Boiler types: which one to choose for your home

From traditional boilers to the most efficient ones: a guide to help you find your way around and choose according to your needs.

When it comes to home heating, choosing the boiler is one of the most important decisions for the comfort and Energy consumption of a home. There are several types of boiler available on the market, each with different technical characteristics, efficiency levels and areas of use.

Knowing the differences between the main types of boiler makes it possible to make a more informed choice, assess the most suitable solution for your situation and compare the available options before speaking with a specialised technician.

How many types of boiler are there and how do they work?

Choosing the ideal model depends on the combination of three fundamental aspects that determine how a system works: combustion technology, the fuel used and the installation method. Understanding how these criteria interact is the first step towards making an informed choice.

From a technological point of view, the main distinction is between condensing, hybrid and traditional boilers with an open or sealed chamber. By fuel type, boilers can be divided into natural gas, LPG and diesel models, although natural gas remains the predominant source in Italian homes connected to the grid. In terms of installation, the main difference is between wall-mounted models (more compact and suitable for limited spaces) and floor-standing models (for higher-power systems or larger homes).

Energy efficiency, measured through the Energy class and seasonal efficiency, is the parameter that most affects costs over time and access to tax incentives.

Condensing boiler: the most widespread option

The condensing boiler is currently the most widely installed type in Italy, both in new buildings and as a replacement for older systems. Its operation is based on recovering the heat contained in the exhaust fumes: instead of dispersing it outside, the system uses it to preheat the incoming water, increasing the overall efficiency of the system. This makes it possible to achieve higher efficiency levels, with significantly lower gas consumption than traditional boilers.

From a regulatory point of view, condensing boilers are the only ones compliant with the European standards currently in force for new installations and replacements. They fall within Energy class A or higher, which makes it possible to access tax deductions such as the Ecobonus and the Conto Termico 3.0, managed by the GSE.

The main advantages of this type are:

high efficiency: above 90% under optimal operating conditions;

compatibility with existing systems: it can be integrated with traditional radiators, provided they are correctly adjusted;

access to tax incentives: it falls within the categories eligible for Energy efficiency incentives;

reduced emissions: it consumes less gas for the same amount of heat produced.

Hybrid boiler: when technologies combine

The hybrid boiler represents a transition solution between gas heating and electric heating from renewable sources. The system combines a condensing boiler with a heat pump: the two technologies work in a coordinated way, automatically choosing the most efficient source based on the outdoor temperature, the home's heating needs and the cost of Energy at that time.

The main advantage of the hybrid boiler is its flexibility: when outdoor temperatures are mild, the heat pump covers the heating demand more efficiently; on colder days, the gas component supplements heat production. This dynamic balance results in reduced gas consumption compared with a traditional boiler and lower bills, especially when combined with a Photovoltaic system to power the heat pump.

From a regulatory point of view, the hybrid boiler is one of the solutions permitted by European regulations for the progressive decarbonisation of residential heating, in line with the objectives of the EPBD Directive (Green Homes Directive). It is among the systems eligible for incentives through the Conto Termico 3.0 and the Ecobonus, subject to specific conditions related to the system's Energy class.

The main use cases in which a hybrid boiler is particularly suitable are:

homes with existing radiant heating systems: the heat pump works well at low temperatures, reducing dependence on gas;

homes with a Photovoltaic system: self-generated electricity powers the heat pump, lowering operating costs;

climate zones with variable temperatures: the system automatically selects the most cost-effective source;

Energy efficiency renovation projects: it is one of the recommended options for improving the building's Energy class.

Other types: traditional, wall-mounted and floor-standing

Still found in many older buildings, it works by expelling combustion fumes without recovering their heat. It has efficiency levels of around 80% and does not comply with European standards for new installations. It can continue to operate where it is already installed, but replacing it is generally recommended to reduce consumption and access incentives.

It is mounted on the wall and takes up little space. It is the most widespread solution in medium-sized homes. Available in both condensing and traditional versions, it is suitable for standard systems with outputs of up to approximately 35 kW.

Suitable for large homes or systems requiring high outputs. It takes up more space but provides robust performance and greater mechanical durability. It is often chosen in rural settings or in homes with centralised heating systems.

What to consider before choosing the type of boiler?

Choosing the type of boiler does not depend only on the available technology, but on a combination of practical factors related to the home and consumption habits. Before proceeding with any purchase or replacement, it is useful to assess:

the size and insulation of the building: these determine the required heating output and the most suitable type of system;

the existing distribution system: radiators, radiant panels or fan coils require different flow temperatures, and not all boilers are optimal for every solution;

the available fuel: natural gas, LPG or diesel affect the technological options and operating costs;

frequency of use: a home used all year round requires a boiler sized differently from a second home;

the maintenance condition of the current boiler: periodic boiler servicing is required by law and can help determine whether to continue using the existing system or proceed with a replacement.

A qualified technician can assess the system and recommend the most suitable solution. Choosing a boiler with a high Energy class also makes it possible to access the available tax incentives, reducing the overall cost of the work.

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Frequently Asked Questions

The distinction is mainly related to output and available space. Wall-mounted boilers are compact, are installed on the wall and provide outputs of up to approximately 35 kW, making them suitable for most medium-sized homes. Floor-standing boilers are larger and are suitable for large spaces or systems requiring high outputs. Both installation types are available in condensing versions, which ensure higher efficiency regardless of their position.

Yes, but some preliminary checks are required. A condensing boiler operates optimally when the system flow temperature is below 55–60°C. Many older radiant heating systems operate at higher temperatures: in this case, it is necessary to assess with a technician whether the system can be adjusted or whether the radiators need to be adapted. With underfloor radiant panels, compatibility is generally excellent, as these already operate at low temperatures.

Traditional boilers (non-condensing) cannot be newly installed as replacements for existing systems since 2015, in compliance with European Directive 92/42/EEC as implemented in Italy. Units that are already installed may continue to operate, but they cannot be replaced with models using the same technology: any replacement requires the installation of a condensing boiler or an efficient alternative system. The EPBD Directive (Green Homes Directive) also sets progressive targets for the decarbonisation of buildings, which will guide further regulatory updates in the coming years.

Annual servicing is required by law in Italy (Presidential Decree 74/2013) and includes checking combustion efficiency, verifying the flue gas exhaust system and inspecting the main components. It must be carried out by a qualified technician, who issues an inspection report. Failing to have the boiler serviced may result in penalties and may invalidate the manufacturer's warranty.

Yes, even without a Photovoltaic system, a hybrid boiler can provide savings compared with a condensing-only boiler, thanks to automatic management that selects the most cost-effective source based on external conditions. However, the actual savings depend on the difference between the price of gas and the price of electricity: when gas is expensive compared with electricity, the heat pump operates more and the savings are greater. With a Photovoltaic system, the advantage increases because part of the electricity consumed by the heat pump is self-generated.