How Heat Pumps Actually Work in Polish Homes

The basic principle

A heat pump moves thermal energy rather than generating it. It takes heat from one source — outdoor air, ground, or groundwater — and transfers it into the building's heating circuit. The process uses electricity to drive a compressor, but the ratio of heat output to electrical input is typically 2.5:1 to 4:1 under real conditions, meaning the unit delivers more energy than it consumes directly.

That ratio is expressed as the Coefficient of Performance (COP). A COP of 3.0 means that for every kilowatt of electricity drawn, three kilowatts of heat are delivered to the building. The figure is not constant — it drops as outdoor temperatures fall, which is the central challenge for heat pumps in Polish conditions.

A COP of 3.0 means three kilowatts of delivered heat per kilowatt of electricity consumed. The figure shifts significantly with outdoor temperature.

Air-to-water heat pumps

The most widely installed type in Poland extracts heat from outdoor air and transfers it to a water-based heating circuit. At +7°C outdoor temperature — the benchmark used in EU certification — these units achieve COP values of 3.0 to 4.5 depending on the model and flow temperature of the heating circuit.

The difficulty arises in January and February, when Warsaw averages around −2°C and temperatures in the northeast (Podlaskie, Warmia-Mazury) can remain below −10°C for extended periods. At −10°C, a typical air-source unit rated A7/W35 drops to a COP of 1.8–2.5. At −15°C, many systems switch partially to an electric backup element, increasing operating costs significantly.

Manufacturers including Mitsubishi Electric, Daikin, and Viessmann publish tested performance curves down to −25°C for their cold-climate models. These figures are worth checking before selecting a unit for a location with harsh winters.

Sizing and flow temperature

An air-to-water pump is typically sized to cover around 80–90% of annual heating demand, with an electric or gas backup handling peak winter loads. Oversizing is a common installation error: a heat pump cycling on and off frequently at partial load is inefficient and accumulates wear faster than one running at sustained output.

Flow temperature matters considerably. A radiator circuit designed for 70°C requires the pump to work at low efficiency. Lowering the circuit to 45°C — feasible with modern low-temperature radiators or underfloor systems — raises COP by roughly 20–30% on a typical unit.

Outdoor unit of an air-source heat pump mounted on a building

Outdoor unit of an air-to-water heat pump. Correct placement affects noise, airflow, and winter performance. Photo: Wikimedia Commons / CC BY 2.0

Ground-source heat pumps

A ground-source (geothermal) unit draws heat from the earth, either via horizontal ground loops buried 1.0–1.5 metres deep or via vertical boreholes reaching 80–150 metres. Ground temperature at that depth remains stable at 8–12°C throughout the year in most of Poland, which means COP values stay higher in winter compared to air-source alternatives.

Typical seasonal COP (expressed as SCOP or SPF) for a ground-source system in Poland runs 3.5–4.8, compared to 2.8–3.8 for a well-configured air-source unit in the same location. The trade-off is installation cost: boreholes require specialised drilling equipment and significantly increase the upfront expense, often by 30–60% compared to an equivalent air-source installation.

Horizontal collectors

Where plot size permits, horizontal collectors offer a lower-cost ground-source option. The collector area must be large — typically 1.5–2.5 times the heated floor area — and cannot be built over or planted with deep-rooted trees. In dense suburban areas, this often rules out the approach entirely.

Regulatory context in Poland

The Czyste Powietrze (Clean Air) programme, administered by the National Fund for Environmental Protection and Water Management, subsidises heat pump installation for private homeowners. Subsidy levels have changed several times since the programme's 2018 launch; current terms are published at czystepowietrze.gov.pl.

Buildings constructed or substantially renovated after 2021 must comply with the WT 2021 technical conditions, which set maximum primary energy consumption figures that make correctly sized heat pumps effectively mandatory in new construction meeting the EP<70 kWh/m²/year target.

What the installation involves

A typical residential air-to-water installation covers: outdoor unit placement (on a wall bracket, roof, or ground slab away from bedrooms and neighbours), refrigerant pipework to the indoor hydraulic module, a buffer tank or hydraulic separator, domestic hot water cylinder, controls, and integration with the existing heating distribution system.

Installation time is generally two to four days for a straightforward air-source job, longer if the existing heating system requires significant modification. Ground-source installations with boreholes typically add two to five days for the drilling phase.

How Heat Pumps Actually Workin Polish Homes