Senior Mechanical Design Engineer (Renewable Thermal Systems) in Bristol

_{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 Focus1. 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.