Air Grilles for HVAC Ventilation in Georgia

What is a ventilation grille?

A ventilation grille is the element that connects the ventilation duct with the space being served.

Its purpose can be to supply air into a room, extract air from a space, change the direction of the airflow, transfer air from one space to another, cover a ventilation opening and visually complete the system. Some models also allow an additional damper to be fitted, which is used to regulate the airflow.

What types of grille are available at NB Group?

The current NB Group category includes: HLM single deflection grille with fixed blades; HTSK single deflection grille with adjustable blades; HCSK double deflection grille with adjustable blades; HLMK, HKK-A and HKPK hinged service grilles; the HPP grille; the HKP egg crate grille; the HKTM door grille; the HYLM floor grille; the HDKM round duct grille; and the HLTM filter grille.

This variety makes it possible to select a grille not only by size, but according to the specific ventilation function.

How to select a ventilation grille

1. Is air supplied or extracted?

First the function of the grille has to be defined. Some grilles are mainly used on the supply side, some on extract or recirculation, and some models can suit both functions. For example, the HCSK double deflection grille with adjustable blades is designed for controlling the direction of supply air, while HTSK is mainly used on the extract side.

2. Grille size

The size of the grille has to match the required air volume and the permissible velocity. If a very large airflow has to pass through a small grille, the air velocity, noise, uncomfortable draught and pressure loss can all increase. A grille should therefore not be selected only by the size of the existing opening.

What is the difference between fixed and adjustable blades?

With fixed blades the direction of the air is predetermined by the construction of the grille. In the NB Group HLM model the blades are fixed and the grille is used both on supply and extract lines.

Adjustable blades make it possible to change the air direction on site. For example, in the HCSK double deflection grille the air direction can be controlled both vertically and horizontally.

Single or double deflection grille?

The NB Group HCSK model has two rows of adjustable blades, which allows the supply air to be directed up, down, right and left. However, a double deflection grille is not automatically better in every case.

What does effective free area mean?

The overall size of a grille and the actual area through which air passes are not the same. The frame and blades take up part of the opening. The effective free area is the part through which air actually moves. This parameter matters for assessing air velocity, determining pressure loss and selecting the right grille size.

What is an egg crate grille?

An egg crate grille is an air transfer element with a cellular structure, often used in extract and recirculation systems. The NB Group HKP model is intended for extract lines and for the recirculation of air conditioning units installed in suspended ceilings. Because of its wide effective free area, its construction is oriented towards low pressure loss.

What is a door grille used for?

A door grille is used for free air transfer between adjoining spaces. For example, if an extract fan runs in a bathroom or technical room but there is no way for fresh air to enter, the capacity of the extract can be limited. The NB Group HKTM door grille has special inverted V shaped blades that allow air movement while restricting direct view from the other side.

What is a floor grille used for?

A floor grille is used where air is supplied or transferred from a raised floor system. The NB Group HYLM model is intended for air conditioning systems in spaces with raised floors and is designed for a more durable construction than an ordinary linear grille, since it may be subject to additional mechanical load.

Is there a grille for round ducts?

Yes. The NB Group HDKM model is used on round ducts, both on supply and extract lines. It can be supplied in single or double deflection versions with adjustable blades. This solution is practical where a round ventilation duct remains exposed in the interior.

What is a filter grille used for?

A filter grille provides an additional filtration function on a return or extract line. The NB Group HLTM Fiber Filter Grille is intended for air return systems and its filter helps capture particles. With a filter grille it is particularly important to check and service the filter regularly.

What is a hinged service grille?

The advantage of a hinged service grille is that its front part opens, making access to the technical element behind it easier. The NB Group range includes several models of this type - HLMK, HKK-A and HKPK. Such a solution is particularly practical where a filter, a fan coil or another serviceable technical component is located behind the grille.

Are a grille and an air diffuser the same thing?

No. Both are used for final air distribution, but their construction and the principle of air spread differ. Grilles often use linear blades that control the direction of the air. Diffusers are usually designed to distribute air over a wider area or according to a specific pattern.

What are the most common mistakes when selecting a grille?

Selecting by size only

Grilles of the same size can have completely different effective free areas and air directions.

Confusing supply and extract

Not every model is equally optimal for both functions.

Using a grille that is too small

This can increase air velocity and noise.

Ignoring air direction

Supply air should not be directed straight at people unless the design intends it.

What information is needed to select a grille?

It helps to know in advance:

• whether air is supplied or extracted;
• how many m3/h have to pass through;
• where it will be installed - wall, ceiling, floor, door or duct;
• the size of the opening;
• what air direction is required;
• whether adjustable blades are needed;
• whether a damper is required;
• how important a low noise level is;
• whether service access is required;
• whether filtration is required.

With this data it becomes possible to choose not simply a suitable size, but the right type of grille for the specific system.

Ventilation grilles at NB Group

NB Group supplies ventilation grilles for air supply, extraction, recirculation and transfer between spaces. The current range includes single and double deflection grilles, adjustable and fixed blades, door, floor, round duct, filter and service models.

When selecting a product it is important to assess the airflow, the size of the opening, the installation location and the required air direction. NB Group branches are located in Tbilisi and Batumi.