Electronic Variable Volume Ceiling Diffuser (VCD, VRD, VSD1)
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.
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 Master Communications Units (MCU2) use – 10VA (24VAC .4A) max and can connect to 60 diffusers.
ON-BOARD SENSING ACCURACY
Rickard Diffusers use innovative forced induction technology resulting in accurate room sensing and flexible zoning.
Master/Slave changes are achieved by installing an onboard controller that is accessible from below the ceiling and is activated using Rickards Free Software.
Electronically adjustable maximum and minimum control disc 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.
CAPITAL & OPERATING COST
Low diffuser height (100mm) can reduce a buildings overall cost by reducing the height of the ceiling void.
Included Jubilee Clamp saves time and material when attaching the flex.
Included plastic packaging can be used to protect the Tile once installed.
Light weight Diffuser.
Tile can be installed separately if required.
Our diffuser range fits most ceiling styles.
No regular maintenance is required.
Working components 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 Rickard range of ceiling diffusers offers a clean uncluttered look. The design hides the internals, is pressed to lie flush with the ceiling and comes in a range of colours and styles to satisfy different tastes.
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.
Stainless steel safety cable supports the working sub-assembly when detached from the back pan.
VAV COOLING AND HEATING
VAV COOLING WITH TERMINAL REHEAT
The RICKARD VARIABLE GEOMETRY VARI-DISC CEILING DIFFUSER is designed for general building zones where uniform radial discharge is the most suitable and desirable supply air distribution pattern. The basic diffuser is available in a wide range of options to suit every individual requirement.
Optimum performance in terms of uniform air distribution and low noise levels have been combined with simple construction and aesthetically pleasing appearance to provide a unit which is both functional and reliable. All diffusers are of steel construction and are finished in a chip resistant baked epoxy coating which is available in a wide range of colours to suit architectural requirements.
Room temperature is controlled by varying the supply air volume in accordance with demand. Volume control is achieved by moving a disc, known as a control disc, vertically up and down within the diffuser so as to vary the aperture through which the air passes. This is effectively what constitutes the “VARIABLE GEOMETRY” concept which maintains acceptable air movement in the room throughout the range from 100% down to as little as 25%.
The position of the control disc is varied by means of an electric actuator which drives the control disc in response to a signal received from a temperature controller. When used in conjunction with one of the RICKARD controllers, the diffuser will control room temperature on a proportional/integral basis. Air is discharged in a horizontal 360º pattern. Used in conjunction with our MLM controls, maximum and minimum supply air volumes may be adjusted to suit the particular design conditions.
In some cases, extra heating may be required in a particularly cold office or corner of the building. In these cases top-up heaters are available. Rickard’s top-up heaters are modular and are easily added to a diffuser to ensure an occupants comfort levels are satisfied.
Rickard offer a number of temperature sensing/controller options: On-board controller and sensing located on the diffuser for maximum floor layout flexibility. A wired wall thermostat with combined controller, sensor and set-point adjuster giving the occupant maximum control and sensing accuracy with slightly less layout flexibility. An on-board controller and sensing with remote infra-red set-point adjuster for maximum flexibility and individual temperature control. An on-board controller with wired remote sensing for exceptionally accurate room sensing. Please see the following Catalogue Sections for more information: Room Sensing Options, Wall Thermostat, Hand-held Infra-red Set Point Adjuster, MLM and MLC Controls Sections.
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 control disc 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.
NOISE LEVEL REQUIREMENTS
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.
DUCT STATIC PRESSURE
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 20-100Pa (0.04-0.40ins Wg), caution should be exercised when selecting diffusers outside the 40-80Pa (0.08-0.32ins 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.
DETERMINING MAXIMUM CEILING HEIGHT
The drawing below describes how to determine the maximum ceiling height that can be achieved from a diffuser. Please see the diffuser performance data page for airflow, throw, noise and pressure information.