Heat Pump Installation and Commissioning
Core concepts
Installation quality determines real-world performance. Candidates must understand siting (clearances, air recirculation, noise, snow and flood risk, wall bracket versus ground slab), refrigerant pipework routes and limits, and hydraulic design - primary/secondary separation, low-loss headers, buffer vessels and volumisers. Know the correct sequence: pressure-test and flush the system, fit strainers and magnetic filters, ensure adequate system volume, then fill, vent and commission. Commissioning includes measuring flow and return temperatures, setting the correct flow rate (often 10–20 K ΔT), balancing emitters, checking refrigerant charge where applicable, recording pressures and temperatures, and completing the commissioning checklist and handover. Understand anti-freeze protection, condensate drainage and defrost management, and the importance of weather compensation settings.
Traps
A common exam trap is confusing flushing with power-flushing on a heat pump system, or omitting a magnetic filter and strainer. Another is failing to check that the existing pipework and emitters suit the lower flow temperature. Questions may test the correct order of operations - for example, pressure testing before insulation or before adding inhibitor. Watch for candidates who ignore minimum system volume or who set the flow rate without checking ΔT.
Worked example / rule of thumb
For a system with a 7 kW heat pump, a 10 K design ΔT and water: flow rate ≈ Q / (4.18 × ΔT) = 7 / (4.18 × 10) ≈ 0.17 kg/s ≈ 0.17 L/s ≈ 10 L/min. Rule of thumb: aim for 10–20 K ΔT; if ΔT is too high, flow is too low and heat output suffers.