Refrigerant Characteristics; Pressure/Temperature Settings; Saturated Refrigerant Pressure - Trane TR-SCS Series Installation, Operation And Maintenance Manual

The head pressure control valve setting is printed on the
valve. This setting is the lowest head pressure that will be
maintained during unit operation. Add refrigerant to the
system (slowly metering). Charge the unit until you reach
the HGBP valve setting if applicable.
Set up the HGBP valve and disable the solenoid after
adjusting. Slowly continue to meter in refrigerant until you
reach the head pressure control valve setting printed on
the valve (225 psig for R407C; 290 psig for R410A).
All other low ambient controls should not be enabled
during the final charging procedure, deenergize the
solenoids to prevent operation. It is best to under charge
the system and operate the unit in the cooling mode to
achieve this, otherwise you may add refrigerant above the
valve setting and then will be unable to test the head
pressure control valve operation.
The head pressure control valve modulates to maintain
system head pressure; you will witness this if the above
procedure is strictly followed. Under low ambient
conditions with the header fan functioning, the head
pressure will lower during operation. The valve will not
allow the pressure to drive below the printed setting on the
valve. Check the system superheat and sub-cooling
temperatures.
Turn the unit off for 15–30 minutes. Restart the system and
observe the operating pressures. The suction pressure
should not dip or drive below the low pressure switch
setting.
Checking the Charge
To ensure you are not over charged, set up the condenser
fan to maintain pressure (320 psig for R407C; 440 psig for
R410A) or your summer maximum operating head
pressure. Hold the pressure steady at this setting. You
should observe that cycling "Off" on head pressure will
not occur now or during warmer temperatures.
If a refrigerant level sight glass is included on the side of
the receiver (optional), it may be used to assist in charging
the air conditioning system. The proper charge can be
confirmed by viewing the level of refrigerant in the
receiver while the unit is running at an elevated discharge
pressure (320 psig for R407C; 440 psig for R410A).
Add refrigerant charge until the refrigerant appears in the
sight glass indicating the receiver is 80% filled. When the
level of refrigerant in the receiver reaches the sight glass,
the unit is fully charged.
Note: Remove the blockage to the air intake of the
condenser.
Final Adjustment
Now you may adjust the condenser fan settings to assist
with low ambient control. The following settings have
proven effective:
R407C Refrigerant
Fan 1 - 320 psig cut-in; 240 psig cut-out
Fan 2 - 330 cut-in; 250 cutout
SS-SVX006C-EN
Fan 3 - 340 cut-in; 260 cutout Fan
Fan 4 - 345 cut-in; 265 cutout
EC Fan (Fan 1 on TR-SCS Condenser) - 240 psig start;
65 psig differential
R410A Refrigerant
Fan 1 - 440 psig cut-in; 330 psig cut-out
Fan 2 - 460 cut-in; 355 cutout
Fan 3 - 475 cut-in; 365 cutout Fan
4 - 485 cut-in; 375 cutout
EC Fan (Fan 1 on TR-SCS Condenser) - 340 psig start;
100 psig differential
Fill out the applicable sections of the Warranty
Registration and Start-Up Checklist.

Refrigerant Characteristics

Pressure/Temperature Settings

The table below is provided to assist with the normal
settings of the system for R407C and R410A refrigerant.
Where applicable, minimum and maximum settings are
given along with normal operating pressures.
Note: The operating pressures for R410A refrigerator
significantly higher than R407C.
Table 8. Refrigerant pressure/Temperature settings
Normal
Sub-cooling °F
Superheat °F
Design Condensing Temp.
@ 95 °F Ambient
Suction Pressure (psig)-
R407C
Suction Pressure (psig)-
R410A
Fan Cycling Control- Fan
On (psig)- R407C
Fan Cycling Control- Fan
On (psig)- R410A
Fan Speed Control (psig)-
R407C
Fan Speed Control (psig)-
R410A

Saturated Refrigerant Pressure

The following refrigerant vapor pressure tables are
provided for reference for R407C and R410A refrigerant.
Installation
Min Max
10 5 20
15 10 20
125 105 140
70 55 85
130 105 155
320 240 340
440 330 480
320
440
21