ATTACK KT extension 0.5 m, diameter 60/100, painted

Product detailed description

ATTACK KT extension 0.5 m, diameter 60/100, painted is part of the original ATTACK KT / KT PLUS flue gas exhaust and combustion air intake system, designed for ATTACK Condensing wall-mounted condensing gas boilers. This component belongs to the category: extension 500 mm, diameter 60/100 mm, made of galvanized steel with a painted surface finish.

Closed combustion chamber and flue gas extraction in ATTACK condensing boilers

ATTACK condensing gas boilers operate with a closed (turbo) combustion chamber – unlike older atmospheric boilers, they do not require air from the room in which they are installed, nor a functional masonry chimney. They draw combustion air directly from outside the building and discharge flue gases outward also by forced draught, provided by a fan built into the boiler. In practice, this closed circuit is solved in two ways: by coaxial (concentric) piping, where a smaller pipe for air intake runs inside a larger pipe and the annular space serves for flue gas discharge, or by a separate system with two independent pipes. The coaxial design with a diameter of 60/100 mm is the most common solution for boilers up to approx. 35 kW, as it allows both the discharge and the intake to be routed through a single opening in the wall or roof, is quick to install and aesthetically unobtrusive.

Every element of the exhaust assembly – elbow, extension, condensate trap, flue terminal and splitter – must be tight, resistant to flue gas temperatures as well as to the condensate that forms in large quantities during operation of a condensing boiler, precisely because the boiler is able to make use of the latent heat of water vapour in the flue gases. It is precisely this condensate that is the reason why the ATTACK KT system cannot be replaced without risk by a common flue component designed for atmospheric boilers – such components are not designed for permanent contact with acidic condensate nor for the correct slope that drains condensate back into the boiler or into the trap.

Extension – how the length of the exhaust route is designed

Extensions are the basic building blocks of the entire exhaust route – by combining 1 m and 0.5 m pieces, the total length of the piping from the boiler flue connection to the roof or facade can be precisely adjusted to match the specific ceiling height of the room or the thickness of the structure. For the 60/100 mm coaxial system, the manufacturer states the maximum permissible exhaust length (the sum of all straight sections and equivalent lengths of elbows) in the operating manual for the specific boiler model – usually in the range of 10 to 15 m of equivalent length for the Condensing KT/KST/KZT range, with each 90° elbow counted as approximately 1 to 1.5 m of straight pipe and a 45° elbow as approximately 0.5 m.

Exceeding the maximum length leads to increased resistance on both the flue gas and intake sides, which the boiler may interpret as a draught fault and shut down via a safety cut-out. Therefore, when designing the route, the required length should always first be calculated according to the actual layout (ceiling height, wall thickness, roof overhang), and only then should the combination of extensions, elbows and the end component be ordered.

Component length: 500 mm.

Example of a typical connection in a real installation:
boiler → flange → extension (added to reach the exact length) → elbow → chimney.

Step-by-step installation procedure

1. According to the route design, calculate in advance how many 1 m and 0.5 m extensions are needed to reach the target length.
2. Join the components using the socket-to-socket push-fit system, making sure to insert them in the correct direction (according to markings).
3. For horizontal runs, check a minimum slope of 3° toward the boiler or the nearest condensate trap using a spirit level.
4. Mechanically support/secure longer horizontal sections with clamps according to the installation manual.
5. Check the tightness of all new joints before continuing with additional route components.

Material and construction

This component is made of galvanized steel with an additional painted surface finish, which increases resistance to weather effects on the exterior part of the route (for example, the flue terminal on the roof) and at the same time gives the component an aesthetic, uniform appearance matching the design of ATTACK Condensing boilers. The surface finish withstands the normal temperatures of flue gases from a condensing boiler and short-term contact with condensate, provided the correct pipe slope ensures that condensate does not remain standing in the component for extended periods.

System classification: coaxial (concentric). Design: both vertical and horizontal.

Compatibility with ATTACK boilers

The PR38 component is designed for the connection system common to the entire range of ATTACK wall-mounted condensing boilers ACKT20, ACKT28 and ACKT48 (Condensing KT range), ATTACK KST24 (Condensing KST) and ATTACK KZT25 (Condensing KZT). Before ordering, we recommend checking the installation manual for the specific boiler model to confirm the exact type of connection socket and the maximum permitted length of the exhaust route, as this may vary slightly depending on the boiler output (20, 28 or 48 kW for the KT range).

Installation and warnings

Extensions are joined using a socket-to-socket push-fit system; the joints are sealed, depending on the type of component, either with an integrated seal or with additional silicone sealant resistant to flue gas temperatures. For horizontal runs, a minimum slope of 3° (approximately 3 cm per metre of length) toward the boiler or the nearest condensate trap must be maintained so that condensate does not remain standing in the piping.

In general, horizontal exhaust sections must have a slope of at least 3° toward the boiler or the nearest condensate trap so that condensate does not accumulate in the piping. Installation should be carried out by a person qualified to install gas appliances and their exhaust systems, in accordance with the installation manual for the specific boiler and with standard STN EN 15287.

Standards and safety requirements

Installation of flue gas exhaust for condensing boilers in Slovakia is governed primarily by standard STN EN 15287 (Chimneys – Design, installation and commissioning of chimneys – Part 1: Chimneys for fan assisted appliances), which sets minimum distances of the terminal from windows, ventilation openings, neighbouring properties and ground level, as well as the minimum height of the terminal above the roof plane. The boiler itself and its exhaust system must also meet the requirements of STN EN 483 (type C gas boilers) and be installed in accordance with the technical and operational regulations (TPP) applicable to gas appliances.

Installation may only be carried out by a person qualified to install and service gas appliances, who, upon completion, shall issue an inspection report or commissioning protocol. In case of any change to the route compared to the originally approved design (e.g. additional extension of the route, change in the number of elbows), it is necessary to check that the boiler still remains within the parameters permitted by the manufacturer – otherwise there is a risk not only of boiler malfunction but also of loss of warranty and, in extreme cases, a safety risk of flue gas leakage.

Maintenance and service inspection

Straight pipe sections, when correctly installed (proper slope, mechanical fastening), do not require special maintenance. During a service inspection, it is recommended to visually check whether longer horizontal sections have sagged and whether the push-fit joints remain tight.

The recommended inspection interval for the entire exhaust route is once a year, usually as part of the regular boiler service inspection carried out by an authorized service technician. On this occasion, this specific component is also checked, along with the patency of the condensate path and the overall condition of the joints along the entire route from the boiler to the outlet outside the building.

Typical usage scenarios

Scenario 1 – fine-tuning the exact route length for a low ceiling height room: the distance from the boiler to the ceiling is unusual and does not match an integer multiple of 1 m – this is compensated by combining 1 m and 0.5 m extensions so that the sum exactly matches the actual height.

Scenario 2 – extending the route for a greater wall thickness or larger roof overhang: for thicker perimeter walls or a larger roof overhang, the required number of extensions is inserted between the boiler and the end component so that the route reliably reaches outside the building.

Related components in the ATTACK KT range

The shorter 0.5 m extension PR38 complements the 1 m long version PR37 and serves primarily for fine-tuning the total route length in cases where the 1 m pieces alone would not give an exact sum matching the actual layout of the room or roof.

A complete overview of all components of the ATTACK KT / KT PLUS flue gas exhaust system (elbows, extensions, flue terminals, condensate traps and splitters for diameters 60/100 mm and 80 mm) can be found in the category Condensing boilers > flue exhaust, flue pipes > accessories by brand > Attack on this e-shop.

Summary

ATTACK KT extension 0.5 m, diameter 60/100, painted (code PR38) is a component of type extension 500 mm with a diameter of 60/100 mm, made of galvanized steel with a painted surface finish, belonging to the coaxial (concentric) system. Recommended installation orientation: both vertical and horizontal. The component is intended for ATTACK boilers ACKT20, ACKT28 and ACKT48 (Condensing KT range), ATTACK KST24 (Condensing KST) and ATTACK KZT25 (Condensing KZT), and is part of the wider range of ATTACK KT exhaust components available on this e-shop, allowing a complete flue gas exhaust route to be assembled exactly according to the layout of a specific installation.

Frequently asked questions

Is the 0.5 m extension suitable for horizontal routing as well, or only for vertical height adjustment?
The PR38 component is universal and can be used in both vertical and horizontal routing – however, it is most commonly used for fine-tuning the total route length in cases where a combination of only 1 m pieces (PR37) would come out either too short or too long.

How many PR38 pieces can be connected in a row in one route?
The number is not fixed by the component itself; the limiting factor is always the total maximum equivalent length of the exhaust route stated in the manual for the specific boiler model – this sum includes the length of all extensions as well as the equivalent length of the elbows used.

Do I need a functional chimney for an ATTACK condensing boiler?
No. ATTACK Condensing KT, KST and KZT condensing boilers have a closed combustion chamber with forced draught – they draw combustion air from outside and discharge flue gases through their own exhaust system (coaxial 60/100 mm or separate Ø80/Ø80). A masonry chimney is therefore not needed; an opening through the wall or roof for the plastic-aluminium piping is sufficient.

What is the maximum flue gas exhaust length for 60/100 mm coaxial piping?
The exact value depends on the specific boiler model (ACKT20, ACKT28, ACKT48, KST24 or KZT25) and is stated in the installation manual – it is usually an equivalent length of 10–15 m, with a 90° elbow counted as approx. 1–1.5 m and a 45° elbow as approx. 0.5 m of straight pipe. Exceeding the limit increases resistance and may cause a boiler fault message.

Why does water actually drip from the flue exhaust?
A condensing boiler cools the flue gases so much that the water vapour contained in them condenses – it is precisely from this heat that the boiler gains its high efficiency. The resulting condensate is slightly acidic and must be drained through the condensate trap into the boiler's siphon; that is why all horizontal pipe sections have a prescribed slope toward the boiler or the trap.

Can the 60/100 mm coaxial piping be combined with the separate Ø80/Ø80 system?
Yes, that is exactly what a splitter (e.g. PR51, PR51A or PR51B) is for – it splits a single coaxial pipe from the boiler into two separate Ø80 mm pipes. It is used for longer routes or when the intake and exhaust need to be routed in different directions.

Can I combine components of different diameters or from another manufacturer with the ATTACK exhaust system?
It is recommended to use a certified system from the same manufacturer as stated in the manual for the specific boiler (for ATTACK Condensing boilers, this is the ATTACK KT/KT PLUS system). Combining components of different diameters, materials or from other manufacturers may result in leaks, incorrect condensate drainage and loss of the boiler warranty.

How often should the exhaust piping and condensate trap be checked?
A visual check of joint tightness and the patency of the condensate trap is recommended at least once a year, ideally during the regular boiler service inspection. For facade or roof outlets, it should also be checked that the terminal grille is not clogged with leaves, insects or snow.

Is it necessary to insulate the flue gas exhaust?
When routed through heated space, insulation is usually not necessary, as the surface temperature of the coaxial piping is low. For longer sections routed through unheated space (attic, facade) or where there is a risk of moisture condensing on the pipe surface, additional insulation is recommended, especially at the condensate trap, to prevent it from freezing.

What happens if the flue gas exhaust is undersized or too long?
If the maximum equivalent exhaust length is exceeded or in case of leaks, the boiler will usually report a fault related to flue gas/air flow (fan fault, pressure switch fault or flue path fault) and shut down for safety reasons. The solution is to recalculate the route according to the manual and make adjustments if needed (shorter route, fewer elbows, or switching to a separate Ø80/Ø80 system).

Can this component also be used in a cascade connection of multiple boilers?
For cascades with multiple boilers, a separate Ø80/Ø80 system with a common collecting flue is usually used, or separate terminals for each boiler according to the cascade's project documentation. The specific components (extensions, elbows, splitters) are also compatible in this configuration, but the minimum distances between terminals according to STN EN 15287 must be observed.

How do I find out exactly which components I need for my installation?
The most reliable approach is to refer to the installation manual for the specific boiler model (ACKT20/28/48, KST24, KZT25), which contains diagrams of typical connections and the maximum permitted lengths. For more complex or non-standard layouts (long route, passage through multiple floors, cascade), we recommend consulting an installation company or the seller directly before ordering the exact number of pieces.

Does the condensate from the flue exhaust need to be neutralized before being discharged into the sewer?
For typical family houses with a small boiler output, neutralization is usually not required due to the small amount of condensate and its dilution with other wastewater; however, applicable legislation and the requirements of the local sewer authority must be followed. For higher outputs or boiler cascades, it is recommended to install a condensate neutralization device before discharge into the public sewer.

Is operation of a condensing boiler with this type of exhaust noisier than with a classic chimney?
Forced draught (from the boiler's fan) may be accompanied by a slight operational noise, which, however, is minimal with a correctly installed and mechanically secured route (without freely vibrating pipe sections) and is generally comparable to or lower than the noise of a classic atmospheric boiler with chimney exhaust.

Can installation of this component be done DIY, or is a professional required?
The mechanical joining of the components (push-fit system) itself is simple, but connecting the exhaust to the condensing boiler, calculating the maximum route length and commissioning the boiler must be carried out by a person qualified to install gas appliances – this is both a manufacturer requirement and a legal requirement for maintaining the warranty and ensuring safe operation.

Does the number and type of these components affect gas consumption or boiler efficiency?
They do not affect consumption directly, but they do indirectly – the greater the resistance of the exhaust route (many elbows, a route near the length limit), the more energy the boiler's fan must expend to overcome this resistance, and the sooner the boiler may limit its output or report a fault. Designing a route with the smallest necessary number of components is therefore also advisable from the point of view of operating economy.

Warranty

This ATTACK exhaust system component is covered by a 24-month warranty from the date of dispatch from the warehouse, the same as other accessories for ATTACK condensing boilers. For warranty claims, we recommend keeping the proof of purchase and, if necessary, photo documentation of the installation method, as with exhaust systems the functionality is closely tied to the correctness of the installation (compliance with slope, maximum route length and distances according to the manual).