Outdoor air conditioner for Free Cooling in containers

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Precision air conditioning units for outdoor installation

WallAir units are compact and weatherproof precision air conditioning units that are mounted outside the container for cooling and so enable the container space to be used to the full.

Optimized for air conditioning containers and modular buildings
Free Cooling
Free Cooling
Maximum potential savings by using cool outside air
Base station
Base station
Reliable air conditioning of telecommunication systems
Plug & Play
Plug & Play
Units immediately ready for connection and operation

Product Overview

At a glance

Most important benefits

  • Up to 84 % savings on running costs thanks to Direct Free Cooling
  • Low refrigerant quantity (less than 10 tons CO2 equivalent)
  • Connectivity: Monitoring and remote access to outdoor air conditioner available via a web interface

Most important features

  • Available with EC compressor
  • Outside air conditions: -20 °C winter/+50 °C summer

Most important technical data

  • Cooling capacity total (kW): 4 – 16
  • Air conduction: Displacement
    • Up to 84 % savings on outdoor air conditioner’s running costs thanks to Direct Free Cooling
    • Low refrigerant quantity (less than 10 tons CO2 equivalent)
    • No annual leak test required in accordance with F-gas regulation*
    • The units are plug and play and therefore immediately ready for connection and use
    • Connectivity: Monitoring and remote access available via a web interface
    • Backup operation (Free Cooling and backup cooling) on failure of the main power supply
    • Automatic restart for the ac outdoor unit after power failure
    • Very long maintenance intervals
    • Robust and designed for continuous 24/7 operation, 365 days a year

    *Due to low refrigerant quantity and hermetically sealed refrigerant circuit (standard for EC compressor, optional for On/Off compressor)

    • Available in 2 sizes
    • Factory tested, filled with refrigerant and ready for operation from the very first day
    • Available with EC compressor
    • Outside air conditions: -20 °C winter/+50 °C summer
    • Filter monitor and airflow alarm
    • Inside and outside temperature sensors
    • Zigzag filter class ISO 16890: ePM10 50 %
    • Condensation pressure control
    • Condenser with microchannel technology
    Technical Data
    Cooling capacity total (kW)4 - 16
    Air conduction Displacement

    R410A (GWP: 2,088)

    R407C (GWP: 1,774)

    R134a (GWP: 1,430)

    All details about WallAir

    Climate. Customized.

    From standard units to fully customized solutions

    The ability to offer such a wide range to customers is the embodiment of our philosophy, "Climate. Customized.". Size, design or control: WallAir is a model of adaptability and the shelter units can be precisely adapted to your individual requirements. In addition, a variety of options and equipment versions are available to achieve the optimum result.

    Learn more about Climate. Customized.

    Climate. Customized.
    Optimum operational reliability for your application

    Connectivity for maximum availability

    Monitoring and remote diagnosis are available for all units via a web interface. This enables rapid intervention and therefore immediate troubleshooting in all situations. What’s more, our outdoor air conditioner units support numerous communication protocols for integration in building services management systems.

    • Data recording
    • Remote configuration
    • Firmware updates
    • Alarm relaying

    Backup operation for maximum reliability

    In telecommunications, in particular, high reliability is vital to prevent any loss of network availability. Thanks to the additional 48 V DC power source, backup operation with Free Cooling is available. If the main power supply fails, the Shelter Cooling units continue providing backup cooling to keep your system running reliably.

    Direct Free Cooling

    In many base stations and small data centers, comfort air conditioning units without Free Cooling mode are still used today for air conditioning, with high energy consumption as the result. Units from STULZ’s Shelter Cooling series exploit the potential of Free Cooling, dramatically lowering your energy costs.

    Savings with Direct Free Cooling
    Efficient air conduction and intelligent control of operating modes enable savings of up to 84 % to be achieved.

    Operating modes

    Direct Free Cooling mode

    At low outside temperatures, outside air is used directly for cooling. The outside air is conveyed into the interior when the air damper is open. Energy-intensive compressor cooling is not needed when outside temperatures are low. This way, Free Cooling brings you huge potential savings.

    Mixed mode

    If Free Cooling is not sufficiently available due to the outside temperature, the unit can still use the outside air to some extent. The result is a combination of compressor cooling and Free Cooling.

    Compressor mode (DX)

    If outside temperatures are so high that the outside air would no longer help to cool the inside, all cooling is generated using the compressor. Even in this mode, the perfectly harmonized components we use keep STULZ air conditioning units working reliably and efficiently.

    Reliable operation in any weather conditions

    Whether your business-critical system is working in temperatures of up to 55 °C, in ambient air contaminated by particles, in temperatures as low as -40 °C, or in a permanently humid environment – you can always rely on systems from STULZ.

    Plug & Play
    • All products in the Shelter Cooling series are factory tested, filled with refrigerant and ready for connection and operation right from the start
    • Reduced installation time and costs
    • Speedier start-up

    Displacement airflow

    Displacement units enable cold supply air to flow close to the floor at low speed. The resulting “pool” of cold air on the floor prevents hot and cold air from mixing. This principle increases the number of operating hours with Free Cooling, achieving maximum potential savings.

    EC compressor

    Advantages of the speed-controlled EC compressor

    • Maximum energy efficiency for hvac outside units in partial load mode
    • Constant supply air temperature
    • Refrigerant R410a
    • Integrated compressor soft start
    • Long service life thanks to continuous operation without compressor on/off cycles

    Control and monitoring

    The SEC.blue/C2020 consists of a controller and optional operator terminal. The controller manages all functions of the WallAir unit. The operator terminal, consisting of a keypad and LCD, displays the outdoor air conditioner’s most important operating states and alerts.



    The SEC.blue enables up to ten units to be configured in a single air conditioning system. If an individual unit drops out or the heat load rises, the standby unit is switched in for additional support.

    Night Mode

    • Time-controlled limitation of the condenser and evaporator fan speed for quiet operation
    • Energy-saving mode

    Monitoring and alarm relaying

    • Via BMS systems (Modbus onboard, further protocols via WIB 1000)
    • Nine potential free contacts are available: Alarms can be assigned a high or low priority
    • Via GSM modem (CompTrol SMS)

    Simple configuration and software updates

    • Central configuration of units from a laptop
    • Hardware key for uploading and downloading software without a laptop and/or copying the configuration onto other units




    The numerous different options and possible equipment enable you to perfectly adapt WallAir hvac outdoor units to your requirements.

    • High-temperature operation up to 55 °C with R134a
    • Winter kit up to -40 °
    • Compressor soft start for low start-up currents
    • Electrical wiring, with connector for plug and play
    • Backup operation with 48 V DC or 230 V/50 Hz/1 Ph
    • External operator terminal
    • Electric heater
    • Humidity sensor

    Close to you around the world

    As a company with locations across the globe, we offer everything you need in the extremely dynamic world of information technology - plus professional advice in the right place at the right time.

    With 21 subsidiaries, 11 production sites, and sales and service partners in over 140 countries, we make sure we are close to our customers wherever they are in the world.

    Locations worldwide

    Service and maintenance

    Our trained and experienced sales and service partners are located in over 140 countries. The resulting proximity to our customers allows fast response times. In addition, regular training courses and an active exchange of information ensure high quality and an extensive knowledge of all our products. This way, you can be sure your products are in the best hands and get the right maintenance – all over the world.


    STULZ Service
    STULZ Service
    STULZ Service
    Test Center

    At our test center, you can have WallAir units tested under your individual operating and site conditions. This creates transparency and confirms the unit's performance and energy consumption.


    Find your individual STULZ contact

    Need more information?

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    Do you have any questions? We will be happy to help! Please call us or follow our contact form.

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    Contact us

    STULZ GmbH
    Holsteiner Chaussee 283
    22457 Hamburg 

    Central Office: +49 40-5585-0
    Fax: +49 40-5585-352

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