Flexit EcoNordic WH4 is a complete indoor climate control centre for residential homes — combining balanced ventilation with heat recovery, domestic hot water heating and space heating in a single unit. Rotary heat exchanger with a thermal efficiency above 90%, heat pump with natural CO₂ refrigerant (GWP 1) and a 197-litre hot water tank. All components are placed indoors — suitable for a utility room or technical cupboard. For homes up to 220 m².
Key Benefits
Ventilation, Heating and Hot Water in One
EcoNordic WH4 replaces three separate appliances. Balanced ventilation with heat recovery, a heat pump for hot water and space heating — all in one compact unit for the utility room.
Modular System — 4 Separate Modules
The unit consists of four separate modules that can be carried and installed individually. Each module has its own access panel for servicing without disassembling the entire unit.
High-Efficiency Heat Pump
The heat pump with natural CO₂ refrigerant achieves COP 3.21 for hot water and SCOP 3.22 for space heating. Compressor output up to 4 kW with operation down to −25 °C outdoor temperature.
Smart Control via Flexit GO
Control the entire indoor climate centre from the mobile app — ventilation, water temperature, heating and operating modes. Smart home integration via Modbus protocol.
Why choose Flexit EcoNordic WH4?
EcoNordic WH4 is designed as a complete indoor climate control centre — instead of three separate units (heat recovery + water heater + heat pump), you get one integrated system. This means lower installation costs, less space in the utility room and simpler maintenance.
When the home requires only a small amount of heating, the system draws energy directly from the tank without starting the compressor — maximising efficiency and reducing running costs. ePM1 55% (F7) filters ensure clean air throughout the home.
Performance Metrics
Key heat pump and heat recovery performance data according to European standards:
(EN 16147)
(EN 14825)
rotary heat exchanger
Hot Water Tank — 197 Litres
The integrated tank maintains water temperature in the 5–65 °C range with automatic Legionella protection at 75 °C. Heating is provided by the CO₂ heat pump, which delivers high efficiency even in cold weather. Nominal operating pressure 4.5 bar.
The system can cover the hot water needs of a 4–5 person household without an external water heater.
Technical Specifications
| Parameter | Value |
|---|---|
| Heat exchanger thermal efficiency | > 90% |
| Max. airflow | 370 m³/h at 100 Pa |
| Ventilation | |
| Heat exchanger type | Rotary |
| Filter class | ePM1 55% (F7) |
| Ventilation duct connection | Ø160 mm |
| Sound power level | 52.0 dB(A) |
| Heat Pump | |
| Refrigerant | CO₂ (R744), 0.5 kg, GWP 1 |
| Compressor output | up to 4 kW |
| COP hot water (EN 16147) | 3.21 |
| SCOP heating (EN 14825) | 3.22 |
| Min. outdoor temperature | −25 °C |
| Max. operating pressure | 14 MPa (140 bar) |
| Compressor control | Inverter-driven |
| Hot Water Tank | |
| Tank volume | 197 litres |
| Water temperature | 5–65 °C (Legionella: 75 °C) |
| Operating pressure | 0.45 / 4.5 MPa (bar) |
| Electrical | |
| Rated voltage | 400 V 3N~ or 230 V 3~ |
| Total rated power | 6.4 kW (4.4 kW) |
| Fuse | 3×16 A (3×10 A) / 3×25 A (3×16 A) |
| IP rating | IP21 |
| Dimensions and Weight | |
| Dimensions (W × H × D) | 1,198 × 1,900 × 650 mm |
| Weight | 220 kg |
| Control | Flexit GO (app, cloud, Modbus) |
| Product number | 800501 |
EcoNordic WH4 vs WH4 XL — which model to choose?
Flexit offers two indoor climate control centre models. EcoNordic WH4 is designed for homes up to 220 m² with a maximum airflow of 370 m³/h. For larger homes up to 300 m², the WH4 XL model is available with airflow up to 524 m³/h.
If you are building a new home or undertaking a major renovation, EcoNordic WH4 is the ideal choice — it replaces your heat recovery unit, heat pump and water heater in a single appliance. For a comparison with a conventional central air handling unit, see the Flexit Nordic S4 or Nordic S7.
Ventilation. Heating. Hot Water. One Unit.
Flexit EcoNordic WH4 is a complete indoor climate control centre for modern low-energy homes — rotary heat exchanger with efficiency above 90%, CO₂ heat pump and a 197-litre hot water tank. All managed through Flexit GO.
| Size | WH4 or WH4 XL |
| Brand | Flexit |