Electronic Variable Volume Linear Aerofoil Diffuser - VLA1 | rickardair

Electronic Variable Volume Linear Aerofoil Diffuser - VLA1

When a buildings thermal efficiency is paramount, the ideal solution to limit thermal losses or gains through its exterior is required. The Rickard Variable Volume Linear Aerofoil Diffuser (VLA1) is the ideal solution to control a buildings internal perimeter zone. It creates a vertical curtain of conditioned air that acts as a barrier to the thermal load transmitted or lost through the building’s exterior. By using innovative forced induction technology the VLA1 accurately senses the temperature and adjusts to precisely meet the demand.

Rickard VAV Diffusers control Room Temperature by adjusting the volume of air at the diffuser outlet. By changing the diffusers exit geometry, Coanda, Air Velocity and Throw is maintained at minimum and maximum volume. This technology prevents cold air from dumping at minimum, ensures excellent ventilation, air mixing, Air Change Effectiveness (ACE) and therefore thermal comfort (ADPI). Rickard VAV diffusers reduce pressure loss in the system due to their aerodynamic design and the absence of restrictions in the duct work.

Green Building Benefits. Receive Management, Indoor Environmental Quality and Energy Efficiency Credits by using Rickard VAV Diffusers.
Rickard MLM controls use energy efficiently. Rickard MLM Diffusers use 2.4 VA (24VDC 100mA) only when the motor is running. MLM24 Power Supply Units use 40VA (220VAC 2A) or (115VAC 35A) max and can supply up to 15 diffusers. MLM Primary Communications Units (MCU2 ) use 10VA (24VAC 4A) max and can connect to 60 diffusers.

Rickard Diffusers use optional forced induction technology resulting in accurate room sensing and flexible zoning.

Master to Secondary changes are achieved by installing an onboard controller or wall thermostat that is activated using Rickard’s Free Software. Electronically adjustable maximum and minimum damper limits allow designed airflow volumes to be achieved. Global manual commands (all diffusers can be driven open) reduce commissioning costs. Cost effective standalone, LonWorks and BACnet BMS integration.

Low plenum height can reduce a buildings overall cost by reducing the height of the ceiling void.

Optional Jubilee Clamp saves time and material when attaching the flex.

Surface mount VLA diffusers working components and controls are all accessible from below the ceiling. No skilled labour or special tools are required. Diffuser life cycle testing gives peace of mind far beyond our two year warranty period (Electronic diffuser range). Life cycle testing is based on 3000 operating hours and 4000 control cycles per year and is the equivalent of 30 years of service.
The VLA diffusers active section is constructed from corrosion resistant mill galvanized sheet steel and aluminium. The diffuser tracks are constructed from aluminium extrusion and are coated with epoxy powder coating.
No regular maintenance is required.

The slim and attractive slot diffuser style provides a clean uninterrupted appearance that meets most architectural requirements.

Rickard offers a 2 year manufacturer’s warranty on its Electronic VAV diffusers. Please see Terms and Conditions for a full description of our warranty. 

Working plastic components are moulded in glass reinforced Makrolon - Makrolon is flame retardant and chlorine and bromine free when burnt. The Rickard Thermo-Disc and Electronic actuators are moulded in Makrolon and are UL Certified.

When a buildings thermal efficiency is paramount, the ideal solution to limit thermal losses or gains through its exterior is required. The Rickard Variable Volume Linear Aerofoil Diffuser (VLA1) is the ideal solution to control a buildings internal perimeter zone. It creates a vertical curtain of conditioned air that acts as a barrier to the thermal load transmitted or lost through the building’s exterior. By using innovative forced induction technology the VLA1 accurately senses the  temperature and adjusts to precisely meet the demand.
Aerodynamic pattern controllers inside the linear slot create a low pressure drop to supply air quietly and efficiently. The pattern controllers can be manually adjusted to direct the air horizontally or vertically.Rickard VLA1 diffuser tracks are  available in 3/4” or 19mm, 1” or 25mm & 1 1/4” or 32mm wide slots. The choice of slot widths give greater choice to select a linear with the correct, flow, throw and noise performance for the specific application. 24” or 600mm, 36” or 900mm, 48” or 1200mm and 60” or 1500mm lengths are available. VLA’s are designed to be joined end-to-end to create uninterrupted lengths of attractive linear track.

Room temperature is intelligently controlled by varying the supply air volume in accordance with demand. The diffuser controller uses a proportional / integral response to achieve this. Volume control is achieved by opening or closing a set of slotted plates using our patented electric stepper motor, so as to vary the aperture through which the supply air passes. This provides true “VARIABLE GEOMETRY VAV” which effectively maintains air discharge velocity throughout the range of volume control from 100% down to as little as 25%.

Air is discharged in a linear vertical or horizontal pattern. Used in conjunction with our MLM controls, maximum and minimum supply air volumes may be adjusted to suit the particular design conditions.

A further useful feature of the RICKARD VLA is the ease with which the direction of airflow may be adjusted. Although airflow direction is not normally changed once the system is operational, it does simplify the ordering procedure. All linear air diffusion track is identical and the choice of one-way (horizontal or vertical) or two-way blow (horizontal) is easily adjusted by simply flipping the flow directional vane to the preferred side.

It is possible to direct air vertically downwards for better room penetration, especially when the VLA is in the heating mode.  

Pattern Controller Adjustment

The first consideration when designing a system is to calculate the required supply air volume and temperature to satisfy room conditions at maximum heat loads. It is recommended that ducting is sized using static regain design principles. Supply air velocities in branch ducts should be between 3.5 and 7.5m/s (650 and 1500ft/min).

This is the distance from the centre of the diffuser to the point at which the supply air velocity has reduced to 0.25m/s (50ft/min) when measured 25mm (1 inch) below the ceiling and the internal volume control damper is in the fully open position. Coning occurs when two airstreams travelling in opposite directions meet and result in a downward moving cone of air. A similar effect is experienced should a diffuser be positioned at a distance from the wall that is less than its throw. The air will strike the wall and flow in a downward direction such that the point at which the air reaches a velocity of 0.25m/s (50ft/min), the sum of the horizontal and vertical travel of the air is equal to the diffuser throw. Throw remains at acceptable levels throughout the range of air flows, a feature of the variable geometry VAV diffuser concept.

The published diffuser noise level must be checked to ensure it is within the project specification. Published diffuser noise levels represent only the noise generated by the diffuser and do not take into consideration any duct-borne noise.

Diffuser performance has been established using diffuser neck TOTAL pressure, although that which is normally known or measured is duct STATIC pressure. What happens between the duct and the diffuser depends on the length and type of flexible duct being used. For simplicity, it can be assumed that the duct STATIC pressure is approximately equal to the diffuser neck total pressure. This is a valid assumption for systems where flexible duct lengths are not excessive and can be explained briefly as follows:
The static pressure loss due to friction in the flexible duct (±10Pa or 0.04ins wg) would normally be about the same as the velocity pressure in the neck of the diffuser and since total pressure is the sum of static and velocity pressure, we can say that neck total pressure is numerically approximately the same as duct static pressure. Although the tables reflect diffuser performance for neck total pressures ranging from 30-70Pa (0.12-0.28ins Wg), caution should be exercised when selecting diffusers outside the 40-80Pa (0.8-0.32ins Wg). At lower pressures air movement and induction may be insufficient and at higher pressures draughts and excessive noise may result. Best results are obtained when diffusers are selected at pressures of 40-60Pa (0.08-0.24ins Wg). Bear in mind that all diffusers served by a common duct will all operate at the same static pressure as controlled by the pressure control damper. Therefore diffusers which are able to supply more air than is necessary will be driven partially closed by the temperature controller and hence the system becomes self-balancing.

NOTE: Avoid upstream restrictions such as manually adjusted dampers or squashed flexible ducting. The reason being that at maximum flow any restrictions will result in a significant static pressure loss (which for some cases may be desirable) whereas at minimum flow conditions offer virtually no restriction, which will result in the static pressure at the diffuser being too high at minimum flow causing over-cooling/heating and increased noise.

VLA Linear Diffusers are available in a range of slot widths and quantities. The slot widths available are 3/4” or 19mm, 1” or 25mm & 1 1/4” or 32mm. A VLA can be ordered with 1 to 4 slots. This allows for a greater range of flow, throw and noise performance values.

The standard VLA is available in unit lengths of:

  • 600mm
  • 900mm
  • 1200mm
  • 1500mm
VLA Linear Tracks are designed to fit Plastered Ceilings (Surface Mount) and most Ceiling Grid (Drop-in) variants.
Rickard VLA Diffuser tracks are designed to be joined end-to-end with alignment pins to create uninterrupted lengths of attractive linear track. VLA Tracks are compatible with other Rickard VLA tracks, Dummy tracks (inactive sections of track often used for return air) or CLN tracks (Constant Volume Linear Diffusers).
VLA Linear Diffusers are available with 1 - 4 Slot tracks. with adjustable pattern controllers for vertical to horizontal blow.
Tracks are finished in a wide range of high quality epoxy powder coated finishes. Matt White comes as standard.
VLA Linear Diffusers with multiple slots require larger and/or more spigots. Please see the VLA Spigot Detail table for more detail.
  • Master (fitted with an onboard sensor and controller)
  • Master-ready Secondary (fitted with an onboard sensor but without an onboard controller)
  • Secondary (to follow a Master Diffuser or be converted to a Remote Master with a Remote Wall Thermostat)