VAV Diffuser System Design
VAV Diffuser System Design
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RSV-SVAD building application that can be designed engineered, such as closed or open offices, libraries, meeting rooms, exhibition halls, shopping markets, rest rooms, banquet halls etc.
New building construction development benefits:
Provide individual zones with class one temperature control with a lower initial investment.
Upgrade the original air conditioning system without any air duct-work changes, realize individual zone temperature control to a over cooled or heated zone.
Meet specific requirements:
Meet the special temperature control requirement of an air conditioning zone easy and a affordable way. Improve the unsatisfied, uncomfortable, energy wasting areas in an air conditioning system that is existing.
(Stand-alone) Wired wall thermostat or Remote control. W-models require standard thermostat 4 conductor wire connection between terminals. R-Models require batteries for power, and communicate via infrared Master Slave, one master diffuser is installed with a wired daisy chain connection for up to 5 diffusers. Installed with two wire twisted shielded, plenum or non-plenum rated wire. Slaves follow the master diffuser.
Web control allows you to see the control of the diffusers. WEB control includes a embedded software and therefore connection can be Networked locally, by local land, by other BMS systems, and wireless from your local network. Using the WEB control allows smart phone access control.Diffuser calibration; each diffuser has a range of calibrations settings that are available at the room units, data listed here. Temperature, temperature control range positive and negative span, reheat range setting, damper running distance, damper position min setting, cooling, heating mode change over and Fahrenheit / Celsius selection. See the manual for the settings.
Requirement for proper operation or design:
Cooling and heating supply air temperatures:
When operating the RSV-SVAD-series Variable Air Diffusers are designed, the air supply temperature are required as the following: Cooling Supply primary air as low as 10 ℃ and for HC models, cooling supply adjustable and factory set at 20℃. Heating supply primary air adjustable and factory set range of 28℃ to 49℃. HC models change over automatically.
Reheat contacts setting temperature difference range is 3℃.
Static air pressure range measured at the neck of the diffuser:
SVAD Variable Air Diffusers operate best when the static air pressure at the neck of the diffuser is controlled at the range adjustment from 12Pa to 62 Pa, to meet adequate design air volumes and to ensure primary a air induction effect in the ports, maintaining precise temperature control accuracy. The maximum static pressure in the neck of the diffuser effects the requirements of the indoor sound standards. Under normal office ambient sound standards (Noise criteria of NC20 to NC35) are designed. the inlet static pressure should be limited to not higher than 70 Pa. When constant pressure is maintained, the noise level will decrease gradually as the air volume and pressure decreases (the air damper closing). Selection of room noise (NC) under different inlet static air pressure is as shown in the performance parameter table.
Factory minimum damper position: Settings for heating or cooling set points are 24℃ with a minimum 30% damper position. 40% and 50% damper position as optional.
Individual Comfort control:
Each engineered RSV Smart Variable Air Diffuser has an adjustable, local sensors for remote or wall mounted thermostat, creating individual zones of comfort. It can not only control the temperature of different rooms, but also can maintain and control the temperature in different areas of the same open space.
Standard room settings 21℃ ~ 26 ℃. Optional 22℃ ~ 27℃.
Uncomplicated installations deployment to office layout changes
Systems designed with RSV SVAD have advantages over designed systems with VAV terminals because VADs are more adaptable to office layout changes. No single smart VAD zone is split up when new office walls are put up or moved, a common problem with VAV systems . If it is necessary to move a thermal VAD, it’s plug and play are simple to extend low voltage control and easier for remote controlled units. RSV SVAD is in comfort control at all times.
Low energy VAV terminal
Compare with VAV terminals, the smart SVAD systems greatly reduce the total air pressure drop compared to VAV terminals allowing a low pressure designed air duct-work system, less fan motor energy with low energy operation; fan energy is further reduced when the air handlers operate with variable speed drives. Each RSV SVAD offers comfortable individual zone control, no portion of the building zone is overcooled or overheated, thus superior low energy consuming system. Additional benefit, each RSV SVAD is a controlling VAV terminal and the control is stand alone or connect to a BA system. SVAD operate and turn down to work at low static duct pressure of (10 pa).
Class 1 building air distribution
Your system design is your signature, standard fixed opening diffusers designed in a VAV terminal system discharge outlets are fixed, allowing the air velocity to be variable. Variable as a terminal lowers the supply flow. This condition is uncomfortable as low air velocity dumps minimum air into the zone, resulting in cold unmixed air supply. RSV SVAD vary the discharge opening varying air volume, thus maintaining a constant discharge air velocity, increasing better throw, steady comfortable air movement and uniform temperature mixing distribution within the air conditioned space .
Constant mixing operation.
Each diffuser is designed to mix air into room and sense the rooms air temperature. In the diffuser a venturi nozzle is designed to use primary air and vent a small quantity of air at a higher velocity and in turn move air across a channel in the diffusers. Because this air is at a higher velocity the diffuser will pick up room air and mix the primary and throw the air across the diffuser and mix again into the room. Our R-models sensor senses the room temperature for control.
Cost per zone are lower
RSV SVAD installation skills are no different then installing standard diffusers. Lower cost than resetting a VAV terminal controller. In addition, RSV SVAD requires limited wires, no penumatic tubing and no medium air pressure system design that can waste energy, saving material and labor costs, and operating cost.
Precise room temperature control
RSV SVADs modes thermostat controls and actuates by adjusting the dampers to maintain a comfortable room temperature average within 0.9℃ of the temperature selected.
RSV SVAD once installed requires little maintenance. RSV SVAD requires standard diffuser cleaning intervals. If Step by step instructions for faults a display will show Error codes Check room temperature, change of sensor, communication, actuator, and remote control.
Architecture friendly appearance
Simple and smooth line profile with RSV SVADs are a easily accepted by architects in a layout of ceilings to match different decorations. Standard color (RAL9016) or adapted a different color each appreciated by both architects and interior designers. No wall thermostat is needed.
Constant air-volume constant static pressure control.
Installing into a constant air volume low pressure air conditioning system, static pressure control does not require additional control upgrades when no more than 30% the air volume in the total system is applied for use with Variable Air Diffusers operation is adaptable.
A. Return Collars (R-Collars)
The R-collars is a designed inlet collar screw mounted inside the diffuser neck of the collar and is connected to straight length of supply air duct-work. The gap between the inlet collar and the diffuser original collar neck allows air to bypass air into the return (negative pressure) ceiling plenum when the VAD damper closes. Model RC06, RC08, RC10 and RC12. ( duct-work is one size less then inlet collar)
Proper return air design is important to achieve a negative plenum pressure relative to the room. otherwise the radiant effect of the ceiling and leakage through the ceiling could result in poor control of the room temperature.
R collars can be used when there is a need to supply air to Variable Air Diffuser from a high or medium pressure duct system, note that the branch air duct static pressure must be considered when selecting the R collars for Variable Air Diffuser, to maintain acceptable NC levels. A manual balancing damper should be installed at the takeoff to each Variable Air Diffuser. Use this balancing damper to adjust for designed air flow from the Variable Air Diffuser. This is a pressure dependent system, if pressure in the higher pressure duct changes, flow through the lower pressure duct will change.
Typically in retrofit work, the energy is recorded and results are clearly compared. Operating a new system comparisons will have to be calculated. The comparatively low static pressure of the variable air diffusers, and thus the low pressure system plus energy savings operating a AHU with a VFD fan contributes to the overall beneficial cost savings of a SVAD system.
Design a Air Flow systems that is quiet, efficient and fully operational.
SVAD air flow systems are quiet, when compared to a VAV air terminal system design that when operating has a higher static pressure requirement. The fan in a SVAD system operates at a lower turn down ratio. The system’s energy is less. With less static pressure to overcome, the fan operates into the optimum operating range. Lowering the sound power level increasing the efficiency and operational performance.
Comparing a VAV air terminal and SVAD systems and side by side we can realize the energy savings.
Diffuser Energy Savings