Carrier 48PG20-28 specifications Installation, Start-Upand Service Instructions, Contents

48PG20-28 Single Package Rooftop Units Electric Cooling/Gas Heating with

Electromechanical Controls and PURON® (R-410A) Refrigerant

Installation, Start-Up and Service Instructions

CONTENTS

Page

SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 1,2

INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-17

Step 1 — Provide Unit Support . . . . . . . . . . . . . . . . . . . . . . . . .2

•ROOF CURB

•ALTERNATE UNIT SUPPORT

•SLAB MOUNT

Step 2 — Remove Shipping Rails . . . . . . . . . . . . . . . . . . . . . . .2 Step 3 — Rig and Place Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

•POSITIONING

•ROOF MOUNT

•INSTALLATION ONTO CURB

Step 4 — Field Fabricate Ductwork . . . . . . . . . . . . . . . . . . . . .9 Step 5 — Make Unit Duct Connections. . . . . . . . . . . . . . . . . .9

•VERTICAL CONFIGURATION

•HORIZONTAL APPLICATIONS

Step 6 — Install Flue Hood and Inlet Hood . . . . . . . . . . . . 10 Step 7 — Trap Condensate Drain . . . . . . . . . . . . . . . . . . . . . 10 Step 8 — Install Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Step 9 — Make Electrical Connections. . . . . . . . . . . . . . . . .11

•FIELD POWER SUPPLY

•FIELD CONTROL WIRING

Step 10 — Install Outdoor-Air Hood. . . . . . . . . . . . . . . . . . . 12

•MANUAL DAMPER ASSEMBLY

Step 11 — Position Optional Power

Exhaust or Barometric Relief Damper Hood . . . . . . . . . 16 Step 12 — Non-Fused Disconnect . . . . . . . . . . . . . . . . . . . . 16 Step 13 — Install All Accessories . . . . . . . . . . . . . . . . . . . . . 16

PRE-START-UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

START-UP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18-45

Unit Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Compressor Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Refrigerant Service Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Crankcase Heater(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Compressor Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Internal Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Subcooler Heat Exchanger (SHX) . . . . . . . . . . . . . . . . . . . . . 18

Evaporator Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Condenser Fans and Motors. . . . . . . . . . . . . . . . . . . . . . . . . . 19

Return-Air Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Outdoor-Air Inlet Screens. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Gas Heat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Optional EconoMi$er IV. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Operating Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

SERVICE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46-57

Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Manual Outdoor Air Damper . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Economizer Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Evaporator Fan Service and Replacement . . . . . . . . . . . . 48

Evaporator Fan Performance Adjustment . . . . . . . . . . . . . 48

Evaporator Fan Belt Tension Adjustment . . . . . . . . . . . . . 48

Condenser Fan Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Verify Sensor Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Economizer Operation During Power Failure. . . . . . . . . . 49

Evacuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Refrigerant Charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Gas Valve Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

High Altitude. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Main Burners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Filter Drier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Protective Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Relief Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Page

Control Circuit, 24-V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Replacement Parts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Diagnostic LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57-61

Unit Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

EconoMi$er IV Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . 60

Phase Loss Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

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

SAFETY CONSIDERATIONS

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

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

Follow all safety codes. Wear safety glasses and work gloves. Use quenching cloth for unbrazing operations. Have fire extinguishers available for all brazing operations.

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

Puron (R-410A) refrigerant systems operate at higher pres- sures than standard R-22 systems. Do not use R-22 service equipment or components on Puron refrigerant equipment. If service equipment is not rated for Puron refrigerant, equipment damage or personal injury may result.

1.Improper installation, adjustment, alteration, service, or maintenance can cause property damage, personal injury, or loss of life. Refer to the User’s Information Manual provided with this unit for more details.

2.Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance.

What to do if you smell gas:

1.DO NOT try to light any appliance.

2.DO NOT touch any electrical switch, or use any phone in your building.

3.IMMEDIATELY call your gas supplier from a neigh- bor’s phone. Follow the gas supplier’s instructions.

4.If you cannot reach your gas supplier, call the fire department.

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

Book	1	4	PC 111	Catalog No. 534-80211	Printed in U.S.A.	Form 48PG-10SI	Pg 1	9-05	Replaces: New
Tab	1a	6a