VARI-AIR-TROL

VARIABLE VOLUME OPPOSED BLADE DAMPER -Model VVOBD

 The Variable Volume Opposed Blade Damper (Model WOBD) is an anodised aluminium opposed blade damper, similar to the AOBD (pg. 6). The WOBD is operated by a 24 volt reverse acting damper motor. It takes six minutes to move from full open to full closed. The WOBD is used when modulating temperature control is needed. Usually, the VVOBD is used on the low pressure side of the main VAV box to sub zone larger VAV systems and provide better temperature control of smaller individual zones.

 Operated by a special dead band thermostat Model WT (ordered separately), the WOBD will modulate the air flow through the duct in order to maintain the VVT set point. The VVT has a built in dead band of OF. Above or below this dead band, the damper will modulate open or closed, depending if the thermostat is operating in heating or cooling mode. As the WT thermostat calls, it will signal the VVOBD to slowly begin opening. If the VVT reaches the set point before the damper is fully open (or closed), the WT will be in the dead band, and stop the damper at that position. 

The VVOBD can also be used to control static pressure in the duct system. By using a static pressure switch in place of the VVT, the WOBD will modulate slowly to maintain a set range of static pressure in the duct system. A SPC Static Pressure Controller is recommended for this application

When the WOBD is used to control heating and cooling, the VVT HC is used. The VVT HC incorporates a built in HEAT COOL switch to manually reverse the action of the thermostat between heating and cooling. For automatic change over of a single WOBD and WT, the DPBT is used to sense the supply air temperature and automatically switch the VVT between Heat and Cool modes. When multiple VVOBD's are used for heating and cooling, the VVCO is recommended. The VVCO can reverse the action of two WT thermostats from one single point, eliminating the need for sub-bases on each thermostat. The VVOBD is recommended on systems up to 1 " of static pressure. Over 1 " we suggest using the CDO52

 NOTE: The VVOBD dampers have no provision for operating the heating or cooling equipment when open. 

ORDERING INFORMATION When ordering, state size, W" x H", for WOBD and WIOBD. Motor and end plate will be on the height dimension (shorter side). When ordering a bottom mount damper, order H" x W". Motor and end plate will be on width dimension (longer side).

 OTHER MODELS AVAILABLE WITH VARIABLE VOLUME MOTORS INCLUDE: VVOBD BM, VV IOBD, W SRTD and W ASCD. These models are the same as the AOBD BM, IOBD, SRTD and ASCD, except they have the variable volume motor in place of the two position motor.