Engineering startup Nusku aims to replace gas boilers in U.K. homes with an air-to-water propane (R290) heat pump featuring an integrated storage tank, according to CEO Russell Murchie.
The startup designed the heat pump for use in retrofit applications in existing U.K. housing with hydronic radiator systems. The unit maintains useful performance in typical winter conditions, with an outlet temperature of up to 65°C (149°F), Murchie told NaturalRefrigerants.com. The company is finalizing the commercial specifications, including heat pump capacity, refrigerant charge and storage volume.
“The system focuses on reducing installation complexity, minimizing ancillary components and integrating thermal storage directly into the unit,” Murchie said. “We believe this can materially reduce both the upfront installation costs and disruption compared with current premium R290 systems on the market.”
The timeline: With prototypes installed in four Bristol homes, Nusku is working to optimize system controls, installation processes and real-world performance.
- Murchie said early feedback from the trials has been “encouraging,” particularly in terms of performance, responsiveness and ease of use.
- The startup expects to commercially launch its first unit for two‒three-bedroom homes in early 2027 after completing field trials, securing certification and ramping up production with manufacturing and supply-chain partners.
- Although the first unit targets smaller homes, Nusku expects to expand the line to multiple capacities and configurations for retrofits and new builds.
State support: Through Nusku’s installer partners, the heat pump is expected to qualify for the £7,500 ($10,000/€8,700) Boiler Upgrade Scheme (BUS) grant in England and Wales.
- In January 2024 the startup received a £727,000 ($974,000/€839,000) grant from the U.K. Department for Energy Security and Net Zero, enabling product testing at the University of Salford’s two-bedroom terraced energy house equipped with an environmental chamber.
Hotbed of activity: Conditions in the U.K. that enable R290 residential heat pump startups to thrive include the government’s trajectory to phase out HFCs, financial incentives and the market potential of replacing millions of gas boilers.
- In November 2024 U.K. technology company Wondrwall launched an AI-enabled propane unit, available in 6 and 8kW (1.7 and 3.2TR) capacity sizes, in partnership with Daikin Air Conditioning UK, a subsidiary of Daikin Europe. The AI management unit reduces home energy heating bills by up to 80% compared to similar homes with standalone heat pumps, according to Wondrwall.
- Swedish home energy company Aira, founded in 2022, produces R290 units in three capacity sizes ‒ 6kW, 8kW and 12kW (1.7TR, 2.3TR and 3.4TR) ‒ with availability in Germany, Italy and the U.K. The units produce water temperatures up to 70°C (158°F) for space heating (via radiators or underfloor piping) and domestic hot water.
- Established companies such as Carrier Global Corporation are also supplying R290 heat pump solutions in the U.K. The company has units, including Vitocal 150-A, Vitocal 250-A Pro, AquaSnap 30AWH-P and AquaSnap 61AQ, listed on a framework operated by Procure Plus for social housing and other public-sector low- and zero-carbon projects.
Quotable: “If heat pumps are going to achieve mass adoption in the U.K., the market needs solutions that reduce both installation costs and consumer reluctance,” Murchie said. “Our product presents an innovative addition and provides solutions to many barriers currently stopping people from switching from gas boilers to heat pumps.”
