General Assist Technical Reference
VRF System - Low Noise Mode Performance Data
Sound pressure, sound power and available capacity by series
Applicable to selected Australian J-IIS, J-IVS, J-II, J-III, J-IV, J-IIIL, J-IVL, VR-II, VR-IV and V-III outdoor units
Low Noise Mode reduces outdoor-unit sound by limiting fan and compressor operation. The available cooling or heating capacity may also reduce, and the effect varies by series, model size and operating mode.
Design warning: Do not assume that Low Noise Mode only affects acoustics. Confirm the model-specific capacity percentage before enabling it on a system with limited design margin or high peak loads.
1. Understanding the data
| Term | Meaning |
|---|---|
| Sound Pressure Level (SPL) | The sound level measured at a specified position and distance under the manufacturer's test conditions. This is generally the figure used when discussing sound at the unit location. |
| Sound Power Level | The total acoustic energy emitted by the unit. It is not measured at a single point and must not be directly compared with an onsite sound-pressure reading. |
| Capacity (%) | Available cooling or heating output in Low Noise Mode relative to the reference capacity used in the source data. |
| Level 1 / Level 2 | Level 2 is the more restrictive acoustic setting and usually creates a greater capacity reduction. Not every series provides both levels. |
2. Series performance summary
| Series | Models covered | Low Noise Level | Low Noise SPL range | Available capacity range |
|---|---|---|---|---|
| J-IIS | 4-6 HP, AJT... | 1 | 48-53 dB(A) | 71.4-94.8% |
| J-IVS | 4-6 HP, AJT... | 1 | 48-53 dB(A) | 83.3-97.3% |
| J-II / J-III | 4-6 HP, AJY... | 1 | 45-47 dB(A) | 60.3-103.7% |
| J-IV | 4-6 HP, AJY... | 1 | 45-47 dB(A) | 82.4-107.7% |
| J-IIIL | 8-16 HP, AJY... | 1 / 2 | L1: 49-55; L2: 46-50 dB(A) | L1: 80-91%; L2: 49-62% |
| J-IVL | 8-16 HP, AJY... | 1 / 2 | L1: 49-55; L2: 46-55 dB(A) | L1: 80-91%; L2: 49-62% |
| VR-II | 8-16 HP, AJT... | 1 / 2 | L1: 51-55; L2: 48-50 dB(A) | L1: 62.6-82.0%; L2: 47.0-82.0% |
| VR-IV | 8-16 HP, AJT... | 1 / 2 | L1: 51-55; L2: 48-50 dB(A) | L1: 73.0-89.3%; L2: 58.1-89.3% |
| V-III | 8-18 HP, AJY... | 1 / 2 | L1: 51-55; L2: 48-50 dB(A) | L1: 62.6-94.3%; L2: 47.0-94.3% |
Capacity values above 100%: Some J-II/J-III and J-IV heating data exceeds 100%. This reflects the source comparison point and does not mean that Low Noise Mode increases the unit's maximum rated capacity. Use the detailed engineering selection data for final design decisions.
3. Compact J-series details
J-IIS - Level 1
| Model size | Normal SPL Cool / Heat | Low Noise SPL Cool / Heat | Capacity Cool / Heat |
|---|---|---|---|
| 4 HP | 51 / 54 | 48 / 51 | 71.4% / 77.9% |
| 5 HP | 53 / 55 | 51 / 52 | 94.8% / 84.8% |
| 6 HP | 56 / 56 | 51 / 53 | 90.2% / 83.3% |
J-IVS - Level 1
| Model size | Normal SPL Cool / Heat | Low Noise SPL Cool / Heat | Capacity Cool / Heat |
|---|---|---|---|
| 4 HP | 53 / 54 | 48 / 51 | 83.3% / 83.3% |
| 5 HP | 54 / 55 | 51 / 52 | 97.3% / 92.9% |
| 6 HP | 56 / 56 | 51 / 53 | 89.2% / 88.9% |
J-II / J-III and J-IV - Level 1 summary
| Series | Normal SPL range | Low Noise SPL range | Capacity range |
|---|---|---|---|
| J-II / J-III | 50-55 dB(A) | 45-47 dB(A) | 60.3-103.7% |
| J-IV | 50-56 dB(A) | 45-47 dB(A) | 82.4-107.7% |
4. Large-capacity series details
| Series | Level | Sound pressure range | Cooling capacity range | Heating capacity range |
|---|---|---|---|---|
| J-IIIL | 1 | 49-55 dB(A) | 80-89% | 80-91% |
| 2 | 46-50 dB(A) | 52-62% | 49-61% | |
| J-IVL | 1 | 49-55 dB(A) | 80-89% | 80-91% |
| 2 | 46-55 dB(A) | 52-62% | 49-61% | |
| VR-II | 1 | 51-55 dB(A) | 73.0-82.0% | 62.6-80.9% |
| 2 | 48-50 dB(A) | 64.3-82.0% | 47.0-73.5% | |
| VR-IV | 1 | 51-55 dB(A) | 73.0-89.3% | 74.7-88.9% |
| 2 | 48-50 dB(A) | 61.7-89.3% | 58.1-83.3% | |
| V-III | 1 | 51-55 dB(A) | 68.9-94.3% | 62.6-78.3% |
| 2 | 48-50 dB(A) | 60.0-94.3% | 47.0-76.9% |
5. Application and service guidance
- Confirm the exact outdoor-unit series and HP size before using the data. Similar model families can have materially different capacity reductions.
- Check cooling and heating separately. The available percentage is not necessarily the same in both modes.
- Level 2 should be treated as a significant capacity limitation on many large-capacity systems, particularly under heating load.
- Do not use sound pressure and sound power figures interchangeably. Site acoustic compliance must be assessed using the correct acoustic metric and installation conditions.
- Published figures are based on controlled test conditions. Walls, corners, screens, plant rooms, reflective surfaces and multiple outdoor units can change the onsite sound level.
- Where Low Noise Mode is scheduled by an external contact or central controller, confirm that the operating period will not coincide with the building's peak heating or cooling requirement.
Practical planning guide: Level 1 commonly provides a moderate noise reduction with a manageable capacity impact, but this is not universal. Level 2 can reduce available output to approximately half of the reference capacity on some models and must be assessed against the system design load.
Technical note: This article summarises the Australian low-noise performance data issued by Fujitsu General Engineering Support. Always use the latest model-specific engineering data and installation documentation when completing an acoustic assessment or system selection.