Heat Pump Energy Management in Nordic Homes
Field Performance of a Tongyi R290 System in Finland
Location: Vantaa, Greater Helsinki Area, Finland
Building: Residential house, 150 m², built 1995
Heat Distribution: Radiant floor heating
DHW Storage: 100-liter water cylinder
System: Tongyi R290 Air-to-Water Heat Pump
Model: TAHMV 10 R – 10 kW, Single Phase
Outdoor Temperature: ~ +0.5 °C
Efficient heat pump energy management is defined not by catalogue values, but by real-world performance under operating conditions. This residential installation in Vantaa, Finland, offers a field-based example of how low-temperature system design and inverter-driven control deliver stable and efficient heating in a Nordic climate.
The assessment is based on monitored operating data from an actual installation and focuses on stabilized inverter operation, rather than estimated or nominal performance values.
System Design and Energy Management Strategy
The Tongyi TAHMV 10 R is installed in a 150 m² detached house built in 1995. The home is equipped with a concrete radiant floor heating system and a 100-liter domestic hot water cylinder.
The heating system operates at a supply water temperature of approximately 27–28 °C. This low flow temperature is well suited to underfloor heating and forms the basis for effective heat pump energy management.
By operating at low temperatures, the inverter-driven compressor can run continuously at partial load. This avoids frequent start–stop cycling, improves seasonal efficiency, and reduces electrical and mechanical stress, while maintaining stable indoor comfort.
Stable Performance Under Nordic Conditions
At an outdoor temperature of approximately +0.5 °C, the heat pump operated in a stable, fully modulating mode. Compressor speed remained steady, and the electronic expansion valve provided consistent superheat control, indicating balanced refrigerant flow and healthy thermodynamic operation.
The heating circuit was hydraulically optimized for radiant floor heating. A modulating circulation pump and a flow-to-return temperature difference of approximately 4 K ensured smooth heat delivery and low distribution losses—an important factor in Nordic residential systems.
Discharge pressure and discharge temperature remained within conservative operating limits, confirming efficient refrigeration cycle behavior and sufficient performance margin for colder winter conditions.
Real-World Efficiency Assessment
Based on monitored thermal output and electrical input during stabilized operation, the system demonstrates a conservative, system-level COP of approximately 5.0.
The reported COP reflects a realistic operating boundary and includes auxiliary electrical consumption, such as circulation pumps and system controls. It therefore represents day-to-day operating efficiency as experienced by the homeowner, rather than compressor-only or instantaneous peak performance.
While higher instantaneous COP values may occur at specific operating points, a conservative system-level approach was deliberately chosen to provide a transparent representation of real-world performance.
R290 Technology and Low-Temperature Heating
This installation highlights how R290 (propane) technology supports advanced heat pump energy management when combined with low-temperature heat distribution systems. Strong modulation capability, high heat transfer efficiency, and stable part-load operation make R290 air-to-water heat pumps particularly suitable for residential buildings in Northern Europe.
For both renovation projects and optimized existing homes, this approach enables high efficiency without increasing flow temperatures or system complexity.
Technical Snapshot
Measurement context:
The COP snapshot was recorded on 15 December. Ambient temperature context refers to the surrounding mid-December period, rather than a single measurement moment.
- Application: Radiant floor heating (low-temperature system)
- Building Size: 150 m²
- Flow Temperature: 27–28 °C
- Outdoor Conditions: ~ +0.5 °C
- Operation: Continuous inverter modulation
- Energy Concept: Optimized heat pump energy management
- Observed System COP: ~ 5.0
(Measured at ~ +0.5 °C outdoor temperature on 15 December. The ambient temperature context refers to the surrounding mid-December period, during which temperatures in Vantaa were typically around –1 °C to –2 °C.) - Refrigerant: R290 (Propane)
- DHW Storage: 100-liter cylinder
