Lennox ELITE 12GCS Series

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Litho U.S.A.

Page 1

Corp. 0003−L3

Service Literature

2 to 5 Ton (7.0 to 17.6 kW)

12GCS/12CHP

Revised 06−2004

12GCS/12CHP ELITE SERIES UNITS

The 12GCS packaged heat/cool units, are available in sizes

ranging from 2 through 5 tons (7.0 through 17.6 kW). 12GCS

series units are designed for outdoor residential use only.

Units can be installed at ground level or roof top applications.

Gas heat sections are available with Lennox S−curve heat ex-

changers in 50,000, 75,000, 100,000 and 125,000 Btuh input

sizes.

The 12CHP packaged heat pump units are available in

sizes ranging from 2 through 5 tons (7.0 through 17.6 kW).

12CHP units are designed for outdoor residential use only.

Units can be installed at ground level or rooftop applica-

tions. Optional field installed supplemental electric heat is

available in 5, 7, 10, 15 and 20 kW.

Both the 12GCS and 12CHP units utilize a scroll compres-

sor. It operates much like a standard compressor, but the

scroll compressor is unique in the way that it compresses

refrigerant. The compressor has overload protection and its

own cover for reducing operating sound levels.

Information contained in this manual is intended for use by

qualified service technicians only. All specifications are sub-

ject to change. Procedures outlined in this manual are pre-

sented as a recommendation only and do not supersede or

replace local or state codes.

WARNING

Improper installation, adjustment, alteration, service

or maintenance can cause property damage, person-

al injury or loss of life. Installation and service must

be performed by a qualified installer or service

agency.

ELECTROSTATIC DISCHARGE (ESD)

Precautions and Procedures

CAUTION

Electrostatic discharge can affect electronic

components. Take precautions during unit instal-

lation and service to protect the unit’s electronic

controls. Precautions will help to avoid control

exposure to electrostatic discharge by putting

the unit, the control and the technician at the

same electrostatic potential. Neutralize electro-

static charge by touching hand and all tools on an

unpainted unit surface before performing any

service procedure.

12GCS

12CHP

TABLE of CONTENTS

Introduction....................................................................1

Specifications/Blower Data 12GCS.............................2,4

High Altitude 12GCS.......................................................4

Specifications/Blower Data 12CHP.............................5,6

Parts Arrangement......................................................7,8

I Application ...................................................................9

II Unit Components ...................................................9,14

III Electric Heat .........................................................15,17

IV Charging ..............................................................18,19

V Maintenance ........................................................... 20

VII Wiring Diagram and Sequence of Operation .......... 21

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Summary

12 GCS Electrical and Blower Data

Unit Components - Control Box

Compressor Contactor, Transformer, Capacitor, Ignition;Blower Control

Details of control box components including contactor, transformer, capacitor, and ignition control.

Unit Components - CHP Controls

Blower Control A15 and Defrost Control CMCI

Information on the blower control module and defrost control for CHP units.

Unit Components - GCS Gas, Sensors, Blower

Gas Components, Electrode;Sensor, Evaporator Blower;Capacitor

Details on GCS gas components, electrode/sensor, and evaporator blower/capacitor.

Unit Components - Heat Exchanger & Burners

Clamshell Heat Exchanger and Burners;Orifices

Information on the clamshell heat exchanger and burner/orifice assemblies.

Cooling Components - Compressor & Fan

Scroll Compressor and Condenser Fan

Details on the scroll compressor and single-phase condenser fans used in the units.

Cooling Components - Refrigerant Circuit

Reversing Valve, Accumulator, Filter Drier, High Pressure Switch

Details on refrigerant circuit components like reversing valve, accumulator, filter drier, and pressure switch.

Electric Heat Components - Limits and Fuses

Primary Limit, Thermal Fuse, Sequencers

Details on electric heat limits, thermal fuses, and sequencer relays.

Electric Heat Components - Circuit Breakers

Circuit Breakers CB1 and CB2

Information on circuit breakers used in electric heat sections.

Charging and Performance - 12 CHP

12 CHP Operating Pressures and Superheat Tables

Tables for normal operating pressures and suction superheat for 12CHP units.

Charging and Performance - 12 GCS

12 GCS Operating Pressures and Superheat Tables

Tables for normal operating pressures and suction superheat for 12GCS units.

Maintenance

Filter, Coil, and Flue Cleaning

Procedures for periodic maintenance including filter, coil, and flue cleaning.

Wiring Diagrams and Sequence of Operation

12 GCS Wiring and Sequence of Operation

Wiring diagrams and operational sequences for 12GCS units.

12 CHP Wiring and Sequence of Operation

12 CHP Cooling, Heating, and Defrost Operation

Sequences of operation for cooling, heating, and defrost modes of 12CHP units.

Electric Heat Wiring and Sequence

ECH29 Electric Heat Stage Operation

Wiring and sequence of operation for ECH29 electric heat stages.

The Lennox 12GCS/12CHP Elite Series Units are single-phase, packaged heat/cool (12GCS) and heat pump (12CHP) units designed for outdoor residential installation on a slab or rooftop. These units are available in three cabinet sizes, ranging from 2 to 5 tons (7.0 to 17.6 kW). The 12GCS units offer gas heat sections with Lennox S-curve heat exchangers in 50,000, 75,000, 100,000, and 125,000 Btuh input sizes. The 12CHP units can be equipped with optional field-installed supplemental electric heat in 5, 7, 10, 15, and 20 kW configurations. Both models utilize a scroll compressor for refrigerant compression, which includes overload protection and a sound-reducing cover.

Important Technical Specifications:

12GCS (Heat/Cool):
- Cooling Capacity: 23,000 to 58,000 Btuh (6.7 to 17.0 kW).
- SEER: 10.45 to 12.00 Btuh/Watt.
- EER: 10.45 to 10.73 Btuh/Watt.
- Heating Capacity Input: 50,000 to 125,000 Btuh (14.7 to 36.6 kW).
- Heating Capacity Output: 40,000 to 100,000 Btuh (11.7 to 29.3 kW).
- AFUE: 80.0%.
- Refrigerant Charge (HCFC-22): 4 lbs 8 oz (2.04 kg) to 10 lbs 4 oz (4.73 kg).
- Blower Motor Horsepower: 1/2 (373 W) to 3/4 (560 W).
- Condenser Fan Motor Horsepower: 1/8 (93 W) to 1/4 (187 W).
- Electrical Characteristics: 208/230V-1ph-60hz.
- Minimum Circuit Ampacity: 17.3 to 37.4 amps.
- Maximum Fuse/Breaker Size: 30 to 50 amps.
- Net Weight: 280 lbs (132 kg) to 440 lbs (207 kg).
12CHP (Heat Pump):
- Cooling Capacity: 23,800 to 57,000 Btuh (7.0 to 16.7 kW).
- SEER: 12.00 Btuh/Watt.
- EER: 10.65 to 11.00 Btuh/Watt.
- High Temperature Heating Capacity: 24,000 to 57,000 Btuh (7.0 to 16.7 kW).
- COP (High Temp Heating): 3.00 to 3.30.
- HSPF (Region IV): 7.00 to 7.20.
- Low Temperature Heating Capacity: 14,800 to 37,300 Btuh (4.3 to 10.9 kW).
- COP (Low Temp Heating): 2.06 to 2.16.
- Refrigerant Charge (HCFC-22): 7 lbs 4 oz (3.29 kg) to 12 lbs 3 oz (5.53 kg).
- Blower Motor Horsepower: 1/2 (373 W) to 3/4 (559 W).
- Condenser Fan Motor Horsepower: 1/4 (187 W).
- Electrical Characteristics: 208-230V, 1ph, 60hz.
- Minimum Circuit Ampacity: 18.2 to 36.7 amps.
- Maximum Fuse/Breaker Size: 25 to 50 amps.
- Net Weight: 275 lbs (125 kg) to 455 lbs (206 kg).

Usage Features:

Control Box Components: Both models share a compressor contactor (K1) and a control transformer (T1). The transformer provides 24VAC power to control circuits and has two primary voltage taps (208/240V). A dual capacitor (C12) is used for both the condenser fan motor and the compressor.
12GCS Ignition/Blower Control (A3): Features an integrated ignition/blower board for controlling ignition, safety circuits, blower operation, and fan off timing. It uses direct spark ignition with a 30-second pre-purge, 10-second spark attempt, and a 1-hour Watchguard mode after three failed ignition attempts. Safety circuits monitor primary and secondary heating limits and a rollout switch.
12CHP Defrost Control (CMCI): Monitors outdoor coil temperature to initiate and terminate defrost cycles. It is time/temperature initiated and temperature terminated, with a maximum defrost time of 10 minutes. Intervals between defrost cycles are factory set at 60 minutes but can be adjusted to 30, 60, or 90 minutes. During defrost, the reversing valve solenoid is energized, the outdoor fan is de-energized, and optional electric heat is energized for comfort.
Gas Components (12GCS Only):
- Primary Limit (S10): Auto-reset, high-temperature limit protecting against high-temperature operation.
- Rollout Switch (S47): Manual-reset, high-temperature limit on the burner box, opening on flame rollout.
- Secondary Limit (S21): Auto-reset disc on the blower scroll, a safety feature if the circulating blower fails.
- Combustion Air Prove Switch (S18): SPST N.O. differential prove switch monitoring combustion air inducer blower operation.
- Combustion Air Inducer (B6): Provides fresh air to burners and clears exhaust gases from the heat exchanger.
- Gas Valve (GV1): Honeywell valve with internal redundancy for safety shutoff. Line pressure for natural gas is 7.0"w.c. (3.5"w.c. manifold pressure) and for LP is 11.0"w.c. (10.0"w.c. manifold pressure).
Heat Exchanger (12GCS Only): Aluminized steel tapered S-curve heat exchanger.
Burners/Orifices (12GCS Only): Inshot burners with flame retention rings.
Electrode/Flame Sensor (12GCS Only): Used for ignition and flame sensing. Spark gap is 1/8". Flame current should be between 1 and 5 microamps.
Evaporator Blower (B3) and Capacitor (C4): Single-phase motors with a permanent split capacitor.
Reversing Valve (L1) (12CHP Only): 24-volt solenoid coil reversing refrigerant flow during cooling and defrost.
Accumulator (12CHP Only): Traps and evaporates liquid refrigerant, preventing it from entering the compressor.
Defrost Thermostat Switch (S6) (12CHP Only): S.P.S.T. N.O. switch closing at 32°F (0°C) to initiate defrost and opening at 55°F (12.7°C) to terminate.
Filter Drier (12CHP Only): Removes contaminants and moisture from the liquid line.
High Pressure Switch (Optional All Models): Auto-reset N.C. switch opening at 450 psig (3102 kPa) and closing at 250 psig (1723 kPa) to de-energize the compressor.
Electric Heat (Optional 12CHP Only):
- Primary Limit (S15): N.C. auto-reset high-temperature limit for each heating element.
- Thermal Fuse (F5): Non-resettable fusible links providing secondary high-temperature protection.
- Sequencer Relays (K32, K33, K34): N.O. sequencer relays with resistive elements, energized by 24V heating demand, controlling heat stages and blower operation.
- Heating Elements (HE1-HE4): Helix-wound bare nichrome wire, energized independently by corresponding relays.

Maintenance Features:

Filters: Inspect monthly. Replace disposable or clean permanent types as necessary.
Motors: Indoor and outdoor fan motors are permanently lubricated and require no maintenance.
Outdoor Coil: Clean as often as necessary using a brush, vacuum cleaner attachment, or water (with power shut off). Care must be taken not to damage coil fins.
Burners (12GCS Only): Remove and vacuum/brush as required.
Vent Outlet (12GCS Only): Visually inspect periodically for soot and dirt buildup.
Flue Passages & Heating Elements (12GCS Only): Clean if sooted by removing the burner assembly, combustion blower, and flue collector box. Use a wire brush on a flexible wand, then blow with air and vacuum. Ensure all joints on the vent side of the combustion system are airtight with high-temperature sealing compound.

Safety Precautions:

Always disconnect electrical power before performing any service or maintenance.
Be aware of electrical shock hazards and discharge capacitors before servicing.
Improper installation, adjustment, alteration, service, or maintenance can cause property damage, personal injury, or loss of life.
Installation and service must be performed by a qualified installer or service agency.
Refrigerant can be harmful if inhaled; use and recover responsibly.
Electrostatic discharge (ESD) can affect electronic components. Take precautions by neutralizing static charge (touching unpainted unit surface) before service.
Limit replacement must be of exact length and setpoint to ensure safe operation.