May 01, 2026
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What is the installation cost of a condensing boiler for a 120m2 house in 2025?

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With the rising energy costs and a significant commitment towards more efficient heating solutions, it becomes crucial to choose an option that not only meets a home's heating needs but also helps reduce energy bills. In 2025, installing a condensing boiler represents an attractive alternative for households. To better understand the financial framework of this installation, let's look at prices, the installation process, as well as the impact on the thermal and financial comfort of your home.

Understanding Condensing Boilers

Before exploring the installation cost, it is essential to understand what a condensing boiler is and why it is preferred by many households. These boilers take advantage of the latent heat of combustion gases, allowing for energy efficiency superior to that of conventional boilers. Indeed, they can reduce energy consumption by approximately 10 to 15 % compared to older heating systems. If you are considering replacing your old system, condensing boilers can meet your needs more efficiently.

Benefits of Condensing Boilers

  • Energy efficiency: Their efficiency can exceed 100 % due to heat recovery.

  • Financial savings: With reduced consumption, households see a significant decrease in their heating bills.

  • Environmental respect: They help reduce polluting emissions, a major asset in the context of fighting climate change.

Installation Costs of a Condensing Boiler in 2025

The installation cost of a condensing boiler in a 120 m² home depends on several factors, including the type of boiler, the complexity of the installation, and the choice of professional. Generally, prices range between €2,500 and €8,500, installation included. This includes the removal of the old boiler, compliance updates, and the delivery of the new boiler.

Different Types of Condensing Boilers

Condensing boilers are primarily divided into two categories:

  1. Wall-mounted Boilers: Suitable for medium-sized housing, they are more economical, with prices ranging between €2,500 and €5,000.

  2. Floor-standing Boilers: Perfect for houses, they offer superior capacity with costs ranging from €3,000 to over €6,000.

Details on Installation Costs

Besides equipment costs, several additional fees may apply during installation:

Type of Fee

Cost (with installation)

Connection to natural gas

€300 to €1,000

Removal of an old oil boiler

€350 to €1,000

Electrical compliance

€1,550 to €2,600

How to Choose the Right Boiler?

The choice of a condensing boiler should be based on several criteria to ensure optimal installation and efficient operation. Here are some elements to consider:

Case Study: Installation Example

Magali and Quentin, a couple living in a 120 m² house in Perreux-sur-Marne, opted for the condensing boiler ThémaPlus Condens F 25 GN from Saunier Duval. They were attracted by its low noise and energy efficiency. After analysis, the presented quote included:

Description

Cost Excl. VAT (€)

VAT 5.5 % (€)

Total Cost Incl. VAT (€)

Wall-mounted gas condensing boiler ThémaPlus

1,642

90.64

1,732.64

Horizontal balanced flue kit

46.27

2.55

48.82

Piping modifications

550

30.25

580.25

Labor

616

33.88

649.88

Total Excl. VAT

4,250

233.75

4,483.75

How to Choose the Right Heating Engineer?

It is crucial to hire a qualified professional for the installation of your condensing boiler. Here are some tips to help you choose:

What Long-term Costs to Expect?

Beyond the installation, it is essential to consider regular maintenance fees, which can amount to approximately €150 to €300 per year. Well-maintained condensing boilers have a lifespan of over 20 years, which represents a long-term investment largely compensated by energy savings.

Energy Savings with a Condensing Boiler

  • Annual savings of up to €500 for heating budgets between €1,500 and €2,500.

  • Reduction of carbon footprint thanks to better energy efficiency.

  • Possibility to achieve efficiency exceeding 92 %.

FAQ

What is the average cost of a condensing boiler for a 120 m² house?

Expect to pay between €2,500 and €8,500 for a condensing boiler, installation included.

How long does it take to install a condensing boiler?

The installation can take between 4 and 5 hours for a simple replacement to several days for complex installations.

Am I eligible for assistance for my installation?

In 2024, only the VAT at 5.5 % and the zero-interest eco-loan are possible, other grants having been removed.

What are the disadvantages of condensing boilers?

Initial purchase costs may be higher, as well as maintenance, and they require specific condensate drainage.

What type of condensing boiler is best for me?

The choice will depend on the size of your home, your hot water needs, and the type of ventilation desired.