Trane TR-OHS RCU Series Installation, Operation And Maintenance Manual page 17

Table 5. Weight of refrigerant (lb/100 ft, Type L)
Liquid Line 105°F Suction Line 40°F
Line Size O.D.
1/2
5/8
7/8
1 1/8
1 3/8
1 5/8
2 1/8
Table 6. Standard refrigerant charge weights
RCU Model Number
-012
-018
-024
-032
-040
-042
-048
-060
(a) Includes Receiver
Ensure an adequate supply of refrigerant is available
before beginning.
Figure 7. Refrigerant charging ports (RCU-O)
Check Valve
Discharge Port
(after check valve)
Head Pressure
Control Valve
Receiver
Service Port
Liquid Line
Sight Glass
Liquid Line
Field Installed 1/4 in.
Schrader Taps
SS-SVX004C-EN
R407C R407C
6.51 0.17
10.46 0.27
21.73 0.57
37.04 0.97
56.43 1.48
79.87 2.09
175.32 4.59
R407C (lb per Unit)
Flooded HP
Fan Control
Control
1.1 10.9
1.1 10.9
1.1 10.9
1.6 11.4
1.6 11.4
3.5 18.8
3.5 18.8
3.5 18.8
When charging a system using a blended refrigerant,
maintaining the composition of the refrigerant is essential.
To ensure correct composition, introduce the refrigerant
(R407C) into the system in liquid rather than vapor form.
Cylinders that do not have dip tubes should be inverted to
allow only liquid refrigerant to charge the system. Keeping
the temperature of the cylinder below 85°F will help
maintain the correct refrigerant composition while the
cylinder is emptied.
Initial System Charge
Introducing the Refrigerant Charge
Follow the steps below to charge systems with R407C
refrigerant. The initial charge will be performed by
introducing liquid refrigerant (R407C) to the discharge
side of the compressor or an available liquid line port with
the A/C unit turned Off.
1. Bleed air from hoses and break the vacuum by
(a)
supplying liquid refrigerant (R407C) to the discharge
port near the compressor until the pressure between
the unit and the refrigerant cylinder is equalized. This
initial charge allows the low pressure switch to HOLD
enabling the compressor to operate throughout the
process of charging the system.
Fine Tuning the System Charge
2. Once the initial charge is completed, additional
refrigerant will need to be added (or removed) with the
unit running until the superheat temperature can be
maintained between 10–15°F and sub-cooling can be
maintained between 5–20°F.
Field Installed
Shut-Off Valves
Installation
Suction
Port
Suction
Line
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