Which homes and apartments suit a 6 kW heat pump?
A 6 kW air source heat pump is designed for small homes, apartments and well-insulated residential units up to roughly 80 m². In practice, a well-insulated newer apartment of 75 to 80 m² with underfloor heating is an ideal match, while a moderately insulated older house of 60 to 70 m² with radiators may also fit within the capacity if flow temperatures stay below 55 °C. The decisive factors are insulation quality, ceiling height, window area and which emitter system is installed. Correct sizing depends on a heat-loss calculation specific to the property, which is exactly what CENTRO-GAS provides through its free sizing consultation. Apartment heat pump installations require attention to outdoor unit placement and noise regulations, and the unit's compact dimensions and low sound output help in that regard.
Why R290 as a refrigerant?
R290 (propane) has a global warming potential (GWP) of only 3, compared to 675 for R32 and 2,088 for R410A. This matters because the EU F-Gas Regulation is phasing down high-GWP refrigerants, and R290 is already compliant with the strictest future requirements. Beyond the environmental benefit, R290's high critical temperature of 96.7 °C means the compressor can produce flow temperatures up to 65 to 75 °C without excessive strain, making the unit compatible with existing radiator systems that need higher supply water temperatures. The R290 propane heat pump also delivers higher seasonal efficiency at part-load conditions compared to equivalent R32 systems, which is why EXINDA chose it across their residential range.
How does it perform at very low outdoor temperatures?
EXINDA tests its residential heat pump range in climate chambers down to -35 °C and certifies stable operation at outdoor temperatures as low as -25 °C. At the standard test point of A7/W35 (7 °C outdoor, 35 °C water), the 6 kW unit delivers its nominal output. At -7 °C outdoor temperature, heating capacity reduces to approximately 4.4 kW, and at -15 °C to approximately 3.3 kW. For the coldest nights in Vojvodina (typically -15 °C to -20 °C in extreme events) and mountain areas of southern Serbia, a hybrid configuration with a backup boiler is a legitimate design option, and CENTRO-GAS has the industrial heating background to engineer both sides of that system.
What is a full DC inverter and why does it matter?
A DC inverter compressor adjusts its speed continuously rather than cycling between on and off at full power. The practical result: the unit runs at 30 to 50 % of nominal load for 60 to 80 % of a typical heating season, and it is precisely at these part-load conditions that seasonal efficiency peaks. A fixed-speed compressor would deliver its rated COP only at full load and waste energy by cycling at every other point. The inverter also reduces start-up current (important for older electrical installations in apartments and small houses) and lowers operational noise, since the fan and compressor run more slowly during mild weather.
Ideal buyer profile for the 6 kW unit
This model fits a specific scenario: a small family house of 60 to 80 m² or a large apartment with individual heating, replacing a gas or electric boiler that is 10 to 15 years old or older. The property has either underfloor heating (ideal) or reasonably sized radiators. A domestic hot water tank of 100 to 200 litres can be connected for sanitary hot water. The owner wants significantly lower heating bills, supported by the fact that heat pumps deliver roughly 3 to 4 times more heat energy than the electricity they consume. A single-phase 230 V supply is already present. If the owner plans solar panels later, the heat pump integrates with photovoltaic systems to reduce operating costs further.
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