Aerothermal or gas boiler: What to choose in 2025?

Aerothermal vs Gas Boiler: Which Heating System is Suitable in 2025?

3 minutes of reading

By Mariona Griera

March 31, 2025

In 2025, choosing between aerothermal and gas boiler is crucial for any heating project. Aerothermal stands out for its high efficiency and sustainability, ideal for new constructions. Gas boilers offer lower initial cost and compatibility with existing systems. Evaluate according to your needs and future regulations.

The choice of the right heating system for a home or building is one of the most important decisions in any renovation or new installation. In 2025, two options stand out as the most common among installers and maintenance companies: aerothermal and gas boilers. Both systems have advantages and limitations, so analyzing them in depth is key to making the best decision according to each case.

In this article, we compare aerothermal and gas boiler systems in terms of energy efficiency, installation cost, consumption, maintenance, current regulations, and compatibility with renewable energies. If you are a renovator, installation technician, or maintenance manager, this guide will help you offer the best solution to your clients.

What is aerothermal energy?

Aerothermal energy is a climate control system that harnesses the energy contained in the outside air to produce heating, cooling, and domestic hot water (DHW). It operates through an air-water heat pump that transfers the heat from the air to the system's hydraulic circuit.

Key advantages:

High energy efficiency (COP of up to 4 or higher).
Allows heating, cooling, and DHW in a single system.
Compatible with low-temperature installations: underfloor heating, low-temperature radiators, fan coils.
Renewable energy recognized by the European Directive 2009/28/EC.
Reduction of CO₂ emissions.

Disadvantages:

High initial investment.
Lower performance in very cold climates if not combined with electric resistance or auxiliary support.
Requires outdoor space for the unit.

What is a gas boiler?

The gas boiler is a traditional system for heating and hot water production that operates through the combustion of natural gas or propane. There are condensing models that recover part of the heat from the exhaust gases to improve their efficiency.

Key advantages:

Lower initial cost than aerothermal.
Well-known and widespread system, easy to install and maintain.
Great heat production capacity in a short time.
Compatible with existing conventional radiator systems.

Disadvantages:

Lower energy efficiency than aerothermal.
Greater dependence on fossil fuels.
Not considered a renewable energy.
Emissions of polluting gases.
Its long-term use may be affected by regulatory restrictions.

Technical Comparison: Aerothermal vs Gas Boiler

Feature	Aerothermal	Gas boiler
Type of energy	Renewable	Fossil (natural gas/propane)
Energy efficiency	Very high (COP 3-5)	Medium (efficiency 90-110%)
DHW production	Yes	Yes
Cooling capacity	Yes	No
Installation cost	High	Medium-low
Maintenance cost	Low	Low-medium
Lifespan	15-20 years	10-15 years
Compatibility with radiators	Only with low-temp radiators	Yes, even old radiators
CO₂ emissions	Very low	High
Requires gas	No	Yes
Needs outdoor space	Yes	No
Available subsidies	Yes (Next Generation, IDAE, etc.)	Less frequent

What does the regulation say in 2025?

In 2025, the European and Spanish regulatory framework continues to clearly favor heating systems based on renewable energies. The aid from the Next Generation program, the National Integrated Energy and Climate Plan (PNIEC), and other regional subsidy lines promote the implementation of heat pumps as a sustainable solution compared to conventional systems based on fossil fuels.

Furthermore, it is expected that the energy efficiency requirements for buildings (according to the CTE and REBT) will progressively increase. This directly impacts the type of installations viable in the long term for new construction and renovation.

Which system suits you according to the type of project?

✅ Comprehensive renovation or new construction housing

Recommendation: Aerothermal

Greater efficiency.
Ideal for combining with underfloor heating or low-temperature radiators.
Guaranteed medium/long-term savings.
Possibility of cooling in summer.

✅ Partial renovation with radiator system already installed

Recommendation: Condensing gas boiler

Lower initial investment.
Simpler installation if the gas network already exists.
Compatible with conventional radiators without modifications.

✅ Project focused on energy sustainability

Recommendation: Aerothermal + solar panels

Possibility of self-consumption and high efficiency.
Reduction of carbon footprint.
Compatible with subsidies and public aid.

Aerothermal or gas boiler, which one to choose?

There is no one-size-fits-all solution. The choice between aerothermal and gas boiler should be based on the type of installation, the available budget, the climatic conditions of the environment, and the medium- and long-term vision of the project.

If you are looking for a more efficient, renewable system aligned with future regulations, aerothermal energy is clearly the option to consider in 2025. On the other hand, if you need a simple, economical installation compatible with existing radiators, the gas boiler may still be a valid solution in certain contexts.

At GroupSumi we offer you heating solutions for both systems, with a wide catalog of leading manufacturers such as Baxi, Ferroli, Saunier Duval, Domusa, Bosch, Daikin, or Mitsubishi Electric, so you can choose the most suitable equipment for each project.

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