First Co WCX12 Replacement Units - Manual (Page 3)

R410a INFORMATION
CAUTION: R410a systems operate at substantially higher pressures than R22 systems. Do not use R22 service
equipment or components on R410a equipment.
Tools Required for Installing and Servicing R410a Units
Manifold Sets
Up to 800 psig High Side
Up to 250 psig Low Side
Caution: R410a is not a direct replacement for R22. Only evaporators approved for use with R410a may be used with
these condensing units. Expansion valves and orifi ces must be calibrated and sized for use with R410a.
If this condensing unit is a replacement for a R22 system the evaporator and refrigerant line sets must be replaced or thoroughly
cleaned to remove residual refrigerant oil and contaminants. Orifi ces and expansion valve must be replaced with the proper
R410a replacement.
REFRIGERANT LINE
In keeping with the need to eliminate recovery of excess refrigerant charge, this unit is provided with a reduced factory charge. At
installation, it may be necessary to add a small amount of refrigerant. See the charging instructions regarding the fi nal charge level
required.
Do not open the service valves until the entire evaporator section and connecting tubing has been installed, leak tested, and evacu-
ated. Only when the unit is ready for operation should the service valves be opened.
In routing the lines from the evaporator coil to the condensing unit keep the length as short as possible. Maximum allowable line
length is 50 feet. Knockouts are provided on the unit cabinet at both upper corners and on each side for line entry into the cabinet.
Knockout only the openings to be used. Any unused openings in the cabinet must be sealed to prevent air from entering or leaving the
cabinet since this will reduce the amount of air being drawn over the condenser coil. The service valves provide for sweat connections
of the lines. Take care not to overheat the service valve. Use a wet cloth on the valve to protect it while sweating the line connec-
tion. In routing the lines, take care not to block removal of the motor or fan (pulls out through the access panel) or to block removal of
the access panel.
The suction line must be insulated to prevent condensation. A minimum insulation wall thickness of 3/8" with adequate vapor
barrier must cover the suction line from the evaporator coil to the condensing unit cabinet. The insulation should penetrate the unit
cabinet by a few inches to be certain any condensation formation will be contained inside the unit cabinet where it can do no damage.
PURGING AND LEAK TESTING
Connect the suction and liquid hoses from a gauge manifold to the service ports on the service valves. A hole covered by a plastic
snap plug is provided to allow entry of the gauge hoses. By using this hole the unit access panel can be put back on the unit without
disturbing the gauge hoses. This will be necessary once the unit is ready for operation. When the gauge hoses have been removed, be
sure to return the plastic plug to cover the service hole.
Connect a cylinder of dry nitrogen to the gauge manifold and open both liquid and suction manifold valves. Once the system has
balanced pressure, leak test all sweat fi ttings. If a leak is found repair the leak and repeat the procedure.
Caution: Do not use R410a refrigerant for the leak test as the mixture of air and R410a becomes combustible at
pressures greater than one atmosphere.
EVACUATION
Since the condensing unit will not have to be evacuated unless it has lost its charge, leave the service valves closed and recover
the refrigerant in the evaporator coil and connecting tubing only. Next connect the vacuum pump to the charging port on the gauge
manifold, start the vacuum pump and open the suction hand valve on the gauge manifold. Allow the pump to operate until a vacuum
of 300 microns is achieved. Shut off the pump and observe the pressure. If the system pressure rises above 500 microns continue the
pumping until the 500 micron pressure can be maintained. Close the hand valves at the gauge manifold, remove the vacuum pump
and open the service valves on the condensing units. The refrigeration system should now be ready to operate.
CHARGING
Should the condensing unit lose its charge the system will have to be evacuated as described and then the charge replaced by weigh-
ing in an amount equal to that shown on the unit nameplate.
WCX12 Condensing units should be attached to evaporators which are fi tted with a thermostatic expansion valve designed and cali-
brated for use with R410a. As a result all charging or charge adjustments must be made by measuring subcooling.
Even though the outdoor unit is factory precharged, the charge must be checked and adjusted if required. Allow suffi cient running
time, 20 to 30 minutes, for the system to balance.