Unit Stop; Capacity Limit Control - Trane Symbio 700 Application Manual

B B u u i i l l d d i i n n g g A A u u t t o o m m a a t t i i o o n n S S y y s s t t e e m m S S u u p p p p o o r r t t S S e e q q u u e e n n c c e e s s
function to prevent excessively cold discharge air from being supplied from the unit. The
sequence for VVZT systems are consistent with CVZT systems, utilizing single-speed, and full
airflow operation.
Supply Air Tempering is not applicable when a Conventional TStat is configured as the Space
Controller.
The following requirements must be met to allow Supply Air Tempering on a Staged Heat unit:
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If the discharge air temperature drops to the Discharge Air Temperature Minimum Cool Limit -
Active and the Space Temperature is less than the Active Space Temp Cooling Setpoint Status –
0.5°F and if there are no stages of heat on, the Supply Air Tempering function will bring ON one
stage of available staged auxiliary heat.
N N o o t t e e : : Heat Pump units will energize 1 stage of auxiliary Heat in order to meet the Supply Air
Once Supply Air Tempering is active, the stage of heat will be turned OFF if the Discharge Air
Temperature rises to 10°F ABOVE the Discharge Air Temperature Minimum Cool Limit - Active,
or the Space Temperature rises to the Space Temp Cooling Setpoint Status. Additionally, if the
Space Heat Control function determines that 1 or more stages of Heat are required to meet the
Space Temp Heating Setpoint Status, Tempering will be discontinued and the unit will stage
heating to meet the current space demand.

Unit Stop

The Unit Stop feature allows for immediate shutdown of all devices in the equipment when
initiated. When a Unit Stop request is received, the following actions are taken:
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The Unit Stop request can be initiated from the following sources:
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If a Unit Stop is initiated, the source of the Unit Stop can be determined by the Unit Stop Source
Point and other status/diagnostic points.

Capacity Limit Control

There are three sources for capacity limitation provided by the Symbio700:
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The supply fan is ON.
The unit is in Occupied mode.
The unit is in any heating mode, including Heat, Emergency Heat, Morning Warmup, Max
Heat but is not actively heating OR
The unit is in any cooling mode except night purge, but not actively cooling and cooling
capacity has been OFF for 5 minutes.
Tempering request; compressor-based heating will not be used to satisfy Supply Air
Tempering.
All equipment control binary outputs are de-energized
– Indoor fan
– Compressors
– Condenser fans
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Unloader solenoids
– Heat stages
All equipment control analog outputs are set to their minimum/off command values.
All communicating devices, such as Supply fan VFD, are commanded to their Off state.
All control algorithms are initialized to their normal startup values and held until the stop
request is released.
Unit Stop Command
Equipment Shutdown Input
Emergency Override BAS
Phase Monitor
ACC-APG001A-EN