Free cooling chillers

Free cooling system developed by Kaltra offers remarkable high energy savings and extended operating envelope of the water chillers


Airside economization

Air-based free cooling uses low-temperature ambient air as a cooling medium for chilled water systems, thus providing significant opportunities to generate energy savings. The more time the chilled water system can operate in the free cooling mode, the greater energy efficiency it can deliver.


Although free cooling technology is not new and widely used in many chilled water applications, there are a variety of ways to raise efficiency, including adopting innovative heat exchangers, engaging the partial free cooling operation mode, and the application of advanced methods for free cooling control.


Partial free cooling

The key condition to start free cooling operation is when the ambient temperature drops below return water temperature. In conditions such as these, free cooling system tops up the cooling demand by running in parallel with compressors. Ambient temperature monitored continuously to run fans as fast as possible and achieve the maximum free cooling while keeping the compressors within the operating envelope.

Full free cooling

When the ambient temperature falls enough for a free cooling system to satisfy the overall cooling demand, the compressors switch off, and the system keeps the required water temperatures by regulating the speed of the fans and water flow.

Elevated water temperatures

Raising chilled water temperatures can generate more free cooling opportunities so that the system will work more hours in free cooling mode, full and partial. In the applications where chilled water temperatures can be lifted without adverse impacts, free cooling technology will provide the constant savings in operational costs.

Recent studies have shown that cooling air temperature in data centers can be raised up to 27°C without damaging the electronic equipment or reducing its lifespan. Therefore chilled water temperature can also be elevated in data center applications, thus ensuring significant power savings.

Extended operating range

The use of air-cooled chillers under cold weather conditions restricted due to refrigeration side limitations. Extreme cold weather is not an issue for free cooling chillers which will continue operation in free cooling mode by regulating fan speed and water flow through the free cooling coils as necessary. In response to temperature changes, water flow regulated automatically by 3-way or 2-way actuated valves, which help to avoid both excessive and minimal flows.

Fan speed control

Variable fan speed control assists to save the energy by regulating the speed of the fans as required rather than running them at full speed as the ambient temperature falls.

Free cooling system by Kaltra

Kaltra uses the newly developed microchannel heat exchangers that feature increased heat transfer rates and capacity as free cooling coils. With these coils, the temperature at which free cooling system satisfies 100% cooling demand is higher by 4°C compared to the system with traditional fin/tube heat exchangers.


Such an increase in free cooling opportunities translates to significant power savings. For example, in Central European climate zone our free cooling chillers enable a saving of up to 250,000kWh per 1000kW of cooling capacity annually.

Kaltra manufactures a comprehensive range of free cooling chillers with different types of compressors and suitable for various applications, starting from air conditioning solutions to process cooling to data center cooling. The whole portfolio includes highly efficient, feature-rich models to select from.

Related products



High-efficient free cooling chillers with inverter compressors and adopted microchannel technology for condensing and free cooling coils. Available in capacity range from 600kW to 1200kW with R1234ze and R134a 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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