Product detailed description

Vaillant flue inspection section 0.25 m with inspection opening, Ø 110 mm

The inspection section with a length of 0.25 metres is a short straight flue section Ø 110 mm which has an inspection (check) opening built into its casing, fitted with a hinged or removable cover. It serves as an ongoing access point into the interior of a long vertical flue run at points where it would otherwise be impossible to inspect or clean the run other than by dismantling the entire assembly.

Vaillant LAS shaft flue gas exhaust system Ø 110 mm

This part is part of the original Vaillant shaft flue gas exhaust system (abbreviated LAS – from the German "Luft-Abgas-System"), which is used with high-capacity condensing boilers (typically higher-output ecoTEC exclusiv/pro/plus ranges and floor-standing ecoCRAFT exclusiv boilers, as well as with output-equivalent Protherm models from the same manufacturing group). Unlike a standard concentric flue (pipe-in-pipe) used with small wall-mounted boilers, the shaft system carries flue gases through a single-wall pipe with a diameter of 110 mm inside an existing building shaft (most commonly an older masonry chimney no longer used for its original purpose), while combustion air is drawn in through the free space of the shaft around this pipe.

The advantage of this solution is that it requires no new penetration through the façade or roof in addition to the existing shaft, and in multi-storey buildings it allows the exhaust to be routed to the required height without the need to build a new chimney. All parts of the system are made of durable polypropylene (PP), which withstands long-term contact with the mildly acidic condensate produced during the operation of a condensing boiler, and are joined by a simple socket-to-socket push-fit system with an integrated sealing ring, without the need for gluing or additional sealing compound.

What the inspection opening in the middle of the run is for

For short assemblies, an inspection point at a single location is sufficient – typically at the inspection elbow at the base of the shaft. For longer vertical runs (multi-storey shafts), however, both technical regulations and the manufacturer itself recommend having an access point along the run as well, so that pipe patency, any deposits, or seal damage can be checked even in sections that would otherwise only be accessible by complex disassembly of the assembly from above or below.

The cover of the inspection opening is fitted with a seal and a closing mechanism (screw-type or clip-type, depending on the specific version), which ensures gas-tightness even when closed – in effect, it is a fully functional flue section that also allows easy visual inspection of the interior at any time without having to remove surrounding parts.

Where to place this part in the assembly

The inspection section should be installed at a point in the run that will remain freely accessible even after construction work is completed (for example, through an inspection hatch in the shaft cladding or in a technical floor). The orientation of the opening should allow it to be conveniently opened towards the accessible space, not towards the inside of the masonry structure.

The connection itself is identical to other straight sections of the same diameter – a push-fit joint with a rubber sealing ring at both ends; the part can be freely combined with 0.5/1.0/2.0 m extensions as well as with elbows from the range.

Step-by-step installation procedure

1. Determine the exact location in the run where the inspection opening will actually be accessible after construction work is completed (for example, near an inspection hatch in the shaft cladding).
2. Check that the push-fit ends and the seal of the inspection cover are clean and undamaged.
3. Insert the part into the assembly in the same way as other straight sections, with the sealing ring lightly coated with a suitable lubricant.
4. Turn the part so that the inspection opening faces the accessible space (not the interior of the masonry structure).
5. After insertion, verify that the inspection cover is properly closed and there is no leakage around it.
6. Record the position of the inspection section in the documentation handed over to the chimney sweep so that it can be easily located during future inspections.

Practical example

When designing the flue gas exhaust for a condensing boiler located in the basement of an apartment building with shaft access only at the level of individual inter-floor landings, the chimney sweep required inspection access not only at the base but also approximately halfway up the run when handing over the installation. Instead of subsequently cutting an inspection opening into an already installed pipe, this 0.25 m inspection section was included right at the design stage at exactly the point where access was available from the intermediate floor through an inspection hatch in the shaft cladding – resolving the chimney sweep's requirement without any additional construction work.

How to determine the correct number of inspection sections

When deciding how many 0.25 m inspection sections with a built-in opening to include in the assembly, base your decision primarily on the actual accessibility of the shaft after construction work is completed – there is no point planning a checkpoint at a location you will not be able to reach later. Map out all the points where the shaft will be accessible from outside (inspection hatches, technical floors, inter-ceiling spaces), and place the inspection sections precisely there. For a typical height of one to two storeys, one inspection access at the base of the shaft is usually sufficient (often already provided by an inspection elbow); for multi-storey runs, it is advisable to add at least one further inspection section or elbow at mid-height. We always recommend confirming the final decision with the locally responsible chimney sweep, who will later carry out regular inspections.

When this part is actually needed

We recommend including it in the assembly whenever:

• the shaft passes through more than one storey and there is no other access point in the middle of the run,
• local regulations or the chimney sweep require inspection access beyond the base of the shaft when handing over the installation,
• it is a long-term investment where it is worth planning for easier future maintenance from the outset instead of potentially having to cut an opening into the existing pipe later.

Compatibility and use in the system

This part belongs to the closed range of original Vaillant accessories for Ø 110 mm shaft flue gas exhaust and is intended to be combined with other parts from the same range – extensions (0.5 m, 1.0 m and 2.0 m), elbows of various angles, inspection sections, a support elbow, spacer holders, mounting bands, and a wall rosette. It is used primarily when installing or replacing high-capacity condensing Vaillant boilers (ecoTEC exclusiv range, higher-output versions of ecoTEC pro/plus, and floor-standing ecoCRAFT exclusiv boilers), as well as with corresponding Protherm models (Panther Condens, Tiger Condens, Bizon Condens in higher outputs) – Vaillant and Protherm belong to the same manufacturing group, so parts of the exhaust system are commonly interchangeable; however, always verify the exact type and connection size in the installation manual for your specific boiler.

Before ordering, we recommend having our customer service or your installation company prepare a simple assembly design based on the height and diameter of your existing shaft – the correct number and combination of parts (length of straight sections, number and angle of elbows, number of spacer holders and mounting bands) is key to safe and standard-compliant operation of the entire exhaust system.

Shaft flue gas exhaust systems of this type are designed and assessed in both Slovakia and the Czech Republic according to the standards of the STN EN 1443 series (Chimneys – General requirements) and STN EN 14471 (Chimneys – System chimneys with plastic flue liners), which, among other things, define the marking of the so-called temperature, pressure, and resistance class of components (for example, condensate resistance class "W" – wet operation, typical precisely for condensing boilers). Original Vaillant parts from this range correspond to the relevant classes stated in the manufacturer's documentation and the installation manual of the specific boiler with which the system is supplied – this compliance is precisely why it is recommended to use parts exclusively from one closed range for shaft flue exhaust, rather than combining them with products from other manufacturers.

Comparison with the 87° inspection elbow

This part is a straight 0.25 m section with a side inspection opening, whereas the 87° inspection elbow also handles a change of direction in the run. If the run does not change direction at a given point but only requires inspection access, this straight inspection section is more suitable – it does not create an unnecessary bend in an otherwise straight passage.

Technical parameters

Maintenance and service inspections

A polypropylene shaft flue gas exhaust system is low-maintenance; however, as part of the flue gas path, it is subject, just like a masonry chimney, to regular inspection by a chimney sweep according to applicable regulations and the intervals set by the boiler manufacturer and local chimney inspection ordinances. During inspection, the tightness of joints, pipe patency (deposits, foreign objects), the condition of sealing rings in push-fit joints, and the proper functioning of condensate drainage from the lower part of the system are checked. Parts made of PP are not usually cleaned with aggressive solvents – mechanical removal of deposits and rinsing with water, or possibly a mild detergent, is sufficient.

Condensate produced during the operation of a condensing boiler is mildly acidic (typically in the pH range of approximately 3 to 5, depending on the type of gas burned and the boiler's operating state), so the entire system run is designed with a slope towards a collection point and condensate drainage either directly into the boiler (where it is usually neutralised or drained into the sewer via a siphon) or into a separate collection point at the base of the shaft. During regular inspection, therefore, also pay attention to whether the condensate is actually draining freely and not pooling at lower points of the run, which could indicate an incorrect slope or a blockage in one of the sections.

Safety and regulatory notes

The presence of a sufficient number of check/inspection access points along the height of the shaft is part of the requirements for safe operation of the flue gas path. We recommend determining the exact number and spacing of inspection access points already at the design stage, together with the installation company and the locally responsible chimney sweep.

Why not to solve inspection by cutting an opening afterwards

Creating a check opening in a smooth pipe after installation is complicated, risks compromising the tightness and strength of the part, and generally does not meet the original certified parameters of the system. By using an original inspection section already during installation, you are guaranteed functional and aesthetic quality for many years of operation.