Variable Refrigerant Flow (VRF) and Variable Refrigerant Volume (VRV) systems represent a significant advancement in commercial HVAC technology, offering superior efficiency and zone-level control. This guide covers integrating these systems with building automation platforms via BACnet.
VRF/VRV systems distribute refrigerant to multiple indoor units, allowing independent temperature control per zone without traditional ductwork. When properly integrated with a BAS, you gain centralized monitoring, advanced scheduling, fault detection, and energy analytics.
VRF (Variable Refrigerant Flow) and VRV (Variable Refrigerant Volume) are essentially identical technologies with different manufacturer branding. Daikin pioneered VRV, while other manufacturers use the VRF designation.
Key characteristics:
| Manufacturer | Brand Name | Key Features | Typical BACnet Gateway |
|---|---|---|---|
| Daikin | VRV | Early leader, reliable, wide product range | Intesis Box VRV, CoolAutomation, proprietary modules |
| Mitsubishi Electric | City Multi | High capacity, good efficiency, robust controls | Mitsubishi interface modules, Intesis |
| LG Electronics | Multi V | Cost-effective, compact outdoor units | CoolAutomation, proprietary gateways |
| Samsung | WindFree | Premium cooling, innovative indoor unit designs | Limited BACnet support, custom gateways |
| Fujitsu | Airstage | Commercial-focused, reliable components | Fujitsu BACnet modules |
| Panasonic | ECOi | European leader, modular approach | Panasonic interface modules |
To integrate VRF/VRV systems with a BAS platform, you need a gateway that translates the proprietary refrigerant management protocol into BACnet objects and properties.
| Gateway Solution | Protocol Support | Advantages | Limitations |
|---|---|---|---|
| Intesis Box VRV/VRF | BACnet/IP, Modbus TCP, web API | Wide VRF manufacturer support, reliable, compact | Higher cost |
| CoolAutomation | BACnet/IP, KNX, cloud API | Intuitive web interface, cloud integration | Annual licensing |
| Manufacturer modules | Varies | Native integration, OEM support, lower cost | Brand-specific |
| Custom development | Custom BACnet/IP | Flexible, tailored to project | High development cost |
Gateway Device ID: 1400100 (example)
Network Number: 0
BACnet/IP Port: 47808
Typical exposed object count per outdoor unit:
- Analog Input: 25-35 points (temperatures, pressures, capacities)
- Analog Output: 8-12 points (setpoints, mode selection)
- Binary Input: 15-20 points (status, alarms, safety switches)
- Binary Output: 4-8 points (command relays)
- Multi-state Input: 6-10 points (mode indicators, fault codes)
| Point Name | Object Type | Units | Range | Writable |
|---|---|---|---|---|
| Unit Enable | Binary Output | on/off | 0-1 | Yes |
| Room Temperature | Analog Input | degC | -10 to 60 | No |
| Setpoint Temperature | Analog Output | degC | 16 to 32 | Yes |
| Operating Mode | Multi-State Output | enum | Heat/Cool/Auto/Off | Yes |
| Fan Speed | Multi-State Output | enum | Off/Low/Med/High/Auto | Yes |
| Unit Status | Multi-State Input | enum | Off/Cooling/Heating/Defrost/Alarm | No |
| Room Humidity | Analog Input | %RH | 0-100 | No |
| Filter Maintenance | Binary Input | dirty/clean | 0-1 | No |
| Fault Code | Multi-State Input | code | 0-999 | No |
| Point Name | Object Type | Units | Range | Writable |
|---|---|---|---|---|
| Outdoor Temperature | Analog Input | degC | -30 to 60 | No |
| Total Heating Capacity | Analog Input | kW | 0-500 | No |
| Total Cooling Capacity | Analog Input | kW | 0-500 | No |
| Refrigerant Charge Level | Analog Input | % | 0-110 | No |
| System Alarm Status | Binary Input | alarm/ok | 0-1 | No |
| Compressor State | Multi-State Input | enum | Off/Running/Fault | No |
| System Mode Override | Binary Output | override/normal | 0-1 | Yes |
| Signal Type | Daikin | Mitsubishi | Wiring | Notes |
|---|---|---|---|---|
| Communication | Hi-Link | MAC | Twisted pair, shielded | 24V source at outdoor unit |
| Control voltage | 24VAC/DC | 24VAC/DC | Separate conduit | Gateway or external PSU |
| Ground | Earth reference | Earth reference | Green/bare wire | Critical for noise immunity |
For Niagara:
For Metasys:
For Desigo:
Problem: Setting one unit to heating while another is cooling causes conflicts.
Solution: Configure BAS rule to enforce compatible modes. For heat-recovery systems, enable 4-pipe mode. Implement outdoor air lockout.
Problem: Writing setpoint outside allowed range causes errors.
Limits: Heating 16-30C, Cooling 18-32C, Deadband minimum 2C.
Solution: Constrain setpoint writes in BAS logic, create alarms for invalid combinations.
Problem: Gateway loses connection during peak operation.
Solution: Run Ethernet in separate conduit from power wiring (50mm min), use shielded Cat6, reduce polling to 10-15 seconds, add second gateway if over 20 indoor units.
| Status | Color | Meaning |
|---|---|---|
| Off/Standby | Gray | Unit inactive |
| Cooling | Blue | Active cooling |
| Heating | Red/Orange | Active heating |
| Defrost | Magenta | Coil defrost |
| Alarm/Fault | Red + Flash | Error condition |
| Maintenance | Yellow | Service needed |
Check at http://[gateway-IP]/status:
Expected: Point reads within 5 seconds, updates every 10-15 seconds
If point reads but freezes: Check network connectivity, possible NAT/firewall
If point does not read: Verify device instance, check firewall port 47808
If value never updates: Possible VRF unit communication loss to gateway