Vaillant recoVAIR 90° elbow for 75/62 mm pipe

Product detailed description

90° elbow for 75/62 mm ducting (Vaillant recoVAIR, code 0020176826)

The 90° elbow for 75/62 mm ducting is an original fitting from the Vaillant recoVAIR ducting system designed to change the direction of the flexible air hose with a circular cross-section of 75/62 mm by a right angle. Unlike the manifold connection adapter (which is used to connect the hose to a different type of component – a manifold, collector, or outlet), this elbow joins two hose sections together at a point where the duct route changes direction, for example when going around a ceiling joist, passing through a partition wall, or running the route below the ceiling structure towards several rooms at once. It is one of the most commonly used fittings in every larger installation of controlled ventilation with heat recovery, since it is rarely possible to run the entire duct route in a single straight line from the manifold to the outlet.

Construction and design

This elbow is supplied in the version without a mounting base – i.e. as a standalone molded fitting with two spigots positioned at a 90° angle to each other, onto which the 75/62 mm flexible hose can be pushed on both sides. Sealing rings are included, ensuring an airtight joint at both ends. There is also an alternative version with a mounting base (designed for direct anchoring into the ceiling or partition structure), but this 0020176826 variant is more flexible to use, as it can be placed anywhere along the hose route without requiring fixed anchoring – it is particularly suitable where the elbow is located in open space between ceiling joists or in the installation gap of a suspended ceiling, where the hose itself with cable ties already provides sufficient positional stability.

As with other fittings in the 75/62 mm series, this elbow is made of rigid plastic with a smooth internal surface, which minimizes turbulent airflow at the point of direction change and thus reduces noise load and pressure loss. A rigid molded fitting is always more advantageous aerodynamically than bending the flexible hose itself to the same angle, since the corrugated wall of the flexible hose at a sharp bend causes significantly higher flow turbulence, and thus higher noise and higher fan energy consumption needed to overcome the increased resistance.

Why use a rigid elbow instead of bending the hose

Many less experienced installers, in an effort to save time, try to change direction simply by bending the flexible hose itself. However, the manufacturer and professional installation practice clearly recommend using a rigid elbow from this range for every direction change greater than approximately 30°. There are three reasons for this:

• Preserving the cross-section – a flexible hose bent sharply kinks slightly on the inner side of the curve and narrows its flow area, creating a local constriction that acts as a throttling element and increases the branch's pressure loss beyond the designed values.
• Lower noise – the smooth internal surface of a rigid elbow causes significantly less turbulence than the corrugated wall of a flexible hose at a bend, which directly affects acoustic comfort in living spaces, especially in bedrooms and living rooms, where quiet ventilation operation is a priority.
• Longer service life – a repeatedly stressed flexible hose at a sharp kink is more prone to mechanical damage or cracks in the corrugated wall over years of operation, while a rigid elbow retains its shape and properties practically without wear throughout the system's service life.

Installing the elbow into the ducting

Installation is simple – both ends of the elbow have a spigot with the same outer diameter, onto which the hose is pushed up to the retaining lip and then secured with a cable tie or clamp. It is important to make sure that the sealing ring on the spigot stays in place and is not shifted or damaged when pushing the hose on – otherwise a leak could occur at the joint. When routing a path with several direction changes, we always recommend choosing the shortest and most direct route possible, since each additional elbow adds extra pressure resistance to the branch. If the route requires a direction change at an angle other than 90° (for example 45°), it is advisable to consult a designer or supplier about an alternative routing, as this particular part is specifically designed for a right-angle direction change.

Compatibility and related parts

The 0020176826 elbow is compatible with all parts of the 75/62 mm series in the Vaillant recoVAIR range – i.e. with the flexible hose (code 0020180824, supplied in a 40 m package), with manifold connection adapters (both straight and 90°, e.g. code 0020176829), with couplers for extending a straight run (code 0020176831), and with end pieces for connecting to DN 125 diameter outlets (code 0020176832). Thanks to this full compatibility, it is possible to assemble the ducting exactly according to the layout of a specific building, without the need for any improvised solutions or cutting and gluing non-original components.

Optimizing the duct route from a designer's perspective

When designing an air handling duct route, it is advisable to keep the number of direction changes per branch as low as possible – ideally a maximum of 2 to 3 elbows between the manifold and the outlet. A higher number of elbows significantly increases the total pressure loss of the branch, which results either in a reduction of the actual airflow into the room compared to the designed value, or in the need to compensate for this drop by increasing the fan speed of the recoVAIR unit, leading to higher electricity consumption and higher noise levels of the whole system. Where a higher number of direction changes cannot be avoided (for example in more complex floor plans with many partitions and ceiling joists), we recommend compensating by shortening the length of the given branch or slightly oversizing the duct diameter, if the layout allows.

Maintenance

The rigid elbow practically requires no maintenance apart from occasional inspection of the sealing rings on both ends, ideally at every filter change of the recoVAIR unit. If the elbow is located in an easily accessible place (for example in a ceiling access opening), we also recommend visually inspecting the internal surface once every few years for dust build-up, which could indicate insufficient filtration of the supply or exhaust air.

Frequently Asked Questions (FAQ)

Material, durability and service life

The elbow body is made of impact-resistant plastic that withstands, without deformation, the typical temperature range found in an attic, installation shaft, or space above a suspended ceiling – i.e. approximately from -20 °C in extreme winter conditions of an unheated attic up to +60 °C in summer under direct sunlight on the roof structure. The plastic is also resistant to the level of UV radiation realistically occurring in concealed installation spaces, and does not become brittle or change colour over years of operation. The sealing rings are made of a flexible elastomer that retains its sealing properties over a wide temperature range and is also resistant to the mild moisture from condensation that may occasionally occur on the exhaust branch in colder months.

Given the enclosed nature of the ducting (the pipe is routed through concealed spaces and is not exposed to direct mechanical stress or weather effects), the actual service life of rigid fittings, including this elbow, is comparable to the service life of the building itself, i.e. several decades. Replacement is generally only needed in the event of mechanical damage during structural work or during a complete renovation of the ventilation ducting.

Typical placement within the house layout

In practice, 75/62 mm elbows are most commonly found where the duct route has to go around a ceiling joist, transitions from one bay between rafters to another, or where it is necessary to change from horizontal routing in a suspended ceiling to vertical routing downwards towards a wall or ceiling outlet in a specific room. In multi-storey family houses, elbows are also commonly found where the ducting passes between floors through an installation shaft. The exact number and placement of elbows in a specific building is determined by the ventilation design project, drawn up based on the floor plan and the structural design of the ceilings and partitions.

Who this product is intended for

The 0020176826 elbow is an essential part of the equipment of every installation company carrying out Vaillant recoVAIR controlled ventilation ducting, since almost no real route in a house or apartment runs in a single straight line. It is equally important for service organizations carrying out repairs and modifications to existing ducting, and for property owners who need to adjust the ventilation route after a layout renovation. In all cases, the original part guarantees precise compatibility with the other system components and preserves the manufacturer's warranty conditions.

Common installation mistakes and how to avoid them

Among the most common shortcomings that service technicians find when inspecting existing installations is the use of an elbow instead of a flexible bend in places where a slight natural bend of the hose without changing the cross-section would have been sufficient (unnecessarily increasing the number of joints, and thus potential leak points), or conversely – trying to replace an elbow with a sharp bend of the hose itself where a rigid molded fitting should have been used. Another common mistake is insufficient tightening of the cable tie on the spigot, which over time, due to fan vibration or thermal expansion of the material, can lead to the hose partially sliding off the spigot and causing a leak. We therefore recommend always using a quality cable tie of sufficient width during installation (for example from the Vaillant range of fixing straps, code 0020231957) and, after tightening, visually checking that the hose is pushed on as far as the retaining lip of the spigot on both sides of the elbow.

Effect on system acoustic attenuation

In addition to changing the direction of airflow, a rigid elbow also partially serves as an acoustic element within the system – the change in flow direction causes slight scattering and attenuation of sound waves travelling through the ducting from the recoVAIR unit's fan towards the room outlet. This effect is secondary compared to the system's main damping elements (the length of the flexible hose itself and any silencers), but with a properly designed route with a reasonable number of direction changes, it contributes to the overall acoustic comfort in ventilated rooms. Conversely, a completely straight route without a single elbow may in some cases transmit fan noise more effectively than a route with one or two gentle direction changes – however, this is a secondary effect and should not be a reason to artificially increase the number of elbows beyond what is actually needed for the given layout.

Summary and package contents

The package contains one 90° elbow for 75/62 mm ducting without a mounting base, including sealing rings on both ends. This is an original accessory part directly from the manufacturer Vaillant, designed to change the direction of the flexible air hose in controlled ventilation ducting with heat recovery of the recoVAIR series. For larger installations, we recommend ordering several pieces at once, since the need for a direction change occurs in practice on almost every duct branch – a typical family house with 4 to 6 duct branches usually requires 8 to 15 pieces of this elbow, depending on the complexity of the floor plan and ceiling construction. We therefore recommend consulting the exact number of pieces needed with a designer or installation company before ordering, based on the approved ventilation design documentation, or including a slightly higher reserve in case of additional route adjustments directly on site.