Specifications

5.3 Air Cooled Systems

5.3.1 Fan Speed Control System Charging

The standard air cooled condenser provided with Data Aire equipment has fan speed control on

the lead motor (nearest the header). After the ﬁ eld refrigerant piping is properly completed connect

the refrigerant drum to the low side and charge with vapor. (Refer to Section 2.6 LEAK TESTING

and Section 2.7 EVACUATION prior to charging the system.)

It is likely that more refrigerant will be required to complete the charging procedure (line runs

need to be taken into account). Make sure all hoses are properly purged. From a vacuum feed liquid

refrigerant into the high side of the system until the pressure equalizes. At this point there will be

about 70-80% of the total charge in the system.

Before starting a compressor, the crankcase heater should be energized for a minimum of 12

hours to reduce the possibility of liquid slugging on start-up. Failure to energize the crankcase heater

could result in compressor damage.

If the system is charged from a vacuum, the preheating of the compressor is not necessary. Start

the system and allow the system to stabilize to room temperature. Bubbles in the sight glass are not

unusual at this point and can be caused by ﬂ ashing from liquid line pressure drop, low sub-cooling

or low charge. It is likely that more refrigerant will be required to complete the charging procedure.

Adjust the refrigerant charge until the sub-cooling is between 8 and 10°F. There may be ﬂ ashing

and/or bubbles in the sight glass when the system is properly charged.

The system should be allowed to stabilize for 15 to 20 minutes before meaningful measurements

can be taken. After the system is allowed to stabilize, veriﬁ cation of a few key measurements should

be noted. The discharge pressure with R-410A should be between 340-415 PSIG and the sub-cooling

should be between 8-10°F depending on ambient conditions. Units with R-407C the discharge

pressure should be between 240-295 PSIG. Suction temperature should be 100 PSIG or greater

with R-410A and 58 PSIG or greater with R-407C. Measure the superheat at the compressor suction

line at least 6 inches away from the compressor. The superheat should be between 8-15°F.

Note: Charging to a full liquid line sight glass should never be the sole means of determining the

correct refrigerant charge. Other parameters such as superheat, suction pressure, head pressure,

sub-cooling and ambient temperature are also important. A system charged to a clear sight glass

is often overcharged.

5.3.2 Flooded System Charging

Flooded type systems are units having refrigerant circuits with an optional liquid receiver and head

pressure control valve. When the ambient temperature falls during cold weather, the head pressure

control valve will regulate the ﬂ ow of refrigerant to ensure nearly constant receiver pressure. The

condenser is partially ﬂ ooded with liquid in cold weather. In warm weather the extra refrigerant is

stored in the receiver.

Flooded systems require more refrigerant than fan speed control systems. Connect the pressure

gauge manifold set to the high and low ports near the compressor. Connect the charging line to

the refrigerant tank and set it for liquid feed. Open the refrigerant tank valve and purge the line.