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VVZT DAT Control Mode
With the Symbio 700 VVZT control sequence, the end user will be able to choose to use the internally
derived Discharge Air Temperature Setpoint Active, or to override the value with their own. Use-cases
for this may include optimizing humidity control sequences per-application or to meet certain product-
level specifications.
If the VVZT DAT Control Mode – Active point is set to “Auto”, the VVZT control algorithm will use the
internally derived Discharge Air Temperature Setpoint Active, for all cooling capacity output control.
If the VVZT DAT Control Mode – Active point is set to “Manual”, the VVZT control algorithm will use the
Discharge Air Cooling Setpoint (Target) – Active as an upper limit for the Discharge Air Temperature
Setpoint Active calculation.
Example: Set to 50F, the unit will use 50F or lower discharge air temperature setpoint for all space
cooling demands.
When space temperature is 2F below cooling setpoint or 1F above heating setpoint, the controller will
suspend the discharge air setpoint active override to maintain space comfort until space temperature
recovers to above cooling setpoint.
Alternatively, the Discharge Air Maximum Cool Limit and Discharge Air Minimum Cool Limit can be set
equal to force the unit to use a constant discharge air temperature setpoint for cooling control.
While these overrides/sequences are not recommended for space comfort control, the control
sequence will support it.
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