The Cooper&Hunter CHML-U28RK4-NG is a powerful inverter outdoor unit from the Nordic Multi Light R32 NG series, designed to create a multi-zone air-conditioning system with 2 to 4 compatible indoor units.
With 8.0 kW cooling capacity and 9.5 kW heating capacity, the unit is suitable for larger apartments, private houses, offices and other multi-room spaces where several indoor units need to be connected to a single outdoor unit. The system uses R32 refrigerant, supports a connected-capacity range of 50–150% of the outdoor unit’s nominal capacity and is designed for operation in cold climates.
Key Features
Powerful Multi-Zone Cooling– The 8.00 kW cooling capacity makes the CHML-U28RK4-NG suitable for multi-room climate control. Up to four compatible indoor units can be connected to one outdoor unit, allowing individual temperature control in different rooms. The system supports operation within 50–150% of the outdoor unit’s nominal capacity, giving greater flexibility when selecting indoor units for rooms with different cooling requirements.
Efficient Heating– The outdoor unit provides a nominal 9.50 kW heating capacity and is designed for year-round operation. According to the detailed manufacturer specification, heating operation is possible from −22°C to +24°C. Cooper&Hunter also highlights the Nordic Multi Light R32 NG platform’s efficient operation at low outdoor temperatures, making it suitable for cold-climate applications.
Stable Inverter Operation– The CHML-U28RK4-NG uses inverter compressor technology to continuously adjust its output according to the actual demand of the connected indoor units. Stable Frequency Control enables smooth compressor operation at ultra-low frequencies down to 15 Hz.
Benefits include:
- Stable indoor temperature
- Efficient operation at partial load
- Reduced unnecessary compressor cycling
- Smooth capacity adjustment
- Lower mechanical stress
- Improved comfort and energy efficiency
Noise Analysis Technology– The outdoor unit incorporates Noise Analysis Technology, designed to optimize system operation and reduce unnecessary noise. The specified outdoor sound level is approximately 58 dB(A). Because this is a relatively powerful multi-split outdoor unit, its installation position should be selected carefully, particularly in residential buildings.
R32 Refrigerant– The system uses R32 refrigerant, with a factory charge of 1.80 kg. The manufacturer specifies an additional charge of 20 g/m when required. The standard refrigerant filling length is 40 m, while the maximum total piping length is 70 m.
Flexible Installation
The CHML-U28RK4-NG offers considerable installation flexibility:
| Installation Parameter | Maximum Value |
|---|---|
| Total refrigerant piping | 70 m |
| Maximum pipe length to one indoor unit | 20 m |
| Maximum height difference | 15 m |
| Standard pipe length without additional charge | 40 m |
| Additional refrigerant | 20 g/m |
This configuration makes the unit suitable for multi-level apartments, private houses and commercial premises where indoor units may be located at different distances from the outdoor unit.
Intelligent Defrosting– The Nordic Multi Light R32 NG series features a new-generation Intelligent Preheating anti-icing system. Instead of relying solely on a fixed time-based defrost cycle, the system initiates defrosting when it is actually necessary. This helps reduce unnecessary defrost cycles and associated energy losses during winter operation.
Reliable Operation
The CHML-U28RK4-NG incorporates several technologies designed for stable operation:
- Stable Frequency Control
- Intelligent Preheating
- Automatic defrosting
- Anti-icing protection
- Multi-speed outdoor fan
- Auto Restart
- Self-Diagnosis
- Voltage protection
- Anti-corrosion protection
The manufacturer also specifies safe start-up within a 96–260 V voltage range.
Wide Operating Temperature Range– The detailed product specification gives the following operating ranges:
Cooling: −15°C to +43°C
Heating: −22°C to +24°C
Cooper&Hunter additionally describes the Nordic Multi Light R32 NG platform as offering efficient operation from approximately −20°C in heating mode and up to +48°C in cooling mode under the series’ specified conditions. For the product specification table, the model-specific values of −15…+43°C / −22…+24°C are preferable.
Recommended Application– With 8.0 kW cooling and 9.5 kW heating capacity, the unit can be used for a multi-room area of approximately 70–90 m² as a general planning guideline.
However, the actual required capacity depends on:
- Building insulation
- Ceiling height
- Window area
- Solar exposure
- Number of occupants
- Heat-generating appliances
- Number of rooms
- Selected indoor-unit capacities
Therefore, a fixed area figure such as 95 m² should be considered only an approximate retailer guideline rather than a guaranteed coverage area.
One Outdoor Unit — Up to Four Indoor Units– A major advantage of the CHML-U28RK4-NG is the ability to connect 2–4 indoor units to a single outdoor block.
This allows you to:
- Reduce the number of outdoor units on the facade
- Create independent climate zones
- Control each room separately
- Save installation space
- Maintain a cleaner exterior appearance
Compatible indoor units must be selected according to Cooper&Hunter’s approved combination tables. The manufacturer provides dedicated combination recommendations for the Nordic Multi Light R32 NG series.
Important Installation Information
The CHML-U28RK4-NG is an outdoor unit only and cannot operate independently.
A complete system requires compatible indoor units and professional installation.
Before purchasing, verify:
- Compatibility of all selected indoor units.
- Total connected indoor-unit capacity.
- Total refrigerant pipe length.
- Maximum distance to each indoor unit.
- Height difference between indoor and outdoor units.
- Required additional R32 refrigerant.
- Electrical requirements.
- Installation clearances and ventilation.
Professional HVAC installation is strongly recommended.
| Specification | Value |
|---|---|
| Model | CHML-U28RK4-NG |
| Series | Nordic Multi Light R32 NG |
| Type | Multi-Split Inverter Outdoor Unit |
| Compatible Indoor Units | 2–4 |
| Cooling Capacity | 8.00 kW |
| Heating Capacity | 9.50 kW |
| System Capacity Range | 50–150% of nominal outdoor-unit capacity |
| Energy Efficiency Class | A |
| Outdoor Airflow | 3,800 m³/h |
| Outdoor Sound Level | 58 dB(A) |
| Refrigerant | R32 |
| Refrigerant Charge | 1.80 kg |
| Additional Refrigerant | 20 g/m |
| Standard Pipe Length Without Additional Charge | 40 m |
| Power Supply | 220–240 V / 50 Hz / 1 Phase |
| Cooling Operating Range | −15°C to +43°C |
| Heating Operating Range | −22°C to +24°C |
| Maximum Total Pipe Length | 70 m |
| Maximum Pipe Length to One Indoor Unit | 20 m |
| Maximum Height Difference | 15 m |
| Outdoor Unit Dimensions (W × D × H) | 964 × 402 × 660 mm |
| Outdoor Unit Net Weight | 51 kg |
| Outdoor Unit Gross Weight | 55.5 kg |
| Mounting Point Distance | 570 mm |
| Liquid Pipe Connection | 1/4″ |
| Gas Pipe Connection | 3/8″ |











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