Lead / Senior Cooling Systems Design Engineer

Runware · Bucharest, Romania (Hybrid) · — · Posted 2026-10-27

Workplace: hybrid

Description

Runware develops AI infrastructure and modular data centres. We are hiring a Lead / Senior Cooling Systems Design Engineer to take cooling equipment from initial requirements through detailed engineering, fabrication, testing and production for European and US markets. This role is for someone who enjoys owning the engineering: performing the calculations, making consequential design decisions, producing the documentation needed to build equipment, and proving its performance through testing.

The technical scope You will bring deep expertise in dry cooling, compressor-based air conditioning and refrigeration, or both, supported by a sound understanding of complete cooling systems. Dry cooling involves rejecting heat from water/glycol circuits to ambient air through liquid-to-air heat exchangers, finned coils, fans, pumps and manifolds. Compressor-based refrigeration involves vapour-compression systems, including compressors, evaporators, condensers, expansion devices and refrigerant circuits. You will integrate equipment into compact, high-density computing infrastructure, addressing air distribution, ducting, liquid distribution, sensors and control strategies.

What you will own

• Translate cooling loads, ambient conditions, temperature limits, space constraints, efficiency targets and noise requirements into clear engineering specifications and justified design margins.
• Perform heat balances, heat-transfer calculations, heat-exchanger sizing, airflow calculations, hydraulic calculations and pressure-drop analysis, accounting for fluid properties and realistic operating conditions.
• Select and size components within your specialist area, including coils, fans, pumps, compressors, valves, expansion devices, piping and insulation, using actual supplier performance data and operating limits.
• Evaluate full-load and part-load performance, extreme ambient conditions and energy consumption. Develop thermal and fluid models, validate assumptions and use simulation where it improves design decisions.
• Produce detailed layouts, 3D assemblies, fabrication drawings, piping and instrumentation diagrams, refrigeration schematics where applicable, bills of materials, component schedules and technical specifications.
• Define materials, dimensions, tolerances, connections, joining methods, service clearances and assembly requirements so manufacturing teams can build and inspect the equipment.
• Develop control sequences, operating envelopes, sensor requirements, alarms, interlocks and protection functions with electrical and controls engineers, including startup, shutdown and fault behaviour.
• Work directly with suppliers and manufacturing teams to resolve fabrication issues and improve designs for assembly, maintenance, cost and repeatable production.
• Plan prototype testing and instrumentation. Compare measured capacity, temperatures, flow, pressure drop, power consumption and noise against predictions; investigate discrepancies and refine the design.
• Prepare commissioning procedures, acceptance criteria and controlled production documentation.
• Identify applicable European and US requirements covering refrigerants, pressure equipment, product safety, electrical integration, energy efficiency and environmental compliance. Work with certification specialists and test laboratories to establish the requirements and evidence for each product. For refrigerant systems, assess relevant EU F-gas and US EPA Technology Transitions and SNAP requirements according to equipment category and intended application. (climate.ec.europa.eu, epa.gov)

Requirements

• An engineering degree in mechanical engineering, thermal engineering, refrigeration or a related discipline, or equivalent practical experience.
• Strong fundamentals in thermodynamics, heat transfer and fluid mechanics, with substantial equipment design expertise in at least one of the cooling technologies described above.
• Evidence of cooling systems you personally designed, supported through fabrication and successfully tested.
• The ability to turn calculations into manufacturable designs and complete, accurate engineering documentation.
• Experience designing equipment for applicable European and US requirements and collaborating across mechanical, electrical, controls and manufacturing disciplines.
• Proficiency in relevant engineering calculation, equipment selection, simulation and mechanical CAD tools.

Examples include REFPROP for thermodynamic and refrigerant properties, Güntner Product Calculator for heat-exchanger selection, Ansys Fluent for CFD, and SolidWorks for mechanical CAD. (nist.gov, guntner.com, ansyshelp.ansys.com, solidworks.com) Equivalent tools are welcome; mastery of every listed package is unnecessary. You must understand the physics, assumptions, boundary conditions and limitations behind your calculations and recognise when further validation is needed.

Benefits

We’re a remote-first collective, meeting in person twice a year to plan, brainstorm, celebrate wins, and enjoy some face-to-face time. We have core hours for cooperative working and calls, but outside of that your calendar is yours. Work the hours that let you perform at your peak while also building a healthy life.

Our release cycles are fast and intense, but they’re followed by real downtime. After big pushes we expect the team to unplug, recharge, and come back ready & stronger than ever for the next leap.

• Generous paid time off – vacation, sick days, public holidays
• Meaningful stock options – share in the upside you create
• Remote-first setup – work from home anywhere we can employ you
• Flexible hours – own your schedule outside core collaboration blocks
• Family leave – paid maternity, paternity, and caregiver time

Apply

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