Vaillant connection kit for separate air supply 80/125 mm

Product detailed description

Vaillant connection kit for separate air supply 80/125 mm

This Vaillant connection kit allows you to convert the standard concentric flue system of the ecoTEC plus condensing boiler with a diameter of Ø 60/100 mm to a variant with separated (split) combustion air supply and flue gas exhaust with a diameter of Ø 80/125 mm. This split configuration is used mainly in situations where it is not possible or advantageous to use a standard concentric flue system – for example when connecting to an existing masonry chimney, when the air supply and flue gas exhaust need to be routed via different paths through the building structure, or when there is a greater distance between the boiler and the outlet point, where a split system offers greater routing flexibility.

Difference between concentric and split flue systems

In a concentric (coaxial) system, the combustion air supply and flue gas exhaust are routed through a single shared pipe, where the inner pipe carries away the hot flue gases and the outer sleeve supplies fresh combustion air – this solution is simple to install and is generally sufficient for most standard installations with a short route to the facade or roof. A split system, on the other hand, routes the air supply and flue gas exhaust through two separate pipes, allowing independent routing – for example, the air supply can be routed via a short path through the facade, while the flue gas exhaust is connected to an existing chimney routed through the roof, or vice versa. This flexibility is the main reason why the split system is chosen especially for more complex or non-standard building layouts.

When is the 80/125 mm split system a suitable choice

The split system is particularly suitable for renovations of older buildings with an existing functional chimney flue that can be used for flue gas exhaust, while the air supply is solved separately via the shortest possible route; for buildings where the layout of the boiler room does not allow a direct short concentric pipe run to the facade or roof; or when there is a need to cover a greater distance between the boiler and the outlet point, where a split system of the same diameter generally offers lower pressure resistance than a concentric solution over the same distance.

Technical parameters and installation

The kit includes the necessary transition and connection components for connecting the ecoTEC plus boiler (standardly equipped for the 60/100 mm concentric flue system) to a split system with a diameter of 80/125 mm, including an adapter that splits the boiler's original common outlet into two separate circuits. Installation of this type of conversion requires professional assessment of the routing of both pipes (air supply and flue gas exhaust), including calculation of the maximum permissible route length and number of elbows according to the manufacturer's installation instructions, since a longer or more complex route increases pressure resistance and may require different boiler settings or additional components.

Compatibility

This connection kit is intended for Vaillant ecoTEC plus boilers, which are prepared from the basic configuration for a 60/100 mm concentric flue system. Before ordering, it is essential to verify the exact boiler model and the planned flue routing, so that a service technician can assess whether this specific split configuration with a diameter of 80/125 mm is suitable and sufficiently sized for your case, given the length and number of elbows in the planned route.

Installation must be performed by a professional

Installation and conversion of the boiler's flue system, including this connection kit, may, in accordance with applicable legislation, be carried out exclusively by a professionally qualified person authorized to install gas appliances and their chimney/flue systems. Proper installation also includes checking the tightness of the entire flue system, the correct slope (for draining any condensate from the flue gas exhaust pipe), and compliance with prescribed distances from combustible materials and window or ventilation openings at the outlet point.

Why choose an original connection kit

The flue gas exhaust system is a safety-critical part of a gas appliance installation – an incorrectly sized or leaking flue system could lead to flue gas leakage into living spaces, which represents a serious health risk. An original Vaillant connection kit guarantees that all system components (boiler, transition pieces, piping) are mutually certified and tested as a functional, safe unit, which cannot always be clearly guaranteed when combining components from different manufacturers.

Maintenance

As part of the boiler's regular annual service inspection, the condition and tightness of the entire flue system, including this connection kit, should also be checked – the service technician should check the mechanical integrity of the piping, the tightness of the joints, and the patency of both circuits (air supply and flue gas exhaust), since any blockage or leak could negatively affect both safety and combustion efficiency.

Frequently asked questions

Broader context – flue flexibility during renovations

In renovations of older buildings, where the original boiler (often atmospheric, with natural chimney draft) is being replaced by a modern condensing boiler, the question of the flue method is one of the key technical challenges of the project. An existing chimney flue originally sized for an atmospheric boiler may not, without modifications, be suitable for direct flue gas exhaust from a condensing boiler (for example, due to a different temperature and humidity regime of the flue gases), but it can often be used precisely in combination with a split system, where the chimney serves only for flue gas exhaust via a suitably sized liner, while the air supply is solved separately via the facade. This connection kit is precisely the tool that allows such a solution to be implemented with certified, mutually compatible components.

When considering this split configuration, we always recommend first having the condition and suitability of the existing chimney assessed by a professional (for example, via a chimney sweep inspection), since not every older chimney flue is, without further modifications, suitable for operation with a condensing boiler – in such a case it may also be necessary to add a suitable chimney liner or other structural modifications beyond the connection kit itself.

Effect of pipe length and routing on boiler performance

For every flue system, both concentric and split, the length of the route and the number of directional changes (elbows) affect the pressure resistance that the boiler's fan must overcome when exhausting flue gases and drawing in combustion air. The manufacturer therefore specifies, for each type and diameter of pipe, a maximum permissible route length, which is generally reduced with each added elbow (for example, one 90° elbow can equivalently "shorten" the permissible length of a straight section by several meters). A split system with a diameter of 80/125 mm generally has lower pressure resistance for the same route length than the smaller 60/100 mm concentric system, which is precisely why it is chosen for longer or more complex routes – however, strict compliance with the limits set by the manufacturer is essential regardless of the chosen system type, in order to maintain the declared efficiency and combustion safety.

Condensate drainage from the flue gas exhaust pipe

Condensing boilers produce acidic condensate during operation, which partly forms directly in the flue gas exhaust pipe as well, especially with longer routes led through cooler parts of the building. For this reason, when installing a split system, it is essential to maintain the prescribed slope of the flue gas exhaust pipe back towards the boiler (where the condensate is drained through the boiler's built-in siphon into the sewage system), so that condensate does not accumulate in low points of the pipe outside the boiler, which could over time lead to pipe corrosion or partial restriction of its patency.

Aesthetic and structural considerations when choosing the route

In addition to purely technical parameters (length, number of elbows, pressure resistance), it is also advisable to consider aesthetic and structural aspects when designing the route of a split system – visible piping routed along the facade can affect the appearance of the building, so for new buildings or larger renovations, routing within installation shafts or hidden spaces is often preferred, if the building layout allows it. For historic or heritage-protected buildings, the choice of route may be additionally limited by requirements to preserve the original appearance of the facade, which is another typical reason why a split system using an existing, already approved chimney flue is chosen in such cases.

Frequently asked questions – additional

Summary

This connection kit for split air supply and flue gas exhaust 80/125 mm is a flexible solution for installations where a standard 60/100 mm concentric flue system is not the most suitable choice for layout, structural, or aesthetic reasons. Given the safety-critical nature of the flue gas exhaust system, we always recommend entrusting both the route design and the installation itself to a professionally qualified person who will take into account all relevant technical limits as well as the local specifics of your building.

Consultation before ordering

Since the choice between a concentric and split flue system, as well as the precise sizing of the route for a split system, depends on many factors specific to a particular building (layout of the boiler room, existence and condition of the chimney, distance to a suitable outlet point, possible heritage protection restrictions), we recommend not ordering this connection kit without prior consultation with an installation company or our technical team. Based on the floor plan of your building and information about the existing or planned location of the boiler, we can help assess whether the 80/125 mm split system is truly the most suitable solution for your case, or whether a simpler and generally cheaper standard concentric flue system will suffice.

For projects connecting to an existing chimney, we also recommend providing, as part of the consultation, information about the condition and diameter of the existing chimney flue, or the result of a chimney sweep inspection if one has already been carried out – this documentation will greatly facilitate the precise design of the entire flue solution before the actual order and installation.

Summary of the advantages of the split solution for more demanding installations

In summary, while the standard 60/100 mm concentric flue system is sufficient for most common installations, for those more complex cases – renovations with an existing chimney, non-standard layouts, longer routes, or aesthetic restrictions – this connection kit with a split system of 80/125 mm represents a practical, manufacturer-certified solution that expands the possibilities for installing the ecoTEC plus boiler even where a standard solution would not be flexible enough. Investing in this kit is therefore particularly worthwhile for projects where, without it, the installation would be more complicated or even impossible in the originally intended form.

Feel free to contact us with the details of your project – we will be happy to help you assess the most suitable flue method for your specific boiler and building, including a recommendation as to whether this split kit of 80/125 mm is the right solution, or whether there is a simpler and more cost-effective alternative that meets your needs. This consultation is free of charge and will help you avoid unnecessary costs and complications during the actual implementation of your specific heating project.

Assessment from the perspective of total project costs

When comparing costs between a standard concentric flue system and this split connection kit, it is advisable to consider not only the acquisition price of the components themselves, but also the total implementation costs, including any structural modifications (for example, breaking through the roof or facade structure, modification or inspection of an existing chimney). In many cases, especially in renovations with an available functional chimney, a split solution using the existing chimney flue may be more advantageous in terms of total project costs than building an entirely new roof penetration for a concentric system, despite the higher price of the connection kit itself compared to a standard concentric solution.