R407C 10HP Heat Recovery VRF – AO90M Design & Technical Data
Technical reference for the legacy AIRSTAGE R407C heat recovery VRF system, based on the AO90M 10HP outdoor unit design and technical data manual.
Outdoor unit: AO90M / AO90MPAMF
Refrigerant: R407C
Nominal size: 28.0 kW cooling / 10HP
Key system specifications
| Item | Specification |
|---|---|
| Cooling capacity | 28.0 kW |
| Heating capacity | 31.5 kW |
| Power supply | 380–415 V, 3-phase 4-wire, 50 Hz |
| Maximum indoor units | 16 |
| Indoor unit connection ratio | 50–130% of outdoor unit capacity (14.0–36.4 kW total connected capacity) |
| Refrigerant | R407C – factory charge 10.0 kg |
| Maximum piping length | 100 m |
| Maximum height difference | 50 m when outdoor unit is above indoor units; system general information notes 40 m when the outdoor unit is below the indoor units |
| Maximum chargeless length | 7.5 m |
| Cooling operating range | -5°C to 52°C outdoor ambient |
| Heating operating range | -15°C to 21°C outdoor ambient |
| Outdoor unit dimensions | 1,380 × 1,300 × 650 mm (H × W × D) |
| Net weight | 306 kg |
| Sound pressure | 57 dB(A) at 415 V normal operation; manual also identifies silent operation capability |
Heat recovery operation
The system allows simultaneous cooling and heating within the same refrigerant circuit. During heat recovery operation, energy is transferred between indoor units requiring cooling and those requiring heating, reducing the amount of compressor work required.
The outdoor unit uses three differently rated constant-speed scroll compressors operating in sequential stages. The manual describes this arrangement as Power Accumulation Technology, which controls refrigerant flow between compressor capacity steps.
Cooling COP/EER: approximately 3.0
Heating COP: 3.15
Refrigerant piping
The heat recovery system uses separation tubes, headers and refrigerant branch (RB) units to distribute refrigerant to indoor units.
| Connection | Outdoor unit pipe size |
|---|---|
| Liquid | 12.7 mm |
| Discharge gas | 19.05 mm |
| Suction gas | 28.58 mm |
General piping limits identified in the manual:
- Actual pipe length: maximum 100 m.
- Equivalent pipe length: maximum 120 m.
- Total system pipe length: maximum 200 m.
- Maximum vertical difference between indoor units: 15 m.
Controls and transmission
The VRF system uses a non-polar 2-core transmission line. Each device on the transmission network processes communication independently, allowing other equipment to continue operating if a single indoor unit fails.
- Up to 16 indoor units can be controlled by one wired, simple or wireless remote controller group.
- A central remote controller can control up to 400 indoor units / 64 groups.
- A PC controller can control up to 400 indoor units / 400 groups.
- Maximum per transmission line: 100 refrigerant systems, 400 indoor units and 100 outdoor units.
- Standard transmission-line length is up to 500 m; signal amplifiers can extend the total transmission line to 2,000 m.
Installation clearances
The manual specifies minimum service and airflow clearances. For an individually installed outdoor unit, the typical minimum clearances shown are:
- Front: 500 mm or more.
- Rear: 300 mm or more.
- Sides: 10 mm or more.
- If front or rear wall height exceeds 1,200 mm, additional clearance is required.
Technical information contained in the full manual
The complete design and technical data manual contains detailed information for:
- System features and model line-up
- Remote controllers, central control, PC control and BMS interfaces
- Outdoor unit specifications, dimensions, refrigerant circuit and wiring diagrams
- Cooling and heating capacity tables
- Indoor unit model line-up, specifications, dimensions and wiring diagrams
- Piping design, additional refrigerant charge calculation and installation limits
- Address and function settings
- External inputs and outputs
- Installation and commissioning procedures
- Troubleshooting and error information
- Optional parts including separation tubes, headers, controllers and converters
This information applies to an older R407C AIRSTAGE VRF platform. Use the model and serial details on the installed equipment when selecting service information and replacement components. Do not apply current-generation VRF specifications to this system unless compatibility has been confirmed.