Free Cooling


    Maximize energy savings with Kaltra’s advanced free cooling chillers

    Water chiller


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 savings it can deliver.

Although free cooling technology is not new and widely used in many installations, there are a variety of ways to raise its efficiency, including adopting innovative heat exchangers, engaging the partial free cooling operation mode, and the use of advanced control techniques.

The free cooling system found in Kaltra chillers has been engineered using all of the above technologies and delivers remarkable high energy savings while extending chillers’ operating envelopes.

Kaltra offers a comprehensive range of free cooling chillers with different types of compressors and optimized 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.

Free cooling system


The free cooling system used in Kaltra chillers is full-featured, controlled by integrated chiller software, includes the following components:

  1. Microchannel free cooling coils
  2. EC-motor fans
  3. Inlet/outlet water connections
  4. Shell-and-tube evaporator
  5. Water distribution pipework
  6. Actuated 3-way mixing valve
  7. Regulating valve
  8. Bypass with regulating valve
  9. Inverter-driven pumps


Partial Free Cooling

The key condition to start a free cooling operation is when the ambient temperature drops below the return water temperature. Then, free cooling system tops up the chiller’s cooling capacity by running in parallel with compressors. Ambient temperature monitored continuously to run fans as fast as possible and achieve 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 water temperature by regulating fan rotation speed and water flow. In low cooling demands, the system maintains minimum water flow through a 3-way mixing valve to avoid freezing of the free cooling coils.

Full and partial free cooling - graph

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 additional savings in operational costs.

Extended Operating Range

Under cold weather conditions, the service of air-cooled chiller is restricted by its refrigeration side, while free cooling chiller can 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 automatically regulates by mixing valve, thus avoiding both excessive and minimal flows.


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

This closer temperature approach leads to expanded free cooling opportunities and, consequently, to higher energy savings for the customers.

Microchannel condenser coil

Free cooling chiller

Lightstream Freecool

Highly efficient free cooling chillers equipped with frequency-controlled screw compressors and adopted microchannel technology for free cooling and condensing coils.
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Lightstream Scroll II air-cooled chiller

Lightstream Scroll II

Multi-refrigerant air-cooled chillers with scroll compressor technology, combining efficient cooling and environment-safe operation for comfort and process cooling.
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Free cooling chiller

Ultracompact II Freecool

Cutting-edge packaged scroll chillers encompassing the benefits of advanced free cooling system, close approach evaporators, and microchannel condensers.
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