Aerothermal, underfloor heating and heat pumps: modern comfort

If you are buying new build on the Costa Blanca, the quality specification probably includes terms like 'aerothermal', 'underfloor heating', 'air-to-water heat pump' and 'COP 4.5'. They sound good in the brochure — but what do they really mean? How much do they cost to run? Are they better than traditional air conditioning? This article explains it in human language.

Aerothermal: what it is and how it works

Aerothermal is an air-to-water heat pump system that extracts thermal energy from outdoor air and transfers it inside. It works for heating (winter), cooling (summer) and domestic hot water (year-round). Three systems in one.

COP: the key metric

COP (Coefficient of Performance) indicates how much thermal energy the pump produces per unit of electricity consumed: COP 4 = 4 kWh of heat per 1 kWh of electricity (75 % free energy from air). COP 5 = 80 % free. Comparison: electric heater COP 1 (0 % free), gas boiler COP ~0.9 (fossil fuel dependent), aerothermal COP 3-5 (the most efficient residential heat source available).

Reference brands

Daikin (Altherma), Mitsubishi Electric (Ecodan), Vaillant (aroTHERM), Saunier Duval (GeniaSet), Samsung (EHS).

Underfloor heating: why it is superior

Water-based underfloor heating uses PEX pipes beneath the flooring carrying warm (30-40 °C) or cool (15-18 °C) water. The floor surface becomes a large heat (or cool) emitter, distributing temperature uniformly.

Advantages over radiators

• Uniform distribution: heat rises from the floor, warming the body bottom-up (warm feet, cool head — the opposite of radiators).
• Lower working temperature: 30-40 °C (vs 60-70 °C for radiators), allowing aerothermal to work at maximum efficiency.
• No visible elements: no wall radiators. More usable space.
• Cooling mode: in summer, circulates cool water. Complete invisible heating+cooling.

Disadvantages

• Thermal inertia: takes 1-2 hours to reach temperature. Not ideal for 'switch on and heat in 10 minutes'. Works best as a continuous system.
• Installation cost: more expensive than radiators or splits. In new build, the difference is absorbed. In renovation, it means lifting the floor — expensive and invasive.
• Floor height: adds 8-10 cm to floor level.

Ducted air conditioning vs splits

Ducted

A central unit distributes air through ducts to grilles in each room. Invisible (only grilles visible), uniform temperature, zone control. Mid-to-high standard in new build.

Splits

Individual units per room. Cheaper to install, individual control, fast cooling. Visible wall units, exterior compressor noise. Mid standard.

Pre-installation only

Basic: ducts and wiring prepared, buyer installs equipment. Additional cost: €2 000-4 000 for ducted, €600-1 200 per split.

Operating costs

Estimated annual costs for 80 m² flat in Alicante (2025):

• Aerothermal + underfloor + ducted: €450-850/year (most efficient).
• Gas boiler + splits: €750-1 200/year.
• All electric (heaters + tank + split): €1 050-1 750/year.

Maintenance

• Aerothermal: filter cleaning every 6 months (DIY). Annual professional check: €80-150. Lifespan: 15-20 years.
• Underfloor: virtually maintenance-free. PEX pipe lifespan: 50+ years. Only circuit purging every 2-3 years.
• Air conditioning: filter cleaning every 3-6 months (DIY). Annual check: €60-120. Lifespan: 10-15 years.

Frequently asked questions

Does aerothermal work in Costa Blanca winters?

Perfectly. Winters are mild (5-18 °C). Aerothermal loses efficiency below -5 to -10 °C — temperatures that do not exist on the Alicante coast.

Can I have aerothermal without underfloor heating?

Yes. It can feed low-temperature radiators, fan coils or air ducts. Underfloor is the most efficient combination but not the only one.

Does underfloor heating warm up quickly?

Not as fast as a split or electric heater. Takes 1-2 hours. Works best as a continuous system (keep it on at low power all day). Once at temperature, it maintains with very low consumption.

Can you walk barefoot on underfloor heating?

Yes — one of the best sensations. Floor temperature: 22-24 °C (does not burn, simply pleasant). In cooling mode: 19-20 °C (cool, not cold). Pure comfort.

How much to install aerothermal in an existing home?

For 80-100 m²: aerothermal (equipment + installation): €6 000-12 000. Adding underfloor heating (lift floor, install pipes, new floor): €8 000-15 000 extra. Total: €14 000-27 000. A significant investment — which is why most underfloor installations happen in new build, where the cost is integrated into the construction price.

If you are looking for a home with modern comfort systems, explore our available properties or contact us for a personalised consultation.