Johnson Controls GVA Series User Manual

5586996-JSG-A-0120
25–50 Tons
Premier Rooftop Units
R-410A
LD26877
Table of Contents
Nomenclature ...................................................................... 4
Pre Start-Up Checklist ......................................................... 7
Start-Up ............................................................................... 9
Long Term Storage ......................................................... 9
Checking System Prior to Initial Start (No Power) ......... 9
Unit Checks (Power Applied) ....................................... 10
Initial Start-Up .............................................................. 16
Refrigerant Charge ............................................... 16
Checking Sub-Cooling and Superheat.................. 16
Leak Checking ...................................................... 17
Gas Heat Models .................................................. 17
Phase Monitor Adjustment .................................... 20
Commissioning Mode................................................... 20
Air Balancing Wizard .................................................... 20
Start-Up Wizard ............................................................ 24
Start-Up Wizard Sequence ................................... 26
Sequences of Operation .................................................... 30
Control Boards ............................................................. 30
Variable Frequency Drives (VFDs) ............................... 37
Unit Type ...................................................................... 38
Occupancy Mode ......................................................... 38
Morning Warm-up/Cool Down ............................... 38
Coast..................................................................... 38
Remote Safety Shutdown ............................................ 39
Low Voltage Monitoring ................................................ 39
Supply Fan Operation .................................................. 39
Supply Fan Alarm.................................................. 39
MZVAV Supply Fan ............................................... 39
SZVAV Supply Fan ............................................... 40
Redundant Supply Fan VFD ................................. 40
Cooling Operation ........................................................ 40
MZVAV Cooling Operation .................................... 40
SZVAV Cooling Operation ..................................... 42
Compressors and Refrigeration Circuits ............... 42
Compressor Staging Sequences .......................... 44
Condenser Systems and Fans.............................. 48
Dehumidication (Hot Gas Reheat) ...................... 49
Economizer ........................................................... 51
Heating ......................................................................... 52
Gas Heating .......................................................... 52
Electric Heating ..................................................... 56
Hydronic Heating .................................................. 56
MZVAV Heating Operation .................................... 56
SZVAV Heating Operation .................................... 57
Ventilation..................................................................... 58
Ventilation Sequences .......................................... 58
Low Mixed Air Temperature Limiting ..................... 58
Demand Control Ventilation .................................. 58
Continuous Ventilation .......................................... 59
Pre-Occupancy Purge........................................... 59
Humidification............................................................... 60
Humidication Sequence ...................................... 60
Exhaust System ........................................................... 60
Modulating Exhaust Fan ....................................... 60
Modulating Exhaust Damper with Fan .................. 60
External Control .................................................... 60
Return Fan ................................................................... 60
Return Fan Discharge Pressure ........................... 61
Supply Fan Airow Tracking.................................. 61
Energy Recovery Wheel .............................................. 61
Single Speed Energy Recovery Wheel ................. 61
Variable Speed Energy Recovery Wheel .............. 61
Ultraviolet Lights........................................................... 61
Smoke Control ............................................................. 62
Purge .................................................................... 62
Pressurization ....................................................... 62
Depressurize ......................................................... 62
START-UP & OPERATION

Johnson Controls GVA Series Specifications

General

Brand	Johnson Controls
Model	GVA Series
Category	Air Conditioner
Language	English

Summary

Nomenclature

Pre Start-Up Checklist

General Inspection

Verifies unit inspection for shipping, storage, rigging damage, clearances, and ductwork completeness before initial operation.

Request for Start-Up

Start-Up

Long Term Storage

Guidelines for storing units long-term, including visual inspection, motor relubrication, and pre-power application procedures.

Checking System Prior to Initial Start (No Power)

Pre-power checks including unit inspection, refrigerant piping leak verification, oil level, control panel, and field wiring.

Unit Checks (Power Applied)

Initial Start-Up

Refrigerant Charge

Information on factory-charged R-410A refrigerant and procedures for verifying the correct charge level.

Checking Sub-Cooling and Superheat

Method for calculating and verifying evaporator superheat and condenser sub-cooling using pressure/temperature charts.

Gas Heat Models

Pre-Start Checks

Essential checks for gas heat units, including leak testing fittings, verifying wiring, and understanding the start-up sequence.

Post Start Checks

Manifold Staged Gas Pressure Adjustment

Procedure for adjusting high and low fire manifold gas pressures using a 3/16" Allen wrench and manometer.

Phase Monitor Adjustment

Commissioning Mode

Air Balancing Wizard

Start-Up Wizard

Start-Up Wizard Sequence

Details the sequence of tests performed by the start-up wizard, covering dampers, ERW, supply fan, cooling, and heating.

Dampers

Energy Recovery Wheel (ERW)

Supply Fan

Cooling

Heating

Sequences of Operation

Control Boards

Identifies standard and optional control boards (UI, Main, Condenser, Options, BSI) and their communication via Modbus.

Variable Frequency Drives (VFDs)

Occupancy Mode

Morning Warm-up/Cool Down

Explains the sequence for morning warm-up/cool down operations based on zone temperature and external inputs.

Compressors and Refrigeration Circuits

Compressor Staging Sequences

Variable Speed Drive Compressor Control

Details the control of variable speed drive compressors, typically on circuit 1, via a VFD, managed by the unit controller.

Envelope Control

Compressor and Refrigeration Circuit Safeties

Liquid Line High Pressure Unloading

Sequence to prevent safety trips by monitoring liquid line pressure and unloading compressors when limits are exceeded.

Suction Line Low Pressure Unloading

Sequence to prevent safety trips by monitoring suction line pressure under low airflow or ambient conditions.

Condenser Systems and Fans

Saturated Liquid Line Temperature Control

How the unit controller regulates condenser fans based on saturated liquid line temperature setpoints.

Low Ambient Operation

Dehumidification (Hot Gas Reheat)

Economizer

Changeover Method

Describes the different economizer options (Dry Bulb, Single Enthalpy, Dual Enthalpy) and setup selections.

Heating

Gas Heating

Details staged and modulating gas heating options, including MBH inputs and operational sequences.

Electric Heating

Staged Electric Heat

Explains how the unit controller manages staged electric heat via 24 VAC signals to the electric heat package.

Modulating Electric Heat

Describes modulating electric heat using an SCR controller for proportional control of the first stage.

Hydronic Heating

Freezestat Alarm

Details the freezestat alarm system that protects hot water/steam coils from freezing by controlling the unit.

MZVAV Heating Operation

Ventilation

Demand Control Ventilation

Explains how CO2 sensors control the outside air damper for optimal indoor air quality management.

Smoke Control

Purge

Describes the purge sequence used to flush the building with 100% outside air during smoke control operations.

Pressurization

Explains the pressurization sequence to force outside air into spaces for building pressure management.

Depressurize

Details the depressurize mode for evacuating air from the building without introducing outside air.

User Interface Display

Status Menu

Displays current unit states, parameters, and sensor readings.

Alarms Menu

Displays the active alarm register with detailed descriptions of each alarm.

Alarm Log Menu

Provides a history of generated alarms, including date and time stamps for analysis.

Turning on the Unit

Using the USB Port

Display Firmware Update

Instructions for updating the unit's display firmware using a USB flash drive.

Rooftop Unit Firmware Update

Steps for uploading the latest firmware to the unit's main control board via USB.

Backup Function

Restore Function

Full Clone Function

Communication

BACnet Integration Setup

Guidance on configuring BACnet IP communication parameters and network settings.

Mobile Access Portal (MAP) Gateway

Verasys

Faults