Mechanical Engineer

Slough (GB), United Kingdom

Full Time

Posted June 10, 2026

£27k - £29k· Est.

Application opens on company website

Octopus Energy's R&D team in Slough is developing the next generation of heat pump systems and hydraulic products that surround them.

Design, build and commission hydraulic test rigs and prototype products that integrate with heat pumps (buffer tanks, hot water cylinders, heat exchangers, circulation and modulation hardware, and similar).
Carry out hands-on assembly and plumbing of water-side and refrigerant-adjacent systems - pipework, fittings, pumps, valves, sensors and controls.
Instrument rigs with temperature, flow and pressure measurement, and run structured test campaigns to characterise both systems and components performance.
Diagnose and troubleshoot hydraulic, thermal and mechanical issues on live systems, and feed findings back into the design.
Work closely with the wider R&D team to iterate designs quickly, balancing performance, cost, manufacturability and serviceability.
Produce clear documentation: test plans, build instructions, results write-ups and design records.

Degree in Mechanical Engineering (or a closely related discipline).
Minimum 5 years' relevant experience in an R&D, product development or test environment.
Demonstrable heat pump knowledge - you understand how heat pumps work, their operating envelopes, and how the hydraulic system around them behaves (flow, temperature, ΔT, defrost, modulation, etc.).
Strong hands-on experience - this is the most important requirement. You can build, plumb, commission and fault-find systems yourself, not just specify them. Practical plumbing and pipework skills are essential.
Experience working with hydraulic systems - pumps, valves, heat exchangers, tanks, pipework and the behaviour of water-side circuits.
Comfortable instrumenting rigs and interpreting test data to draw engineering conclusions.
CAD proficiency for designing rig components and prototype parts.
Able to work independently and using own initiative on-site in Slough and move quickly in a fast-paced R&D environment.