Buying guide for a gas boiler: advice, quotes and prices


Gas is an interesting energy, especially when you are connected to town gas, or natural gas. Less polluting than fuel oil and less expensive than electricity, it combines performance and energy savings.

However, if this type of device has many advantages, there are so many models that finding your way around and making the right choice is not always easy. Our experts will guide you through your purchase, provide you with advice and provide you with information on prices for your convenience!

What are the characteristics of a gas boiler?

The main feature of the gas boiler is that it is an economical heating system. To suit all needs, it is available in several types, hanging systems and dimensions. It is dimensioned in particular according to the area to be heated within the home and the condensing models are the most interesting in economic and ecological terms when it comes to heating large homes.

The gas boiler can be used only for heating the house, or it can also produce domestic hot water, or DHW. In this case, it is said to be mixed or double service. The evacuation of fumes is possible thanks to three means: the suction cup system, the so-called natural draft and the VMC.

The fuel should also be chosen, since a gas boiler can use both city or natural gas as well as propane gas. However, the options differ between the two modes. In addition, to benefit from a good level of heating, the useful power must be 20% greater than the heat losses in your home.

When and why should you change your gas boiler?

Even if its lifespan is longer, a boiler of more than 15 years can be replaced by a more efficient model to achieve energy savings – and therefore financial – and to gain in safety and comfort.

In addition, state aid can make this type of purchase particularly interesting in financial terms, since energy renovation is one of the government’s priorities.

How does a gas boiler work?

The gas boiler is equipped with a burner which heats the water it contains to 40 ° or 90 ° depending on the model. This is then distributed within the home, through a heating network divided into supply pipes, to hot water radiators or underfloor heating. There are two types of gas boilers: the low temperature system and the condensing model, whose efficiency is higher.

Choosing the right gas boiler: which model to choose?

There are three types of gas boilers: low temperature models, condensing models and mixed models.

The low temperature gas boiler

This model heats the water up to 40 °. It is more economical to purchase and allows savings of nearly 20% compared to a conventional boiler model. However, its efficiency remains lower than the condensing boiler.

The low temperature gas boiler can be flue or chimney for venting.

  • The suction cup system has the advantage of avoiding the installation of a chimney flue and therefore sometimes important work. It has two circuits, one for the intake of air from outside and the other for evacuating fumes. Its tightness allows it to be installed in a closed room without danger.
  • The chimney system, on the other hand, draws the air it needs from the room where the boiler is located, which does not make it airtight and limits, or even forbids, its use in a closed room. The smoke evacuation is possible thanks to a cased chimney pipe.

The low-temperature boiler is suitable for: housing that is not very spacious, well insulated, and for those who do not want to invest in an expensive boiler model.

The condensing gas boiler

This model works by heating the water to a temperature of around 90 °, for an interesting efficiency greater than 105%. This system operates on latent energy, in other words the energy produced by the condensation of the fumes emitted and containing water vapor.

This device is more expensive to buy, but it is more economical to use since by consuming less gas, it allows savings of up to 30% compared to a conventional model, and up to 10% with respect to a device at low temperature.

It does not require a conduit and works by means of two circuits in suction cup. It draws the necessary air from the outside and evacuates the fumes through another circuit.

The condensing boiler is suitable for: those who have high heating and domestic hot water needs, those who are willing to spend more on the purchase to achieve more savings later, those who wish to benefit from the tax credit and those who can connect the boiler to wastewater.

The mixed or double service boiler

This device produces domestic hot water, or DHW, in addition to the production of heat for heating the house.

There are three types of hot water production: the storage system, the micro-storage system and the instantaneous system.

  • The storage boiler : the hot water produced is stored in a tank whose dimensions are chosen according to needs. Bulky, it is also more comfortable.
  • The micro-accumulation boiler : only 3 to 5 liters of hot water are stored in the tank. This reserve allows hot water to be quickly available while a larger volume does not heat up.
  • Instant boiler : this compact model is ideal for small hot water needs, but it is not recommended for houses with several bathrooms and large families.

Choosing the right gas boiler: a wall or floor model?

The wall-mounted gas boiler

This is fixed on one of the walls of the house. Thanks to its small footprint, it is ideal for small homes. However, it is not enough to cover the heating and hot water needs of a large family and its lifespan is shorter than a floor model.

The wall-mounted boiler suitable for those on a budget and small accommodation.

Floor standing gas boiler

This larger model needs space and is therefore recommended in large homes that have a dedicated space. In addition, its large hot water tank can quickly meet the needs of a large family. On the other hand, it is more expensive to install than its mural cousin.

The floor-standing boiler suitable for those who have the ability to spend more, those with large housing and those with significant heating and hot water needs.

What price for a gas boiler?

A gas boiler can be more economical and advantageous to purchase than its electric, fuel oil, hybrid and wood equivalents. Count in fact an average of 500 euros to 8,000 euros for a gas model, against 1,000 euros to 4,000 euros for an electric boiler, 1,700 euros to 10,000 euros for an oil-fired appliance and 5,000 euros to 20,000 euros. euros for a wood-fired boiler.

For the installation of a gas boiler by a professional service provider, count between 500 euros and 1,500 euros. The price may vary depending on the model chosen, the context and the installation facilities, the prices charged by the service provider and the geographical area.

How to benefit from state aid to equip yourself with a gas boiler?

Only high-performance and quality boilers can allow you to benefit from financial aid from the State. A low-cost model will not allow you to do this. In addition, the device must be installed by a qualified craftsman RGE (Recognized guarantors of the environment) and a certificate must be issued to you.