Diffuser connection boxes GM

Purpose and Functions

A GM series plenum box is a professional end-piece component in radial MVHR (Mechanical Ventilation with Heat Recovery) systems. Its purpose is to serve as an aerodynamically efficient and completely airtight transition from the flexible duct to the diffuser.

The key feature of the GM series is its classic all-metal construction from galvanized steel with factory-installed double rubber (EPDM) seals on the spigots. This solution transforms airtightness from an installer's task into a guaranteed product characteristic. For projects where the maximum speed of "dry" installation via a mechanical lock is a priority, consider our alternative hybrid PK series.

The Role of the Plenum Box in System Efficiency and Longevity

A high-quality plenum box is key to low operational costs and the durability of the entire ventilation system. The GM series ensures this through the following fundamental advantages:

• Guaranteed Energy Efficiency (Class D): Factory installation of EPDM seals guarantees the highest airtightness class, D. This eliminates the risk of errors during manual sealing and prevents "energy penalties": increased energy consumption by the heat recovery unit's fan and thermal losses, which can reach 25-45% in non-airtight systems.
• Durability and Serviceability: Galvanized steel is a time-tested material with a long service life. Unlike non-demountable glued systems, the modular design of metal components allows for maintenance and seal replacement even after decades, ensuring a low total cost of ownership in the long run.
• Hygiene and Cleanability: The smooth metal surface is inherently hygienic and does not support pathogen growth. Importantly, a system based on steel components remains fully cleanable throughout its service life, which is critical for maintaining high indoor air quality (IAQ).
• Strength and Fire Safety: The steel body possesses high structural rigidity, necessary for installation in concrete, and is a non-combustible material, ensuring compliance with strict fire safety regulations.

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.

Key Technical Solutions

High performance is achieved through the following design features:

The Economic Impact of Airtightness

Air leaks in a ventilation system lead to disproportionately large energy losses. The need to compensate for these losses forces the fan to run at a higher power, which exponentially increases operational costs.

Choosing components with guaranteed Class D airtightness, like the GM series, is a direct investment in reducing future operational expenditures (OpEx).

Acoustic Comfort: What to Consider

Metal components provide excellent aerodynamics but can transmit structural vibrations from the ventilation equipment. To create an acoustically comfortable system, in addition to using silencers in the main ducts, it is recommended to apply vibration-damping materials to the flat surfaces of plenum boxes and manifolds to dampen resonance.

Types and Selection

The GM series plenum boxes vary in the number and location of spigots for connecting flexible ducts, allowing for the selection of an optimal solution for any room.

• By Number of Spigots: Models are available for connecting 1, 2, or 3 ducts (usually ø75 mm), which allows for adjusting the supplied air volume based on the area and purpose of the room.
• By Outlet Location: There are models with a straight (vertical) outlet for standard installation in a suspended ceiling and models with a side outlet for installation in height-restricted spaces.

GM Plenum Box Selection Criteria

When choosing a classic galvanized plenum box, pay attention to:

• Certified Class D Airtightness: This is a key indicator confirming the product's quality.
• EPDM Gasket Quality: The seals must be elastic and securely fixed on the spigots.
• Strength and Body Material: The galvanized steel construction must be rigid and suitable for the installation type.
• Compatibility with Dampers: Ensure the design allows for the installation of dampers for subsequent balancing.

Main Installation Steps

• Securing the Body: The robust steel body of the plenum box is securely fastened to the supporting structure (floor, ceiling, or wall).
• Connecting the Duct: The flexible duct is inserted into the spigot with the double rubber seal, ensuring a tight and airtight Class D connection.
• Installing the Regulating Damper: If necessary, a regulating damper is installed in the dedicated housing inside the box for precise balancing.
• Connecting the Diffuser: After finishing work is complete, the diffuser's adapter is connected to the box.

Need Help with Your System?

Our engineers are ready to help you calculate and specify the right ductwork system for your project. You can also purchase all the necessary components in our online store.

Need Help with Your System?

Our engineers are ready to help you calculate and specify the right ductwork system for your project. You can also purchase all the necessary components in our online store.