10.After the disc has been removed, burnish the external sur- faces and clean the internal surfaces as outlined above.
The suction piping can now be brazed to the suction connection on the evaporator coil while maintaining a minimum flow of dry nitrogen.
Before brazing the suction line to the condensing unit;
1.Move the dry nitrogen supply to the access port on the suc- tion service valve of the condensing unit.
2.Burnish the external surfaces and clean the internal sur- faces of both the suction connection and the suction piping.
The suction line can now be brazed to the suction con- nection on the condensing unit while maintaining the flow of dry nitrogen.
After the liquid and suction lines have been installed, the system should be evacuated and charged.
EVACUATION AND CHARGING
With the liquid and suction line service valves closed, connect a vacuum pump through a charging manifold to the access ports on both the liquid and suction line service valves.
Note: The vacuum pump connection should be short and no smaller than 3/8" O.D.
The refrigerant lines and the evaporator coil can now be evacu- ated to 500 Microns without disturbing the charge in the con- denser coil or the compressor.
After proper evacuation and dehydration, charge refrigerant through the access port on the liquid line service valve allowing the vacuum to draw in as much refrigerant as possible.
CAUTION: Do not charge liquid refrigerant through the com- pressor suction connection.
CAUTION: Do not attempt to start the compressor without at least 8 hours of crankcase heat or compressor damage will occur.
To continue charging refrigerant, open the liquid and the suc- tion line service valves fully. Turn the stem of the liquid service valve clockwise 1/4 turn to open its access port for reading pressure.
Start the compressor (after 8 hours of crankcase heat), turn the stem of the suction line service valve clockwise 1/4 turn to open its service port and continue to charge refrigerant gas through this suction access port until you meet the conditions shown on the charging curve, Fig.
Open the liquid and vapor line service valves fully to close their access ports after the system has been charged.
Alternate Charging Methods
If you are starting a unit when the ambient temperature is higher or lower than those shown in Fig.
Method 1: Determine the total weight of the refrigerant for the total system by adding the required charge for the outdoor unit, the indoor unit and the refrigerant lines using information in Tables 2 (Physical Data) and 6 (Refrigerant Line Charge).
Using the charging procedures outlined above, weigh the required amount of refrigerant charge into the unit.
Method 2: Install a field supplied moisture indicating sight glass in the liquid line between the
Using the charging procedure outlined above, charge refrigerant until the moisture indicating sight glass is clear. Add approximately 1 extra pound of refrigerant for the 090 and 120 or 3 extra pounds for the 150 to assure a liquid refrigerant seal at the expansion valve under all operating conditions. Block the flow of the condenser air, if necessary, to assure a head pressure of 280 psig during the charging procedure.
Note: The installer should return to the job to verify the operating charge when the ambient temperature is within the conditions shown in Fig.
10 | Unitary Products Group |