ATTACK PLUS vertical/horizontal splitter, D60/100-D80/D80, AL/AL

Product detailed description

The ATTACK PLUS vertical/horizontal splitter, D60/100-D80/D80, AL/AL 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: splitter – universal (vertical and horizontal), diameter 60/100 mm → 80/80 mm, material aluminium (AL) – both pipes.

Closed combustion chamber and flue gas exhaust for ATTACK condensing boilers

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

Every element of the exhaust assembly – elbow, extension, condensate trap, chimney terminal and splitter – must be leak-tight, resistant to flue gas temperatures as well as to condensate, which is produced in large quantities during operation of a condensing boiler precisely because the boiler is able to make use of the latent heat of the water vapour in the flue gases. It is precisely this condensate that is the reason why the ATTACK KT system cannot be safely replaced with a standard chimney component intended for atmospheric boilers – such components are not designed for permanent contact with acidic condensate, nor for the correct slope that carries the condensate back to the boiler or to the condensate trap.

Since this component connects both systems, the rules of both the coaxial routing (on the side connecting to the boiler) and the separate Ø80/Ø80 system (on the side of the continuing branches) apply to it simultaneously – see also the explanation below in the section on the separate system.

At higher outputs or with more complex exhaust routes (longer runs, more direction changes, a shared flue for multiple boilers), the 60/100 mm coaxial pipe can no longer be used efficiently – the flow resistance would be too high and the boiler's output would be limited. For this reason, in these cases a switch is made to a separate (two-pipe) system with an 80 mm diameter, where air intake and flue gas discharge are routed through two independent pipes, which may even follow different routes (for example, flue gas discharge above the roof and air intake through a side wall). This system is referred to in technical terminology as Ø80/Ø80 or C83/C93, depending on the method of termination, and is common with boiler cascades, with higher-output boilers, or wherever a greater distance to the façade or roof needs to be bridged.

Separate-system ATTACK KT components with an 80 mm diameter 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 coefficient of friction, which reduces pressure losses over longer runs. As these are separate pipes, both (exhaust and intake) must be routed with the same slope and the same logic as the coaxial pipe – flue gases must not accumulate in horizontal sections, and condensate must always flow back by gravity toward the boiler or into the condensate trap.

Splitter – transition from a coaxial to a separate system

The splitter is a component that divides a single 60/100 mm coaxial pipe coming from the boiler into two independent 80 mm diameter pipes – one for flue gas discharge and the other for combustion air intake. It is used wherever a longer route needs to be bridged than the coaxial pipe alone allows, or where the intake and exhaust need to be routed along different paths (for example, exhaust above the roof and intake through a side wall of the plant room).

The "vertical/horizontal" (universal) version can be installed in either position depending on the requirements of the specific installation, while the "vertical" version is intended exclusively for vertical installation directly behind the boiler, from which the two separate vertical (or subsequently deflected) branches continue. The aluminium/aluminium material combination is used where the intake branch is also routed through metal piping (for example due to a requirement for greater mechanical resistance along the route), while the aluminium/PP combination is more common – the exhaust (flue gas) branch remains aluminium and the intake branch switches to lighter polypropylene.

Example of a typical connection in a real installation:
boiler → flange → splitter 60/100 → 80/80 → separate flue gas branch (Ø80) above the roof + separate intake branch (Ø80) through the side wall.

Step-by-step installation procedure

1. Fit the splitter directly behind the boiler outlet (or behind the flange), check the correct orientation according to the version (vertical/horizontal, or vertical only in the case of the PLUS vertical type).
2. Plan the routes of both branches (exhaust and intake) so that each individually complies with the maximum length stated in the boiler's manual.
3. Connect further components (pipes, elbows, chimney terminal) to the exhaust branch, maintaining a minimum slope of 3° toward the boiler.
4. Connect the intake branch, and check that its outlet is not located in close proximity to the exhaust outlet (risk of flue gas re-intake).
5. Once both branches are connected, check the tightness of all joints on the splitter and on the connected components.

Material and construction

Both branches of the splitter – exhaust and intake – are made of aluminium in this version. This all-metal construction is chosen where the route needs to be mechanically more resistant (for example, when routed alongside other metal structures, or when the investor prefers a uniform metal appearance for both branches), with aluminium on both sides being equally resistant to condensate as on the coaxial side of the splitter.

System classification: transition from coaxial to separate system (splitter). Version: vertical and horizontal.

Compatibility with ATTACK boilers

The PR51B component is intended for the connection system common to the entire range of ATTACK ACKT20, ACKT28 and ACKT48 (Condensing KT range) wall-mounted condensing boilers, 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 nozzle 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

The splitter is installed directly behind the boiler outlet (or behind the flange), with the route design already taking into account that from this point onward two separate branches continue, each with its own length limits according to the boiler's manual. When installing the universal version horizontally, the permitted orientation specified in the manufacturer's manual must be checked so as not to impair condensate drainage from the exhaust branch.

As a general rule, horizontal sections of the exhaust route must have a slope of at least 3° toward 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 exhaust systems, in accordance with the installation manual for the specific boiler and with standard STN EN 15287.

Standards and safety requirements

In Slovakia, the installation of flue gas exhaust for condensing boilers is governed primarily by standard STN EN 15287 (Chimneys – Design, installation and commissioning of chimneys – Part 1: Chimneys for fan-assisted appliances), which sets out minimum clearances of the terminal from windows, ventilation openings, adjacent 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 comply with the requirements of STN EN 483 (Type C gas boilers) and must 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, issues an inspection report or commissioning report. In the event 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 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

During a service inspection of the splitter, the tightness of both outlet joints is checked, as is the absence of unwanted condensation forming at the branching point outside the intended drainage path – especially at the transition from the metal to the plastic branch, where the materials may have different thermal expansion rates.

The recommended inspection interval for the entire exhaust route is once a year, usually as part of the boiler's regular service inspection carried out by an authorised 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 – long route exceeding the coaxial pipe limit: the distance from the boiler to the façade or roof exceeds the maximum permitted length for 60/100 mm, so the splitter converts the route to a separate Ø80/Ø80 system with lower pressure losses immediately behind the boiler.

Scenario 2 – intake and exhaust need to be routed in different directions: the building layout requires flue gases to be discharged above the roof, while combustion air is drawn in through a side wall of the plant room – the splitter allows both branches to be routed completely independently.

Related components in the ATTACK KT range

The all-aluminium universal version of the splitter is complemented in the range by the combined AL/PP version PR51 (same positional versatility, lighter intake branch) and the vertical PLUS version PR51A (same material mix as PR51, but for vertical installation only). Choosing the PR51B is particularly worthwhile when an all-metal construction of both branches is required.

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

Summary

The ATTACK PLUS vertical/horizontal splitter, D60/100-D80/D80, AL/AL (code PR51B) is a splitter-type component – universal (vertical and horizontal) with a diameter of 60/100 mm → 80/80 mm, made of aluminium (AL) – both pipes, belonging to the transition from coaxial to separate system (splitter). Recommended installation orientation: vertical and horizontal. The component is intended for ATTACK ACKT20, ACKT28 and ACKT48 (Condensing KT range) boilers, ATTACK KST24 (Condensing KST) and ATTACK KZT25 (Condensing KZT) boilers, 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 the specific installation.

Frequently Asked Questions

Why choose the all-aluminium PR51B splitter instead of the combined AL/PP version PR51?
The all-aluminium PR51B version is worthwhile where the intake branch also needs to be mechanically more resistant (for example, when routed in an exposed environment or alongside other metal structures) or when the investor requires a uniform metal appearance for both branches behind the splitter.

Is the all-aluminium PR51B splitter heavier than the combined PR51 version?
Yes, since the intake branch is also made of aluminium instead of lighter polypropylene, the PR51B is somewhat heavier than the PR51 – however, the difference is negligible when installing a single component and does not require any special additional fastening compared to the combined version.

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 required; an opening through the wall or roof for the plastic-aluminium pipe is sufficient.

What is the maximum flue gas exhaust 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 – typically 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 may cause a boiler fault message.

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

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

Can I combine components of different diameters or from a different manufacturer with the ATTACK exhaust 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 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 pipe and condensate trap be inspected?
A visual check of joint tightness and condensate trap patency is recommended at least once a year, ideally during the boiler's regular service inspection. For façade or roof terminals, it is also necessary to check that the terminal grille is not blocked by leaves, insects or snow.

Does the flue gas exhaust need to be insulated?
When routed through heated spaces, 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 gas exhaust is undersized or too long?
If the maximum equivalent exhaust length is exceeded or in the event of leaks, the boiler will typically report a fault related to flue gas/air flow (fan fault, pressure switch fault or flue path fault) and will shut down for safety reasons. The solution is to recalculate the route according to the manual and make appropriate adjustments (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 shared collecting flue is generally used, or possibly 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 terminal clearances 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 base your choice on the installation manual for the specific boiler model (ACKT20/28/48, KST24, KZT25), which contains diagrams of typical connections and maximum permitted lengths. For a more complex or atypical layout (long route, passage through multiple floors, cascade), we recommend consulting an installation company or directly with the seller before ordering the exact number of pieces.

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

Is the 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 associated with a slight operational noise, which, however, is minimal when the route is correctly 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 exhaust.

Can this component be installed by myself, or is a professional required?
The mechanical connection 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 directly affect consumption, but they do so indirectly – the greater the resistance of the exhaust route (many elbows, a long route close to the 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 the route with the smallest possible 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. In the event of a claim, we recommend keeping proof of purchase and, if necessary, photographic documentation of the installation method, as with exhaust systems the functionality is closely linked to the correctness of the installation (compliance with slope, maximum route length and clearances according to the manual).