CyberOne EC DX IOM Manual
conditions, refrigerant may need to be added or removed
when fine tuning the charge to obtain the correct superheat
and sub-cooling temperatures.
Table 1.
Weight of Refrigerant
(lb/100 ft of type L tubing)
Line Size
O.D.
Liquid Line
Discharge
Line
R407C
R407C
1/2
6.51
0.87
5/8
10.46
1.40
7/8
21.73
2.91
1 1/8
37.04
4.95
1 3/8
56.43
7.55
1 5/8
79.87
10.68
2 1/8
175.32
23.44
Example:
Estimate the amount of refrigerant required for
a refrigeration circuit in a system using R407C refrigerant
consisting of a 5 ton COS-060-AR A/C unit with Hot Gas
Reheat and Hot Gas Bypass connected with a 1/2” x
30 ft liquid line and 7/8” x 30 ft discharge line to a STULZ
Model SCS-060-SAA -30 °F condenser with flooded head
pressure control and a receiver. Refer to the SCS Installation,
Operation and Maintenance Manual for details.
Condenser w/Receiver
=
12.2 lb
+ 1/2” Liquid Line- 30.0 × 6.51
=
1.953 lb
100
+ 7/8” Discharge Line- 30.0 × 2.91 =
0.873 lb
100
+ A/C Unit
=
4.0 lb
+ Adder for HGRH and HGBP
=
3.2 lb
Estimated Refrigerant Charge
=
22.226 lb
2.8.6
Preparing System for Charging
1.
With all the system piping connections made, perform
a dry nitrogen leak detection test on the system. Using
dry nitrogen only, pressurize the system to150 psig.
Ensure all service and solenoid valves are energized
open and that no part of the system is isolated from the
pressurized nitrogen (liquid, suction or discharge lines
and reheat coil).
2.
Since there is no refrigerant in the system to detect at
this point, leaks may be detected by observing if there’s
been a change in the standing pressure after 12 hours.
A significant drop in pressure (>10 psig) indicates a leak
in the system that needs to be repaired. After the system
is determined to be free of leaks, you may evacuate the
system.
CAUTION
A proper vacuum must be drawn on the refrigerant
system to remove moisture prior to charging. If this
Table 2. Weight of Refrigerant For A/C Units (lb)
COS EC Model
Number
Approximate R407C Charge
Base
Charge
Charge
Adder w/
HGRH* &
HGBP**
024- AHU
3.1
3.6
024- AR
3.2
3.6
042- AHU
3.9
3.6
042- AR
4.0
3.6
060- AHU
3.9
3.6
060- AR
4.0
3.6
096- AR
6.8
3.6
120- AR
6.8
3.6
*HGRH = Hot Gas Reheat
**HGBP = Hot Gas Bypass
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