Under RE2020, the heat pump has become the benchmark heating system in new builds. It extracts heat from the outside air, water or ground and releases it into the building. For the commissioning engineer, it is a central piece of equipment that requires specific expertise.
Types of heat pump
- • Air-to-air heat pump (split, multi-split): the simplest type, it heats and cools the room air directly. COP of 3 to 4.
- • Air-to-water heat pump: extracts heat from the air and supplies a hydronic system (radiators, underfloor heating, AHUs). COP of 3 to 5.
- • Water-to-water heat pump (geothermal): draws on groundwater or geothermal boreholes. COP > 4, very stable.
- • Ground-to-water heat pump (ground collectors): horizontal collectors or vertical boreholes. Suitable for buildings without groundwater access.
- • VRV/VRF (Variable Refrigerant Volume/Flow): a multi-zone direct-expansion system, ideal for commercial buildings. Up to 64 indoor units per module.
COP, SCOP and real-world performance
The COP (Coefficient of Performance) is the ratio of thermal energy produced to electrical energy consumed. A COP of 4 means the heat pump produces 4 kWh of heat for every 1 kWh of electricity. The SCOP (Seasonal COP) is the annual average, which takes account of variations in outdoor temperature.
Commissioning a heat pump: checkpoints
- • Check the refrigerant charge (subcooling and superheat).
- • Set the heating curve according to outdoor temperature.
- • Test the heat pump/back-up cascade (changeover, temperature thresholds, priority).
- • Measure the actual COP under operating conditions (electricity meters + heat meter, or ΔT × flow rate).
- • Check the protections: frost protection, high/low pressure, minimum flow.
- • Test fallback modes: what happens if the heat pump fails? Does the back-up take over?
- • Configure defrost: frequency, duration, mode (reverse cycle or electric heater).
F-Gas regulation
The European F-Gas Regulation (517/2014) governs the use of refrigerants with a high global warming potential (GWP). It requires periodic leak checks and a progressive phase-down of HFC quotas. R32 (GWP 675) and R290 (propane, GWP 3) are gradually replacing R410A (GWP 2088).
To measure the actual COP of a heat pump, install a dedicated electricity meter and a heat meter on the hydronic circuit. Compare the values over a full week to get a representative result.