Object type: Old-construction apartment complex (50 apartments of 50 m² each)
Location: Kaavi, Finland
Total area: ~2500 m²
Equipment: 2 units of “IGLU Inuit Mono 12” (hybrid-cascade system with an existing liquid-fuel boiler)
Heating method: Radiator heating system
Partner / Installer: GEON OY
Challenge: extreme cold and a large heating area in an older building
In the north of Finland, in the town of Kaavi, a residential complex with 50 apartments faced the challenge of high heating costs. The building, with energy efficiency class D, has a radiator system that requires a high-temperature heat carrier, and during winter the outdoor temperature in this region can drop to as low as -35 °C for several weeks in a row.
The company GEON OY was looking for a reliable solution that would significantly reduce liquid fuel (diesel) consumption while ensuring an uninterrupted heat supply even at the lowest temperatures.
Solution: IGLU hybrid cascade with a liquid-fuel boiler
To achieve maximum efficiency, a non-conventional, highly flexible hybrid solution was chosen for the site. Two units were connected in parallel: “IGLU Inuit Mono 12” air-to-water heat pumps operating in a smart cascade system together with the remaining old diesel boiler:
- Smart heat distribution: The heat pumps transfer heat directly to the radiator system (without additional integrated tanks).
- Two-stage operation and rotation: A “temporary cascade” logic was applied, where the pumps operate according to different temperature curves. The first heat pump starts heating, and if additional power is needed, the second one switches on. To ensure even equipment wear, the roles of the primary and auxiliary pumps (Master–Slave) are periodically swapped.
- Peak support in extreme cold: The liquid-fuel boiler remained responsible for domestic hot water (DHW) production, and during extreme cold spells the auxiliary capacity of the diesel boiler helps the heat pumps raise the supply temperature in the radiators.
Engineering handover and results
Together with IGLU TECH service engineers, a full commissioning and start-up of the cascade system was carried out. The applied control logic ensured smooth cooperation between both heat pumps and the diesel boiler without any system issues.
Key project outcomes:
- Drastically reduced fuel consumption: For most of the year and during shoulder seasons, the heating needs of the building are fully covered by the highly efficient IGLU Inuit Mono 12 heat pumps.
- Assured backup in the harshest conditions: Even when the outdoor temperature drops to -35 °C, the hybrid model guarantees the required high temperature in the radiators.
- Long-term equipment reliability: Automatic rotation of the heat pumps’ operation ensures even compressor loading and a longer service life.
- Replicable solution: The successfully implemented project proved the capabilities of IGLU equipment in semi-industrial facilities and became a benchmark model for other similar sites in the Finnish market.
Key figures and facts:
- Building area: ~2500 m² (50 apartments)
- Climate conditions: Extreme (down to -35 °C)
- Equipment: 2x IGLU Inuit Mono 12
- System type: Air–water hybrid cascade with a liquid-fuel boiler
- Heating devices: Radiators
Looking for an efficient heating solution for apartment buildings, older constructions, or commercial properties? Contact the IGLU TECH team for negotiations and a consultation.
