VRF External Input and Output Handbook
External control, monitoring, energy-saving and cold-climate functions for AIRSTAGE VRF systems
Overview
The AIRSTAGE VRF external input and output functions allow additional controls and monitoring devices to be connected to indoor units, outdoor units and central controllers. Depending on the equipment and configuration, these functions can support energy saving, occupancy control, noise reduction, ventilation interlocking, status monitoring, emergency shutdown and cold-climate protection.
1. Energy-saving functions
Automatic Off Function
A field-supplied human-presence sensor can be used to stop an indoor unit automatically after the room has remained unoccupied for a defined period. Typical applications include meeting rooms, reception areas, smoking rooms and lounges.
| Connection point | Optional kit | Key setting |
|---|---|---|
| Indoor unit CNA02 | UTY-XWZXZD | Function 46, Setting 00; SET2-2 ON for pulse input |
Peak Cut Power Consumption Function
Peak cut limits the outdoor unit capacity when a building is approaching a nominated power-demand threshold. The limit can be selected between 40% and 100%, depending on the outdoor unit settings.
| Connection point | Optional kit | Input device |
|---|---|---|
| Outdoor unit CN133 | UTY-XWZXZ6 | Field-supplied volt-free ON/OFF switch or BMS contact |
Keycard Interlocked Operation Function
This function links an indoor unit to a hotel keycard system. Removing the keycard stops the air conditioner and prevents normal remote-controller operation until the card is reinserted.
| Connection point | Optional kit | Key setting |
|---|---|---|
| Indoor unit CNA02 | UTY-XWZXZD | Function 49, Setting 02 |
2. Comfort and noise-reduction functions
Nighttime Low Noise Function Using Optical Sensors
An illuminance sensor can automatically enable low-noise operation at night. Two reduction levels are available, and the system can be configured to prioritise either quieter operation or capacity maintenance.
- Level 1: approximately 3 dB reduction
- Level 2: approximately 5 dB reduction
- Mode selection: quiet priority or capacity priority
| Connection point | Optional kit | Outdoor settings |
|---|---|---|
| Outdoor unit CN131 | UTY-XWZXZ6 | Modes 40, 41 and 42 |
Ventilation Interlocked Operation Function
A ventilator can be interlocked with indoor fan operation. This helps maintain comfort by stopping outside-air ventilation when the indoor fan stops during heating start-up or defrost.
| Connection point | Optional kit | Output |
|---|---|---|
| Indoor unit CNB01 | UTY-XWZXZC | Indoor fan operation output through a field-supplied relay |
3. Monitoring and control functions
Operation Status Monitoring
External lamps, relays or a monitoring system can display indoor-unit operation and fault status. This is useful in hotels, hospitals and control rooms where multiple rooms need to be supervised centrally.
| Connection point | Optional kit | Available status |
|---|---|---|
| Indoor unit CNB01 | UTY-XWZXZC | Operation/stop and normal/error |
Batch Stop Function for One Refrigerant System
A single external contact can stop all indoor units within the same refrigerant system. The units remain locked out from normal remote-controller operation until the batch-stop input is released.
| Connection point | Optional kit | Key setting |
|---|---|---|
| Indoor unit CNA02 | UTY-XWZXZD | Function 49, Setting 01 |
Emergency Automatic Batch Stop via Central Remote Controller
A fire alarm or emergency-stop contact can be connected to the central remote controller. When activated, all indoor units managed by that controller are stopped.
| Connection point | Optional kit | Maximum wiring length |
|---|---|---|
| Central remote controller CN6 | UTY-XWZXZ7 | 25 m |
4. Cold-climate function
Antifreeze Base-Heater Function
The outdoor unit can switch a base heater on when the outdoor temperature falls to approximately 2°C. The heater helps prevent freezing around the outdoor-unit drain outlet and switches off again as the temperature rises.
| Connection point | Optional kit | Output arrangement |
|---|---|---|
| Outdoor unit CN115 | UTY-XWZXZ9 | Base-heater output through the specified relay arrangement |
5. External input and output terminal summary
| Equipment | Terminal | Function | Optional kit used in handbook example |
|---|---|---|---|
| Outdoor unit | CN131 | Low-noise mode input | UTY-XWZXZ6 |
| Outdoor unit | CN133 | Peak-control input | UTY-XWZXZ6 |
| Outdoor unit | CN134 | Emergency stop / batch stop input | Confirm by model manual |
| Outdoor unit | CN115 | Base-heater output | UTY-XWZXZ9 |
| Indoor unit | CNA01 / CNA02 | Operation/stop, emergency stop or forced stop input | UTY-XWZXZD for featured CNA02 applications |
| Indoor unit | CNA03 / CNA04 | Forced thermostat-off input | Confirm by model manual |
| Indoor unit | CNB01 | Operation/stop, normal/error and indoor-fan output | UTY-XWZXZC |
| Central remote controller | CN6 / CN7 / CN11 / CN12 | Emergency stop and all on/off inputs | UTY-XWZXZ7 for the featured CN6 application |
6. Installation requirements
- Use the specified Fujitsu external connection kit for the applicable terminal.
- Use field-supplied relays, switches and sensors that meet the contact ratings shown in the applicable manual.
- Do not apply an external voltage directly to a dry-contact input terminal.
- Keep signal wiring separated from mains-voltage wiring and follow local electrical requirements.
- Complete all required function settings before operation testing.
- Test both the normal and fail-safe operating states before handing the system over.
Conclusion
External input and output terminals significantly expand the control capability of AIRSTAGE VRF systems. When the correct optional kit, field devices and function settings are used, the system can integrate with occupancy sensors, keycard systems, building-management contacts, ventilation equipment, monitoring lamps, fire-alarm interfaces and base heaters.