Vaillant Flue Extension 0.5 m, Ø 160 mm

Product detailed description

Flue Extension 0.5 m Ø 160 mm – the shortest straight-section module

Flue extensions are straight sections of pipe used within a cascade flue assembly to bridge the distances between individual fittings (elbows, collecting pieces, the vertical riser) exactly according to the actual dimensions of a specific boiler room. The 0.5 m version is the shortest module available (alongside the 1.0 m and 2.0 m lengths) and is used mainly for fine-tuning the total route length or for bridging short distances where a longer piece would otherwise have to be unnecessarily cut to size on site during installation.

By combining several lengths (0.5 m, 1.0 m, 2.0 m), it is possible in practice to assemble almost any required length of a straight section of the route without having to cut the pipe to size on site – saving installation time and reducing the risk of leaks at improvised cut points.

Flue gas discharge systems for Vaillant cascade boiler rooms

When a single condensing boiler is not enough to cover the heat demand of a building – an apartment building, hotel, industrial hall, office building or a larger technological boiler room – this is usually solved not with one large boiler, but with a cascade of several smaller or medium-output Vaillant condensing boilers connected in parallel. The advantage of a cascade solution is higher operational reliability (a failure of one boiler does not mean a heating outage for the whole building), better output regulation according to current demand (the number of running boilers and the output of each can be modulated), and easier future expansion of the boiler room with an additional boiler if heat demand increases.

Each boiler in a cascade has its own flue gas outlet and combustion air intake socket, but for practical, economic and structural reasons the flue gases of all the boilers are usually discharged through one common collecting flue (manifold) into a single chimney or through a single roof/facade penetration. This is exactly the purpose of the range of components described below – these are parts of a separate (non-concentric) flue gas discharge system with a diameter of 160 mm or 200 mm, which connects to the sockets of the individual boilers and joins them into one common pipe.

The system is modular – it consists of basic connection sets (for the first two boilers in the cascade, including the fittings needed for condensate drainage), extension sets (for each additional boiler added to the cascade), individual elbows of various angles for bypassing obstacles and changing the direction of the route, extensions of various lengths for bridging the distance between the boilers and the vertical riser, and finally a set for connecting the whole assembly to a masonry chimney shaft.

Use within the assembly

The short, 0.5-metre extension is most commonly used right at the boiler outlet socket (where the distance to the first elbow is usually short), between two elbows when bypassing an obstacle, or as an additional piece for fine-tuning the total route length so that the last section (for example an inspection piece or the connection to the riser) ends up exactly at the planned position.

The part is fully compatible with the other components of the Ø 160 mm range and connects using the same socket joint with a sealing ring.

Material and construction – why polypropylene (PP)

All parts in this range are made of polypropylene (PP) – a plastic used in condensing boiler flue gas discharge systems precisely because it perfectly resists the chemically aggressive condensate that naturally forms during the operation of condensing technology. A condensing boiler, unlike a conventional (non-condensing) boiler, also makes use of the latent heat contained in the water vapour of the flue gases – this vapour is cooled below the dew point in the flue gas heat exchanger and condenses, producing condensate that is slightly acidic (pH approximately 3–5, depending on the fuel type and operating conditions). Metal (e.g. stainless steel) flues can also withstand this load, but plastic PP systems are lighter to handle, faster to install thanks to sealing-ring joints that require no welding or special tools, and, at comparable quality, are usually also more cost-effective.

The flue gas operating temperature in condensing boilers is relatively low (typically up to around 80–120 °C, depending on the operating mode and boiler output) – which is precisely why using plastic PP piping instead of a conventional metal flue (common, for example, with older atmospheric or low-temperature boilers) is not only possible, but also more suitable in terms of resistance to condensate. The system is certified and dimensioned by the manufacturer specifically for use with Vaillant condensing boilers of the corresponding output range and socket designation.

The individual parts are joined by socket insertion with a rubber sealing ring (a so-called socket joint) – this design allows for simple, tight yet demountable installation without gluing or welding, which greatly simplifies any future adjustments to the route, replacement of a damaged part, or expansion of the cascade with another boiler.

Practical example

When installing a cascade of two boilers in a row, the distance between the outlet socket of the first boiler and the nearest elbow is usually around 40–45 cm – instead of cutting a longer extension to size on site (with the risk of an imprecise cut and the need for additional edge finishing), a ready-made 0.5-metre extension is simply used, which precisely bridges this distance while maintaining full tightness of the socket joint at both ends.

Comparison of available Ø 160 mm extension lengths

Vaillant offers extensions in three lengths – 0.5 m, 1.0 m and 2.0 m – which can be freely combined so that the resulting route exactly matches the actual dimensions of a specific boiler room without having to cut the pipe to size on site. The shorter, 0.5-metre piece is best suited precisely for making up the "remainder" of the length after assembling the main route from longer modules (1.0 m or 2.0 m) – it thus functions as an additional, fine-tuning part.

Ordering: When calculating the material needed for the entire route, we recommend first assembling the main length from the longer modules (2.0 m, or 1.0 m) and only then filling in the remaining, shorter distance with this 0.5-metre piece – this minimises both the number of joints and the total amount of material used.

Assembly and installation

The installation of a flue gas discharge system for gas appliances (including cascade boiler rooms) in Slovakia is subject to the requirements of the standards STN EN 1443 (Chimneys), STN 73 4201 (Chimneys and flues) and related gas industry technical rules (TPP), and must be carried out by an authorised and professionally qualified person – an authorised service technician or an installation company with the relevant authorisation to install gas appliances and their flue gas discharge systems. Commissioning the boiler room also includes an inspection of the chimney/flue carried out by a chimney sweep company, with the issuance of the relevant inspection report.

When designing the route of a cascade flue, the following must be taken into account in particular: the total rated heat output of all the boilers in the cascade (this determines the required diameter of the collecting pipe – 160 mm or 200 mm), the maximum permissible route length and number of elbows (the manufacturer specifies equivalent lengths for individual fittings), the slope of horizontal sections back towards the boiler or the condensate separator (typically at least 3° so that condensate can drain by gravity and does not remain standing in the pipe), sufficient securing of the pipe with spacer brackets at regular intervals (typically every 1–1.5 m) so that no sagging or excessive stress occurs on the socket joints, and maintaining access to inspection openings and inspection elbows for regular cleaning and inspection of patency.

When cascading several boilers into one collecting pipe, it is also essential to respect the order and direction of connection of the individual branches according to the manufacturer's installation instructions (including the recommended use of check valves in cascades with three or more boilers, so that when one boiler is shut down, flue gases from the running boilers do not flow back into the shut-down unit) and to maintain the prescribed minimum rise and direction towards the common chimney or facade/roof outlet.

Care of the extension during operation

Straight sections of pipe generally do not require any special maintenance beyond a routine visual inspection during the annual service check – it is mainly important to verify that the spacer brackets along this section keep the pipe in the prescribed position and slope, and that the socket joints at both ends remain tight. With the shorter, 0.5-metre piece, the risk of sagging is minimal even without additional fastening at the midpoint of its length.

Storage and handling before installation

Due to its compact dimensions, the short 0.5-metre section is easy to transport and store – nevertheless, the same principle applies as with other PP parts in this range: protect it from direct sunlight during long-term storage and from mechanical damage to the sealing rings at both socket ends. When ordering, we recommend considering at least one extra piece as a reserve in case of an additional adjustment to the route length during installation.

Service, cleaning and service life

Regular inspection and cleaning of the flue gas discharge system is part of the standard annual service check of a condensing boiler room. Thanks to the inspection openings and inspection elbows in the assembly, individual pipe sections can be checked and, if necessary, cleaned (e.g. of any deposits) without having to completely dismantle the entire route. The condensate separator, if included in the assembly, must be regularly checked and, if necessary, emptied/flushed to prevent it from becoming clogged and causing condensate to back up into the pipe.

The service life of a quality PP flue gas discharge system from the manufacturer, directly compatible with the given boiler range, is comparable to the service life of the boiler itself when properly installed and regularly serviced – that is, roughly 15 years or more of operation. When replacing or adding individual parts in the future (for example, when expanding the cascade with an additional boiler), it is advisable to use original components of the same manufacturer and diameter to maintain full compatibility of the joints and the validity of the warranty on the entire flue gas discharge system.

Frequently Asked Questions

Why buy this Vaillant accessory at ATRIA.SK

The 0.5 m Ø 160 mm flue extension is a practical addition for precisely fine-tuning the length of a cascade flue route – we always recommend keeping at least one extra piece in stock in case of an additional adjustment to the assembly during installation.

When purchasing any part of the flue gas discharge system, we are happy to advise you on choosing the right combination of components for your specific boiler room – just contact us with details about the type and number of boilers, or with the project documentation. We usually ship goods within 24–48 hours of ordering; for larger assemblies, we will inform you in advance of the delivery date if necessary.