VAVVA - VA Series VAV Terminal

The Regulator VA series of pressure independant VAV terminals consist of a microprocessor controller installed on a low noise VAV terminal. The heart of the package is the intelligent VAV controller. This controller has the ability to comunicate on a RS485 network for remote monitoring/configeration via a host personal computer.

There are three analogue inputs and a RS485 Comms port. The temperature sensor is a 2000 ohm NTC thermistor at 25 deg C. The velocity sensor is an averaging pitot tube type which accurately measures the duct velocity as well as the duct supply air temperature. This is used to automatically reverse the controller output to the damper motor when in a heat/cool mode. EG:Reverse cycle units. The changeover point is 23 deg C. The remote setpoint has a range of 20 to 25 deg C and is normally concealed under the sensor housing when fitted.

For ease of operation there are only two adjustments on the front panel of the controller. The first is the room temperature setpoint with a range of 10 to 35 deg C, which when turned fully counter-clockwise will look for the remote setpoint, when connected. The remote setpoint would normally have a range of 20 to 25 deg C. The second adjustment is the velocity setpoint, this is adjustable from 3 metres per second up to 15 metres per second. The one adjustment adjusts both the maximum and minimun airflows. The minimun airflow is a preset percentage of the set maximun, the factory defult is 60%, however this can be changed by the use of a personal computer. The current status of the controller can be determined by the seven LED’s on the front panel.Two for heating stages, two for cooling stages, one for the Reverse Acting output, one for the Direct Acting output, and one for the controller status. Note: The XC2902 controller does not have Direct or Reverse Acting outputs, nor any relay outputs.

Pressure Independant
Low noise design
Averaging pi tot tube sensor
Low pressure drop design
Prewired and tested
RA and DA 0-10VDC outputs
Auto change-over with hot/cold supply air
Room sensor with concealed setpoint
200 -265 VAC powered
Australian designed and manufactured

The servomotor is driven directly from the internal power supply of the controller via a three wire connection. This is a nominal 24vac reversing output. There are two 0-10VDC outputs, one Reverse Acting (heating) and one Direct Acting (cooling). These can be used to control the central plant. (XC2942 Controller only) As standard there are four internal relays that are programmed as two stage cooling (relays 3& 4 ) and two stages of time proportional heating (relays 1 & 2).The relays are rated at 10A 250VAC. (XC2942 Controller only)

The SM2010D servomotor is a 24VAC/DC three wire reversing actuator with 15NM outputtorque. As an option it can be fitted with a Power Fail Module so that the VAV can be driven
open or closed on power failure.

The VA series VAV terminal is constructed from zinc coated sheet steel with a minimum thickness of 0.7mm. As this is a low height VAV terminal (250mm), 32mm Transverse Duct Flanges are standard fitting to increase the rigidity of the unit and to ease installation. Both inlet and outlet are of the same dimensions, again easing installation. The VAV terminal is lined with 25mm silver foil faced fibreglass insulation to indusry standard 880. No raw edges are exposed to the airstream. The damper blade assembly is constructed from 1.0mm zinc coated steel and pivots on a 12.7mm dia. aluminium shaft rotating in two nylon bushes. With the damper blade in the fully closed position, there is a maximum leakage of 2% at 250Pa differential pressure. The VA series VAV terminals can be fitted with Electric Heater modules (600mm length) for electric reheat or with Hot Water coils as required.