Trane Symbio 210 Installation, Operation And Maintenance Manual page 36

Symbio 210 Controller Points and Parameters
Flow Setpoints Setup
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Discharge Air Reset Limits
The following parameters are used for Single Duct Units that are equipped with either modulating
hot water reheat or SCR electric heat, which allows variable airflow when reheat is activated (for
example, "dual maximums" control sequence).
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Airflow Setpoint Minimum: Although the UCM will read flow down to 5% of cataloged, the
range of MIN FLOW settings is 0% or 10% to 100% of cataloged. The UCM will not drive its flow
below this minimum flow value under normal operating conditions while in the cool mode.
Cool mode occurs when cool air is in the supply duct. The entry in this field must be less than
or equal to the entry in the Airflow Setpoint Maximum field.
Airflow Setpoint Maximum: This range is 10% to 100% of the cataloged unit CFM size. Cooling
and heating flow can be edited to zero.The UCM will not drive its flow above this maximum flow
value under normal operating conditions while in the Cool mode. Cool mode occurs when cool
air is in the supply duct. The entry in this field must be greater than or equal to the entry in any
of the Minimum fields.
Standby Minimum Airflow: Occupied standby mode is used to reduce the heating and cooling
demands during the occupied hours when the space is temporarily unoccupied. For example,
it can be activated for a classroom currently not in use. Standby Minimum is the minimum
amount of airflow desired during this mode.
Airflow Setpoint Minimum Standby Heat: Occupied standby mode is used to reduce the
heating and cooling demands during the occupied hours when the space is temporarily
unoccupied. For example, it can be activated for a classroom currently not in use. Airflow
Setpoint Minimum Standby Heating is the minimum amount of airflow desired when in the
heat mode during this mode.
Airflow Setpoint Minimum Heat: The UCM will not drive its position/flow below this value
under normal operating conditions while in the HEAT mode (warm air in the supply duct) or
while it is using local heat.
Airflow Setpoint Maximum Heat: The controller enters maximum flow heat on receipt of a
communicated command and remains in Airflow Setpoint Maximum Heat until the command
changes. The controller maintains the flow rate at the heating maximum airflow. This is
normally used with a rooftop unit with staged heat that needs a Max constant volume of air
movement to keep the heat exchanger from overheating and tripping the heat in the rooftop
unit tripping on a high limit safety.
Airflow Setpoint Minimum Local Heat: If the Min Local Heat flow is enabled, then this Minimum
Local Heat setpoint is used to determine the minimum position/flow instead of the Airflow
Setpoint Minimum Heat when local heat is on. This entry must be less than or equal to the entry
for the Airflow Setpoint Maximum Heat.
Airflow Setpoint Reset Minimum Local Heat: The minimum position/flow when local heat
(either modulating hot water or SCR electric) is on. This entry must be less than or equal to the
entry for Airflow Setpoint Reset Maximum Local Heat. When reheat is initially activated the air
valve opens to, and remains at, this minimum position/flow setpoint, while reheat capacity is
modulated to maintain the space temperature at the active heating setpoint. Once reheat
capacity has increased to the point that the discharge air temperature reaches the Discharge Air
Temperature Design Setpoint, the controller will begin to increase airflow above this minimum
setpoint.
Airflow Setpoint Reset Maximum Local Heat: The maximum position/flow when local
heat (either modulating hot water or SCR electric) is on. This entry must be greater than or equal
to the entry for Airflow Setpoint Reset Minimum Local Heat. Once reheat capacity has increased
to the point that the discharge air temperature has reached the Discharge Air Temperature
Design Setpoint, the controller will begin to increase airflow above Airflow Setpoint Reset
Minimum Local Heat. If the air valve reaches this maximum setpoint, reheat capacity is allowed
BAS-SVX084A-EN