Stulz releases fourth-generation TelAir and WallAir cooling units for edge and 5G sites

Hamburg-based cooling specialist Stulz has introduced the fourth generation of its TelAir and WallAir shelter-cooling series, targeting edge data centers, 5G infrastructure, telecommunications containers, and radio stations. Both product lines are available in two enclosure sizes and four cooling capacity classes, ranging from 6 kW to 17 kW, and are available to order as of 1 September 2026^[1].

What changed in the fourth generation

The redesign is driven by two converging pressures: rising thermal densities at distributed sites and the tightened refrigerant rules under the amended European F-Gas Regulation (EU) 2024/573. The TelAir 4 and WallAir 4 use low-GWP R454C refrigerant, integrated free cooling, and a certified EN 378 safety architecture^[1].

R454C carries a global warming potential of 148, well below the high-GWP HFCs it replaces. The units' electronically commutated (EC) fans already comply with the requirements of the upcoming ErP 2027 Ecodesign Directive, and both series operate across a temperature range of -20 °C to +54 °C, with an optional winter kit extending operation to -40 °C.

A two-stage refrigerant sensor system governs safety: fan speed increases and selected electrical loads shut down at 10 percent of the lower flammability limit, with full power disconnection at 20 percent. Stulz's E² BASIC controller provides Ethernet connectivity, Modbus support, and interfaces for building management and DCIM systems, as well as inputs for fire, smoke, and intrusion alarms.

Two installation concepts

The product line splits into two distinct form factors:

• TelAir 4 - indoor installation, suited to shelters and enclosed equipment rooms
• WallAir 4 - externally mounted monoblock, fixed to a container wall, leaving the full interior footprint available for IT racks and network hardware

Customers can also choose between classic on/off compressor systems with a thermostatic expansion valve, or continuously modulating EC inverter compressors paired with an electronic expansion valve, depending on load profile requirements.

Efficiency claim

In combined free-cooling and mixed-mode operation, Stulz says the units can reduce operating costs by up to 80 percent. The free-cooling mode uses ambient air when outdoor temperatures are low enough, cutting compressor run-time - a meaningful lever for distributed sites where energy costs are often unmanaged and remote.

Context

The launch extends a product line that Stulz updated last year with an air-cooled side pod for edge deployments^[1]. The German firm also sells liquid cooling systems for higher-density applications, but the TelAir and WallAir series address the lower end of the thermal spectrum - the thousands of small, unmanned sites that underpin 5G rollout and distributed compute.

What to watch: whether the 80 percent operating-cost reduction claim holds across the range of ambient conditions typical of far-edge deployments, and how quickly European operators move to R454C-compliant units ahead of the F-Gas phase-down schedule.