Start-Up and Shutdown
66
RTAF-SVX001K-EN
Satisfied Setpoint
The figure below shows the normal transition from
Running to shutting down due to the Evap Leaving water
temp falling below the differential to stop setpoint.
Figure 44.
Sequence of events: satisfied setpoint
*
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 in the following configurations when:
Water with 2-Pass Evaporator:
-The evaporator (suction) pressure is at or below the “Pumpdown Termination Pressure” setting OR
LERTC saturated pressure (28.6F), which ever is greater
-The condenser (compressor discharge) pressure exceeds 315psia.
-The compressor pressure ratio exceeds 8.
-The system differential pressure exceeds 265psid or <25min.
Glycol with 2-Pass Evaporator:
The evaporator (suction) pressure is at or below the “Pumpdown Termination Pressure” setting OR
LERTC saturated pressure (per guidance -5F minimum), which ever is greater
-The condenser (compressor discharge) pressure exceeds 315psia.
-The compressor pressure ratio exceeds 8.
-The system differential pressure exceeds 265psid or <25min.
Water with Single Pass Evaporator:
-The evaporator (suction) pressure is at or below the “Pumpdown Termination Pressure” setting OR
LERTC saturated pressure (32F), which ever is greater
-The condenser (compressor discharge) pressure exceeds 315psia.
-The compressor pressure ratio exceeds 12.3
-The system differential pressure exceeds 265psid.
Glycol with Single Pass Evaporator:
-The evaporator (suction) pressure is at or below the “Pumpdown Termination Pressure” setting OR
LERTC saturated pressure (per guidance -5F minimum), 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.
***
Automatic evaporator isolation valve control will close valve if Outdoor Ambient Air Temperature at
circuit shutdown is less than evaporator leaving water cutout setpoint plus 3°C.
****
If Condenser Refrigerant Tanks are installed
8/
//
8 1
// 0/
//
0 2
// 012 - 10/
//
0 1
// 3/
//
3 2
// 012
Shutting Down
Last Circuit Mode: Shutting Down
SubMode: Operational Pumpdown
*
6/
/
/
/
6 1
// 2/
/
/
/
2 2
// 012 - 8/
/
/
/
8 1
// 0/
/
/
/
0 2
// 012
Running
Last Circuit Mode:
Running
10/
/
/
/
0 1
// 3/
/
/
/
3 2
// 012 - 12/
/
/
/
2 1
// 1/
/
/
/
2
// 012
Auto
Both Circuit Modes:
Waiting for Need to Cool
8/
8
8 11/
1 2012
6/
6
6 13/
3
3 2012
Running
Last
Compressor
At Min
Capacity
10/
0
0 14/
4
4 2012
Differential to Stop is Met
Operational Pumpdown
(See max time allowed below)
Fully Close EXV
Close 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
6
6
6
6
6
6
6
/
/
/
/
/
/
/
/
6
6
6
6
6
6
6
6
6
1
1
1
1
1
1
2
2
2
2
2
2
/
/
/
/
/
/
/
/
2
2
2
2
2
2
2
2
2
2
2
2
2
0
0
0
0
0
0
0
1
1
1
1
1
1
2
2
2
2
2
2
-
-
-
1
1
1
1
1
1
2
2
2
2
2
2
/
/
/
/
/
/
/
/
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
/
/
/
/
/
/
/
/
1
1
1
1
1
1
2
2
2
2
2
2
0
0
0
0
0
0
0
1
1
1
1
1
1
2
2
2
2
2
2
Enforce All Non Running
Mode Diagnostics
6/
6 1
1
1
1
1
1
//
5
5
5
5
5
/
/
/
/
/
5
5
5
5
2
2
2
2
2
/
/
/
/
/
/
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
E
2
2
2
2
2
2
2
En
12/
2
2 11/
1 2012
Auto
Close EXV
(0 to 25 Seconds)
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
/
/
/
/
/
/
/
/
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
/
/
/
/
/
/
/
/
/
/
/
/
/
1
1
1
1
1
1
1
1
/
/
/
/
/
/
/
/
/
2
2
2
2
2
2
2
2
2
2
2
2
/
/
/
/
/
/
/
/
/
/
/
/
//
0
0
12
1
1
1
1
1
1
1
nn
2
2
2
2
2
2
2
ni
/
/
/
/
/
/
/
/
in
2
2
2
2
i
1
1
1
1
1
1
1
ng
/
/
/
/
/
/
/
n
1
1
1
1
1
1
1
g
/
/
/
/
/
/
/
/
/
2
2
2
2
2
2
2
2
2
2
/
/
/
/
/
/
/
/
/
/
/
/
//
0
0
0
12
Energize Last Circuit
Oil Heaters
6/
6
6 1
1
1
1
//
3
3
3
3
3
3
3
/
/
/
/
/
3
3
3
3
2
2
2
2
2
/
/
/
/
/
/
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
6/
6
6 12/
2
2 2012 -12/
2
2 10/
0
0 2012
Check for
Normal Pumpdown
Termination Criteria Met
**
***
Automatic Evaporator
Isolation Valve control may
close valve
Perform Operational
Pumpdown for Last
Circuit if Required