Remote Minimum Position Control; Demand Controlled Ventilation (Dcv) - Trane Symbio 700 Controller Application Manual

Outdoor Air Damper Control

Remote Minimum Position Control

With an installed Customer Connection Module and Remote Minimum Position is configured in the
Symbio™ 700, a wired potentiometer can be used to adjust the outdoor air damper minimum position
setpoint in the range of 0 to 50%. The setting is reported via Remote Minimum Position. If Remote
Minimum Position input and Demand Controlled Ventilation is installed, the Remote Minimum Position
provides the minimum damper position setpoint at full fan capacity. Tables below provide details of when
the Remote Minimum Position input is utilized in minimum ventilation control.
When Remote Minimum Position is installed with Demand Controlled Ventilation, the Remote Minimum
Position input is used in place of Design Minimum OA Damper Position at Full Fan Capacity setpoint.
See tables below for more details.

Demand Controlled Ventilation (DCV)

Demand controlled ventilation reduces energy consumption by reducing the outdoor air damper below
design minimum ventilation based on space CO2. When Demand Controlled Ventilation is configured
and Supply Fan Compensation is enabled, DCV resets the outdoor air damper minimum position based
on space CO2 and supply fan speed. Decreasing CO2 levels will decrease damper position below the
Design Minimum toward the DCV minimum damper position setpoint. Increasing CO2 level will increase
damper position toward design minimum setpoint. DCV requires a valid space CO2 value from a
building management system or wired sensor. If Space CO2 value is invalid or Supply Fan
Compensation is disabled, the Symbio™ 700 will revert to Outdoor Air Minimum Position Control.
Demand controlled ventilation setpoints used in all methods.
•
•
Occupied and Occupied-Bypass mode. If the supply fan is at 100% and CO2 is at the Space CO2 High
Limit (1500 ppm default), the outdoor air damper will be positioned at Design Minimum OA Damper
Position at Full Fan Capacity (10% default). As CO2 in the space reduces below the high limit, the
outdoor air damper will close. If CO2 falls below the Space CO2 Low Limit, the damper position will be
at DCV Minimum OA Damper Position at Full Fan Capacity (5% default).
Occupied-Standby mode. The damper will reset, based on CO2, between the Standby Minimum OA
Damper Position at Full/Mid/Min Fan Capacity and DCV Minimum OA Damper Position at Full/Mid/Min
Fan Capacity.
The following tables define the Symbio 700 setpoints for Demand Controlled Ventilation control, which
depend on the features enabled and configuration options installed. Each table is based on the supply
fan and damper type installed. Supply Fan Compensation is a feature that can be enabled or disabled.
Demand Controlled Ventilation and Remote Minimum Position are Symbio 700 configurations.
Table 6. 0 to 100% economizer – variable speed supply fan
Supply Fan
Compensa-
30
Space CO2 High Limit
Space CO2 Low Limit
Demand
Controlled Minimum
tion Ventilation
Enabled Installed
Enabled Installed Not Installed
Remote
Occupancy
Status
Position
Remote Minimum Position (Full Fan Capacity)
Design Minimum OA Damper Position at Mid Fan Capacity
Occupied,
Design Minimum OA Damper Position at Min Fan Capacity
Occupied
Installed
Bypass DCV Minimum OA Damper Position at Full Fan Capacity
DCV Minimum OA Damper Position at Mid Fan Capacity
DCV Minimum OA Damper Position at Min Fan Capacity
Design Minimum OA Damper Position at Full Fan Capacity
Occupied, Design Minimum OA Damper Position at Mid Fan Capacity
Occupied
Design Minimum OA Damper Position at Min Fan Capacity
Bypass
DCV Minimum OA Damper Position at Full Fan Capacity
Outdoor Air Damper Controlling Setpoints
ACC-APG002A-EN