hood (target) for proper operation. If the pilot flame ap pears too hard (lifting and blowing) or too soft (unstable), check inlet gas pressure for proper value. (See Table 4.) The spark electrode must be located so the spark travels through a combustible mixture of gas; if necessary, readjust the electrode as shown in Fig. 15; be certain to maintain the

Vs-in. spark gap.

TARGET

Fig. 15 — Position of Electrode to Pilot

Condenser Coil, Evaporator Coil and Conden sate Drain Pan — Inspect the condenser coil, evapo

rator coil and condensate drain pan at least once each year. Proper inspection and cleaning requires the removal of the unit top. See Unit Top Removal section.

The coils are easily cleaned when dry; therefore, inspect and clean the coils either before or after each cooling sea son. Remove all obstructions, including weeds and shrubs, that interfere with the airflow, through the condenser coil.

Straighten bent fins with a fin comb. If coated with dirt or lint, clean the coils with a vacuum cleaner, using the soft

brush attachment. Be careful not to bend the fins. If coated

with oil or grease, clean the coils with a mild detergentand-water solution. Rinse coils with clear water, using a garden hose. Be careful not to splash water on motors, in sulation, wiring or air filter(s). For best results, spray con denser coil fins from inside to outside the unit. On units with an outer and inner condenser coil, be sure to clean be tween the coils. Be sure to flush all dirt and debris from the unit base.

Inspect the drain pan and condensate drain line when in

specting the coils. Clean the drain pan and condensate drain by removing all foreign matter from the pan. Flush the pan and drain tube with clear water. Do not splash water on the insulation, motor, wiring or air filter(s). If the drain tube is restricted, clear it with a “plumbers snake” or similar probe device.

Page 25

Condenser Fan

A CAUTION

Keep the condenser fan free from all obstructions to ensure proper cooling operation. Never place articles on top of the unit. Damage to unit may result.

Remove control and compressor access panels. Inspect

the fan blades for cracks or bends each year. Make sure

__________

that blades clear the motor by no more than % inch. If the

blade assembly has slipped down the motor shaft, adjust the fan position on the motor shaft by loosening the set-

screw(s), then moving the blade assembly up. Be sure that the setscrew(s) is on the flat(s) of the motor shaft before

tightening.

Electrical Controls and Wiring - Inspect and check

the electrical controls and wiring annually. Be sure to turn

off the gas supply, and then the electrical power to the unit.

Remove the control, blower and compressor compart ment access panels to locate all the electrical controls and wiring. Check all electrical connections for tightness. Tighten all screw connections. If any smoky or burned connections are noticed, disassemble the connection, clean all the parts, restrip the wire end and reassemble the connection properly and securely.

After inspecting the electrical controls and wiring, re place all the panels. Start the unit, and observe at least one complete heating cycle and one complete cooling cycle to ensure proper operation. If discrepancies are observed in either or both operating cycles, or if a suspected malfunc tion has occurred, check each electrical component with the proper electrical instrumentation. Refer to the unit wiring label when making these checkouts.

NOTE: Refer to the heating and/or cooling sequence of op

eration in this publication as an aid in determining proper control operation.

Refrigerant Circuit — Inspect all refrigerant tubing con

nections and the unit base for oil accumulations annually. Detecting oil generally indicates a refrigerant leak.

If oil is detected or if low cooling performance is sus pected, leak-test all refrigerant tubing using an electronic leak-detector, or liquid-soap solution. If a refrigerant leak is detected, refer to Start-Up, Check for Refrigerant Leaks section.

If no refrigerant leaks are found and low cooling perfor mance is suspected, refer to Checking and Adjusting Re frigerant Charge section.

Gas Input — The gas input does not require checking

unless improper heating performance is suspected. If a prob lem exists, refer to Start-Up section.

Evaporator Airflow — The heating and/or cooling air

flow does not require checking unless improper perfor mance is suspected. If a problem exists, be sure that all

supply- and return-air grilles are open and free from ob structions, and that the air filter is clean. When necessary,

refer to Indoor Airflow and Airflow Adjustment section to check the system airflow.

Metering Device Servicing - See Fig. 16 for me

tering device components. The piston has a refrigerant me tering orifice through it. The retainer forms a sealing sur face for liquid line flare connection. To check, clean or replace piston:

1. Shut off power to unit.

2. Remove refrigerant from unit using approved refrigerant removal methods from both high- and low-service port connections.

3. Remove liquid line flare connections from metering device.

4. Note position of arrow on metering device body with respect to unit.

5. Pull retainer out of body. Be careful not to scratch flare sealing surface. If retainer does not pull out easily, care fully use locking pliers to remove retainer. Replace

scratched or damaged retainer.

6. Slide piston out by inserting a small, soft wire through

metering hole (18-gage thermostat wire). See that me tering hole, sealing surface around piston cones and fluted portion of piston are not damaged.

7. Use the chart on the unit access panel to determine proper

arrangement and size of piston. See Table 13 for piston sizes.

8. Clean piston refrigerant-metering orifice.

9. Replace retainer 0-ring (part no. 99CC501052).

Liquid Line Strainer — The liquid line strainer (t<

protect metering device) is made of wire mesh and locate«

in the liquid line on inlet side. Strainer is pressed into th line. Remove strainer by threading a no, 10 sheet-metal scre\ into strainer and pulling the screw with pliers.

FLARE NUT

STRAINER

RETAINER

COOLING

Fig. 16 — Metering Device Components

Page 26

Table 13 — Piston Sizes

UNIT 48 NLT018 NLT024

PISTON IDENTIFICATION

59 63

NHT024 63 NLT030 73

NMT030 73 NHT030 73

NET036 80 NLT036 80 NMT036 80 NHT036 80 NVT036

NET042 NLT042 NMT042 NHT042 NVT042

NLT048 NMT048 NHT048 NVT048

NLT060 NMT060 NHT060 NVT060

80 82

82 82 84 84

86 86

101 101 101 101

Page 27

B^DokM |4 PC 111 Catalog No. 564-920 Printed in U.S.A Form 48NT-20SI Pg 28 11-91 Replaces: 48NT-19SI

Tab hah a

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

Carrier 48NLT User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

A CAUTION

A CAUTION

Fig. 4 - Suggested Rigging

A CAUTION

A CAUTION

A CAUTION

A WARNING

Fig. 8 — Location of Coii Area Not to be Drilled

A CAUTION

A WARNING

A CAUTION

Á WARNING

Fig. 10 — High- and Control-Voltage Connections

A WARNING

A WARNING

Fig. 13 — Typical Single-Phase Wiring Diagram

Fig. 14 — Typical 3-Phase Wiring Diagram

A CAUTION

A CAUTION

A CAUTION

A WARNING

A CAUTION

A WARNING

A CAUTION

A CAUTION

A WARNING

A CAUTION