ATTACK KT chimney, diameter 80, PP

Product detailed description

ATTACK KT chimney, diameter 80, PP is part of the original flue gas discharge and combustion air intake system ATTACK KT / KT PLUS, designed for wall-mounted condensing gas boilers ATTACK Condensing. This part belongs to the category: chimney – final roof element for the separate system, diameter 80 mm, made of polypropylene (PP), both exhaust and intake roof set.

Closed combustion chamber and flue gas discharge for ATTACK condensing boilers

For higher outputs or more complex flue routes (longer runs, more direction changes, a shared flue for multiple boilers), a 60/100 mm coaxial pipe can no longer be used efficiently – flow resistance would be too high and the boiler's output would be restricted. In these cases, a separate (twin-pipe) system with a diameter of 80 mm is used instead, where air intake and flue gas discharge run through two independent pipes that can even follow different routes (for example, flue discharge above the roof and air intake through a side wall). This system is technically referred to as Ø80/Ø80 or C83/C93, depending on the outlet configuration, and is common with boiler cascades, higher-output boilers, or where a greater distance to the façade or roof needs to be covered.

The 80 mm separate-system components of the ATTACK KT system are made of polypropylene (PP) – a material that is long-term resistant to the acidic condensate produced during flue gas condensation, has low weight and a low friction coefficient, which reduces pressure losses over longer runs. Since these are separate pipes, both the exhaust and intake pipes must be routed with the same slope and following the same logic as a coaxial pipe – flue gases must not accumulate in horizontal sections, and condensate must always flow back by gravity towards the boiler or to a condensate trap.

Ø80 chimney set – roof outlet of the separate system

This chimney set forms the final element of the Ø80/Ø80 separate system where it passes through the roof. As this involves two independent pipes (exhaust and intake), the part includes a complete set for both branches, including eaves collars and protective terminals against water and debris ingress, which also explains the higher price compared to a simple coaxial chimney terminal – it is effectively two terminals and two roof penetrations in one assembly (or in close proximity, if each branch exits separately).

As with a coaxial terminal, the minimum height above the roof plane and clearances from windows and ventilation openings must be observed according to STN EN 15287. For a separate system, it is additionally checked that the intake terminal is not placed too close to the exhaust terminal so that the boiler does not draw in its own flue gases – the manufacturer therefore also specifies a minimum distance between the two outlets in the manual, if they are not routed through a shared flue duct.

Example of a typical connection in a real installation:
boiler → 60/100→80/80 splitter → two independent Ø80 branches → Ø80 chimney set (roof penetration, exhaust and intake).

Step-by-step installation procedure

1. Determine the roof penetration locations for both branches (exhaust and intake), taking into account the minimum mutual clearances according to STN EN 15287.
2. Install the eaves collars of both terminals so that they overlap the roof covering within the range specified by its manufacturer.
3. Connect both terminals to the respective vertical pipe branches, seal the joints and secure them mechanically.
4. Check that the intake terminal is not positioned in the flow direction of flue gases from the exhaust terminal.
5. After the first rain following installation, check the watertightness of both penetrations from the attic.

Material and construction

The set is made of polypropylene, which is long-term resistant to the acidic condensate produced during flue gas condensation and also withstands outdoor weather conditions well (UV radiation, rain, frost) on the exterior part of the roof penetration. The material's low weight makes handling easier during installation at heights.

System classification: separate (Ø80/Ø80). Configuration: vertical, roof penetration.

Compatibility with ATTACK boilers

Part PR50 is designed for the connection system shared across 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 exact connection socket type and the maximum permitted flue run length in the installation manual for the specific boiler model, as this may vary slightly depending on boiler output (20, 28 or 48 kW for the KT range).

Installation and warnings

Both terminals (exhaust and intake) must be installed observing the minimum height above the roof plane and clearances from surrounding structures according to STN EN 15287. The manufacturer usually also specifies a minimum mutual distance between the two outlets if they are not routed through a shared flue duct, to prevent flue gases from being drawn back into the intake branch.

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

Standards and safety requirements

Installation of flue gas discharge for condensing boilers in Slovakia is governed primarily by the STN EN 15287 standard (Chimneys – Design, installation and commissioning of chimneys – Part 1: Chimneys for fan-assisted appliances), which sets out minimum clearances of the outlet from windows, ventilation openings, neighbouring properties and ground level, as well as the minimum outlet height above the roof plane. The boiler itself and its flue 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 must issue an inspection report or commissioning protocol upon completion. For any change to the route compared to the originally approved design (e.g. additional extension of the run, change in the number of elbows), it is necessary to check whether the boiler still falls 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

It is recommended to check both terminals of the roof set at least once a year, ideally before winter – especially the condition of the sealing collars and the patency of both grilles (exhaust and intake), as blockage of either one affects the operation of the entire boiler.

The recommended inspection interval for the entire flue route is once a year, usually as part of the regular boiler service inspection carried out by an authorised service technician. This is also an opportunity to check this specific part, 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 – boiler cascade with a shared roof outlet: several boilers share a separate Ø80/Ø80 system routed to a common location on the roof, where the chimney set handles the outlet of the collecting branch.

Scenario 2 – long run through multiple floors: when the separate system passes through several floors up to the roof, this set handles the final penetration through the roof structure for both independent pipes.

Related parts in the ATTACK KT range

The Ø80 chimney set connects to the PR45 pipes and PR51/PR51A/PR51B splitters, which bring both branches of the separate system up to the roof penetration. Compared to the PR39 coaxial terminal, it handles the outlet of two independent pipes at once instead of a single shared one.

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

Summary

ATTACK KT chimney, diameter 80, PP (code PR50) is a chimney-type part – the final roof element for the separate system with a diameter of 80 mm, made of polypropylene (PP), both exhaust and intake roof set, belonging to the separate system (Ø80/Ø80). Recommended installation orientation: vertical, roof penetration. The part is designed for boilers ATTACK 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 flue components available on this e-shop, allowing a complete flue route to be assembled exactly according to the layout of the specific installation.

Frequently asked questions

Why is the Ø80 chimney set (PR50) more expensive than the 60/100 mm coaxial chimney terminal (PR39)?
The PR50 set handles the outlet of both independent pipes of the separate system (exhaust and intake), including two sets of sealing collars and protective terminals, while the PR39 coaxial terminal handles a single shared pipe – the amount of material and work needed for a complete outlet is therefore greater with the separate system.

Do both terminals of the PR50 set have to be routed right next to each other, or can they be separated?
Depending on the layout and the boiler manual, both terminals can also be routed separately (for example, exhaust through the roof and intake through a side wall) – in this case, parts appropriate to the specific route are used instead of the shared set, while maintaining the minimum distance between outlets required by the standard.

Do I need a functional chimney flue 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 flue system (coaxial 60/100 mm or separate Ø80/Ø80). A masonry chimney is therefore not necessary; a wall or roof penetration for the plastic-aluminium pipe is sufficient.

What is the maximum flue discharge length for a 60/100 mm coaxial pipe?
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 approximately 1–1.5 m and a 45° elbow as approximately 0.5 m of straight pipe. Exceeding the limit increases resistance and can trigger a boiler fault message.

Why does water actually drip from the flue discharge?
A condensing boiler cools the flue gases so much that the water vapour they contain condenses – it is precisely this additional heat that gives the boiler its high efficiency. The resulting condensate is mildly acidic and must be discharged via a condensate trap into the boiler's siphon; this is why all horizontal pipe sections have a prescribed slope towards the boiler or the trap.

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

Can I combine parts of different diameters or from another manufacturer with the ATTACK flue system?
It is recommended to use a certified system from the same manufacturer as specified in the manual for the specific boiler (for ATTACK Condensing boilers, this is the ATTACK KT/KT PLUS system). Combining parts 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 flue pipe and condensate trap be inspected?
A visual inspection of joint tightness and condensate trap patency is recommended at least once a year, ideally during the regular boiler service inspection. For a façade or roof outlet, it is also necessary to check that the terminal grille is not blocked by leaves, insects or snow.

Does the flue discharge need to be insulated?
When routed through a heated space, insulation is usually not necessary, as the surface temperature of the coaxial pipe is low. For longer sections routed through unheated spaces (attic, façade) 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 discharge is undersized or too long?
If the maximum equivalent flue length is exceeded or there are 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 necessary (shorter route, fewer elbows, or switching to a separate Ø80/Ø80 system).

Can this part also be used in a cascade connection of multiple boilers?
Cascades with multiple boilers usually use a separate Ø80/Ø80 system with a shared collecting flue, or separate terminals for each boiler according to the cascade's design documentation. The specific components (extensions, elbows, splitters) are also compatible in this configuration, but the minimum outlet clearances according to STN EN 15287 must be observed.

How do I know exactly which parts 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 configurations and maximum permitted lengths. For more complex or non-standard layouts (long run, penetration through multiple floors, cascade), we recommend consulting an installation company or the retailer directly before ordering the exact number of pieces.

Does the condensate from the flue discharge need to be neutralised before being discharged into the sewer system?
For typical family homes with a small boiler output, neutralisation 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 system operator must be observed. For higher outputs or boiler cascades, it is recommended to install a condensate neutralisation unit before discharge into the public sewer system.

Is a condensing boiler with this type of flue discharge noisier than one with a traditional chimney?
Forced draught (via the boiler's fan) may be associated with a slight operating noise, which, however, is minimal when the route is properly installed and mechanically secured (without freely vibrating pipe sections) and is generally comparable to or lower than the noise of a classic atmospheric boiler with chimney discharge.

Can this part be installed by yourself, or is a professional required?
The mechanical connection of the parts themselves (plug-in system) is simple, but connecting the flue discharge 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 to maintain the warranty and ensure safe operation.

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

Warranty

This part of the ATTACK flue system is covered by a 24-month warranty from the date of dispatch from the warehouse, the same as other accessories for ATTACK condensing boilers. When making a claim, we recommend keeping the proof of purchase and, if necessary, photographic documentation of the installation method, as with flue systems the functionality is closely linked to the correctness of the installation (compliance with slope, maximum route length and clearances according to the manual).