When choosing a boiler, it’s essential to understand the differences between the different types available on the market. Two popular options are flue and chimney boilers. Each has its advantages and disadvantages, depending on the specific needs of your home and heating system. In this article, we’ll look at the main differences between these two types of boiler, to help you make an informed choice.

What is a suction boiler?

A vented boiler is a type of boiler that uses a sealed ventilation system to vent combustion gases to the outside. This means it doesn’t need a traditional chimney flue to evacuate the fumes. The venting system draws the air needed for combustion directly from outside the building and discharges the flue gases via rigid or flexible plastic pipes.

Advantages of a suction boiler

• Simplified installation: Since the boiler does not require a traditional chimney flue, installation is often simpler and less costly. This is particularly useful in homes with no existing chimney.
• Suitable for all types of housing: It can be installed in places where there is no chimney, such as apartments or modern houses, as it does not require access to a chimney flue.
• Improved safety: The suction cup system ensures total control of air inlets and outlets, resulting in cleaner, safer combustion.

Disadvantages of a suction boiler

• Requires a specific location: The vented boiler must be installed in a location where it can vent flue gases to the outside, which may limit installation options.
• Regular maintenance: Although maintenance is generally straightforward, the suction pipes can become clogged over time, requiring regular cleaning.

What is a chimney boiler?

Chimney boilers, also known as natural draft boilers, use a chimney flue to discharge combustion gases. The air required for combustion is taken directly from the room where the boiler is installed, and the flue gases are discharged through a vertical or horizontal flue leading to the outside of the building.

Advantages of the chimney boiler

• Proven system: Chimney boilers have been in use for a long time and are a reliable choice for many households. They are suitable for older homes or buildings with a chimney already installed.
• Less noise: Compared to a vented boiler, a chimney boiler is generally quieter, as it doesn’t need motors to draw in air.
• Fewer installation constraints: If you already have a chimney, installing this type of boiler can be relatively straightforward.

Disadvantages of the chimney boiler

• Room air consumption: The chimney boiler uses room air for combustion, which can be a problem in poorly ventilated spaces, where combustion may be less efficient.
• Costly installation: If you don’t have an existing chimney, installing a chimney boiler requires additional work to create a flue. This can increase the initial cost.
• Lower efficiency: Compared to a vented boiler, a chimney boiler can have a lower efficiency, as it relies on a natural draught for gas evacuation, which can make combustion less optimal.

Comparison of the two types of boiler

Installation

• Wall-mounted boiler: Easier to install in houses without chimneys. However, installation requires access to the outside for gas evacuation.
• Chimney boiler: Requires an existing chimney or work to create one. This can make installation more costly and complex.

Energy efficiency

• Top-ventilated boilers: In general, they offer better energy efficiency thanks to their airtight ventilation system and their ability to control combustion.
• Chimney boiler: Less efficient than the vented boiler because of the natural draught, which can make combustion less optimized.

Safety and maintenance

• Wall-mounted boiler: Safer because it exhausts gases outdoors without relying on ambient air. Requires regular maintenance to avoid blockages in the vent pipes.
• Chimney boiler: Less safe if there’s insufficient air in the room, and requires more frequent maintenance to check that the flue is not blocked.

Cost

• Underfloor heating: Less expensive to install, but with regular maintenance costs.
• Chimney boiler: More expensive to install if a chimney is not already present, but maintenance is generally less frequent.

Conclusion: Which boiler to choose?

The choice between a vented boiler and a chimney boiler depends on a number of factors, including your housing type, the presence of an existing chimney and your energy efficiency preferences. If you live in a house without a chimney, a vented boiler will probably be the best option. However, if you already have a chimney and want a tried-and-tested system, a chimney boiler may be an advantageous choice.

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