21st April, 2026 Position: Senior Mechanical Design Engineer (Renewable Thermal Systems) Location: Bristol/ Hybrid Salary: £65,000 - £80,000 We are looking for a specialist Mechanical Design Engineer to lead the transition from fossil fuel combustion to Large-Scale Heat Pump Technology. You will be responsible for the "physics" of the system—ensuring that high-capacity heat pumps are integrated into hydronic circuits that actually deliver on their efficiency promises. Core Technology Focus 1. Air Source Heat Pumps (ASHP) Cascade Systems: Designing multi-unit ASHP arrays for commercial peak loads. Defrost & Ambient Logic: Managing acoustic mitigation, airflow requirements, and defrost cycle impacts on system continuity. Bivalent Integration: Designing systems that integrate ASHPs with existing LTHW or backup heat sources. 2. Ground Source Heat Pumps (GSHP) Array Design: Coordinating borehole heat exchangers (BHE), horizontal loops, and thermal conductivity testing. Ambient Loops: Designing 5th Generation heat networks and "sharing" energy across multi-user sites. Passive Cooling: Leveraging ground temperatures for high-efficiency cooling integration. 3. Hydronic Architecture (The "Engine Room") Low-Temperature Hot Water (LTHW): Designing for Heat Pump efficiency (e.g., 45°C flow / 35°C return). Buffer & Separation: Precise sizing of buffer vessels and Low-Loss Headers to prevent short-cycling and maintain hydraulic separation. System Balancing: Specifying PICVs and variable-speed pumping to ensure optimal mass flow rates. Key Professional Duties Detailed Modeling: Using IESVE or Hevacomp to ensure heat loss calculations meet BS EN 12831 standards. BIM Coordination: Utilizing Revit MEP for 3D spatial coordination of complex plant rooms. Technical Compliance: Ensuring all designs meet CIBSE CP1 (Heat Networks) and MIS 3005 (MCS) standards. Candidate Profile Technical Background: Degree-qualified (BEng/MEng) with a deep understanding of thermodynamics. Professional Status: CEng or MCIBSE preferred. Experience: You must have a proven track record of designing ASHP or GSHP systems —not just supervising them, but performing the actual hydronic and thermal calculations.