Why radiators are a challenge for a heat pump<\/h2>\n
A heat pump is most efficient when it heats water to the lowest possible temperature. Manufacturers describe a flow temperature of around 35 \u00b0C as ideal, and above roughly 45 \u00b0C efficiency drops noticeably while electricity use climbs. That is why heat pumps pair best with underfloor or wall heating.<\/p>\n
Conventional radiators in older homes were sized for oil, gas or wood boilers that heated water to 70 \u00b0C or more. A heat pump can run them, but the water has to be warm enough to cover the house’s heat loss on the coldest days. That temperature decides which unit you need and how much you will pay for electricity.<\/p>\n
A simple test for your home<\/h3>\n
During a cold week, gradually lower the flow temperature on your existing boiler, for example to 55 \u00b0C and then to 50 \u00b0C. If the rooms are still comfortably warm, your radiators are big enough for a standard heat pump. If it gets chilly, note the temperature at which that happened and pass it on to your installer.<\/p>\n
How much a heat pump for radiator heating costs<\/h2>\n
The price depends on the type, output, complexity of installation and extra equipment. The figures below are indicative prices quoted by suppliers on the Slovenian market and include installation, but not new radiators or underfloor heating. Prices elsewhere can differ.<\/p>\n
| System<\/th>\n | Indicative installed price<\/th>\n | Best suited to<\/th>\n<\/tr>\n<\/thead>\n |
|---|---|---|
| Air-to-water, standard (around 8 kW)<\/td>\n | from about \u20ac6,000<\/td>\n | well-insulated houses with large enough radiators<\/td>\n<\/tr>\n |
| Air-to-water, larger or more complex systems and high-temperature units<\/td>\n | from about \u20ac7,000 to \u20ac15,000 and more<\/td>\n | older houses that need 60\u201370 \u00b0C<\/td>\n<\/tr>\n |
| Ground-to-water or water-to-water<\/td>\n | about \u20ac8,000 to \u20ac18,000<\/td>\n | larger houses where boreholes or groundwater are an option<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n With ground-source and groundwater systems, a large share of the cost goes on the borehole, the collector, geological surveys and, for groundwater, a water permit. With air-to-water, the unit itself is the main expense.<\/p>\n What a quote often leaves out<\/h3>\nHigh-temperature or standard heat pump<\/h2>\nHigh-temperature heat pumps heat water to 65\u201380 \u00b0C, so they can replace a boiler without changes to the radiators. Newer models manage this even at outdoor temperatures of around \u201315 \u00b0C. Suppliers quote a coefficient of performance (COP) of about 3 to 4.5, meaning you get 3 to 4.5 kWh of heat from every kilowatt-hour of electricity.<\/p>\n The downsides are a higher purchase price and slightly lower efficiency than low-temperature units. Some cheaper models switch on an electric backup heater in severe frost, which pushes up consumption. If the test shows your house stays warm at 50\u201355 \u00b0C, a standard air-to-water unit is usually the better choice.<\/p>\n In April 2026, Slovenia’s Eco Fund published a new public call with higher grants for investments made from 1 March 2026. When you replace an old heating system, you can receive up to 50% of eligible costs. The cap is \u20ac4,500 for an air-to-water heat pump and \u20ac8,000 for ground-to-water and water-to-water systems. Other countries run their own support schemes.<\/p>\n You apply after the investment is complete, so keep your invoices and other paperwork. The building must be legally built, and the unit must meet the technical requirements of the call, which are worth checking before you sign with an installer. The Eco Fund also offers low-interest loans, and the ENSVET network of energy advisers gives free advice.<\/p>\n Example: if your house needs an air-to-water unit costing \u20ac9,000 installed and all costs are eligible, half is \u20ac4,500, which is also the cap. Your own outlay would be about \u20ac4,500.<\/p>\n The best unit is not necessarily the most expensive one, but the one that is correctly sized for your house. When comparing quotes, look at:<\/p>\n With a good-quality unit and regular servicing, you can expect 15 to 20 years of operation. According to supplier estimates, replacing an old oil or gas boiler cuts annual heating costs by 40\u201360%, but only if the unit and the radiators are properly matched.<\/p>\n Yes, if they are large enough to heat the house with water at around 50\u201355 \u00b0C. If they need 70 \u00b0C, choose a high-temperature unit or replace the undersized radiators.<\/p>\n Installed, roughly from \u20ac6,000 for a smaller, well-insulated house to \u20ac15,000 or more for larger or high-temperature systems, before subsidies.<\/p>\n When replacing old heating, up to 50% of eligible costs, capped at \u20ac4,500 for air-to-water and \u20ac8,000 for ground-to-water or water-to-water, for investments from 1 March 2026.<\/p>\n Most installers recommend one for radiator heating. A rule of thumb is 20\u201325 litres per kilowatt of heat pump output.<\/p>\n |
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