Trane Ascend ACR C Series User Manual

AC-SVX003A-EN
87
Satisfied Setpoint with Operational
Pumpdown
The following diagram shows the normal transition from
running to shutting down due to the evaporator leaving
water temperature falling below the differential to stop
setpoint. It also outlines the termination criteria for
operational pumpdown.
Figure 33. Sequence of events: satisfied setpoint with operational pumpdown
* Operational Pumpdown is required if the Outdoor Air Temperature is less than 50F, or the Entering Evaporator Water
Temperature is greater than (outdoor air temperature – 10°F). With AFD, compressors will be at max speed for operational
pumpdown.
** Operational pumpdown is terminated normally when:
-The evaporator (suction) pressure is at or below the “Pumpdown Termination Pressure” setting OR LERTC saturated
pressure (32F for water [default]; -5F for glycol), which ever is greater
-The condenser (compressor discharge) pressure exceeds 315psia.
-The compressor pressure ratio exceeds 12.3
-The system differential pressure exceeds 265psid
** The maximum allowed time for Operational Pumpdown is Max Pumpdown Time setting (default to 120 sec.) * number of
compressors configured on the circuit.
Shutting Down
Last Circuit Mode: Shutting Down
SubMode: Operational Pumpdown
*
Shutting Down
Last Circuit Mode: Shutting Down
SubMode: Operational Pumpdown
*
Running
Last Circuit Mode:
Running
Running
Last Circuit Mode:
Running
Auto
Both Circuit Modes:
Waiting for Need to Cool
Auto
Both Circuit Modes:
Waiting for Need to Cool
Running
Last
Compressor
At Min
Capacity
Differential to Stop is Met
Operational Pumpdown
(See max time allowed below)
Fully Close EXV
Condenser Rfgt
Tank Solenoid Valve
Send Stop Command
To Compressor(s)
IF*
No Pumpdown Required
Pumpdown
Required
Turn Off Last Circuit’s
Condenser Fans
Normal Pumpdown Termination
**
Criteria is Met for Last Circuit
Enforce All Non Running
Mode Diagnostics
Enforce All Non Running
Mode Diagnostics
Auto
Close EXV
(0 to 25 Seconds)
Check for
Normal Pumpdown
Termination Criteria Met
**
Check for
Normal Pumpdown
Termination Criteria Met
**
* Operational Pumpdown is required if the Outdoor Air Temperature is less than 50F, or the Entering Evaporator Water
Temperature is greater than (outdoor air temperature – 10°F). With AFD, compressors will be at max speed for operational
pumpdown.
** Operational pumpdown is terminated normally when:
-The evaporator (suction) pressure is at or below the “Pumpdown Termination Pressure” setting OR LERTC saturated
pressure (32F for water [default]; -5F for glycol), which ever is greater
-The condenser (compressor discharge) pressure exceeds 315psia.
-The compressor pressure ratio exceeds 12.3
-The system differential pressure exceeds 265psid
** The maximum allowed time for Operational Pumpdown is Max Pumpdown Time setting (default to 120 sec.) * number of
compressors configured on the circuit.
Shutting Down
Last Circuit Mode: Shutting Down
SubMode: Operational Pumpdown
*
Running
Last Circuit Mode:
Running
Auto
Both Circuit Modes:
Waiting for Need to Cool
Running
Last
Compressor
At Min
Capacity
Differential to Stop is Met
Operational Pumpdown
(See max time allowed below)
Fully Close EXV
Condenser Rfgt
Tank Solenoid Valve
Send Stop Command
To Compressor(s)
IF*
No Pumpdown Required
Pumpdown
Required
Turn Off Last Circuit’s
Condenser Fans
Normal Pumpdown Termination
**
Criteria is Met for Last Circuit
Enforce All Non Running
Mode Diagnostics
Auto
Close EXV
(0 to 25 Seconds)
Check for
Normal Pumpdown
Termination Criteria Met
**
Perform Operational
Pumpdown for Last
Circuit if Required
Energize Last Circuit
Oil Heaters
Start-up and Shutdown

Trane Ascend ACR C Series Specifications

General

Brand	Trane
Model	Ascend ACR C Series
Category	Chiller
Language	English