Cool - Economizer; Cool - Economizer + Dx; Supply Air Tempering - Space Temperature Control; Unoccupied Cooling - Trane Symbio 700 Controller Application Manual

Space Temperature Control
Cool — Economizer
If the unit is configured for a modulating outdoor air damper and conditions are suitable for economizer
cooling, the supply fan will operate at minimum speed while the economizer damper modulates between
the Outdoor Air Damper Minimum Position Setpoint and 100% to satisfy the discharge air temperature
setpoint. If the economizer damper reaches 100% open and additional cooling capacity is required, the
supply fan will increase toward 100% to provide additional cooling to the space.
Cool — Economizer + DX
Economizer Cooling + DX is a mode of operation when both economizer and DX cooling are active. If
actively economizing, outdoor air damper is 100% and supply fan speed reaches 100% then DX cooling
will be added if the unit is not satisfying space cooling requirements.
If DX cooling is active and economizer cooling enables, the control will transition to increase economizer
damper above minimum position to 100% to satisfy space cooling while decreasing DX cooling. DX
cooling will steadily be removed as long as economizer cooling is able to satisfy the cooling load. The
supply fan operates to the lowest speed possible during the transition.
Supply Air Tempering — Space Temperature Control
If the Supply Air Tempering function is configured and the Discharge Air Temperature local sensor is
valid, this function prevents excessively cold discharge air from being supplied to the space. Supply Air
Tempering is an option for VVZT and multi-speed supply fan units when auxiliary heat is installed.
Supply Air Tempering is not supported when a Conventional TStat is configured.
The following requirements must be met to allow Supply Air Tempering on a Staged Heat unit:
•
•
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, the
Supply Air Tempering function will bring ON one stage of auxiliary heat.
Supply Air Tempering terminates 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 one or more
stages of Heat are required to meet the Space Temp Heating Setpoint Status, Supply Air Tempering will
terminate and the unit will stage heating to meet the current space demand.

Unoccupied Cooling

Unoccupied mode is used when the building is unoccupied, and the space conditions are exceeding
temperature limits. The unit is normally off in unoccupied mode, but unoccupied operation is allowed in
any heat cool mode except OFF.
If a valid space temperature input rises above the Unoccupied Cooling Setpoint, unit operation starts
unoccupied cooling to manage space temperature. The controller operates in Single Loop Space
Temperature Control with ventilation disabled. DX or economizer cooling will steadily increase to 100%
capacity. The supply fan will follow capacity control until it reaches 100% fan speed. Cooling continues
until space temperature is 4°F less than the Unoccupied Cooling Setpoint, the unit will then cycle off.

Unoccupied Heating

When the unit is in unoccupied mode and the valid space temperature input falls below the Unoccupied
Heating Setpoint, unit operation starts unoccupied heating to manage space temperature. The controller
operates in Single Loop Space Temperature Control with ventilation disabled. The supply fan starts
increases with heating capacity unit both reach 100%. Heating continues until space temperature is 4°F
greater than the Unoccupied Heating Setpoint, the unit will then cycle off.
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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.
ACC-APG002A-EN