Vaillant EPP roof transition piece flat roof - recoVAIR /4

Product detailed description

Vaillant EPP flat roof transition piece - for the recoVAIR /4 system

The flat roof transition piece is an original accessory part of the Vaillant recoVAIR /4 system designed to route the main ventilation duct made of EPP (expanded polypropylene) vertically through a flat or near-flat roof structure. Unlike the transition piece for pitched roofs, which must follow the slope of the roof plane, this part has a simple straight, vertical shape, since on a flat roof the ventilation duct is routed vertically upwards without the need for any angular adjustment.

The part is designed to match the round EPP duct used on the main route between the central heat recovery unit (recoVAIR VAR 150/4, VAR 260/4 or VAR 360/4) and the roof outlet, or connects directly to the smaller-diameter EPP duct of 180/150 mm, which is used in the recoVAIR /4 system mainly with smaller central units and shorter routes. Thanks to the EPP material, the part is lightweight, mechanically resistant, and has its own thermal insulation function that limits condensation at the point of passage through the cold roof structure.

Designing a roof penetration on a flat roof usually also involves coordination with other penetrations on the same roof plane - chimneys, sewage ventilation, kitchen extraction ductwork, or photovoltaic panel installations. We therefore recommend addressing the position of the recoVAIR ventilation penetration in a joint drawing of all roof penetrations, rather than in isolation without regard to other trades.

Technical characteristics

• Purpose: vertical roof penetration for EPP duct on flat and near-flat roofs (slope up to approx. 5-10°)
• Material: expanded polypropylene (EPP), closed-cell structure with its own thermal insulation
• Compatible duct diameters: EPP duct system recoVAIR /4 (roughly Ø180/150 mm, depending on the specific route configuration)
• Joint type: push-fit joint with overlap to the straight connecting section of EPP duct
• Resistant to moisture and weather influences for long-term outdoor installation
• Compatibility with units: recoVAIR VAR 150/4 L, VAR 150/4 R, VAR 260/4, VAR 260/4 E, VAR 360/4, VAR 360/4 E
• Country of origin: Germany (Vaillant Group production plant)
• Warranty: 2 years from sale to the end customer

When you need this transition piece

You should choose this part whenever the roof of the building where the ventilation duct of the recoVAIR system passes through is flat or has only a minimal slope (typically modern new buildings with a flat roof, or extensions and converted attic apartments with a flat roof terrace). The most common use cases are:

• Extracting exhaust air from the central unit through a flat roof to the exterior.
• Drawing in fresh outdoor air through the same type of penetration on the opposite side of the route.
• Combination with a connecting roof terminal, if the duct needs to be extended higher above the level of the roof covering/waterproofing (e.g. due to clearance distances from parapets or other penetrations).

For gable or otherwise sloped roofs with a slope of 25° or more, a separate pitched roof transition piece (a separate product in our range) with an adjustable collar shape should be used instead of this part.

Related components you will likely also need

When implementing a complete roof penetration on a flat roof, the components most commonly ordered together with this transition piece are the connecting parts of the same ventilation route - straight sections of EPP duct of the required length from the unit to the transition piece, or a roof terminal, if the duct needs to be extended higher above the level of the waterproofing. We recommend ordering these parts together to ensure compatibility of diameters and joint type before starting installation work on the roof, thereby avoiding delays caused by having to additionally purchase missing route parts during ongoing construction.

Installation - procedure and recommendations

1. The exact location of the penetration is determined according to the ventilation project, generally away from valleys, rainwater outlets, and areas where water is expected to accumulate on the flat roof.
2. An opening is cut into the roof structure (load-bearing structure, thermal insulation, waterproofing membrane) exactly according to the diameter of the transition piece.
3. The EPP transition piece is slid onto the duct coming from the unit and fitted vertically into the prepared opening.
4. Connection to the waterproofing layer of the flat roof (membrane or bituminous waterproofing) is carried out by a roofing technician using system collars/sleeves recommended by the manufacturer of the given waterproofing, to ensure 100% watertightness of the penetration.
5. The part is extended above the level of the waterproofing to the required height (for flat roofs, a higher minimum penetration height is recommended than for pitched roofs, due to the greater accumulation of snow that can occur on a flat roof).
6. If needed, a roof terminal with a protective grille against insects, leaves, and birds is connected to the upper part.

Compatibility with the recoVAIR /4 system

The part is part of a comprehensive accessory system for Vaillant recoVAIR /4 central units and connects to:

• straight sections and bends of EPP duct of the same diameter,
• a roof terminal, if a higher extension above the roof plane is needed,
• low-profile and standard air distributors on the interior side of the distribution system.

The part is not intended to be combined with duct systems from other manufacturers with a different profile or diameter - such a combination could result in a leaky joint and loss of warranty on the functionality of the entire distribution system.

Flat roofs and specifics of ventilation penetrations

A flat roof places different demands on a roof penetration than a pitched roof - water does not drain away from the penetration along a slope, but can temporarily accumulate around the penetration, especially with insufficient fall towards drains or if drains are blocked by leaves and debris. It is therefore essential to:

• place the penetration at the highest point of the given roof plane, or at least away from areas where water accumulation is expected,
• choose a sufficient height of the extension above the level of the waterproofing (typically at least 300 mm, depending on the specific project and snow region),
• ensure a quality connection of the transition piece collar to the membrane or bituminous roof waterproofing using system components from the roof covering manufacturer.

An incorrectly resolved penetration detail is one of the most common causes of subsequent leakage complaints on flat roofs, so this part of the installation should definitely not be underestimated, even in residential new builds with a simple floor plan.

Why the recoVAIR /4 system uses EPP duct

Expanded polypropylene (EPP) is a material that has become established in heat recovery ventilation technology mainly thanks to a combination of low weight, high rigidity, and its own thermal insulation capability given by its closed-cell structure. Compared to a conventional smooth plastic or galvanized sheet metal duct, which requires additional cladding with mineral wool or foam insulation to achieve the same thermal insulation properties, EPP brings these advantages already within the duct material itself:

• Lower weight - installation and handling of the parts is easier, especially in confined spaces such as attics or interstitial spaces.
• Built-in thermal insulation - limits condensation on the duct surface without the need for additional cladding, which is advantageous precisely in cold spaces such as attics or roof penetration points.
• Resistance to mechanical damage - EPP is more flexible and resistant to denting than thin sheet metal, reducing the risk of damage during installation and operation.
• Easy joining - push-fit joints with overlap allow quick installation without the need for special tools for cutting sheet metal or welding joints.

These properties make the EPP duct system a natural choice specifically for the main route between the recoVAIR central unit and the roof or facade outlet, where the heated and unheated areas of the building most often meet.

Connection to the energy performance of the building

A properly executed and airtight ventilation distribution system directly affects the actual energy demand of the building. Leaks in ducts or at roof penetrations mean that part of the supplied air does not reach where it should (living rooms), and conversely, part of the extracted air may escape without passing through the unit's heat exchanger, without heat being recovered from it. In projects aimed at a passive or low-energy standard, the airtightness of every detail of the distribution system - including a seemingly simple roof penetration - is therefore one of the factors that will actually show up on the heating bill.

Maintenance and care

As a passive building element, the transition piece requires no maintenance in the form of parts replacement. It is recommended to:

• check the condition and tightness of this penetration during the regular annual inspection of the flat roof (recommended for all flat roofs regardless of the type of ventilation system),
• keep the area around the penetration free of accumulated leaves, moss, and debris, which could obstruct water drainage,
• in case of mechanical damage to the collar or waterproofing around the penetration, carry out a repair as soon as possible to prevent leakage into the roof structure.

Why choose an original Vaillant part

Dimensional and material compatibility of this part with the entire recoVAIR /4 system is essential to maintain the declared parameters of the unit - distribution tightness, pressure losses, and heat recovery efficiency. A non-original part of a different diameter or material may cause leaks, unwanted air flow around the duct, moisture condensation, or reduced service life of the roof waterproofing at the penetration point. By purchasing an original part from an authorized Vaillant partner, you can be sure that the part exactly matches the manufacturer's requirements for the given system.

Another significant advantage is that in the event of a warranty claim for a leak or malfunction, a service technician can clearly verify the origin and type of the part used based on the Vaillant order number, which is often not possible with non-original or unknown replacements and can complicate or completely prevent claiming the warranty on surrounding distribution components.

Frequently asked questions

Shipping and packaging

Due to the size and shape of this roof part, the product, given its bulkiness, is not shipped via parcel lockers/pickup boxes - it is delivered by courier directly to the address to prevent damage to its shape during transport.