In Uniclima Solutions we have been for more than 15 years installing and maintaining air conditioning systems in Madrid. In this guide, we will explain to you, with clear and non-technical languageHow does an aerothermal system actually work, how does it differ from a conventional boiler, how much can it save you per month on your electricity and gas bill, what components are involved in a domestic installation, and what should you consider before hiring it?
We will also see the actual efficiencies (COP and SPF), the current subsidies in 2026common faults that reduce efficiency and when it is worthwhile (or not) to replace your current system with an aerothermal heat pump. If after reading the guide you still have specific questions about your home, at the end you will find how to request a personalized study from us.
What exactly is aerothermal energy?
Aerothermal is a climate control system based on an air-to-water heat pump. that extracts thermal energy from the outside air and transfers it to the heating, cooling, and domestic hot water (DHW) circuit of the home. It does so without combustion: it does not burn gas, oil, or biomass.
According to Directive 2009/28/EC of the European Union, Aerothermal energy is officially a renewable energy source. when the Seasonal Performance Factor (SPF) exceeds 2.5. Modern aerothermal heat pumps comfortably surpass this threshold.
How does it work step by step?
Quick response: The system uses a refrigerant circuit that continuously evaporates, compresses, condenses, and expands, capturing heat from the outside air and delivering it indoors.
- Collection. A fan passes the outside air through a evaporator, where a refrigerant at a very low temperature absorbs heat from the air and evaporates.
- Compression. An electric compressor raises the pressure of the refrigerant gas and, with it, its temperature to 60–80 °C.
- Condensation. The hot refrigerant transfers its energy to the water in the internal circuit (underfloor heating, fan coils, or low-temperature radiators) in a capacitor and returns to a liquid state.
- Expansion. A valve sharply reduces the pressure of the liquid, cooling it again, and the cycle starts over.
Parts of an aerothermal installation
A typical domestic installation is composed of five clearly differentiated elements:
- Outdoor unit (heat pump): It contains the compressor, the evaporator, and the fan. It is placed on the facade, patio, or roof.
- Indoor unit (hydrobox): manages the exchange to the water circuit and usually integrates the pump group and the expansion vessel.
- DHW tank: Hot water storage tank (usually 150–300 L) to cover peak consumption in shower, kitchen, and bathrooms.
- Distribution system: Underfloor heating-cooling (the most efficient), fan coils or low-temperature radiators.
- Smart control: Thermostat/mobile app that automatically adjusts setpoint, scheduling, and eco modes.
Real advantages over a gas boiler
These are the fundamental differences between an aerothermal heat pump and a natural gas condensing boiler:
| Criterion | Aerothermal | Gas boiler |
|---|---|---|
| Efficiency (COP / η) | 3 – 4 (300–400 %) | 0,95 – 1,08 (95–108 %) |
| Energy source | Outdoor air + electricity | Natural gas (fossil) |
| CO₂ emissions | Almost zero with renewable energy | ~200 g CO₂/kWh |
| Cold in summer | Yes (same equipment) | No |
| Legal maintenance | Inspection every 4 years | Annual inspection + 4 years |
| Average lifespan | 18 – 25 years | 12 – 18 years |
| 2026 subsidies | MOVES Plan / Next Gen until 50 % | Very limited, becoming extinct |
Why is aerothermal energy a sustainable option?
- Renewable energy recognized by the EU. At least 75% of the energy it delivers comes from the air — an inexhaustible and local source.
- Zero combustion on site. No burner, no chimney, no risk of leaks or fumes.
- Decreasing carbon footprint. As the Spanish electricity mix incorporates more renewables, aerothermal energy becomes even cleaner without changing anything at home.
- Compatible with photovoltaic self-consumption. If you have solar panels, aerothermal systems utilize the surplus for DHW and air conditioning.
- New generation refrigerants (R32, R290). Lower Global Warming Potential (GWP) compared to older gases like R410A.
How much can be saved with an aerothermal system?
Quick response: in a typical 100 m² home in Madrid, the average savings compared to a gas boiler range between 500 € and 900 € per year in the combined energy bill (heating + DHW + cooling).
The figure depends on four main factors:
- Home insulation — A modern thermal envelope multiplies savings.
- Emission system — Underfloor heating increases the actual COP compared to radiators.
- Electricity tariff — with time-of-use tariffs, the savings improve significantly.
- Usage habits — programming and realistic temperatures (20–22 °C in winter).
Installation: 5 keys for success
- Hire a certified company. You must have installers with RITE certification and F-Gas certification. Uniclima Solutions we deliver both in writing.
- Request a real sizing, not a "one-size-fits-all". A thermal load study according to the UNE-EN 12831 standard prevents oversizing (expensive) or undersizing (doesn't heat).
- Choose the location of the outdoor unit carefully. Ventilated, unobstructed, and maintaining distances from windows and neighbours. Noise accounts for 95% of poorly resolved complaints.
- Integrate smart control from day one. Thermostat with external sensors and compensation curve: the actual performance depends on it.
- Requires documented commissioning. Pressures, flow rates, factory settings, and first annual inspection included by contract.
Maintenance and lifespan
Does aerothermal energy need low maintenance, but the one required is critical:
- Professional inspection every 4 years mandatory by the RITE (IT.3.3) for equipment over 12 kW.
- Annual cleaning of the evaporator and the filters (the user can handle the filters).
- Hydraulic circuit control: pressure of the primary circuit, expansion vessel, and safety valves.
- Refrigerant tightness: inspection according to F-Gas regulation based on the charge.
Frequently Asked Questions about Aerothermal Systems
Tell us about your home and a technician will prepare a fixed quote in 48 h: sizing, recommended brand, installation and processing of subsidies. No subcontractors, no small print.
- ✓ 15 years installing air conditioning in Madrid
- ✓ Official factory warranty + 2 years of installation
- ✓ We process MOVES and Next Generation grants for you