Italian manufacturer Frascold has launched its new generation of NEXUS semi-hermetic screw compressors for high-temperature heat pumps, which are compatible with hydrocarbon refrigerants, including butane (R600) and isopentane (R601a).
The NEXUS screw compressors have a maximum operating temperature of 140°C (284°F) and a heating capacity of over 1MW (284TR), with volumetric displacements from 316 to 912m³/h (186 to 537CFM) at 50Hz and motors up to 300HP. They are designed to work in air-to-water and water-to-water configurations with butane and isopentane. In addition to hydrocarbons, the compressor is also compatible with R1233zd.
The new compressors feature high-efficiency motors sized to operate in extreme thermal conditions, bearings manufactured with new-generation materials and a redesigned electric plate that has been optimized to withstand high temperatures, according to Frascold. The new NEXUS screw compressors allow suction temperatures up to 100°C (212°F) and discharge temperatures up to 150°C (302°F).
“The reliability of NEXUS compressors has been confirmed by a number of field applications, in particular, an in-depth test campaign conducted at the Danish Technological Institute between February 2024 and July 2025,” said Maurizio Mastrapasqua, Product Manager at Frascold. “Frascold is ready to introduce important innovations in the field of high temperatures, with future developments that will take performance to even higher levels.”
The company has also updated the lubrication circuit, reducing the solubility of the refrigerant in the oil to ensure stable viscosity and reliable lubrication under all operating conditions, even at high temperatures. To further improve the reliability of the system, the crankcase heaters have been updated to ensure stable oil temperature and viscosity prior to start-up.
Powering heat pumps
Italian chiller and heat pump manufacturer Tecnofreddo released a propane (R290) air-to-water high-temperature heat pump in April 2025 that featured Frascold’s ATEX-HT semi-hermetic reciprocating compressor. The new heat pump, part of the company’s “Danae line,” offered an outlet temperature of 80°C (176°F). This was a marked improvement over the previous maximum outlet temperature for Danae heat pumps of 45°C (113°F).
The ATEX-HT semi-hermetic reciprocating compressor features a line start permanent magnet (LSPM) electric motor that increases efficiency by 6% compared to a standard asynchronous motor, according to Tecnofreddo. LSPM motors start like induction motors but have permanent magnets on the rotor to eliminate slip – the lag between the stator and rotor – that leads to energy loss.
