Carrier 48N User Manual

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Page 1

48N

HEATING A COOLING

Packaged Heating/Cooling Units

Installation Instructions

NOTE TO INSTALLER: Leave these instructions, the User’s

Manual, and Parts Replacement Guide with the unit after

installation.

A WARNING

Improper installation, adjustment, alteration, service, maintenance, or use can cause carbon monoxide poison ing, explosion, fire, electric shock, or other occurrences which may injure you or damage your property. Con

sult a quahfi^ed installer, service agency, or the gas suppher for information or assistance. The qualified agency must use factory authorized kits and accessories when modifying this unit.

NOTE: The installation of this unit must conform to the

guidelines presented in these unit Installation Instructions. Read and become familiar with this publication before start ing the installation.

INTRODUCTION

Model 48N Packaged Gas/Electric Unit is fully self-con tained, combination gas heating/electric cooling unit designed for outdoor installation. Model 48N may be installed either on a rooftop or groimd-level slab. See Fig. 1. For rooftop downflow applications, an accessory roof mounting curb must be used.

Model 48N Unit meets the California maximum oxides of nitrogen (Nox) emission regulations.

These units are equipped with an energy-saving, automatic, intermittent, electric spark ignition system that does not have a continuously burning phot. All units are manufac tured with natural gas controls.

These units are designed for a minimum continuous return air temperature of 60 °F. (dry bulb) or an intermittent opera tion down to 55°F. (dry bulb) such as when used with a

night set back thermostat. Model 48N is A.G.A. and C.G.A. design-certified. See

Tables 2 thru 7 for the heating input ratings. These units are factory-charged with R-22 refrigerant.

Installation is simple: connect gas supply, air ducts, highand low-voltage wiring, condensate drain, and instedl a fieldsupplied air filter.

All units can be connected into existing duct systems that

are properly sized and designed to handle an airflow of 350 to 450 Cfm per each 12,000 Btuh of rated cooling capacity.

See Tables 2 thru 7 for cooling and heating airflow require

ments.

NOTE: When installing any accessory item, see the manu

facturer’s Installation Instructions packaged with the ac cessory. The Qualified Agency must use factory authorized kits or accessories when modifying this unit.

Fig. 1—Model 48N

IMPORTANT—READ BEFORE INSTALLING

1. This installation must conform with all applicable local and national codes.

2. The power supply (volts, hertz, and phase) must corre spond to that specified on unit rating plate.

3. The electrical supply provided by the utility must be sufficient to handle load imposed by this unit.

4. Refer to the 48N dimensional drawing for locations of

gas inlet, electrical inlets, condensate drain, duct con nections, and required clearances before setting unit in place. Figs. 2 and 3.

5. Locate the unit where the vent cap will be a minimum

of 4-ft from openable windows or doors.

6. This installation must conform with local building codes and with the National Fuel Gas Code ANSI

Z223.1-1984 and Addenda Z223.la-1987 (In Canada, CAN/CGA B149.1, (2)-M86) or NFPA 54-1984 TIA-5484-1. Refer to Provincial and local plumbing or wastewater codes and other applicable local codes.

7. For outdoor installation on wood flooring or on class A,

B, C roof covering materials.

GENERAL

Model 48N Packaged Gas/Electric Unit has been designed and tested in accordance with ANSI Z21.47-1987, ARI Standard 210-81, and ARI Standard 270-84, CAN/CGA-2.3M86, CAN 1-2.17-M80, CAN 1-2.21-M85, CSA C22.2 No. 0-

1982, No. 3-1979 and No. 119-M1985. The appliance design is certified by the American Gas Association (A.G.A.) and Canadian Gas Association (C.G.A.) for use with natural or LP (propane) gases with appropriate controls and orifices.

A87316

Tab llalla

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

^ PC 101 Catalog No. 564-816 Printed in U.S.A. Form 48NT-9SI Pg 1 9-88 Replaces: 48NT-8SI

Page 2

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EFFICIENCY RATING

CERTIFIED

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Unit Weights

Unit lbs.

48NLT018 47D 48NLT024 48NLT030 48NHT024

48NMT030

48NLT036 506 48NLT042

48NHT030 48NMT036 510 48NMT042

Above unit top

Duct side of unit____6 min. Side opposite blower access panel........30

Side opposite ducts NOTE: Provision must be made for fresh ambient air to reach the outdoor coil without recirculation of the air from the outdoor fan discharge.

Shipping Wt. Operating Wt.

474 454 490 480 460 486 476

516 496 500

520

48N REQUIRED CLEARANCES (Inches)

.....................

48 Blower access panel side

.........

30 Bottom of unit

lbs. A

450

470 103

486 107

480 106 490 108 500 110

..........................................

Corner Wt. lbs.

B C D

126 126 99

100

127 127 100 132 132 103

101

129 129 101

105 133 133 105

136 136 107

109

139 139 109 134 134 106 137 137 108 140 140 110

......................

BURNER ACCESS

RIGHT SIDE vmw

REAR VIEW

LEFT SIDE VIEM

FRONT VIFR

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EFFICIENCY RATING CERTIFIED

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Unit Weights

Shipping Wt.

550 556

594 600 060 624 630 636 616

48N REQUIRED CLEARANCES (Inches)

...................

___

48 Blower access panel side

6 min. Side opposite blower access panel

OPTIONAL SUPPLY-

AIR OPENING

-OPTIONAL RETURN AIR OPENING

Unit lbs. lbs. A

48NHT036 48NVT036 48NHT042 570 550 122 48NVT042 576 48NLT048 48NMT048 48NHT048 48NLT060 48NMT060 48NHT060

Above unit top Duct side of unit

Side opposite ducts...........30 Bottom of unit

NOTE: Provision must be made for fresh ambient air to reach the outdoor coil without recirculation of the air from the outdoor fan discharge.

Operating Wt.

530 117 536 119

556 124 574 128 580 130 159 160 586 131 161 162 604 610 138

..........................................

Corner Wt. lbs.

136

139 169 169 140

.......................

B C D

148

147 148 149 120 152 153 123 153 158 159 129

165 166 137 166 167 139

........

154

30 0

118

125

131 132

Page 4

This publication contains the following:

Step 1. Moving and Setting Unit in Place Step Step Step Step Step Step Step Step Step 10.

Step 1—Moving and Setting Unit in Place

Condensate Disposal Venting Gas Piping Duct Connections Electrical Connections

7. Preparing Unit for Steurtup

8. Heating Section Startup and Adjustments

9. Cooling Section Startup and Adjustments Care and Maintenance

A CAUTION

Use spreader bars and crate top when rigging the unit to be lifted. Model 48N must be rigged for lifting as shown in Fig. 4. Use extreme caution to prevent dam age when moving the unit. Unit must remain in an upright position during eJl rigging and moving opera tions. The unit must be level for proper condensate

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, ensure that the support is level and properly supports the unit.

A. Rooftop installation

A CAUTION

When installing the unit on a rooftop, be sure that the

roof will support the additional weight. Refer to Figs. 2 & 3 for Model 48N to obtain toted weight and corner weight information.

For downflow applications, an accessory roof-mounting curb must be installed on, and flashed into the roof before unit installation. The instructions for installing the acces sory curb are packaged with the curb.

For end-discharge applications place the unit on a level base

that provides proper support. On flat roofs, be sure that the unit is located at least 4-ins. above the highest expected water level on the roof to prevent flooding.

B. Ground-Level Installation

Place the unit on a sohd, level, concrete pad that is a mini

mum of 2-ins. thick and that extends approximately 2-in. beyond the casing on all four sides of the unit. Do not secure the unit to the pad except when required by local codes.

C. Clearances

The required minimiim operating and service clearances are shown in Figs. 2 and 3. Adequate combustion, ventilation and condenser air must be provided.

A CAUTION

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

The condenser fan discharges through the top of the unit. Ensure that the fan discheirge does not recirculate to the condenser coil. Do not locate the unit in either a corner or under a complete overhead obstruction. The minimum clear ance under a partial overhang (such as a normal house roof overhang) is 48-ins. above unit top. The maximum horizon tal extension of a partial overhang must not exceed 48-in..

Do not locate the unit where water, ice, or snow from an overhang or roof wiU damage or flood the unit by falling on the top. Do not locate the unit where grass, shrubs, or other plants will interfere with the airflow either into or out of the unit. Do not install the unit on carpeting, tile, or other com bustible material other than wood flooring. Furnace may be installed on wood flooriag or on Class A, B, or C roof cover ing materials.

Step 2—Condensate Disposal NOTE: Ensure that condensate-water disposal methods

comply with local codes, restrictions, and practices. Model 48N disposes of condensate water through a 3/4-in.,

Male Female NPT drain fitting. See Figs. 2 and 3 for location.

Install a 2-in. trap at the drain fitting to ensure proper drainage. See Fig. 5. Make sure that the outlet of the trap is at least 1-in. lower than the unit drain pan connection to 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 7/8-in. OD copper tubing, 3/4-in. galvanized pipe, or 3/4-in. plastic pipe. Do not undersize the tube. Pitch the drain tube downward at a slope of at least 1-in. in every 10ft of horizontal run. Be sure to check the drain tube for leaks.

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 3—Venting

The vent-cap assembly is shipped in the burner compart ment. Remove the access door to locate the assembly.

Page 5

Table 1—Maximum Gas Flow Capacity of Pipe in Cubic Feet of Gas Per Hour for Gas

Pressures of 0.5 PSIG or Less and a Pressure Drop of 0.5 inch Water Coiumn

(Based on a 0.60 Specific Gravity Gas)

Nominal

Iron Pipe,

Size,

Inches

1/2 .622 3/4

1 1-1/4 1-1/2

Ref: Table 0^4, NFPA 54—1984

*This length includes an ordinary number of fittings.

Internal

Diameter,

Inches

.824

1.049

1.380

1.610

10 20 30 40 50 60 70 80 90

175 120 97 82 73 66 360 250

680 455 375 320 285 260 240 220 205 195 175 160 145 1,400 950 770 600 580 530 490 460 430 400 360 325 300 280 2,100 1,460 1,180 990 900 810

170 151 138

200

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; thereby, ensuring proper orientation 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, and secure

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

2. Place the vent cap guard over the vent cap, orient holes

in vent cap guard with holes in vent cap and flue panel.

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

Step 4—Gas Piping

The gas supply pipe enters the unit through the access hole provided. The gas connection to the unit is made to the 1/2-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 1 and the National Fuel Gas Code for gas pipe sizing. Do not use cast-

iron pipe. Check the local utihty for recommendations con

cerning 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 1/2-in. FPT gas inlet on the unit

gas valve.

When instaUing the gas supply hne, observe local codes per taining to gas pipe installations. Refer to the National Fuel Gas Code ANSI Z223.1-1984 (In Canada, CAN/CGA B 149.1, (2)-M86) or NFPA 54-1984 in the absence of local buUding codes. Adhere to the following pertinent recom mendations:

1. Avoid low spots in long runs of pipe. Grade aU pipe 1/4-in. 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 1/2-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 lique fied petroleum gases as specified by local and/or national codes. Never use teflon tape.

Length of Pipe, Feet*

200

— —

135

125

750

100 125

118

690 650 620 550 500 460 430

53 50 44

110 103 93

150 175

40 84 77 72

4. Install sediment trap in riser leading to heating sec tion. This drip leg functions as a trap for dirt and con densate. Install trap where condensate can not freeze. Install this sediment trap by connecting a piping tee to riser leading to heating section, so that straightthrough section of tee is vertical. See Fig. 7. Then, con nect capped nipple into lower end of tee. Extend capped nipple below level of gas controls.

Install an accessible, external, manual main shut-off

5. valve in gas supply pipe within 6-ft of heating section.

Install ground-joint union close to heating section

6. between 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 piping to unit.

NOTE: When pressure testing the gas supply system after

the gas supply piping has been coimected to the unit gas valve, the supply piping must be disconnected from the gas vedve during any pressure testing of the piping systems at test pressure in excess of 0.5 psig. When pressure testing the gas supply piping system at test pressures equal to or less than 0.5 psig, the unit heating section must be isolated from the gas piping system by closing the external main manual shut-off valve and slightly opening the ground-joint

union.

Fig. 6—Vent Cap Assembly

Page 6

A73130

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 authority having jurisdiction, black iron pipe shall be installed at the gas valve and extend a minimum of 2-ins. 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 adhere to this warning could result in an explosion.

8. Check for gas leaks at all field-installed and factoryinstalled gas lines after all piping connections have been completed. Use soap-and-water solution (or method specified by local codes and/or regulations).

2. Select and size ductwork, supply-air registers, and return-air grilles according to ASHRAE recom mendations.

A CAUTION

When the duct-system fastening holes are being drilled into side of Model 48N instead of the unit duct flanges, use extreme ceire to avoid puncturing the coil or cofl. tubes.

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 gaskets 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 Tables 2 thru 7.

5. Size aU 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 located outdoors. Insulate ducts passing thru uncondi tioned space, and use vapor barrier in accordance with latest issue of SMACNÀ and ACCA minimum installa tion standards for heating and air conditioning sys tems. Secure aU 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 6—Electrical Connections

A WARNING

The unit cabinet must have an uninterrupted, unbro ken, electrical ground to minimize the possibility of per sonal injury if an electrical fault should occur. This ground may consist of electrical wire connected to the unit ground lug in the control compartment, or conduit approved for electrical ground when installed in accor dance with the National Electrical Code ANSI/NFPA 70-1987 (in Canada, Canadian Electrical Code CSA C22.1) and local electrical codes. Do not use gas piping as an electrical ground. A failure to adhere to this warn ing could result in the installer being hable for the per sonal injury of others.

Step 5—Duct Connections

Model 48N has duct flanges on the supply- and return-air openings on the side and bottom of the unit. See Figs. 2 and 3 for connection sizes emd locations.

NOTE: The design and installation of the duct system must be in accordance with the standards of the National Fire Protection Association for installation of nonresidence-type air conditioning and ventilating systems, NFPA No. 90A or 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. Remove appropriate panels from unit to obtain either side or bottom discharge. If models 48NLT018 thru 48NMT042 are installed in horizontal discharge apphcations, remove side duct covers, save screws, and install the covers on bottom duct openings. For models 48NHT036 thru 48NHT060 remove either side or bot tom duct covers as needed and discard.

A CAUTION

A failure to follow these precautions could result in damage to the unit being installed:

1. Make all electrical connections in accordance with National Electrical Code ANSI/NFPA 70-1987 and

local electrical codes governing such wiring. In Canada,

all electrical connections must be in accordance with CSA standard C22.1 Cemadian 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. Ensure that high-voltage power to unit is within oper ating voltage range indicated on unit rating plate. On 3-phase units, ensure that phases are balanced within 2%. Consult local power company for correction of improper voltage and/or phase balance.

Page 7

Table 2—Specifications—Models 48N (Sizes NLT018300 thru NLT036600)

MODEL 48N SIZE Unit Volts—Phase (60 Hz) Operating Voltage Range Unit Full Load Amps Maximum Fuse Size (Amps) Minimum Ampacity for Wire Sizing* Minimum Wire Size (75 C Copper) Maximum Wire Length (Ft.) Cooling Capacity (Btuh)t Rated Cooling Airflow (cfm)t

External Static Pressure (In.

water)t

ARI Sound Rating^

Rated Heating Input (cfm)

Output Capacity (Btuh)** AFUE(%)**

Rated Heating Airflow (cfm) Recommended Minimum Field-

Supplied Filter Size (Sq ln.)tt

Disposable-Type Cleanable- or High-Capacity Type

LT018300 LT024300

208/230—1 208/230—1

187—253

(Applicable notes are listed below Table 4.)

48N 48N

HT024300 LT030300 MT030300

48N 48N

HT030300

208/230—1 208/230—1 208/230—1 208/230—1

11.5

187—253

14.2

187—253 187—253 187—253 187—253

14.2

16.8 16.8 17.3

20 25 25 30 30

13.6 17.1 17.1 20.4 20.4 14 60 70

17,800 23,800 23,800 29,000 29,000

600

0.10

7.8 40,000 40,000 60,000 40,000 31,000 31,000 46,000

12 12

10 10 10 10

100 100 100 75

29,000

800 800 1100 1100 1100 1300 1300

0.10 0.10 0.15 0.15 0.15 0.15 0.15

8.0 8.0 8.0 8.0 8.0 8.0 8.0 60,000 80,000 60,000 60,000 60,000

31,000 46,000 61,000 46,000 48,000

77.5 77.5 77.5 77.5 77.5 77.5 658 658 740 658

288 192 256

384 384 528

256 352

740 987

48N

20.7

48N 48N

LT036300 LT036500

208/230—1

187—253

208/230—3

187—253 414—506

21.2 14.6 40 25

26.9

18.6 12 65

35,200 35,200

77.5

—

987 987 987

624 416

48N

LT036600

460—3

7.7 15

9.0 14

110

35,200

1300

0.15

8.0

48,000

—

Table 3—Specifications—Models 48N (Sizes MT036300 thru VT036600)

MODEL SIZE

Unit Volts—Phase (60 Hz) Operating Voltage Range Unit Full Load Amps Maximum Fuse Size (Amps) Minimum Ampacity for Wire Sizing* Minimum Wire Size (75 C Copper) Maximum Wire Length (Ft.) Cooling Capacity (Btuh)f Rated Cooling Airflow (cfm)f

External Static Pressure (In.

water)t ARI Sound Ratingf: Rated Heating Input (cfm)

Output Capacity (Btuh)** AFUE(%)**

Rated Heating Airflow (cfm) Recommended Minimum FieldSupplied Filter Size (Sq ln.)tt

Disposable-Type Cleanable- or High-Capacity Type

48N 48N

MT036300

MT036500 MT036600 HT036300

48N 48N 48N

208/230—1 208/230—3 460—3

187—253

21.2 14.6 40

26.9 10 75

35,200

1300

0.15 0.15

8.0 80,000 61,000

77.5

187—253 414—506

7.7

25 15

18.6 9,0 12 14 41 65 110

35,200 35,200 35,800

1300 1300

0.15 0.15 0.15 0.15

8.0 8.0 8.0 80,000 80,00 100,0000 64,000 64,000 78,000

—

987 987 987 1481

624 416

HT036500 HT036600

208/230—1 208/230—3

48N

460—3 208/230—1

187—253 187—253 414—506

22.4 16.8 8.5 ' 40 25 15

26.2 19.3 9.8

12 12

60 70 70

35,800 35,800

1300 1300 1300

8.0 8.0 100,000 100,000 80,000 80,000

77.5

—

— 77.5

1481 1481

48N 48N

VT036300

VT036500 VT036600

208/230—3

187—253

187—253 414—506

22.4 16.8 40

26.2

19.3 9.8

10 10

100

35,800

1300

0.15

8.0

100

35,800 35,800

1300 1300

0.15

8.0 8.0 120,000 120,000 93,000 96,000

—

1367

1367 1367

624 416

(Applicable notes are listed below Table 4.)

Table 4—Specifications-

MODEL SIZE Unit Volts—Phase (60 Hz) Operating Voltage Range Unit Full Load Amps Maximum Fuse Size (Amps) Minimum Ampacity for Wire Sizing* Minimum Wire Size (75 C Copper) Maximum Wire Length (Ft.) Cooling Capacity (Btuh)t Rated Cooling Airflow (cfm)f

External Static Pressure (In.

water)t ARI Sound Rating^: Rated Heating Input (cfm)

Output Capacity (Btuh)** AFUE(%)**

Rated Heating Airflow (cfm) Recommended Minimum FieldSupplied Filter Size (Sq ln.)ft

Disposable-Type Cleanable- or High-Capacity Type

48N

LT042300

208/230—1

187—253

24.6 16.0 50

31.1

41,500

1500 1500

0.15 0.15

7.8 8.0

60,000 60,000 46,000 48,000 48,000

77.5

987

- Models 48N (Sizes LT042300 thru HT042600)

48N 48N 48N

LT042500 LT042600 MT042300

208/230—1 460—3

208/230—1 208/230—3

187—253 414—506 187—253

8.8 24.6

15 50 30

20.4 10.3 31.1 10

100 100

14 8 10

95 100 100

41,500 41,500 41,500

1500 1500

0.15 0.15 0.15 0.15

8.0 8.0

60,00 80,000 80,000

61,000 64,000 64,000

—

987

—

77.5

987 987 987 987

720 480

48N 48N

MT042500

MT042600 HT042300

460—3 208/230—1

187—253 414—506

16.0 8.8

2.4 10.3

41,500 41,500

1500 1500 1500

8.0 8.0 80,000 100,000

48N

187—253

26.7

15 45

31.7

14 10

41,500 41,500

0.15

8.2 8.2

78,000

77.5

1481 1481

48N 48N

HT042500

208/230—3

187—253

18.2 9.6 30

21.1

65 110

1500

0.15

100,000

80,000 80,000

— —

720 480

*lf other than 75 C copper wire is used, determine size from unit ampacity and the National Electrical Code. Voltage drop of wire must be less than 2%

of unit rated voltage. tRated in accordance with U.S. Government D.O.E. test procedures and/or ARI Standard 210. tRated in accordance with ARI Standard 270.

**The capacity ratings of single-phase units are in accordance with U.S. Government D.O.E. test procedures and/or A.G.A. certification requirements. For

3-phase units, the efficiency rating is a product thermal efficiency rating determined under continuous operating conditions, independent of any

installed system.

ttRequired filter areas shown are based on the larger of the ARI-rated 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.-water.

48N

460—3

8.5 15

100

0.15

120,000 96,000

—

HT042600

460—3

414—506

11.1 14

41,500

1500

0.15

8.2

100,000

1481

Page 8

Table 5—Specifications—Models 48N (Sizes VT042300 thru MT048600)

MODEL 48N 48N 48N 48N

SIZE VT042300

Unit Volts—Phase (60 Hz)

Operating Voltage Range

Unit Full Load Amps Maximum Fuse Size (Amps) Minimum Ampacity for Wire Sizing* Minimum Wire Size (75 C Copper) 10 12

Maximum Wire Length (Ft.) Cooling Capacity (Btuh)f Rated Cooling Airflow (cfm)f

External Static Pressure (In.

water)t

ARI Sound Rating^:

Rated Heating Input (cfm)

Output Capacity (Btuh)** 93,000 96,000 96,000 AFUE(%)** 77.5

Rated Heating Airflow (cfm) Recommended Minimum Field-

Supplied Filter Size (Sq ln.)tt

Disposable-Type

Cleanable- or High-Capacity Type 480 544

208/230—1 208/230—3 460—3 208/230—1

187—253 187—253 414—506

26.7 45 30 15

31.7 75

41,500

1500

0.15 0.15 0.15

8.2

120,000

1367 1367 1367

VT042500 VT042600 LT048300

187—253 187—253

18.2 9.6 27.2 50 40 20

21.1 65

11.1 32.7 14

110 95

41,500 41,500 47,500

1500 1500 1700

0.20

8.2

120,000 120,000 80,000

62,000 64,000 48,000

—

77.5

1481

720 816

(Applicable notes are listed below Table 7.)

48N

LT048500

208/230—3

22.1

26.0 13.1 10

100

47,500

1700 1500

0.20

8.2

80,000

— —

1481

48N

LT048600

460—3

414—506

11.0

100

47,500

0.15

8.2

60,000

1481

48N

MT048300

208/230—1

187—253 187—253 414—506

27.5 22.1 11.0 50

32.7 26.1 13.1

8 10 14

47,500

1700

0.20 0.20 0.20

8.2 8.2 8.2

100,000 100,000 100,000

78,000

77.5

1481 1481 ,1481

48N 48N

MT048500

MT048600

208/230—3

40 20

100 100

47,500

1700 1700

80,000 80,000

— —

816 544

460-3

Table 6—Specifications—Models 48N (Sizes HT048300 thru MT060600)

MODEL

SIZE

Unit Volts—Phase (60 Hz)

Operating Voltage Range

Unit Full Load Amps Maximum Fuse Size (Amps) Minimum Ampacity for Wire Sizing* Minimum Wire Size (75 C Copper) Maximum Wire Length (Ft.) 75 65

Cooling Capacity (Btuh)t

Rated Cooling Airflow (cfm)t

External Static Pressure (In.

water)t ARI Sound Ratingf: Rated Heating input (cfm)

Output Capacity (Btuh)** AFUE (%)** 77.5

Rated Heating Airflow (cfm) Recommended Minimum FieldSupplied Filter Size (Sq ln.)tt

Disposable-Type Cleanable- or High-Capacity Type

48N

HT048300

48N 48N

HT048500 HT048600

208/230—1 208/230—3 460—3 208/230—1 208/230—3 460—3

187—253 187—253 414—506 187—253 187—253 414—506

27.5 22.1 11.0 40.8 31.6 14.6 50

32.7

26.0 13.1 48.5 37.0

10 12 14 8 10 14

47,500 47,500 47,500 59,500 59,500 59,500

1700

0.20 0.20

8.2 8.2 8.2 8.4 8.4 8.4

120,000

93,000 96,000 96,000

1367 1367 1367 1481 1481 1481

816 960 544

20 60 50 25

110 95 100 100

1700 2000 2000 2000

0.20 0.20

120,000 80,000

—

48N

LT060300 LT060500 LT060600

48N 48N

17.2 48.5

0.20 0.20

80,000 100,000

—

62,000

77.5

0.20

80,000

64,000 64,000

—

640

48N

MT060300 MT060500 MT060600

208/230—1

187—253

40.8 60 50 25

8 10

95 100 100

59,500 59,500 59,500

2000 2000 2000

8.4

78,000

77.5

1646 1646 1646

(Applicable notes are listed below Table 7.)

Table 7—Specifications-

MODEL SIZE HT060300 Unit Volts—Phase (60 Hz) 208/230—1 208/230—3 Operating Voltage Range Unit Full Load Amps Maximum Fuse Size (Amps) 60 50 Minimum Ampacity for wire Sizing* 48.5 37.0 Minimum Wire Size (75 C Copper) Maximum Wire Length (Ft.) 75 65 Cooling Capacity (Btuh)t Rated Cooling Airflow (cfm)t

External Static Pressure (in. water)t

ARI Sound Ratingt

Rated Heating Input (Btuh)**

Output Capacity (Btuh)** 93,000 96,000 96,000 AFUE(%)** 77.5

Rated Heating Airflow (cfm) Recommended Minimum Field-

Supplied Filter Sizeft

Disposable-Type Cleanable- or High-Capacity Type 640

- Models 48N (Sizes HT060300 thru HT060600)

48N 48N

187—253

40.8 31.6

10 12

59,500 59,500

2000 2000

0.20 0.20

8.4 8.4

120,000

1975 1975

HT060500 HT060600

187—253 414—506

120,000

— —

960

*lf other than 75 C copper wire is used, determine size from unit ampacity and the National Electrical Code. Voltage drop of wire must be less than 2%

of unit rated voltage. fRated in accordance with U.S. Government D.O.E. test procedures and/or ARI Standard 210. tRated in accordance with ARI Standard 270.

**The capacity ratings of single-phase units are in accordance with U.S. Government D.O.E. test procedures and/or A.G.A. certification requirements. For

3-phase units, the efficiency rating is a product thermal efficiency rating determined under continuous operating conditions, independent of any

installed system.

ttRequIred filter areas shown are based on the larger of the ARI-rated cooling airflow or the heating airflow at a velocity of 300 ft/min for disposable type

or 450 ft/mln for hIgh-capacIty type. Air filter pressure drop must not exceed 0.08 in.-water.

48N 48N

208/230—3 460-3

187—253

31.6

414—506

14.6

37.0 17.2 14

0.20 0.20

8.4

100,000 100,000

80,000

— —

80,000

960 640

48N

460—3

14.6 25

17.2 14

110

59,500

2000

0.20

8.4

120,000

1975

Page 9

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

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

A. High-Voltage Connections

The unit must have a separate electrical service with a field-

supphed, waterproof, fused disconnect switch mounted at, or within sight from the unit. Refer to the unit rating plate for maximum fuse size and minimum circuit amps (ampac ity) for wire sizing. Tables 2 thru 7 show recommended wire sizes based on rating plate data.

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

Proceed as follows to complete the high-voltage connections

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. 8.

B. Special Procedures for 208-V Operation

A 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.

For operation on 208 volts, disconnect the orange transformer-primary lead from the contactor. See the unit wiring label. Remove the tape and cover from the terminal on the end of the red transformer-primary lead. Save the cover. Connect the red lead to the contactor terminal from which the orange lead was disconnected.

Using the cover removed from the red lead, insulate the loose terminal on the orange lead. Wrap the cover with elec trical tape so that the metal terminal can not be seen.

Indoor blower motor speed taps should be changed for 208V operation on 208/230v rated units. Interchange motor leads at printed circuit board (PCI) in unit control box. High speed for coohng and medium speed for heating operation. See Step 9-C and unit wiring label. Do not change blower speed setting for 460V rated units.

C. 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 coohng or heating source or direct exposure to sunhght. Mount the thermostat 4 to 5-ft above the floor.

Use No. 18 AWG color-coded, insulated (35 C minimum) wires to make the control voltage 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. See Figs. 2 and 3. Run the low-voltage leads from the thermostat, thru the inlet hole, and to the control voltage terminals through a hole in the bottom of the unit control box. Pass control volt age leads through wire ties located under unit control box. Connect the thermostat leads to the terminals as shown in Fig. 8.

D. Heat Anticipator Setting

The room thermostat heat anticipator must be properly

adjusted to ensure proper heating performance. Set the heat anticipator, using an ammeter to determine the exact required setting.

NOTE: For thermostat selection purposes, use 1.0 amp for

the approximate required setting.

THERMOSTAT (TYPICAL)

-TERMINAL BOARD rCONTACTOR TERMINALS

(SEE UNIT WIRING LABEL)

CONTROL BOX

• FIELD CONTROL-VOLTAGE WIRING ' FIELD HIGH-VOLTAGE WIRING

Fig. 8—High and Control Voltage Connections

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 shghtly to provide a greater degree of comfort for a particular installation.

E. Circuit Breaker

Unit has manual reset circuit breaker which is located in the

low voltage wiring box adjacent to low voltage terminal board. If unit fails to operate, first check breaker for tripped position. If breaker is tripped, re-set and try to start unit. If breaker continues to trip there is a problem in the low volt

age electrical circuit. (Electrical short, ground, or trans

former overload) Correct the condition and check for normal unit operation.

Step 7—Preparing Unit for Startup

DANGER: 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 termineJ cover is in place and secured.

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

4. Reheve 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 refrigeremt system is under pressure.

6. Do not use torch to remove any component. System contains oil emd refrigerant under pressure. To remove a component, wear protective goggles and proceed as follows: a. Shut off gas supply and then electrical power to

unit.

b. Relieve all pressure from system.

c. Cut component connecting tubing with tubing

cutter and remove component from unit.

d. Carefully unsweat remaining tubing stubs when

necessary. Oil can ignite when exposed to torch flame.

GND

FIELD SUPPLIED FUSED DISCONNECT

- 3-PHASE UNITS ONLY

A WARNING

A87380

Page 10

A. Prestartup Procedures

Proceed as follows to inspect eind prepare the unit for initial startup:

1. Remove all access panels.

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

3. 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 a refrigerant leak. Leak-test all refrigerant tubing

connections using electronic leak detector, hahde torch, or hquid-soap solution. If refrigerant leak is detected, see “Refrigerant Leaks” in the next part of this section.

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

sure that connections are completed and tight.

d. Inspect coil fins. If damaged during shipping and

handling, carefully stredghten fins with a fin comb.

4. 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 adhere to this warning could result in an explosion.

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

that aU 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 1/4-in..

c. Make sure that air filter(s) is in place.

d. Make sure that condensate drain pan is filled with

water to ensure proper drainage.

e. Make sure that all tools and miscellaneous loose

parts have been removed.

Unit is now ready for initial startup.

B. Refrigerant Leaks

Proceed as foUows to repair a refrigerant leak and to charge the unit:

1. Locate leak and ensure 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 refriger

ant to compensate for internal volume of filter-drier.

NOTE: See Step 9, part B for checking and adjusting refrig

erant charge.

Step 8—Heating Section Startup and Adjustments

A CAUTION

Complete the required procedures given in Step 7, ' paring Unit for Startup,” before starting the unit.

‘Pre-

Do not jumper any safety devices when operating the unit. Ensure that burner orifices are properly aligned. Unstable

operation may occur when the burner orifices in the mani fold are misaligned.

NOTE: When installing a unit in extremely cold chmate

areas, a run-in period for the inducer motor is recom mended. After the unit has been installed disconnect the red wire from terminal 2 at the ignition control (IGN) and

jumper terminals R-W at the control voltage termineJ

board. See Figs. 12, 13, & 14. The inducer motor should run but burner ignition will not occur. Allow inducer motor to run for 4 to 5 hours. Reconnect red wire to terminal 2 at ignition control (IGN) and remove R-W jumper at the con trol voltage terminal board. Proceed as follows to complete heating section start up.

Follow the fighting instructions on the heating section oper ation label (located inside the burner access door) to start

the heating section. However, when fighting the unit for the first time, perform

the following additional steps:

1. If the gas supply pipe was not purged before connect ing the unit, it will be full of air. It is recommended that the ground joint union be loosened, and the supply fine be allowed to purge until the odor of gas is detected. Never purge gas fines into a combustion chamber. Immediately upon detection of gas odor,

retighten the union. Allow 5 minutes to elapse, then fight unit in accordance with Step 8, part A below.

A. Checking Heating Controi Operation

Start and check the unit for proper heating control opera tion as follows: (See furnace fighting instructions located inside burner access panel.)

Place the room thermostat SYSTEM switch in the HEAT position and the FAN switch in the AUTO position. Set the heating temperature control of the thermostat above room temperature. Observe that after built-in time delays, the

pilot automatically fights, the burners fight, and the blower

motor starts. 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: 060 size 460V models are equipped with a 3-phase

blower motor. Check blower wheel for correct rotation as indicated by arrow on blower housing. If blower wheel rotates in opposite direction, reverse any two blower motor leads or any two fine voltage leads. Recheck blower wheel rotation if necessary to reverse leads.

B. Gas Input

Check gas input and manifold pressure after unit start-up. (See Table 8) If adjustment is required proceed as follows.

A CAUTION

These units are designed to consume the rated gas inputs using the fixed orifices at specified manifold pressures as shown in Table 8. DO NOT REDRILL THE ORIFICES UNDER ANY CIRCUMSTANCES.

The rated gas inputs shown in Table 8 are for eiltitudes 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 LP (propane) gas with a heating value of 2500 Btu/ft^ 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

Page 11

codes, or contact your Distributor or Branch to determine the required orifice size.

C. Adjusting Gas Input

The gas input to the unit is determined by measuring the gas flow at the meter or by measuring the manifold pres sure. Measuring the gas flow at the meter is recommended for natural gas units. The manifold pressure must be mea sured to determine the input of propane gas units.

1. Measuring Gas Flow at Meter Method—Natural Gas Units

Minor adjustment can be made by changing the manifold pressure. The manifold pressure must be maintained between 3.2 and 3.8-in. water. If larger adjustments are required, change main burner orifices following the recom mendations of national and local codes.

NOTE: All other apphances that use the same meter must

be turned off when gas flow is measured at the meter. Proceed as follows:

Turn off gas supply to unit.

Remove pipe plug on outlet of gas valve, then con

nect manometer at this point. Turn on gas to unit.

Record number of seconds for gas meter test dial to

make one revolution.

Divide number of seconds in step c into 3600 (num

ber of seconds in 1 hour). Multiply result of step d by the number of cubic ft

shown for one revolution of test dial to obtain cubic

ft of gas flow per hour.

f. Multiply result of step e by Btu heating value of gas

to obtain total measured input in Btuh. Compare this value with heating input shown in Table 8. (Consult the local gas suppher if the heating value of gas is not known.)

Example: Assume that the size of test dial is 1 cubic ft, one

revolution takes 30 seconds, eind the heating value of the gas is 1050 Btu/ft®, then proceed as follows:

a. 30 seconds to complete one revolution.

b. 3600 -30 = 120.

c. 120 X 1 = 120 ft® of gas flow/hr.

d. 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:

Remove cover screw over regulator adjustment

screw on gas valve.

Turn regulator adjustment screw clockwise to

increase gas input, or turn regulator adjustment screw counterclockwise to decrease input. Manifold pressure must be between 3.2 and 3.8-in.-water.

A WARNING

Unsafe operation of the unit may result if manifold pressure is outside this range. Personal injury or unit damage may result.

c. Replace cover screw cap on gas valve.

d. Turn off gas supply to unit. Remove manometer

from pressure tap. Replace pipe plug on gas valve. Turn on gas to unit. Check for leaks.

2. Measuring Manifold Pressure—Propane Gas 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. water.

Proceed as follows to adjust gas input on a propane gas

unit:

a. Turn off gas to unit.

b. Remove pipe plug on outlet of gas valve then con

nect memometer at this point.

c. Turn on gas to unit.

d. Remove cover screw over REG ADJ screw on gas

valve.

e. Adjust regulator adjustment screw for a manifold

pressure reading of 10.5-in.-water. Turn adjusting screw clockwise to increase manifold pressure, or turn adjusting screw counterclockwise to decrease manifold pressure.

f. Replace cover screw.

g. Turn off gas to unit. Remove manometer from pres

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

D. Check Burner Flame

Observe the unit heatmg operation, and watch the burner flames through the observation port to see if they are light blue and soft in appearance, and the flames are approxi mately the same for each burner. See Fig. 10.

E. 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” cycles. The “on” cycle is factory set for 1 min ute on timing. The adjusting dial on the relay (See Fig. 9) is factory-set at the minimum position to provide optimum performance for most installations. On unusual installa tions, the length of time the blower remains on may require increasing. To increase blower operation time, rotate the adjusting dial counter-clockwise. To decrease blower opera tion time, rotate dial clockwise. (Minimum time 1 minute.) Maximum time 3 minutes.)

F. Airflow and Temperature Rise

The heating section of each size of unit is designed and approved for heating operation within the temperature rise range stamped on the unit rating plate.

Table 8—Rated Gas Inputs at Indicated Manifold Pressures

Gas Supply Pressure

Number

Model

No.

48NLT018, 024, 030

48NHT024, MT030, LT036, LT042

48NHT030, MT036, MT042, LT048, LT060 4 5.0

48NHT036, HT042, MT048, MT060 5 5.0 13.6 11.0 13.6 3.5

48NVT036, VT042, HT048, HT060 6 5.0 13.6 11.0 13.6 3.5 10.5 5536544 120,000 55365-55 120,000

♦Based on altitudes from sea level up to 2000 feet above sea level. For altitudes above 2000 feet, reduce input rating 4% for each 1000 feet above sea

level. In Canada, from 2000 ft. above sea level to 4,500 ft. above sea level, derate the unit 10%.

fWhen a 48N is converted to propane, the burners must be modified. See kit instructions.

Orifices

Min Max Min Max Natural Propane

2 5.0 13.6 3 5.0 13.6 11.0

(in. wc)

Natural Propane

11.0 13.0 3.5 10.5

13.6

11.0 13.0 3.5 10.5 55365-44 80,000 55365-55 80,000

13.0

Manifold Pressure

(In. wc)

3.5

10.5

12.5

Natural Gas

Orifice

P/N

55365-44 55365-44

55365-44 100,000

Heating

Input

(Btuh)*

40,000 55365-55 40,000 60,000 55365-55 60,000

Propane Gast

Input

P/N

55365-55

Heating

(Btuh)*

100,000

Page 12

Table 9 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 temperature rise that fedls within the approved range.

Refer to Step 9, part C, of these instructions to adjust heat

ing airflow, when required.

G. Safety Check of Limit Control

The control shuts off the combustion gas supply and ener gizes the circulating-air blower motor if the furnace overheats.

The recommended method of checking this hmit 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 hmit control functions, the retum-air opening should be unblocked to permit normal eiir circulation. By using this method to check the hmit control, it can be estabhshed that the hmit is functioning properly and the furnace will “fail safe” if there is a restricted circulating air supply or motor failure. If the hmit control does not function during this test, the cause must be determined emd corrected.

H. Heating Sequence of Operation See Figs. 12,13 or 14

Room thermostat cahs for heat closing circuit between “ R” and “W” 24 volt control circuit terminals. (Power to the “R” terminal is supphed through “CB” Circuit Breaker and “LS, ALS Emd FL” safety switches) “PC2” inducer control

board is energized which starts the inducer motor “IM”. The inducer motor comes up to speed, the vacuum in the col lector box increases, opening the normahy closed and clos ing the normahy open contacts of the contacts of the pres sure switch “PS” energizing the circuit to the “IGN” igni tion control and the phot valve “PV”. If the flame sensor

proves the presence of the pilot flame the internal switching

of the ingition control de-energizes the spark generator and

energizes the main gas valve, “MV” and the “IFR2” elec tronic timer. Gas flows to the main burners and is ignited by the phot flame. The “PCI” electronic timer will close the

“IFR2” relay between 60 to 90 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 con trol and the “IGN” ignition module which causes the main gas vedve to close instantly and the inducer motor is de energized. The electronic timer “PCI” will keep the “IFM” blower motor running Em additional 1 to 3 minutes. Then the blower stops and the unit is on standby until another call for heat.

NOTE: If the main limit switch opens due to the unit over

heating, the blower motor is turned on thru the electronic board.

If the pilot fails to hght within a 50 second trail for ignition period from the initial caff for heat the ignition control “IGN” will lockout the system and prevent further hghting attempts. To reset, open the “R” - “W” thermostat circuit for 30 seconds and re-close.

I. Limit Switches

Furnace limit switch “LS” (See Figs. 12, 13 or 14.) closes the gas valve if the leaving-eur temperature exceeds the maximum allowable temperature.

Normally closed hmit switch “LS” completes the control circuit through the thermostat “R” circuit, See Figs. 12, 13 or 14. Should the leaving-air temperature rise above the maximum allowable temperature the hmit switch opens emd the “R” control circuit “bresiks.” Any interruption in the “R” control circuit instantly closes the gas valve and stops gas flow to the burners and phot. The blower motor contin

ues to run until the time-delay sequence of blower relay

“PCI” is completed.

When the air temperature at the hmit switch drops to the low-temperature setting of the hmit switch, the switch closes and completes the “R” control circuit. The electricspark ignition system cycles and the unit retm-ns to normal heating operation.

J. Auxiliary Limit Switch

Auxihary hmit switch “ALS” is a temperature-actuated

manual reset switch and is connected in series with the hmit

switch “LS.” The function of the switch is to prevent abnor mal blower compartment temperatures. The switch is mounted on the blower housing. When the temperature at the auxihary switch reaches the maximum allowable tem perature the “R” control circuit “breaks”, closing the gas valve and stopping gas flow to the burners and pilot. To reset switch push in on red push button. If it cycles again, shut down the unit and cah for service.

K. Fusible Link

Fusible Link “FL” is a temperature-actuated device con

nected in series with the hmit switch “LS.” It is located iu the wire bundle adjacent to the burner manifold.

The function of the device is to prevent abnormaUy high burner compartment temperatures. The hnk will melt if an overheating condition caused by inadequate combustion air supply or improper venting occurs. Do not jumper this fuse. Correct the condition and replace the fuse with an identical

part.

Step 9—Cooling Section Startup and Adjustments

CAUTION

Complete the required procedures given in Step 7, “Pre paring Unit for Startup,” before starting the unit.

Do not jumper emy safety devices when operating the unit.

Do not operate the compressor when the outdoor tem perature is below 55 F (unless accessory low-temp kit is installed).

Do not rapid-cycle the compressor. AUow 5 minutes between “on” cycles to prevent compressor damage.

A. Checking Cooling Control Operation

StEurt 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 temperature. Observe that compressor, con denser fan, and evaporator blower motors start. Observe that cooHng cycle shuts down when control setting is satisfied. Blower motor has off delay of approximately one minute on shut down.

3. When using an autochangeover 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 “caU for heating” (above room temperature) and operates in coohng mode when temperature control is set to “call for cooling” (below room temperature).

NOTE: 060 size 460V models are equipped with a 3-phase

Page 13

blower motor. Check blower wheel for correct rotation as indicated by arrow on blower housing. If blower wheel rotates in opposite direction, reverse any two blower motor leads or any two line voltage leads. Recheck blower wheel rotation if necessary to reverse leads.

B. Checking and Adjusting Refrigerant Charge

The refrigerant system is fuUy charged with R-22 refriger ant, 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. For all appHcations, 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 DB outdoor and 80 F DB/67 F WB indoor.

A superheat charging label is attached to the outside of the compressor access door. The label includes a “Field Super heat Charging Table” and a “Required Suction-Tube (F)” temperature chart.

An accurate superheat thermocouple-, or thermistor-type thermometer, a shng psychrometer, and a gauge manifold are required when using the superheat charging method for evaluating 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 low- and high-pressure service fittings.

2. Using hoses with valve core depressors, attach low-and high-pressure gauge hoses to low- and high-pressure service fittings, respectively.

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

4. Measure and record the following:

a. Outdoor eunbient-air temperature (F DB).

b. Evaporator inlet-air temperature (F WB).

c. Suction-tube temperature (F) at low-side service fit

ting.

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

5. Using “Field Superheat Charging Table,” compare

PILOT FLAME BURNER FLAME

outdoor-air temperature (F DB) with evaporator inletair temperature (F WB) to determine desired system operating superheat temperature. See Table 10.

6. Next, using “Required Suction-Tube (F)” table, com pare desired superheat temperature with suction (lowside) operating pressure (PSIG) to determine proper suction-tube temperature. See Table 11.

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, see Step 7, part B, of these instructions.

C. Indoor Airflow and Airflow Adjustments

A CAUTION

For coohng operation, the recommended airflow is 350 to 450 Cfm per each 12,000 Btuh of rated cooling capac ity. For heating operation, the airflow must produce a temperature rise that falls within the range steunped on the unit rating plate.

Model 018-048 size units have direct-drive blower motors. Blower motors are factory-connected to dehver the proper heating and coohng airflows at normal external static pres sures (medium speed coohng, low speed heating for 230v units and high speed coohng, heating for 460v units).

060 size units have belt drive blower motors which have the motor puUey factory set at four turns open.

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

Table 9 shows the temperature rise at various airflow rates. Tables 12 and 13 show both heating and coohng airflows at various external static pressures. Refer to these tables to determine the airflow for the system being instaUed. See Tables 2 thru 7 for the rated heating and coohng airflows.

NOTE: Be sure that ah supply- emd return-air grflles 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 dis connecting electrical power.) Electrical shock can cause personal injury or death.

Page 14

A CAUTION

Do not change the blower-motor lead connections on 460-V units from the factory setting. Damage to unit may result.

The heating emd/or cooling airflow of 208/230-V direct-drive blower motors can be changed by changing the lead connec tions of the blower motor. The motor leads are color-coded as follows:

black = high speed blue = medium speed red = low speed

NOTE: For all 208/230 V direct-drive units, the motor lead

connected to the heat relay (L) on PCI blower control deter mines the heating speed and resulting air-flow; and the motor lead connected to the cooMng relay (H) on PCI blower control determines the coohng speed and resulting airflow. See the unit wiring label.

To change the heating and/or coohng speed of a direct-drive motor, connect the appropriate color-coded lead to the appropriate relay. Connect unused motor lead to terminal Ml on the PCI blower control.

When installing a 208- or 230-V direct-drive unit that is factory-connected for heating and coohng speeds that are not the same, and the same speed for both heating and cool ing is required for a particular application, connect the appropriate color-coded lead to terminal H of coohng relay and connect a field-supplied jumper between terminal L on heat relay and terminal H of coohng relay. Connect unused leads to terminals Ml and M2 on PCI blower control.

D. Unit Controls

All compressors have the following internal-protection controls:

1. High-pressure Relief Valve—T\ds 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 temperature 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 thru the over load with an ohmmeter or continuity tester.

E. Cooling Sequence of Operation

NOTE: Although the actual unit wiring may vary slightly

from that shown in Figs. 12, 13 or 14, the sequence of opera tion win 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 thermostat completes the circuit between thermostat termi nal “R” to terminals “Y” and “G.” These completed cir cuits through the thermostat connect contactor coil “C” (through unit wire “Y”) and relay coil “IFRl” (through unit wire “G”) across the 24-volt secondary of tremsformer “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” closes and completes the circuit through evapora tor blower motor “IFM.” The blower motor starts

instantly.

NOTE: The cooling cycle remains “on” until the room

termperature drops to point that is slightly below the cool ing control setting of the room thermostat. At this point, the thermostat “breaks” the circuit between thermostat ter minal “R” to terminals “Y” and “G.” These open circuits deenergize contactor coU “C” and relay coil “IFRl”. The condenser and compressor motors stop. After a one minute delay the blower motor stops. The unit is in a “standby” condition, waiting for the next “call for cooling” from the

room thermostat.

Step 10—Care and Maintenance

To ensure continuing high performance, and to minimize the possibility of premature equipment failure, periodic mainte nance must be performed on this equipment. This combina tion heating/cooling unit should be inspected at least once each year by a qualified service person.

NOTE TO EQUIPMENT OWNER: Consult your local Dealer

about the avedlability of a maintenance contract.

A WARNING

The ability to properly perform maintenance on this equipment requires certain expertise, mechanical skills, tools, and equipment. If you do not possess these, do not attempt to perform any maintenance on this equip ment other than those procedures recommended in the Users Manual. A FAILURE TO HEED THIS WARN ING COULD RESULT IN SERIOUS PERSONAL INJURY AND POSSIBLE DAMAGE TO THIS

EQUIPMENT.

The rninimum maintenance requirements for this equipment 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 when necessary.

4. Check electrical connections for tightness and controls

for proper operation each heating and cooling season. Service when necessary.

5. Check emd inspect heating section before each heating

season. Clean and adjust when necessary.

6. Check and clean vent screen if needed.

A WARNING

A failure to foUow these warnings could result in seri ous 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 15

Table 9—Air Delivery (Cfm) at Indicated

Temperature Rise and Rated Heating Input

Nominal Size

48NLT018 48NLT024 48NLT030

48NHT024 48NMT030

48NLT036 48NLT042 60,000

48NHT030 48NMT036 48NMT042

48NLT048 48NLT060 80,000 2370

48NHT036 48NHT042 48NMT048

48NMT060 100,000 48NVT036

48NHT042 48NHT048

48NHT060

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

Heating

Input (Btuh) 25

40,000

60,000

80,000

100,000

120,000

— — — —

—

120,000

30 35 40

—

987 846 740

_ _ _

1481 1269

1975

—

2469 2116

— —

2962 2539 2222

1111

1693 1481

2116 1851

1851

—

45 50

658 592

987 888 987

888 808

1316 1185

1316 1185 1077 1646

1481

1646 1481 1346 1234

—

1975

1777 1616 1777

Table 10—Superheat Charging Table

(Superheat Entering Suction Service Valve)

Outdoor

Temp (F)

55 9 60 7 65 70 75 80 85 — 90 95 —

100 105 110 — — — 115

52 54 56

12 14 17 10 12 15

—

6 10 13 — — — —

—

— ~ 6 9 12 — —

— —

— — —

—

— —

7 10

—

— —

—

— —

—

— — —

— — — — — — —

NOTE: Do not attempt to charge system under these conditions or refrigerant slugging may occur.

Indoor Coil Entering Air Temp (F WB)

58 60 62 64

20 23 18 21 16 19 13 16

26 29 24 27 30

21 24 27

19 21 24 15 18 21 24 28

5 8

—

— — — —

12 15 18

8 5 9 13

—

— — —

— —

538

808

1077

1346

60 65 70

493

740 740

— — —

683 634 592

_ _ _

987 911

_ _

1234 1139

846

_ _

— — —

— —

1481

1616 1481

32 35

1367

— — — —

33 35

1269 1185 1111

40 42

38 30 33 36 38 41 27

33 36

15 19 22

28 31

26 30 33 16 210 24

10 14 18 22 25

12 15

20 23 27

5 9 13 17 22

15 20

14 18 23

75 80

790

31 29

26 25

—

45 43

39 37 35

Table 11—Required Suction-Tube Temperature (F)

(Entering Suction Service Valve)

Superheat

Temp (F) 61.5 64.2 67.1 70.0

35 37 39 41 2 37 39 41 4 39 41 43 45 47 6 8 43 45

10 45

43 45 47

49 51 53 12 47 49 51 14 49 51 53 16 51 53 55 57 59 18 53 55 57 59 61 20 22 24 59

55 57 57

59 61 63 61 63 65 67

26 61 63 65 67 69 28 63

67 30 65 67 69 71 73 32 67 34

69 71 73 75 77

36 71

75 77 79 38 73 75 77 79 40 75 77 79

Suction Pressure At Service Port (Psig)

43 45 47

49 ~ 51

53 55 55 57

69 71

73 75

73.0 76.0 79.2 43 45

47 49 51

82.4

49 51

49 51 53 55 53

55 57

51 53 55

57 59 59

57 59 61 63 59 61 63 65 61 63 65 63 65 67 69

65 67 69 71 73

73 75 71 73 75 77 73 75 77 79 75

79 77 79 81 79

83 81 83 85

81 83 85 87 89 83

87 89 91

85.7

81 83 85 87

Page 16

Table 12—Model 48N Air Delivery (Cfm) at Indicated External

Static Pressure & Voitage (Sizes 48NLT018 thru 48NHT048)

48N Motor Volt/Ph/Hz 48NLT018,

48NLT024, 48NHT024AtLow 712 700 689

208/230-1-60

48NLT030, 48NMT030

208/230-1-60

48NHT030, LT036 48NMT036, LT042

48NMT042

208/230-1-60

208/230-3-60, 460-3-60 Hi

48NHT036, NVT036

48NHT042

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

460-3-60t

48NLT048, NMT048

48NHT048

208/230-3-60

460-3-60t

(Applicable notes are listed below Table 13.)

Speed 0.0

•t

Med 1185

Hi 1370 1291 1221

Low

•t

Med 1184 1163 1150

Hi 1443

Low 1002 970

•t

Med 1515

Low

•

Med 1913

Hi 2032 1942 1844 A

Low 1627 1589 1527

•

Med

Hi 2138 2045 1943 1846 1738

735

1764 1705 1610

1945 1880 1796 1708

0.1 0.2 0.3 0.4 0.5

1129

726

1414

1452

1570 1504 1435 1358 1260 1787 1820

End Discharge

208V

1088

713

1376

938

1389

1621

1736

External Static Pressure-Inches Water

0.0

680 663 651

1026 979 922 1142

1134 1329 1279 1197

1308 1227 1102 1597 1530 1521

1645 1544 1428 1976 1909 1806 1759

1449 1364 1282 1807 1758 1704

1063 1003 1442 1359

702

898 854 796 1056

689 675

1105

1383

1636

1611

1064

1254 1857 1795 1708

1514

1508 1624

750

1256

775

1248 1519

2086

2061 1970 1892

2178

0.1

1195 1148

1226 1489 1449

1022 986

1733

1983 1883

2081

230V or 460V

0.2 0.3

737 726

1285

763

751 740

1211

1464 1378

1641 1559 1458 1345

1941 1869 1769 1650

0.4

716

1081 1202

1194 1164 1120 1399

946

1603

1714 1603 1495 1782

1607 1518

1813

700 686

1031 1119 1056

726

1347

900 839

1293

1457 1321

1665 1545

1704

0.5

971

' 711

1261

1164-

1404

1580

Tabie 13—Down Discharge

48N Motor Volt/Ph/Hz Speed 0.0 0.1 0.2 48NLT018

48NLT024, 48NHT024АФLow

208/230-1-60

48NLT030, 48NMT030

208/230-1-60

48NHT030, LT036

48NMT036, LT042,

48NMT042

208/230-1-60

208/230-3-60, 460-3-60t

48NHT036, NVT036

48NHT042, NVT048

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

460-3-60t

48NLT048, 48NMT048

48NHT048

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

208/230-3-60

460-3-60t

• Factory blower motor speed setting for cooling operation.

AFactory blower motor speed setting for heating operation.

*Air delivery values are without air filter and are for dry coil. See Table 16 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. t460 volt units high speed only. Do not change blower speed settings. tFor 208V operation, change the blower motor speed setting to the next higher speed. See steps 6 and 9.

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. Indoor coil icing may occur

at airflows below this point.

•t

Med

Hi 1308

Low

•t

Med 1155 1138 1120

Hi 1411 1362 1326

АФ

Low 969 947

•t

Med

Hi 1683 1615 1536 A

Low 1534 1493 1430

•

Med 1797 1709 1620

Hi 1885 1779 1704 A

Low 1539 1515 1466

•

Med 1833 1768 1700

Hi 1957 1873 1786 1699 1598 1495 1997

705 692 684

1138 1102 1045

1234 1162

724 715

1494 1430

208V

706

911 863

1358

External Static Pressure—Inches Water

0.3 0.4 0.5

671

996

1084

695 682 665 763

1104 1249

1273 1440 1274 1153 1763 1700

1359 1547

1608

1410

1599

657 942

1020 951 1379

1073 1195

816

1174 1058 1574

1280 1448 1315 1855 1707 1684

1507

1325 1505

639 889

1031 1218 1200 1182

1133 1493 1457 1412

760 1022 998

1200 1704 1638

1404

1229 1390

0.0

743

1196

1906

1735 1918

0.1

1161 1301 1225 1143

1507 1431

1821 1722

1688 1613 1849 1752

1907

230V or 460V

0.2 0.3

730

754 744 733

721 707 693

1101 1050 993

1165 1358

960 910 860 801

1341 1237 1115

1619 1492

1553 1468 1390 1304

1574 1498 1623 1533 1410

1539 1440 1334 1670 1561

1817 1713 1618 1506

0.4 0.5

674

1075 1002

719 701

1132 1088 1274

1343

932

1218

1215

1361

1442

Page 17

Table 14—Model 48NT060 (Belt Drive) Air Delivery (Cfm) At Indicated External

Static Pressure (in. W.C.) (Dry Coil without Air Filter*)

End Discharge

EXTERNAL STATIC PRESSURE—INCHES WATER

208V

2343

2129

1775

0.6

2152 1965 2035 1829 1921

— —

0.8

0.0

2808

2716 2585 2454 2287

230V or 460V

0.2 0.4

2588

2498 2282

2355 2154 2209 2028 1780

2331 2189

1966

0.6

2075 1921 1733

— —

0.8

2007 1864

—

RPM 1430

1380 2 1330 3 1280 4 1230

PULLEY TURNS

OPEN

1 See Note #2 2761 2534

5 2287 1964

0.0 0.2 0.4

2685 2583 2445 2174 1960 — —

2444 2230 2341

Table 15—Model 48NT060 (Belt Drive) Air Delivery (Cfm) At Indicated External

Static Pressure (in. W.C.) (Dry Coil without Air Filter*)

Down Discharge

RPM 1430 1380 2

1330 1280 1230

NOTES: 1. Factory setting is 4 turns open.

’Air delivery values are without air filter. Air delivery values are for dry coil. See Table 16, page 10 for coil pressure drop. Deduct field supplied filter pressure

drop and wet coil pressure drop to obtain external static pressure available for ducting.

PULLEY TURNS

OPEN

1 See Note #2

3 2454 2221 4 5

2. Do not operate biower beiow 1 turn open on motor puiiey. Motor overheating may resuit.

3. Do not operate unit in cooiing mode at airfiow rate beiow 1750 cfm. Indoor coii icing may occur.

0.0 0.2 0.4

2623 2407 2225 2044 1867 2551 2322

2323 2065 1862 — — 2272

1866

EXTERNAL STATIC PRESSURE—INCHES WATER

208V

2118 1933 1737 2022 1825

—

0.6 0.8

—

— —

0.0

2667 2458 2243 2580 2373 2168

2465 2237 2046 2331 2173 1927

0.2

2098

230V or 460V

0.4

1867

— — —

0.6 0.8

2078 1906 1971 1771 1825

—

— —

Table 16—Wet Coil Pressure Drop

Airflow

(CFM)

650 0.038 850

1050 0.066 1250 0.081 1450 0.111 1650 0.129 1850

2050 0.180

2250

A. Air Filter

Pressure Drop

(in. W.C.)

0.046

0.150

0.198

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 Tables 2 thru 7 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 seune dimensional size and type as originally provided, when necessary.

B. Unit Top Removal

A CAUTION

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

NOTE: When performing maintenance or service procedures

that require removal of the unit top, be sure to perform all of the routine maintenance procedures that require top

removal, including: inspection of the heat exchanger area, coil inspection and cleaning, emd 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 euound four 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-ins. long to prevent sides from falling when top is removed.

4. Lift top from unit carefully. Set top on edge and ensure that top is supported by unit side that is opposite duct (or plenum) side. Use extreme care to prevent damage

to the fan blades, motor, and insulation.

5. Carefully replace and secure unit top to unit, using screws removed in step 3, when maintenance and/or service procedures are concluded. (Be sure to use origi

nal screws that have rubber washers to seal out water when securing top to internal divider panels.)

C. Evaporator Blower and Motor

For longer life, operating economy, and continuing efl&ciency; clean accumulated dirt and grease from the blower wheel and motor annually.

Lubricate the motor every 5 years if the motor is used inter mittently (thermostat FAN switch in AUTO position), or every 2 yeeus if the motor is used continuously (thermostat

FAN switch in ON position).

A WARNING

Turn off the gas supply, then disconnect and tag electri cal power to the unit before cleaning and lubricating the blower motor and wheel. Failure to adhere to this warn ing could cause personal injury or death.

Page 18

Clean and lubricate the blower motor and wheel for direct drive models as follows:

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 yeUow lead from control box at capacitor. Disconnect auxUliary hmit switch 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, 5cc, 3/16 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 orien

tation and cutoff plate location.

b. Remove screws holding cutoff plate, emd remove

plate from housing.

c. Lift wheel from housing. When hemdhng and/or

cleaning blower wheel, be sure not to disturb bal

ance weights (chps) 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 cutoff plate into housing.

f. Reassemble motor into housing. Be sure setscrews

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

¡lean and lubricate the blower motor and wheel as follows or belt drive models:

1. Remove blower assembly as follows: a. Remove blower access door from unit.

b. Disconnect auxiliary hmit switch leads at switch.

c. Remove blower assembly and motor from unit. Be

careful not to tear insulation in blower compart ment. Support assembly to prevent damage to motor leads.

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, 5cc, 3/16 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. Remove blower belt, then remove blower pulley.

b. Remove blower shaft bearing retainers.

c. Loosen blower wheel setscrew, then pull blower

shaft from wheel.

d. Remove screws holding cutoff plate, then remove

cutoff plate.

e. Lift wheel from housing. When handhng and/or

cleaning, be sure not to disturb balance weights on blower wheel vanes.

f. 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. g. Reassemble wheel and cutoff plate into housing. h. Reinstall blower shaft, bearing retainers, blower

pulley, and belt.

4. Reinstall blower assembly into unit, route blower motor leads into control compartment, and reconnect all blower motor leads to proper termination point in unit control box. Replace panels.

5. Restore electrical power, then gas supply to unit. Start unit and check for proper blower rotation and motor speeds during heating and cooling cycles. 5

D. 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 two wires from inducer motor.

4. Remove complete inducer assembly from unit.

5. Remove screws that secure collector box to heat exchanger, exposing flue openings.

6. Remove flue choke.

7. Using field-provided small wire brush, steel spring cable, reversible electric drill, and vacuum cleaner; clean cells.

a. Assemble wire brush and steel spring cable.

(1.) Use 4-ft of 1/4-in. diameter high-grade steel

spring cable (commonly known as drain cleanout or Roto-Rooter cable).

(2.) Use 1/4-in. diameter wire brush (commonly

known as 25-caliber rifle cleaning brush).

NOTE: The items called for in sections 1 and 2 can be pur

chased at a local heirdware store.

(3.) Insert twisted wire end of brush into end of

spring cable, and crimp tight with crimping tool or strike with ball-peen hammer. Tightness is

very important.

(4.) Remove metal sleeve from wire brush to allow

proper brush action.

b. Cleem each heat exchanger cell.

(1.) Attach variable-speed reversible drill to end of

spring cable (end opposite brush).

(2.) 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 two upper passes of cell.

Page 19

(3.) Work cable in and out of cell three or four times

to obtain sufficient cleaning. Do not pull cable with great force. Reverse drill and gradually work cable out.

(4.) Remove burner assembly.

(5.) Insert brush end of cable in lower opening of

cell, and proceed to clean in same manner.

(6.) Repeat foregoing procedures until each ceU in

unit has been cleaned.

(7.) Using vacuum cleaner, remove residue from

each cell.

(8.) Using vacuum cleaner with soft brush attach

ment, clean burner assembly.

(9.) Reinstall burner assembly.

8. After cleaning, check sealant and gaskets to ensure 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 tight.

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

11. Replace inducer assembly.

12. Recoimect two wires to inducer motor.

13. Replace burner access door.

14. Turn on power and gas.

15. Set thermostat and check unit for proper operation.

E. Pilot

Inspect the pilot and clean (when necessary) at the begin

ning of each heating season. Remove the accumulation of

soot and carbon from the pilot. The pilot flame must be high enough for proper impingement on the flame sensor. Pilot flame must also come in contact with the pilot hood (target) for proper operation. If the pilot flame appears too hard (lift ing and blowing) or too soft (unstable) check inlet gas pres sure for proper value. See Table 8. The spark electrode must be located so the spark travels through a combustible mix ture of gas, if necessary, readjust the electrode as shown in Fig. 11 be certain to maintain the 1/8-in. spark gap.

G. 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. Ensure that blades clear the motor by no more than 1/4-in. If the blade assembly has slipped down the motor shaft, adjust the fan position on the motor shaft by loosening the setscrew(s), then moving the blade assembly up. Be sure that the setscrew(s) is on the

flat(s) of the motor shaft before tightening.

H. Electrical Controls and Wiring

Inspect and check the electrical controls emd wiring annu ally. Be sure to turn off the gas supply and then the electri

cal power to the unit.

Remove the control, blower, and compressor compartment 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 aU the parts, restrip the wire end, and reassemble the connection properly

and securely. After inspecting the electrical controls and wiring, replace

all the panels. Start the unit, and observe at least one com plete 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 malfunction has

F. Condenser Coil, Evaporator Coil, and Condensate Drain Pan

Inspect the condenser coil, evaporator coil, and condensate drain pan at least once each year. Proper inspection and cleaning requires the removal of the unit top. See part B of

this section. The coils are easily cleaned when dry; therefore, inspect and

clean the coils either before or after each cooling season. 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 Hnt, 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 coUs with a rtuld detergent-andwater solution. Rinse coils with clear water, using a garden hose. Be careful not to splash water on motors, insulation, wiring, or air filter(s). For best results, spray condenser coU fins from inside to outside the unit. On units with an outer and inner condenser coU, be sure to clean between the coils. Be sure to flush all dirt and debris from the unit base.

Inspect the drain pan and condensate drain line when inspecting 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 fiilter(s). If the drain tube is restricted, cleeur it with a “plumbers snake” or similar probe device.

Fig. 11—Position of Electrode to Pilot

Page 20

Fig. 12—Wiring Schematic—1 Phase-230V (Typical)

))

A88078

Page 21

Page 22

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 oper

ation in this publication as an aid in determining proper con

trol operation.

I. Refrigerant Circuit

Inspect all refrigerant tubing connections and the unit base for oil accumulations annually. Detecting oil generally indi

cates a refrigerant leak. If oil is detected or if low cooUng performance is suspected,

leak-test all refrigerant tubing; using an electronic leak-

detector, halide torch, or liquid-soap solution. If a refriger ant leak is detected, see Step 7, part B, “Refrigerant

Leaks,” in this publication. If no refrigerant leaks are found and low cooling perform

ance is suspected, see Step 9, part B, “Checking and Adjusting Refrigerant Charge,” in this pubhcation.

J. Gas Input

The gas input does not require checking unless improper heating performance is suspected. If a problem exists, refer to Step 8 of this publication.

K. Evaporator Airflow

The heating and/or cooling airflow does not require checking

unless improper performance is suspected. If a problem

exists, be sure that all supply- and return-air grilles are open

and free from obstructions, and that the air filter is clean.

When necessary, refer to Step 9, part C, of this pubhcation to check the system airflow.

L. Metering Device Servicing

See Fig. 15 for metering device components. The piston has a refrigerant metering orifice through it. The retainer forms a seahng surface for hquid hne flare connection. To check,

clean or replace piston:

1. Shut off power to unit.

2. Remove refrigerant from unit using approved refriger ant removed methods.

3. Remove hquid line flare connections from metering device.

4. Note position of arrow on metering device body with

respect to unit.

5. PuU retainer out of body. Be careful not to scratch flare seahng surface. If retainer does not puU out easily, carefuhy use locking phers to remove retainer. Replace scratched or damaged retainer.

6. Slide piston out by inserting a smah soft wire through

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

7. Chart on unit access panel ihustrates proper arrange

ment and size of piston. See Table 17 for piston sizes.

8. Clean piston refrigerant metering orifice.

9. Replace reteuner 0-riug Part No. is 99CC501052.

M. Liquid Line Strainer

The Liquid Line Strainer (to protect metering device), is made of wire mesh and located in the hquid hne on inlet

side. Strainer is pressed into the hne. Remove strainer by threading a No. 10 sheet metal screw into strainer and puUing the screw with phers.

Page 23

SYMPTOM

Pilot will not light.

Burners will not ignite.

Inadequate heating

Poor flame

characteristics

Table 18—Heating Sen/ice Analysis Chart

CAUSE

No spark at electrode

Spark shorting out to main burner

No gas at pilot burner

Water in gas line

No power to furnace

No 24-volt power supply to control circuit Miswired or loose connections Dirty pilot—yellow flame Pilot burning improperly—sharp blue flame 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 for application Restricted airflow Blower speed too low

Limit switch cycles main burners

Incomplete combustion results in:

Aldehyde odors, (CO), sooting flame—

floating flame

REMEDY

Check air gap between electrode tip and pilot target. Gap should be as shown in Fig. 11. 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 insure voltage to unit. Check for 24-volts between 2 and GR, and between 6 and GR. If you read 24 volts and above steps have been completed, replace electronic control head portion of control head/gas valve assembly. Realign electrode tip away from main burner but maintain spark gap to pilot burner. See Fig. 11. Clean pilot orifice. Check inlet pressure to gas value. Recommended operating pressure 7-in. w.c. natural gas, 11-in w.c. LP gas. 0.5 psig (14-in w.c.) max. pressure Check for 24 volts between terminals 1 and GR. If you read 24 volts and above steps have been completed, replace gas valve portion of control head/gas valve assembly. Drain—install water trap. Check power supply, fuses, wiring, or circuit breaker. Check transformer—replace if necessary. Check all wiring and wirenut connections. Clean pilot orifice. Replace pilot. Replace thermostat.

1. Check for 24 volts between terminals 3 and GR on control head. If you read 24 volts, replace gas valve portion of control head/gas valve assembly.

2. If 24 volts is not present, check flame sensor for cracked ceramic insulator or shorted sensor cable.

3. Use flame simulator Y99AW-1 to test sensing circuit. Follow instructions packaged with simulator. Replace electronic control if sensor circuit is not defective.

Run continuity check to locate break. Clean or replace filter as necessary. Check gas pressure at manifold. Clock gas meter for input. If too 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. Use faster speed tap—or install optional blower. Dirty air filters-clean or replace. Registers closed, restricted ductwork—open or remove restriction. 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 to burner alignment.

Page 24

FLARE NUT STRAINER RETAINER COOLING

Fig. 15—Metering Device Components

Table 19—Cooling Service Analysis Chart

SYMPTOM CAUSE

Power failure

Compressor 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 pressure

Head pressure too low

Excessive suction pressure

Suction pressure too low

Fuse blown or circuit breaker tripped Defective thermostat, contactor, transformer, or

controi relay

Insufficient line voltage

Incorrect or faulty wiring Thermostat setting too high Faulty wiring or loose connections in compressor circuit Compressor motor burned out, seized, or internal overload open Defective run/start capacitor, overload, start relay One leg of three-phase power dead

Refrigerant overcharge or undercharge

Defective compressor Insufficient line voltage Blocked condenser Defective run/start capacitor, overload, or start relay Defective thermostat Faulty condenser fan motor or capacitor Restriction in refrigerant system

Dirty air filter Unit undersized for load

Thermostat set too low

Low refrigerant charge Leaking valves in compressor

Air in system Condenser coil dirty or restricted

Dirty air filter Dirty condenser coil

Refrigerant overcharged Air in system Condenser air restricted or air short-cycling

Low refrigerant charge

Compressor valves leaking

Restriction in liquid tube

High heat load Compressor valves leaking

Refrigerant overcharged Dirty air filter Low refrigerant charge Metering device or low side restricted

Insufficient evaporator airflow

Temperature too low in conditioned area Outdoor ambient below 55 F

Field-installed filter-drier restricted

INDOOR

COIL

FLARE NUT

(TOWARD INDOOR COIL)

REMEDY

Call power company. Replace fuse or reset circuit breaker. Replace component.

Determine cause and correct.

Check wiring diagram and rewire correctly.

Lower thermostat setting below room temperature.

Check wiring and repair or replace.

Determine cause. Replace compressor.

Determine cause and replace. Replace fuse or reset circuit breaker. Determine cause.

Blow refrigerant, evacuate system, and recharge to nameplate. Replace and determine cause. Determine cause and correct. Determine cause and correct. Determine cause and replace. Replace thermostat. Replace. Locate restriction and remove.

Replace filter. Decrease load or increase unit size. Reset thermostat. Locate leak, repair, and recharge. Replace compressor. Blow refrigerant, evacuate system, and recharge.

Clean coil or remove restriction. Replace filter.

Clean coil. Purge excess refrigerant. Blow refrigerant, evacuate system, and recharge. Determine cause and correct. Check for leaks, repair, and recharge. Replace compressor. Remove restriction. Check for source and eliminate. Replace compressor.

Purge excess refrigerant. Replace filter. Check for leaks, repair, and recharge. Remove source of restriction. Increase air quantity. Check filter—replace if necessary. Reset thermostat. Install low-ambient kit.

Replace.

Tab I la I la

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

^ PC 101 Catalog No. 564-816 Printed in U.S.A. Form 48NT-9SI Pg 24 9-88 Replaces: 48NT-8SI

Carrier 48N User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Unit Weights

Step 1—Moving and Setting Unit in Place

A. Rooftop installation

B. Ground-Level Installation

C. Clearances

Step 3—Venting

- Models 48N (Sizes LT042300 thru HT042600)

- Models 48N (Sizes HT060300 thru HT060600)

Fig. 8—High and Control Voltage Connections

Tabie 13—Down Discharge

I. Refrigerant Circuit

J. Gas Input

K. Evaporator Airflow

L. Metering Device Servicing

M. Liquid Line Strainer

FLARE NUT STRAINER RETAINER COOLING

INDOOR

COIL