Diffuser connection boxes PK

Purpose and Hybrid Construction

A plenum box with polymer connectors (PK series) is a hybrid component for radial heat recovery ventilation systems, combining the best of both worlds. Its main purpose is to serve as an airtight and acoustically effective transition from the flexible duct to the diffuser.

In contrast to the classic all-metal OC series boxes, the key feature of boxes with polymer connectors is the hybrid design: a robust galvanized steel body is combined with high-tech polymer spigots. The steel body provides mechanical rigidity, while the polymer connectors ensure a perfect seal, hygiene, and the speed of "dry" installation.

The Role of the Plenum Box in System Efficiency

The PK series hybrid plenum boxes perform the same key functions as the classic ones but emphasize the speed of installation and the hygienic advantages of polymer connections:

• Guaranteed Energy Efficiency (Class D): The mechanical snap-fit system, combined with an EPDM gasket, provides maximum Class D airtightness. This completely eliminates leaks and ensures that the heat recovery unit's fan operates with minimal energy consumption (low SFP).
• Highest Level of Hygiene (VOC-Free): "Dry" installation without glue or sealants prevents the emission of harmful volatile organic compounds. Furthermore, the smooth antistatic surface of the polymer spigots inhibits dust accumulation, improving indoor air quality (IAQ).
• Acoustic Comfort and Balancing: Like any expansion chamber, the plenum box dampens aerodynamic noise, and the ability to install regulating dampers allows for precise system balancing for quiet operation.
• Strength and Reliability: The robust galvanized steel body ensures the product will not deform under the weight of concrete when installed in a screed, maintaining the integrity and airtightness of the connections for the entire service life.

Explanation of Airtightness Classes (EN 12237 standard)

The airtightness class is a key indicator that defines the quality of the entire ductwork system. It specifies the volume of air lost due to leaks in the connections. The standard establishes four main classes:

• Class A: A basic level with high permissible leakage. It is not used in modern energy-efficient buildings.
• Class B: An improved class, formerly the standard for general ventilation. It is insufficient for heat recovery systems due to significant losses.
• Class C: A high class of airtightness. It is considered the mandatory minimum for quality ventilation systems aiming to meet energy efficiency standards.
• Class D: The highest possible class, with maximum airtightness. Air leakage is practically reduced to zero. This is the "gold standard" for passive and nearly zero-energy buildings (NZEB), guaranteeing that no energy spent on air treatment is wasted.

Comparison of Connection Technologies

PK Plenum Box Selection Criteria

When choosing a hybrid plenum box with polymer connectors, pay attention to:

• Guaranteed Class D Airtightness: Ensure the locking system and gaskets are certified.
• Polymer Quality: Prefer virgin HDPE with hygiene certificates (TÜV, Greenguard).
• Steel Body Strength: The thickness and quality of galvanization are important for durability in concealed installations.
• Compatibility with Dampers: Check that the design allows for easy installation of balancing elements.

Main Installation Steps

Thanks to the mechanical locking system, the installation of PK series boxes is extremely fast and simple:

• Securing the Body: The steel body of the plenum box is securely fastened to the supporting structure (floor, ceiling, or wall).
• Connecting the Duct: The flexible duct is simply inserted into the polymer spigot until it clicks. The connection is now complete—100% airtight and securely locked.
• Installing the Regulating Damper: If needed, the regulating damper is placed in its designated housing inside the box.
• Connecting the Diffuser: After finishing work is complete, the diffuser's adapter is connected to the box.

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