Lennox GCS16-1853-235

SERVICE
GCS16
UNIT
INFORMATION
6-25 TON UNITS
Page 1
1994 Lennox Industries Inc.
Corp. 9322-L3 Litho U.S.A.
GCS16 SERIES
GCS16 series units in the 6 ton and larger cooling size are
packaged combination two-stage gas heat / two-stage dx
cool units designed for commercial applications. Gas heat
sections are designed with Lennox' aluminized steel tube
heat exchangers ranging in size from 135,000 to 470,000
Btuh input. Units are designed for rooftop or side of building
installation with either bottom or horizontal discharge and
return air.
For commercial applications, the GCS16 is designed to ac
cept any of several different thermostat control systems with
minimum field wiring. Control options such as economizer,
warm up kit, Honeywell W973 control, Honeywell W7400
control or other field specified controls connect to the unit
with jack-plugs. When plugged in" the controls become an
integral part of the unit wiring. Units are also equipped with a
low voltage terminal strip to facilitate thermostat field wiring.
All specifications in this manual are subject to change.
GCS16-1853 SHOWN
TABLE OF CONTENTS
Introduction Page 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications Pages 2-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Data Page 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Blower Data Pages 11-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Resistance Data Pages 17-18. . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Arrangement Pages 18-22. . . . . . . . . . . . . . . . . . . . . . . . . . . .
I- APPLICATION Page 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
II- UNIT COMPONENTS Pages 22-41. . . . . . . . . . . . . . . . . . . . . . . . .
Control Box Components Pages 22-25. . . . . . . . . . . . . . . . . . . . . .
Heating Components Pages 26-34. . . . . . . . . . . . . . . . . . . . . . . . . .
Cooling Components Pages 34-40. . . . . . . . . . . . . . . . . . . . . . . . . .
Blower Compartment Components Pages 40-41. . . . . . . . . . . . . .
III- ELECTRICAL CONNECTIONS Page 41. . . . . . . . . . . . . . . . . . . .
IV- PLACEMENT AND INSTALLATION Page 41. . . . . . . . . . . . . . .
V- START UP - OPERATION Pages 41-42. . . . . . . . . . . . . . . . . . . . .
Preliminary Checks Page 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cooling / Heating Start Up Pages 41-42. . . . . . . . . . . . . . . . . . . . . .
Safety or Emergency Shut Down Page 42. . . . . . . . . . . . . . . . .
VI- COOLING SYSTEM CHECKS Page 42. . . . . . . . . . . . . . . . . . . . .
Gauge Manifold Attachment Page 42. . . . . . . . . . . . . . . . . . . . . . .
Charging Page 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VII- HEATIING SYSTEM SERVICE CHECKS Pages 42-46. . . . . . . .
A.G.A./C.G.A. Applications and Requirements Page 42-43. . . . .
Gas Piping Page 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing Gas Piping Page 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing Supply Pressure Page 43. . . . . . . . . . . . . . . . . . . . . . . . . .
Check and Adjust Manifold Pressure Page 43-44. . . . . . . . . . . . .
Proper Gas Flow Page 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Altitude Derate Pages 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inshot Burner Pages 44-45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heat Exchanger Page 45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Control Page 45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrode Gap and Flame Sensing Pages 45-46. . . . . . . . . . . . .
Combustion Air Blower Page 46. . . . . . . . . . . . . . . . . . . . . . . . . . .
VIII- INDOOR BLOWER OPERATION / ADJUSTMENT
Pages 46-47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Blower Operation Page 46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Determining Unit CFM Page 46. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Blower Belt Adjustment Pages 46-47. . . . . . . . . . . . . . . . . . . . . . .
IX- MAINTENANCE Page 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filters Page 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lubrication Page 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Supply Air Blower Wheel Page 47. . . . . . . . . . . . . . . . . . . . . . . . . .
Evaporator and Condenser Coil Page 47. . . . . . . . . . . . . . . . . . . .
Electrical Page 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
X- ACCESSORIES Pages 48-63. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RMF16 Roof Mounting Frame Page 48. . . . . . . . . . . . . . . . . . . . .
OAD16 Outdoor Air Damper Page 48. . . . . . . . . . . . . . . . . . . . . . .
Economizers Pages 48-54. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transitions and Supply / Return Diffusers Page 54. . . . . . . . . . . .
Firestats Page 54. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cycle Control Kit Page 55. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Ambient Kit Page 56. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Status Panels Pages 56-57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Commercial Controls Hardware Pages 58-59. . . . . . . . . . . . . . . .
Optional Commecial Controls Systems Pages 59-63. . . . . . . . . .
Clocks / Timers Page 63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
XI- WIRING DIAGRAMS / OPERATION SEQUENCE
Pages 64-79. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Operation Sequence Pages 64-75. . . . . . . . . . . . . . . . . . . . .
REMD16M Economizer Operation Sequence Pages 76-77. . . .
Warm Up Kit Operation Sequence Pages 78-79. . . . . . . . . . . . . .
Библиотека СОК 

Lennox GCS16-1853-235 Specifications

General

Brand	Lennox
Model	GCS16-1853-235
Category	Gas Heater
Language	English

Summary

Specifications

GCS16-823 & GCS16-953

Provides detailed specifications for GCS16-823 and GCS16-953 models.

GCS16-1353 & GCS16-1603

Provides detailed specifications for GCS16-1353 and GCS16-1603 models.

GCS16-1853-235 & GCS16-1853-330

Provides detailed specifications for GCS16-1853-235 and GCS16-1853-330 models.

GCS16-2553-235 & GCS16-2553-470

Provides detailed specifications for GCS16-2553-235 and GCS16-2553-470 models.

GCS16-2753-235 & GCS16-2753-470

Provides detailed specifications for GCS16-2753-235 and GCS16-2753-470 models.

GCS16-3003-235 & GCS16-3003-470

Provides detailed specifications for GCS16-3003-235 and GCS16-3003-470 models.

Optional Accessories

GCS16-823 & GCS16-953 (Ordered Extra)

Lists optional accessories for GCS16-823 and GCS16-953 models.

GCS16-1353 & GCS16-1603 (Ordered Extra)

Lists optional accessories for GCS16-1353 and GCS16-1603 models.

GCS16-1853 (Ordered Extra)

Lists optional accessories for GCS16-1853 models.

GCS16-2553, GCS16-2753 & GCS16-3003 (Ordered Extra)

Lists optional accessories for GCS16-2553/2753/3003 models.

Electrical Data

GCS16-823, -953, -1353 & -1603

Provides electrical data for specific GCS16 models.

GCS16-1853, -2553 & -2753

Provides electrical data for specific GCS16 models.

Blower Performance

GCS16-823 BLOWER PERFORMANCE

Details blower performance data for GCS16-823 models.

GCS16-953 BLOWER PERFORMANCE

Details blower performance data for GCS16-953 models.

GCS16-1353 BLOWER PERFORMANCE

Details blower performance data for GCS16-1353 models.

GCS16-1603 BLOWER PERFORMANCE

Details blower performance data for GCS16-1603 models.

GCS16-1853-235 BLOWER PERFORMANCE

Details blower performance data for GCS16-1853-235 models.

GCS16-1853-330 BLOWER PERFORMANCE

Details blower performance data for GCS16-1853-330 models.

GCS16-2553-235 & GCS16-2753-235 BLOWER PERFORMANCE

Details blower performance for GCS16-2553/2753-235 models.

GCS16-2553-470 & GCS16-2753-470 BLOWER PERFORMANCE

Details blower performance for GCS16-2553/2753-470 models.

GCS16-3003-235 BLOWER PERFORMANCE

Details blower performance data for GCS16-3003-235 models.

GCS16-3003-470 BLOWER PERFORMANCE

Details blower performance data for GCS16-3003-470 models.

Accessory Air Resistance

GCS16-823 GCS16-953

Air resistance data for GCS16-823 and GCS16-953 models.

GCS16-1353

Air resistance data for GCS16-1353 models.

GCS16-1603

Air resistance data for GCS16-1603 models.

GCS16-1853

Air resistance data for GCS16-1853 models.

GCS16-2553 GCS16-2753 GCS16-3003

Air resistance data for GCS16-2553/2753/3003 models.

Parts Arrangement

823953 PARTS ARRANGEMENT

Diagram showing component layout for GCS16-823/953 units.

13531603 PARTS ARRANGEMENT

Diagram showing component layout for GCS16-1353/1603 units.

1853 PARTS ARRANGEMENT

Diagram showing component layout for GCS16-1853 units.

255327533003 PARTS ARRANGEMENT (SLAB COIL SHOWN)

Diagram for slab coil units GCS16-2553/2753/3003.

Control Box Components

GCS16-823, -953 CONTROL BOX COMPONENTS

Diagram of control box for GCS16-823 and GCS16-953.

GCS16-1353, -1603 CONTROL BOX COMPONENTS

Diagram of control box for GCS16-1353 and GCS16-1603.

GCS16-1853 UNIT CONTROL BOX

Diagram of the control box for GCS16-1853 units.

Power Distribution Terminal Block TB13

Explains the power distribution terminal block for larger units.

Terminal Strip TB1

Details the low voltage terminal strip for thermostat and control wiring.

Terminal Block TB17 (-2553, -2753, -3003)

Low voltage terminal block for diagnostic troubleshooting.

Transformer T1 (all units)

Single line voltage to 24VAC transformer for control circuits.

Transformer Fuse F1 (all units)

Fuse for transformer T1, accessed outside the transformer.

Transformer T18 (-2553, -2753, -3003 only)

Line voltage to 24VAC transformer for contactors.

Transformer T3 (all 460 V and 575 V units)

Autotransformer for combustion air blower power.

Condenser Fan Motor Fuse F10 (-2553, -2753, -3003 only)

Provides overcurrent protection for condenser fans.

Unit Line Voltage Fuses F16 (-1853, -2553, -2753, -3003)

Provides overcurrent protection for line voltage components.

Circuit Breaker CB4, CB5 (-1603 Y voltage only)

Overcurrent protection for condenser fans.

Compressor Contactor K1 (all units)

Contactor for the first stage compressor.

Blower Motor Overload Relay S42 (5 & 10 HP Motors only)

Thermal overload relay for blower motor.

Compressor Contactor K2 (all units)

Contactor for the second stage compressor.

Compressor Contactor K14 (-1853 only)

Contactor for the third compressor.

Indoor Blower Contactor K3 (all units)

Contactor for the indoor blower motor.

Condenser Fan Contactor K10 (all units except -1353)

Contactor for condenser fans.

Combustion Air Blower Relay K13 (all units)

Relay for the combustion air blower.

Condenser Outdoor Fan Contactor K68 (-2553, -2753, -3003 only)

Contactor for condenser outdoor fan.

Pilot Relay Board A11 (-1853, -2553, -2753, -3003 only)

Board used to reduce contactor chattering.

Compressor Motor Protector A9, A10 (-2553, -2753, -3003 only) 575 Volt Only

Protects compressors by sensing motor winding temperature.

Low Ambient Lockout Switch (Compressor Monitor) S3 (all units)

Opens to disconnect compressors when outdoor temp drops below 40°F.

Low Ambient Lockout Switch (Compressor Monitor) S30 (-1353, -1603 only)

Second compressor monitor protecting second stage compressors.

Compressor Delay DL15 (-1603 Y voltage, -1853 all voltages)

Time delay switch to prevent voltage drop during compressor start.

Heating Control Components

GCS16-823, -953, -1353, -1603 HEATING CONTROL COMPONENTS

Diagram of heating control components for specific models.

HEATING CONTROL COMPONENTS GCS16-1853,-2553, -2753, -3003 UNITS EQUIPPED WITH SINGLE HEAT EXCHANGER

Diagram of heating controls for single heat exchanger units.

HEATING CONTROL COMPONENTS GCS16-1853, -2553, -2753, -3003 UNITS EQUIPPED WITH DUAL HEAT EXCHANGERS

Diagram of heating controls for dual heat exchanger units.

Transformer T3

Autotransformer for combustion air blower.

Transformer T12 (1853, 2553, 2753, 3003)

Transformer for heating control circuits.

Transformer T13

Transformer for second stage combustion air blower.

Combustion Air Blower Relay K13 (1 st Stage Heat Relay)

Energizes combustion air blower for heating sequence.

Indoor Blower (Limit) Relay K20

Energizes indoor blower on high temp limit trip or reset.

2 nd Stage Heat Relay K19

Energizes 2nd stage operation for heating.

1 st Stage Heat Blower Relay K56

Energizes indoor blower for 1st stage heat (dual units).

2 nd Stage Heat Blower Relay K57

Energizes indoor blower for 2nd stage heat (dual units).

2 nd Stage Gas Heat Delay DL3

Time delay for 2nd stage gas heating operation.

Blower Delay Relay K25

Coordinates blower operation with burner sequence.

Burner Ignition Controls A3, A12

Controls ignition spark, flame sensing, and gas valve.

Spark ElectrodeFlame Sensor Gap

Details the gap requirement for ignition electrodes.

Flame Sensing

Explains how flame is sensed by rectification.

Heat Exchanger and Burners

Heat Exchanger

Describes the aluminized steel inshot burners and heat exchangers.

Burner Assembly (Figure 24)

Details burner assembly components and their function.

Burners

Information on inshot burners, air shutters, and flame viewing.

Orifice

Describes the burner orifice and its sizing.

Primary High Temperature Limit S10

Primary safety shut-down function.

Secondary High Temperature Limit S21

Secondary safety shut-down function.

Flame Rollout Switch S47

High temperature cutoff fuse for flame rollout.

Flame Rollout Switch S69

Rollout switch for second stage heat exchanger.

Combustion Air Prove Switch S18

Monitors combustion air blower operation.

Combustion Air Prove Switch S45

Prove switch for second stage heat exchanger.

Combustion Air Blower B6, B15

Provides fresh air to burners and clears exhaust gases.

Cooling Components and Plumbing

Cooling Components - Summary of Features

Overview of GCS16 independent cooling circuits.

GCS16-823, -953 PLUMBING COMPONENTS

Diagram of plumbing components for GCS16-823,-953 units.

GCS16-1353,-1603 END VIEW COMPRESSOR COMPARTMENT

Diagram of compressor compartment for GCS16-1353/1603.

GCS16-1853 PLUMBING COMPONENTS CONDENSING SECTION - VAPOR LINES

Diagram of vapor lines in the condensing section.

GCS16-1853 PLUMBING COMPONENTS CONDENSING SECTION - LIQUID LINES

Diagram of liquid lines in the condensing section.

GCS16-2553, -2753, -3003 PLUMBING COMPONENTS CONDENSING SECTION - LIQUID AND SUCTION LINES

Diagram of liquid and suction lines for slab coil units.

GCS16-823, -953, -1353, -1603 EVAPORATOR PLUMBING

Diagram of evaporator plumbing for specific models.

GCS16-1853 PLUMBING COMPONENTS EVAPORATOR SECTION

Diagram of evaporator section plumbing for GCS16-1853.

GCS16-2553, -2753, -3003 PLUMBING COMPONENTS EVAPORATOR SECTION

Diagram of evaporator section plumbing for GCS16-2553/2753/3003.

Compressors B1, B2 and B13

Details compressors used in GCS16 units.

System Safety and Limits

Crankcase Heaters HR1, HR2 and HR5

Details the self-regulating crankcase heaters.

High Pressure Limit S4, S7 and S28

Manually reset switch opening on pressure rise.

Loss of Charge Switch S24, S25 and S34

Auto-reset switch opening on pressure drop.

Thermometer Well (Figure 37)

Well for charging the unit and measuring liquid line temperature.

Freezestats S49, S50 and S53

Low temperature limits on evaporators.

Blower Compartment and Maintenance

Indoor Blower Motor B3

Details the three-phase single-speed blower motor.

Filters

Instructions for checking and replacing filters.

Lubrication

Notes that motors are prelubricated.

Supply Air Blower Wheel

Annual inspection for dirt or dust.

Evaporator Coil

Inspect and clean evaporator coil.

Condenser Coil

Annual cleaning of condenser coil.

Electrical

Check wiring for loose connections and voltage.

Accessories

RMF16 Mounting Frame

Roof mounting frame for downflow discharge applications.

OAD16 Outdoor Air Damper

Manual damper section for fixed outside air.

Economizer

Assembly for recirculated and outdoor air control.

REMD16 M Downflow Economizer (all units)

Economizer for downflow use, adaptable to horizontal discharge.

REMD16 M Horizontal Economizer (-823, -953, -1353, -1603 only)

Horizontal economizer for specific models requiring horizontal discharge.

EMDH16 M Horizontal Economizer (-823, -953, -1353, -1603 only)

Horizontal economizer for specific models.

PED16 Power Exhaust Damper (-1853, -2553, -2753, -3003 only)

Power exhaust fans for economizer systems.

Economizer Accessories

Accessories for economizer systems.

Differential Enthalpy (all economizers)

Optional control for monitoring air conditions.

Economizer Operation and Controls (all economizers)

Controls economizer based on outdoor air enthalpy.

Warm Up Kit (units equipped with standard or electronic thermostat and night setback function)

Holds outdoor air dampers closed during morning warm-up.

Minimum Positioner

Adjusts minimum position of outdoor dampers.

Enthalpy Sensor

Monitors outdoor air heat content for cooling control.

Mixed Air Sensor

Measures mixed air temperature for economizer control.

Wiring, Installation, Maintenance

Instructions for economizer wiring and maintenance.

Modulating Damper Motor Check

Procedure to check the damper motor operation.

Transitions

Optional supply/return transition SRT16.

Supply and Return Diffusers

Optional flush mount and extended mount diffusers.

Firestats

Firestats for automatic shutdown or control.

Cycle Control Kit

Low Ambient Kit (all units)

Allows mechanical cooling at low outdoor temperatures.

Status Panels SP11 and SSP11

Panels for remote system monitoring.

SP11 Application

Application of SP11 to any control system.

SSP11 Application

SSP11 application for specific thermostat systems.

Indications and Functions

Describes status panel LEDs and switch functions.

Commercial Controls Hardware

Jack J2(opt. Plug P2)

Connection point for heating section.

Jack J3 Plug P3

Connection for economizer or relay kits.

Jack J16 Plug P16

Connection for optional control system.

Jack J18 Plug P18

Extension harness for power exhaust damper fans.

Jack J24 (opt. Plug P24)

Connection for optional power exhaust damper control kit.

Jack J25 (opt. Plug P25)

Connection for optional status panel.

Jack J33 (opt. Plug P34)

Connection for optional third stage heating relay.

Jack J35 Plug P35

Used for assembly line tests only.

Jack J36 Plug P36

Used for assembly line tests only.

Jack J57 (opt. Plug P57)

Connection for 'dirty filter' indicator switch.

Optional Commercial Controls Systems

Wiring Diagram D5 - Modulating Economizer

Diagram for modulating economizer.

Warm-Up Kit

Accessory for economizer (diagram D5).

WARM UP KIT RELAY KIT INSTALLATION 12.5 AND SMALLER UNITS

Installation of warm-up kit relay for smaller units.

WARM UP KIT RELAY KIT INSTALLATION 15 AND LARGER UNITS

Installation of warm-up kit relay for larger units.

C1 Wiring Diagram

Thermostat wiring for units without economizer/warm-up.

C2-1 Wiring Diagram

Thermostat wiring for units with economizer/warm-up.

C11-1 Wiring Diagram

Thermostat wiring with night setback function.

C3 Wiring Diagram

Flexstat thermostat wiring for units without economizer/warm-up.

C4 Wiring Diagram

Flexstat thermostat wiring with economizer/warm-up.

C5 Wiring Diagram

Prostat thermostat wiring for units without economizer/warm-up.

C6 Wiring Diagram

Prostat thermostat wiring with economizer/warm-up.

C7-3 Wiring Diagram

W7400 control system wiring.

C8-1 Wiring Diagram

W973 control system wiring without economizer/warm-up.

C12 Wiring Diagram

T7300 thermostat wiring for units without economizer.

C12-2 Wiring Diagram

T7300 thermostat wiring with economizer.

Clocks Timers (CMC3-1)

Optional clocks for setback operation.

Wiring Diagrams and Operating Sequence

B1 diagram with C1 diagram GCS16-823 or -953 with basic standard thermostat

Wiring and operation sequence for GCS16-823/953 with C1 thermostat.

C1 DIAGRAM WITH B1 DIAGRAM Electromechanical Thermostat Connected to GCS16-823 or GCS16-953 (Without Economizer)

Wiring and operation sequence for GCS16-823/953.

Operation Sequence: C1 and B1 Sections (electromechanical thermostat wired to GCS16-823 or GCS16-953)

Step-by-step operation for C1/B1 wiring.

B2 diagram with C1 diagram gcs16-1353 with basic standard thermostat

Wiring for GCS16-1353 with C1 thermostat and B2 diagram.

C1 DIAGRAM WITH B2 DIAGRAM Electromechanical Thermostat Connected to GCS16-1353 (Without Economizer)

Wiring and operation sequence for GCS16-1353.

Operation Sequence: C1 and B2 Sections (electromechanical thermostat wired to GCS16-1353)

Step-by-step operation for C1/B2 wiring.

C1 DIAGRAM WITH B2 DIAGRAM Electromechanical Thermostat Connected to GCS16-1603 (Without Economizer)

Wiring and operation sequence for GCS16-1603.

Operation Sequence: C1 and B2 Sections (electromechanical thermostat wired to GCS16-1603)

Step-by-step operation for C1/B2 wiring.

B41 and A8 diagrams with C1 diagram GCS16-2553,-GCS16-2753-470 or GCS16-3003-470 with basic standard thermostat

Wiring diagrams for GCS16-2553/2753/3003 with C1 thermostat.

C1 DIAGRAM WITH B41 and A8 DIAGRAMS Electromechanical Thermostat Connected to GCS16-2553, -2753 or -3003 with 235,000 BTUH Input Heat (Without Economizer)

Wiring and operation sequence for GCS16-2553/2753/3003.

Operation Sequence: C1 and B9 and A8 Sections (electromechanical thermostat wired to GCS16-1853)

Step-by-step operation for C1/B9/A8 wiring.

C1 DIAGRAM WITH B41 and A8 DIAGRAMS Electromechanical Thermostat Connected to GCS16-2553, -2753 or -3003 with 470,000 BTUH Input Heat (Without Economizer)

Wiring and operation sequence for higher capacity units.

Operation Sequence: C1 and B41 and A8 Sections (electromechanical thermostat wired to GCS16)

Step-by-step operation for C1/B41/A8 wiring.