Six isobutane (R600a)/propane (R290) heat pumps produced by Danish manufacturer Fenagy will supply more than 30MW (8,530TR) of heat to a district heating network in a Finnish city using waste heat from a local data center.
The customized HCI 3000 units provide both heating and cooling and will be delivered to a utility company in northeastern Finland via Finnish contractor Caverion. Each heat pump contains three compressors: two with R600a and one with R290.
“The heat pumps will raise the roughly 30°C [86°F] data center excess heat to approximately 85°C [185°F] to meet the district heating requirements,” Fenagy said. “On the cold side, [the units] provide 20°C [68°F] water for server room cooling, independent of the return temperature from the district heating network, which in this case is about 50°C [122°F].”
The installation will occur in stages, with the heat pumps delivered two at a time in two-week intervals, Klaus Jensen, Sales Director of Industrial Refrigeration and Heating at Fenagy, told NaturalRefrigerants.com. “Commissioning is set for autumn 2025, with the project handed over [to the utility company] by the end of the year,” he said.
The installation: The data center ‒ located near the Finnish city’s district heating plant ‒ generates heat year-round from server room cooling.
- The heat pumps will connect to the data center’s current water cooling circuit and handle the full cooling load, with the chillers remaining in place for emergency backup.
- The first phase of the installation will generate 18MW (5,118TR) of district heating for the city.
Advantages: Using heat pumps provides data centers and district heating networks with several benefits, according to Fenagy.
- The data center’s waste heat can be sold to utility companies, greenhouse operators and other industries.
- Reversible units support data center cooling, which lowers the electrical consumption of the chillers or dry coolers.
- “With the constant high-temperature output of data centers, district heating networks can operate a stable heat pump at a very high COP,” said Kim Christensen, Managing Director and Co-Founder of Fenagy, in a company video.
Other isobutane news: Fenagy and Caverion have other applications involving R600a heat pumps.
- Fenagy released a 1MW (284TR) isobutane heat pump in June 2024 designed to subcool the 45‒50°C (104‒122°F) return water temperature of a CO2 (R744) heat pump used in a district heating system.
- In December 2024, the manufacturer reported that the isobutane/CO2 combination could improve efficiency by up to 10% and increase capacity by 20–30% compared to a CO2 heat pump without a subcooler based on data from a district heating installation in Jægerspris, Denmark.
- Caverion installed an R600a heat pump to reuse waste heat generated at the factory of a bio-based products company in Finland. It is estimated that the heat pump will cut emissions by more than 900 metric tons annually.
Quotable: “We are very excited to be part of this forward-looking project ‒ the first of its kind where waste heat from a large data center is recovered for district heating through heat pumps using the natural refrigerant isobutane,” Jensen said. “By integrating heat pumps for both server room cooling and heat recovery, we can significantly reduce CO2e emissions and environmental impact, therefore this project marks an important step forward in Finland’s green transition.”
