Stulz CyberOne EC DX User Manual (English)

Questions and Answers:

B
Brian SmithAug 14, 2025
What to do if the Stulz Air Conditioner compressor fails to start?
- G
  Gregory RichardsonAug 14, 2025
  If the compressor fails to start, there could be several reasons. The temperature setpoint might be too high, so adjust it to the desired level. The compressor's internal overload protector could be open, in which case you should check the compressor for a short circuit or ground. A complete loss of refrigerant charge could trigger the low-pressure safety switch, requiring you to locate and repair any leaks and then recharge the system. Alternatively, high condenser pressure might activate the high-pressure safety switch, so inspect the condenser for obstructions. Finally, the compressor might be waiting for its minimum off time to expire.
G
Glenn CochranAug 17, 2025
Why does the Stulz Air Conditioner evaporator coil ice up?
- R
  Ryan WolfeAug 17, 2025
  Icing of the evaporator coil can occur due to a few reasons. The temperature setting might be too low, so increase the temperature setpoint to at least 68 °F. Another cause could be discharge air short cycling back to the return, so check the discharge grille orientation. Finally, a low refrigerant charge could also cause icing; in this case, find the leak, repair it, and recharge the system.
L
lucasdarrellAug 21, 2025
How to fix a Stulz Air Conditioner system with short capacity?
- Y
  yscottAug 21, 2025
  A system with short capacity may be caused by: * Low refrigerant, indicated by bubbles in the sight glass. Check for leaks, repair, and recharge the system. * An expansion valve that is stuck or obstructed, leading to short cycling or continuous running. Remove the valve and clear any obstruction, or replace the valve. * A blocked drier/strainer, which will feel cold to the touch. Replace it with a new drier/strainer.
S
savannahgomezAug 28, 2025
Why is the suction pressure too low in my Stulz Air Conditioner?
- A
  Ashley CookeAug 28, 2025
  Low suction pressure can be due to a loss of refrigerant, indicated by excessive bubbles in the sight glass. You should locate the leak, repair it, and then recharge the system. Alternatively, the expansion valve might be stuck or obstructed, causing short cycling or continuous running. In this case, remove and clean or replace the valve.
A
Ana DouglasSep 1, 2025
How to troubleshoot an inoperative heater in a Stulz Air Conditioner?
- D
  Devon HardingSep 1, 2025
  If the heater is inoperative, start by checking for blown fuses and replace them after checking for any short circuits. Ensure the temperature isn't set too low by increasing the temperature set point. Also, inspect for an open overheat switch due to insufficient airflow across the heater elements; look for dirty filters or obstructions, correcting or replacing them as needed. Furthermore, check if the manual-reset overheat safety switch has tripped and reset it. Lastly, test the heater element for continuity with an ohmmeter and replace it if burned out.
T
Tyler Villegas PhDSep 5, 2025
What to do if the water/glycol valve fails to open or close in my Stulz Air Conditioner?
- A
  Antonio ContrerasSep 5, 2025
  If the water/glycol valve isn't opening or closing, the temperature set point might be too high, so adjust it to the correct setting. Also, check if there's control power to the valve and ensure the thermostat is wired correctly, referring to the wiring diagram and rewiring if needed. Finally, the actuator itself might have failed, requiring replacement.
W
William BradleySep 9, 2025
Why is the humidifier in my Stulz Air Conditioner not working?
- S
  Susan GriffinSep 9, 2025
  If the humidifier is not working, first check if the water supply has been turned off or is not connected, and connect and/or turn it on. Ensure the humidifier switch is in the “Auto/On” position. Tighten any loose electrical connections. If the humidifier circuit breaker has tripped, check for overcurrent by the humidifier electrodes, drain water from the tank and refill, then reset the circuit breaker. If the relative humidity is above the set point, adjust the humidistat set point. If water conductivity is too low, add 1/4 teaspoon (1.23 ml) of table salt to the water through the top of the cylinder, typically only required on initial start-up.

Stulz CyberOne EC DX Specifications

General

Brand	Stulz
Model	CyberOne EC DX
Category	Air Conditioner
Language	English

Summary

1.0 Introduction

1.1 General System Overview

Details the CyberOne EC system, its manufacturer, and manual importance.

1.2 Product Description

Describes system types, capacities, configurations, and features.

1.3 Safety Guidelines

Explains safety symbols, notes, cautions, and warnings.

1.3 Safety Guidelines

1.3.2 Safety Summary

Provides crucial safety warnings for installation, operation, and maintenance.

1.4 General Design

1.4.1 Electrical Compartment

Details the location and safety features of the electrical compartment.

1.4 General Design

1.4.2 Circuit Breakers, Heaters, and Fans

Explains component protection, optional heaters, EC fans, and sensors.

1.5 Optional Equipment

Lists and briefly describes optional components like humidifiers and detectors.

1.6 Free-cooling Operation

1.7 AWS Operation

2.0 Installation

2.1 Equipment Receiving and Inspection

Guides on inspecting the unit upon delivery and handling shipping damage.

2.2 Moving and Storing Equipment

Instructions for safely moving and storing the unit before installation.

2.3 Site Preparation

Details requirements for the installation site, including clearances and access.

2.3 Site Preparation

2.2.1 Conditioned Space Requirements

Specifies environmental conditions for the installation space.

2.3 Mounting and Placement

Guides on unit placement, leveling, and securing.

2.3 Mounting and Placement

2.3.1 Precision A/C Unit Mounting

Details mounting procedures for the main unit and optional floor stands.

2.3.2 Outdoor Equipment Installation

Provides guidelines for installing remote condenser units.

2.4 Air Distribution Connection

Explains how to connect ductwork for air supply and return.

2.4.1 Downflow Air Patterns

Describes typical air patterns for downflow configurations.

2.4 Air Distribution Connection

2.4.2 Upflow Air Patterns

Describes air patterns for upflow configurations with plenum boxes or ducting.

2.5 Optional Field Installed Equipment

2.5.1 Floor Stand and Remote Display Installation

Details installation of optional floor stands and remote displays.

2.5.3 Remote Sensor Installation

Guides on mounting the remote temperature/humidity sensor.

2.6 Piping Connections

2.6.1 Refrigerant Piping

Details field-installed refrigerant piping for split systems.

2.6 Piping Connections

2.6.1 Refrigerant Piping Specifics

Specifics on traps, insulation, line sizing, and materials for refrigerant piping.

2.6.2 Water/Glycol & Condensate Systems

Covers water/glycol piping, condensate drain, and optional pump installation.

2.6.4 Humidifier Water Supply

Instructions for connecting the water supply to the humidifier.

2.7 Utility Connections

2.7.1 Main Power Connection

Explains main power supply requirements, nameplate data, and wiring.

2.7 Utility Connections

2.7.1 Main Power Connection Details

Covers voltage tolerances and buck/boost transformer applications for single-phase units.

2.7 Utility Connections

2.7.1 Main Power & Control Wiring

Details three-phase unit wiring, control system wiring, and optional equipment wiring.

2.7.4 Air-Cooled Split Systems Wiring

Covers field wiring for split systems, remote condensers, and condensing units.

2.7.4 Air-Cooled Split Systems Wiring

2.7.4.1 Remote Condenser Control Wiring

Explains control wiring requirements for remote condenser models.

2.7.4 Air-Cooled Split Systems Wiring

2.7.4.2 Remote Condensing Unit Wiring

Details control wiring for remote condensing units.

2.7.5 Glycol System Wiring

Outlines wiring for glycol-cooled systems and pump packages.

2.8 System Charging Procedures

2.8.1 Water/Glycol Systems Charging

Notes that these systems are factory charged and require no field charging.

2.8 System Charging Procedures

2.8.2 DX Unit Charging Requirements

Provides best practices for performing DX unit refrigerant charging.

2.8.3 Remote Air-Cooled Systems Charging

Covers removing nitrogen charge and performing charging on remote air-cooled units.

2.8 System Charging Procedures

2.8.4 R407C Refrigerant Characteristics

Details the properties and safety considerations of R407C refrigerant.

2.8.5 Estimating Refrigerant Charge

Explains how to estimate refrigerant charge using tables and examples.

2.8 System Charging Procedures

2.8.6 Preparing System for Charging

Outlines steps for leak detection, evacuation, and system preparation before charging.

2.8 System Charging Procedures

2.8.7 Refrigerant Charging Procedures

Details initial charging and fine-tuning of the refrigerant charge.

2.8 System Charging Procedures

2.8.7 Refrigerant Charging Procedures (Continued)

Specific procedures for fan cycling, variable speed, and flooded head pressure control charging.

2.8.8 Refrigerant Characteristics Tables

Provides pressure/temperature settings and saturated pressure tables for R407C.

2.9 System Settings and Adjustments

2.9.1 Pressure Limit Switches

Explains the function and fixed settings of high/low pressure limit switches.

2.9.2 Air-Cooled Head Pressure Controls

Details various head pressure control methods for air-cooled systems.

2.9 System Settings and Adjustments

2.9.2 Air-Cooled Head Pressure Controls (Continued)

Describes intelligent control, flooded head pressure control for air-cooled units.

2.9.3 Water/Glycol Head Pressure Controls

Explains how head pressure is maintained in water/glycol cooled systems.

2.9 System Settings and Adjustments

2.9.3 Water/Glycol Head Pressure Controls (Continued)

Details adjustment procedures for water/glycol system pressure controls.

2.9.4 Humidifier and EC Fan Adjustments

Covers adjustments for humidifier capacity and EC fan speed control.

2.9.6 TEV and Hot Gas Reheat

Explains Thermal Expansion Valve function and optional Hot Gas Reheat operation.

2.9 System Settings and Adjustments

2.9.7 Hot Gas Bypass Options

Describes snap acting and full floating hot gas bypass systems.

3.0 Commissioning, Operation & Decommissioning

3.1 Commissioning and Start-Up

Details the process of commissioning and starting up the unit.

3.0 Commissioning, Operation & Decommissioning

3.1 Commissioning and Start-Up (Continued)

Describes testing cooling, heating, humidification, and dehumidification functions.

3.1.2 Controller Programming

Information on microprocessor controller programming and settings.

3.2 Unit Decommissioning

Procedures for safely decommissioning the unit and recovering refrigerant.

4.0 Maintenance

4.1 Periodic General Maintenance

Outlines general maintenance tasks and the importance of a checklist.

4.1.1 CyberOne EC DX A/C Unit Maintenance

Specific maintenance tasks for the A/C unit, including filters, fans, and coils.

4.1 Periodic General Maintenance

4.1.1 CyberOne EC DX A/C Unit Maintenance (Continued)

Covers maintenance for condensate pump, condenser, and humidifier cylinder replacement.

4.2 Troubleshooting Overview

Troubleshooting: Pressure and Blower Issues

Addresses low suction pressure, valve failures, coil icing, and blower failures.

4.2 Troubleshooting Overview

Troubleshooting: Controls and Condenser Pressure

Covers erratic controls, high/low condenser pressure, and blower failures.

4.2 Troubleshooting Overview

Troubleshooting: Compressor and System Capacity

Addresses noisy compressors, starting failures, short capacity, and short cycling.

4.2 Troubleshooting Overview

Troubleshooting: Heater and Humidifier Inoperability

Diagnoses and resolves issues with the heater and humidifier components.

4.3 Field Service Procedures

4.3.1 Leak Detection and Repair

Details methods for detecting and repairing refrigerant leaks.

4.3.3 Refrigerant Piping Service

Covers replacement of refrigerant components and piping.

4.3 Field Service Procedures

4.3.4 Component Replacement and Cleanup

Covers compressor failure diagnosis, standard/acidic cleanup, and humidifier cylinder replacement.

4.3 Field Service Procedures

4.3.4 Component Replacement and Cleanup (Continued)

Details air filter replacement procedures and humidifier cylinder replacement steps.

Glossary

5.0 Product Support

5.1 Technical Support

Details how to contact STULZ for technical assistance and required information.

5.2 Obtaining Warranty Parts

Outlines the process for requesting and obtaining warranty replacement parts.

Installation Checklist

Maintenance Checklist

Glossary

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Stulz CyberOne EC DX User Manual

Table of Contents

Questions and Answers:

Stulz CyberOne EC DX Specifications

Summary

1.0 Introduction

1.1 General System Overview

1.2 Product Description

1.3 Safety Guidelines

1.3 Safety Guidelines

1.3.2 Safety Summary

1.4 General Design

1.4.1 Electrical Compartment

1.4 General Design

1.4.2 Circuit Breakers, Heaters, and Fans

1.5 Optional Equipment

1.6 Free-cooling Operation

1.7 AWS Operation

2.0 Installation

2.1 Equipment Receiving and Inspection

2.2 Moving and Storing Equipment

2.3 Site Preparation

2.3 Site Preparation

2.2.1 Conditioned Space Requirements

2.3 Mounting and Placement

2.3 Mounting and Placement

2.3.1 Precision A/C Unit Mounting

2.3.2 Outdoor Equipment Installation

2.4 Air Distribution Connection

2.4.1 Downflow Air Patterns

2.4 Air Distribution Connection

2.4.2 Upflow Air Patterns

2.5 Optional Field Installed Equipment

2.5.1 Floor Stand and Remote Display Installation

2.5.3 Remote Sensor Installation

2.6 Piping Connections

2.6.1 Refrigerant Piping

2.6 Piping Connections

2.6.1 Refrigerant Piping Specifics

2.6.2 Water/Glycol & Condensate Systems

2.6.4 Humidifier Water Supply

2.7 Utility Connections

2.7.1 Main Power Connection

2.7 Utility Connections

2.7.1 Main Power Connection Details

2.7 Utility Connections

2.7.1 Main Power & Control Wiring

2.7.4 Air-Cooled Split Systems Wiring

2.7.4 Air-Cooled Split Systems Wiring

2.7.4.1 Remote Condenser Control Wiring

2.7.4 Air-Cooled Split Systems Wiring

2.7.4.2 Remote Condensing Unit Wiring

2.7.5 Glycol System Wiring

2.8 System Charging Procedures

2.8.1 Water/Glycol Systems Charging

2.8 System Charging Procedures

2.8.2 DX Unit Charging Requirements

2.8.3 Remote Air-Cooled Systems Charging

2.8 System Charging Procedures

2.8.4 R407C Refrigerant Characteristics

2.8.5 Estimating Refrigerant Charge

2.8 System Charging Procedures

2.8.6 Preparing System for Charging

2.8 System Charging Procedures

2.8.7 Refrigerant Charging Procedures

2.8 System Charging Procedures

2.8.7 Refrigerant Charging Procedures (Continued)

2.8.8 Refrigerant Characteristics Tables

2.9 System Settings and Adjustments

2.9.1 Pressure Limit Switches

2.9.2 Air-Cooled Head Pressure Controls

2.9 System Settings and Adjustments

2.9.2 Air-Cooled Head Pressure Controls (Continued)

2.9.3 Water/Glycol Head Pressure Controls

2.9 System Settings and Adjustments

2.9.3 Water/Glycol Head Pressure Controls (Continued)

2.9.4 Humidifier and EC Fan Adjustments

2.9.6 TEV and Hot Gas Reheat

2.9 System Settings and Adjustments

2.9.7 Hot Gas Bypass Options