Tranquilair™ Displacement Ventilation Diffusers

Displacement ventilation is a type of indoor air ventilation system that was first used in Scandinavia in the 1970's, the system is designed to provide comfortable and efficient air distribution within the building's interior spaces.

Unlike traditional mixed-air systems that distribute air from high level, displacement ventilation delivers conditioned air at low velocities near floor level, the conditioned air gradually displaces the warmer air in the occupied zone, by taking advantage of thermal stratification, so pushing up the staler room air to high level, where it can be extracted.

This use of displacing air via natural buoyancy helps to improve indoor air quality by minimising the mixing of air layers. Since the supply air is introduced near the floor and extracted at the ceiling level, contaminants, particulates, and pollutants are effectively removed from the occupied zone.

Design Considerations

Effective design and layout are crucial for the successful implementation of displacement ventilation systems. Factors such as room layout, occupant density, supply air temperature, and diffuser placement need to be considered to ensure optimal performance.

Should you require any technical assistance for selections or project specific testing in one of Frenger's 3 number state-of-art Climatic Testing Laboratories, Frenger are ready to assist.

The Frenger's Tranquilair™ Displacement Ventilation Diffusers are manufactured from 1mm thick Zintec steel as standard with an option to manufacture from thicker material if greater robustness is required.

Frenger can also supply colour matched duct Boxing to cover/ conceal exposed ductwork connecting to the displacement diffusers.

Dimensions: Tranquilair™ Wall Mounted Units are available in five widths, as standard - 0.3m, 0.45m, 0.6m, 0.75m and 0.9m, six depths from as standard - 0.15m, 0.18m, 0.22m, 0.25m 0.33m and 0.4m, and with heights from 0.32m to 1.82m in 100mm increments.

Corner Units are available in five widths, as standard - 0.35m, 0.45m, 0.6m, 0.75m and 0.9m, five depths from as standard - 0.265m, 0.34m, 0.45m, 0.56m and 0.67m with heights from 0.42m to 1.92m in 100mm increments.

Free Standing Units are available in three widths, as standard - 0.55m, 0.75m and 0.95m with heights from 1.22m to 1.72m in 100mm increments.

Air Connections: Tranquilair™ wall mounted units are available with various air connection configurations with single connections available in Ø125mm, Ø160mm, Ø200mm, Ø250mm and Ø300mm and dual connections in Ø250mm and Ø300mm.

Corner units are available with various air connection configurations with single connections available in Ø125mm, Ø160mm, Ø200mm, Ø250mm, Ø300mm and Ø355mm

Free standing units are available with various air connection configurations with single connections available in Ø300mm, Ø350mm, Ø400mm, Ø450mm and Ø500mm

Tranquilair™ Displacement Ventilation Diffusers can also be supplied with top entry or floor entry air connections. See brochure page 8 for further details.

Surface finish: Tranquilair™ units are pre-coated White as standard (equivalent to RAL 9016, 25% gloss). Frenger also offer all RAL classic colour options to suit any architectural aesthetics (other colours available on request at additional cost). Tranquilair™ units can also be supplied with BioCote® antimicrobial coating technology to give increased protection against bacteria and mould at additional cost.

Colour Options

Colour helps to create atmosphere within a space, the Tranquilair™ units provide a unique way to integrate colour into different environments. Frenger's Tranquilair™ units are pre-coated white standard, Frenger also offer powder units powder-coated in any RAL classic colour options to suit all architectual aesthetics (other colours available on request)

Research has been done into the effects different colours have on wellbeing and from this their suitability for different environments has been established. Blue has been found to induce calmness and improve concentration. Its mental benefits make it a perfect choice for office environments. Red has been shown to have more physical effects, encouraging creativity. Yellow is associated with creativity and is ideal for creative workspaces. Neutral and cool tones are more suitable for healthcare environments, but depending on the purpose, it can be useful to include color—such as in children's hospitals—to provide stimulation.

Standard Pre-Coated RAL 9016 Equivalent	Powder-Coated RAL 9004 Signal Black	Powder-Coated RAL 5012 Light Blue
Powder-Coated RAL 1003 Signal Yellow	Powder-Coated RAL 4008 Signal Violet	Powder-Coated RAL 3018 Strawberry Red

Frenger's Tranquilair™ Displacement Ventilation Diffusers have preforated sections to facilitate the gentle air flow supplied by the unit. As standard, Frenger offer the 7mm and 4mm Double Dot Perforation.

7mm and 4mm Double Dot Perforation Order Code DD	Slot Perforation Order Code 5S
7mm Dot Perforation Order Code 7D	Diamond Perforation Order Code DMD

Alternative perforation patterns are available for architectual purposes, however the technical data provided here would not be applicable to the other perforation patterns. Seek advice from technical@frenger.co.uk.

Our range of displacement ventilation diffusers is designed to suit a variety of spaces and installation needs. Each model is engineered for optimal airflow and comfort, ensuring efficient air distribution with minimal turbulence.

• 1-Way Air Discharge (Wall-Mounted) - Ideal for targeted airflow, this model directs air in a single direction, making it perfect for controlled venitilation in offices, classrooms and meeting rooms.


• 3-Way Air Discharge (Wall-Mounted) - Designed for broader coverage, this model distributes air in three directions, ensuring even airflow across larger spaces such as auditoriums and open-plan offices.


• Corner Mounted - Optimised for placement in a room corners, this model maximises space efficiency while providing msooth, consistent air distribution.


• Free Standing - A versatile solution for flexible layouts, the free-standing model offers powerful, low-velocity air distribution without the need for wall mounting.

Standard Wall-Mounted Unit	3-Way Wall-Mounted Unit
Free-Standing Unit	Corner-Mounted Unit

All models are available with either top air entry or floor air entry, allowing for seamless integration into different building designs and HVAC systems. No matter the application, our displacement diffusers deliver superior air quality and comfort.

Bespoke architectural designs and use of such materials as "Stainless Steel" are available upon request.

Frenger's Tranquilair™ displacement ventilation diffusers are designed and manufactured in the UK by Frenger and have the following key features:

• Conditioned air low velocity discharge which provides superior thermal comfort compared to traditional ventilation systems. By delivering conditioned air at low velocities near the floor, occupants experience less movement and drafts, resulting in a more comfortable environment.


• Displacement function using low static pressures of typically between 2 and 15Pa depending upon size and required fresh air volumes, ensuring the ventilation system uses less energy for air distribution and conditioning, resulting in potential energy savings.


• Variety of displacement diffuser design options and sizes to suit a projects particular requirement, non-standard made to measure versions also available upon request.


• Easy to install with removable perforated fascia to conceal fixings


• Finished in RAL 9016 white powder coated as standard, other colours available upon request.


• Multiple perforation patterns available, although this will be depending upon specific air discharge volume and unit size

If you require any further information, or have a project to discuss, please contact us on +44(0)1332 295 678 or sales@frenger.co.uk as our technical team are here to assist.