Trane Symbio 210 Installation, Operation And Maintenance Manual page 42

Controller Points and Parameters
•
Flow Setpoints Setup
•
•
•
•
•
•
•
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).
•
•
42
Space CO High Limit: The controller adjusts the ventilation setpoint based on the current CO2
2
concentration. When the concentration is greater than or equal to this high limit, the zone is most
likely at design occupancy and the ventilation setpoint is set equal to Ventilation Setpoint Local.
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 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 to increase further, raising the
discharge air temperature, while the air valve remains at Airflow Setpoint Reset Maximum Local
Heat.
BAS-SVX091A-EN