Lightstream Screw V Inverter

Variable-speed chillers with air-cooled condensers, efficient at full and partial loads thank precise capacity control. The chillers are fully compliant with ErP 2021 directive requirements



Highly efficient, future-proof solution

Highly versatile, environment-friendly, efficient on full and part loads chillers suitable for all kinds of applications, including air conditioning, industrial process cooling, and mission-critical tasks. Lightstream Screw V Inverter chillers offer highest level of reliability and flexibility, reduced maintenance costs, and extended operating range.


Lightstream Screw V Inverter synthesizes Kaltra's experience and knowledge in screw compressor technology into high performing solution that meets the objectives of different industries and businesses.

Precise capacity control

The compact frequency-controlled screw compressors of Lightstream Screw V Inverter series chillers are especially suitable for systems that frequently operated under part-load, and optimized for the ambient temperature profile specified by the Ecodesign Directive for water chillers (European Chiller Energy Efficiency Standard EU 2016/2281 Tier 1, effective from January 2018).


These compressors also achieve impressively high full-load efficiency and significantly improved ESEER and SCOP values. Advanced oil management system enhances the oil circulation, thus delivering a remarkable increase in the compressor efficiency at partial loads.


The compressors monitor its own application limits and communicate via Modbus with the master system controls. The integrated data log can be used at any time to analyze operation over the running time and optimize the system settings.


Microchannel condenser coils


For Lightstream Screw V Inverter chillers we use microchannel condenser coils of a new design - with optimized louvered fin geometry and microchannel tubes with reduced port size - both made from long-life aluminium alloys. This new design enhances the overall heat transfer while reducing airside pressure drop as compared to coils of the previous generation, thus enabling fan energy savings.


The chillers characterized by noticeably reduced refrigerant charge as new coils have reduced internal volume, and this translates to lower initial and maintenance costs. High heat transfer rates lead to considerable lower condensing temperatures, which in turn enables the savings on compressor energy.


For installations in aggressive or highly-polluted environments, as well as for seashore installations, we recommend e-coated coils with high corrosion resistance to ensure long service life.

Intelligent fan system


EC motors use commutation electronics to sense the rotor position and adjust supply current, thus eliminating the need for mechanical brushes to deliver current to the motor windings. Elimination of physical contact reduces internal wear within the fan motor and significantly increases reliability.


Our new generation fan system not only reduces power consumption by up to 30% while efficiently managing the extraordinarily high volume flows – it also works at much reduced operating noise.


The smart fan system includes the unique fan impellers with bionic wing concept, the most advanced EC motor technology, and multifunctional air diffusers, resulting in an extra economic efficiency for the customers.


EC motor technology does not provide savings only during full-load operation - it is exactly when operating under partial load that EC motors lose much less of their efficiency compared to AC fans.



For shell-and-tube evaporators, thermal performance and pressure drop are considered as major factors which are directly related to operating costs and overall chiller efficiency. Both thermal performance and pressure drop are dependent on the flow paths and types of baffles used to increase the fluid velocity - by diverting the flow across the tube bundle to obtain higher heat transfer coefficient.


The shell-and-tube evaporators used in Lightstream Screw V Inverter chillers feature both high heat transfer performance, close approach temperatures, as well as low pressure drops, as it combines an innovative tube bundle design and optimized baffle geometry. The net result is improved system performance, as well as tight control of return water temperatures.

Eco-friendly refrigerants


The portfolio of Lightstream Screw V Inverter chillers includes the models that use low-GWP alternatives to R134a. The customers may choose from zero ozone depletion potential refrigerants R1234ze and R513a with the GWP values of less than 1 and 573, respectively.


Recently developed R1234ze refrigerant features low global warming potential and zero ozone depletion potential and fulfills EU regulatory requirements for reducing the use of high global warming potential (GWP) substances. At the same time, R1234ze almost exactly matches the efficiency of R134a. R513a is an azeotropic low-GWP, and non-ozone depleting refrigerant based on hydrofluoro-olefin (HFO), developed to replace R134a. Its energy efficiency and capacity match those for R134a, while its environmental impact significantly reduced.


With low-GWP refrigerants, Lightstream Screw V Inverter chiller is the environmentally-friendly leader of the range, while achieving the best energy performance levels for applications.

Extended operating range

Lightstream Screw V Inverter chillers are equipped with sophisticated capacity control based on a combination of chiller hardware and software that extends the chiller operating range for both ambient and plant water temperatures and improves chiller performance.


With the optional kits specially engineered for high and low ambient temperature operations, Lightstream Screw V Inverter chiller is suitable for running in climate conditions from -15°C to 52°C, while plant water temperatures may vary from -2°C to 20°C. Moreover, a condenser bypass option is suitable for chiller operation in extreme cold environments (to -30°C).

Pumps and flow control

Lightstream Screw V Inverter chillers can be equipped with factory-installed variable or fixed-speed pumps. The pumps feature reduced life-cycle costs, optimized efficiency, and high standard of corrosion protection thanks to cataphoretic coating. Variable-speed pumps have a broad performance range, which enables them to perform efficiently under widely varied conditions and to meet a wide range of requirements.


Based on the required performance, customers may select from inline - single or twin - or end-suction pumps installed in soundproof enclosures.

Chillers can be configured for constant or variable flow depending on a configuration of chilled water system. For the systems with a primary-only circuit, constant pressure differential or constant temperature differential flow control can be selected, while constant temperature differential control is available for primary/secondary systems. Flow control logic dynamically adjusts the pump speed based on the actual load, thus optimizing pump energy consumption and ensuring the stable operation of the chilled water plant.

Free cooling option


The Lightstream Screw V Inverter chillers can supply chilled water with fairly high temperatures, thus maximizing the amount of time the system can produce chilled water without running mechanical cooling mode. Compared to conventional chillers, Lightstream Screw V Inverter equipped with freecooling system generates the energy savings of up to 50% and return the investments within a short timeframe.

When running in concurrent freecooling and mechanical cooling mode,  the control system constantly monitors the condensing temperature and keep it within the compressor envelope to allow the maximum possible fan speed and achieve the most freecooling. During the periods when the fan speed must be reduced to a minimum, the chilled water temperature is controlled via motorized valves.


Cooling capacity



Up to 3.26


Up to 5.32


Inverter Screw







Fan type


Free cooling


Heat recovery


Related products



High-capacity air-cooled chillers with inverter-driven screw compressors and microchannel condensing coils. Available with R134a and low-GWP, ozone-friendly R1234ze refrigerants

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Kaltra Innovativtechnik GmbH

Max-Reger-Str. 44
90571 Schwaig

+49(0)911 715 32021

VAT: DE300943964

Kaltra is a customer-focused developer and supplier of reliable, energy efficient thermal management equipment and solutions.


From the professionalism of our research and development engineers to the wide experience of our service team, we are dedicated to delivering you the best service possible.

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