A heat pump moves heat from outside air, the ground or water into a building, delivering 3–5 kWh of heat per kWh of electricity — an efficiency no combustion boiler can approach. This guide explains COP and SCOP, the main heat pump types, cold-climate performance, the EU's 2027 F-Gas refrigerant deadline, a European market that grew 13% in 2025, and how to size a system correctly.
How does a heat pump work?
A heat pump moves existing heat from a low-temperature source — outside air, the ground or groundwater — into a building, using a refrigeration cycle driven by electricity. Because it transfers heat rather than generating it, it delivers 3–5 kWh of heat per kWh of electricity consumed, where even the best condensing gas boiler extracts less than 1 kWh of heat per kWh of fuel.
The cycle has four stages. Cold liquid refrigerant absorbs low-grade heat from the source and evaporates; the compressor raises its pressure and temperature; the hot gas condenses in a heat exchanger, releasing heat into the heating water; an expansion valve drops the pressure and the cycle repeats. Run in reverse, the same machine cools. Air-to-water heat pumps — the dominant type in European building heat — feed this output into radiators, underfloor circuits and a domestic hot water cylinder, which is why they slot into existing hydronic systems.
What do COP and SCOP actually tell you?
COP is the instantaneous ratio of heat delivered to electricity consumed at a standard rating point; SCOP averages that performance over a full heating season including part-load operation and defrost. COP is measured under EN 14511 at defined points such as A7/W35 — 7 °C outside air, 35 °C flow water. Quality air-to-water units reach COP values around 4.5–5 at this point; Solimpeks' Varm Up Series rates up to 4.9 at A7/W35. SCOP, measured under EN 14825 for defined European climate zones, is the number behind the energy label and the one that predicts your bill.
Two temperatures decide real-world efficiency: source and flow. Efficiency improves roughly 2–3% for every kelvin the source rises or the flow temperature falls. The cheapest efficiency upgrade in most projects is not a better machine — it is a lower flow temperature, achieved through larger radiators, underfloor heating or simply weather-compensated control.
Which type of heat pump should you choose?
Choose air-to-water for most homes and businesses with wet heating systems, ground source where drilling is feasible and loads are large, and a dedicated DHW heat pump where only hot water is needed. The table summarises the field:
| Type | Heat source | Typical SCOP | Best fit |
|---|---|---|---|
| Air-to-water | Outside air | 3.0–4.3 | Retrofits and new builds with radiators/underfloor |
| Ground source (brine-water) | Borehole or ground loop | 4.0–5.0 | Larger properties, cold climates, new builds |
| Water source | Groundwater or surface water | 4.0–5.5 | Sites with accessible water and permits |
| Air-to-air | Outside air | 3.5–4.5 | Buildings without a wet heating system |
| DHW heat pump (HPWH) | Ambient or exhaust air | COP 2.5–3.5 (EN 16147) | Hot water only, plant-room installs |
| PVT source (brine-water) | Solar + ambient via roof panels | Ground-source class | Roofs replacing boreholes, silent operation |
Air-to-water units come in two builds: monoblock, with the entire refrigerant circuit factory-sealed in the outdoor unit and only water pipes entering the building, and split, with the refrigerant line run between outdoor and indoor units by a certified installer. The monoblock vs split decision now carries a regulatory dimension — the 2027 refrigerant rules below hit the two designs differently.
Do heat pumps work below freezing?
Yes. Modern air-source heat pumps heat reliably at −20 °C, and EVI (enhanced vapour injection) compressors extend operation further — Solimpeks' Varm Up Series EVI models are specified for operation down to −30 °C. The physics is a gradient, not a cliff: capacity and COP fall as the source gets colder, with COP at A-7/W35 typically in the 2.5–3.0 range, and the unit periodically reverses to defrost its evaporator.
The proof is geographic: Norway, Sweden and Finland have Europe's highest heat pump penetration per household. Cold climate is a sizing problem, not a feasibility problem — the machine must be selected for the local design temperature with its capacity table, not its nameplate, and the backup heater should be an insurance policy, not a crutch.
What does the 2027 F-Gas deadline mean for heat pump buyers?
According to the latest EU F-Gas Regulation (2024/573) rules, new monoblock heat pumps and air conditioners up to 12 kW placed on the EU market from 1 January 2027 must use refrigerants with a GWP below 150, with exemptions where safety requirements demand otherwise; split air-to-water systems up to 12 kW follow the same 2027 limit. In practice the small-unit segment is moving from R32 (GWP 675) and R410A (GWP 2,088) to propane (R290, GWP about 3) — the refrigerant behind Solimpeks' Varm Boost and Commercial Duo series and the Solido hot water heat pump. Installed units keep operating and can be serviced, and outside the EU national rules differ.
| Date | New-equipment ban (F-Gas Regulation 2024/573, Annex IV) |
|---|---|
| 1 Jan 2027 | Monoblock heat pumps/AC ≤12 kW and split air-to-water ≤12 kW with refrigerant GWP ≥150 |
| 1 Jan 2029 | Split air-to-air ≤12 kW with GWP ≥150; splits >12 kW with GWP ≥750 |
| 1 Jan 2032 | Any F-gas refrigerant in monoblocks ≤12 kW |
| 1 Jan 2035 | Any F-gas refrigerant in splits ≤12 kW |
Behind the bans sits a supply squeeze: the EU HFC quota drops from 42.9 Mt CO2e in 2025–2026 to about 21.7 Mt for 2027–2029 — roughly a further halving — which pushes F-gas refrigerant prices structurally upward. The practical read for buyers: an R290 monoblock bought today is future-proof through the entire phase-down; R290's A3 flammability is managed through siting clearances rather than indoor restrictions, and installers need certification that covers flammable natural refrigerants under the updated EU training and certification rules. The rules are still being implemented nationally, so check current requirements with your installer or with us; the full regulatory picture is in the F-Gas and R290 guide.
How fast is the European heat pump market growing?
European heat pump sales grew 13% in 2025 to 2.88 million units across the 21 markets tracked by EHPA — recovering from 2.56 million in 2024, though still below the 2022 record of 3.31 million. Germany rebounded 50%, where heat pumps took 50% of new space-heater sales for the first time; France led in volume with 528,000 units and Italy followed with 423,000. The installed stock across those markets now stands at 29.3 million units, and Q1 2026 sales rose a further 17% across the 11 markets EHPA tracks quarterly.
Policy is set to push harder. The EU's Electrification Action Plan (July 2026) targets 4 million heat pump installations per year by 2030, up from 2.4 million in 2025. The ETS2 carbon price reaches heating fuels in 2028 — roughly +1 cent per kWh on gas for every €50/tonne — while the EPBD requires zero-emission new public buildings from 2028 and all new buildings from 2030, with fossil-boiler subsidies already banned since January 2025. Every one of these instruments moves demand in the same direction.
How do you size and design a heat pump system?
Size a heat pump from a room-by-room heat-load calculation at the local design temperature — never from the old boiler's nameplate. Boilers are habitually oversized by a factor of two or more; copying that figure produces a heat pump that short-cycles, wears early and never reaches its rated SCOP. Slight undersizing with backup for the coldest days usually beats oversizing.
The design checklist that follows the load calculation: keep flow temperature at or below 45–55 °C with existing radiators (many are generous enough once checked room by room), or 30–35 °C with underfloor heating; add a buffer tank of 20–50 litres per kW where zoning, low system volume or defrost demands it; and choose a DHW cylinder with a large coil surface designed for heat pump temperatures. Solar integration is the natural next step — solar thermal or PVT covers summer hot water so the heat pump rests, or PVT serves directly as the heat source. Solimpeks manufactures this chain in Konya — Solimpeks heat pumps, Solibuffer buffer tanks from 50 to 1,000 litres, and PV-T hybrid panels — a portfolio built on solar collector manufacturing since the company was established in 2001.
Frequently asked questions
How much electricity does a heat pump use per year?
A typical European home needing 12,000 kWh of heat per year draws about 3,000–4,000 kWh of electricity at a seasonal efficiency (SCOP) of 3–4. The exact figure follows directly from your building's heat demand divided by the system's SCOP — which is why flow temperature and correct sizing matter more than brand.
Are heat pumps cheaper to run than gas boilers?
At a SCOP of 3.5, a heat pump beats a 95%-efficient gas boiler on running cost whenever electricity costs less than about 3.7 times the gas price per kWh. Many European markets already sit below that ratio, and the ETS2 carbon price arriving on heating fuels in 2028 shifts the comparison further toward the heat pump.
What temperature can a heat pump heat water to?
Standard air-to-water units deliver 55–60 °C, which covers radiators and domestic hot water. R290 propane models reach 65–75 °C without an electric backup element, making them suitable for radiator retrofits and anti-legionella cycles.
Do I need to replace my radiators for a heat pump?
Often not. Radiators are commonly oversized for their rooms, and a room-by-room check frequently shows they can run at 45–55 °C flow temperature. Where individual radiators fall short, exchanging only those — or stepping up to low-temperature convectors — is far cheaper than a full system replacement.
Which refrigerant should a new heat pump use in 2026?
For new monoblock units up to 12 kW in the EU, R290 propane is the natural choice: under the latest F-Gas rules, new units in that class placed on the market from 1 January 2027 must use refrigerants below GWP 150, and R290 (GWP about 3) is the industry's answer — Solimpeks' Varm Boost Series is built on it. R290 also delivers high water temperatures, and its flammability is handled by standard siting clearances.