Fan Speed Control System Charging - Data Aire MINI CEILING SERIES Installation, Operation And Maintenance Manual

Adjust the refrigerant charge until the sight glass has only sparse bubbles. The unit should be
allowed to stabilize for several minutes before meaningful measurements can be taken. A properly
charged system operating at typical parameters will have a head pressure of 225 to 275 psi. Suction
temperature should be 58 psi or greater. The super heat at the compressor suction line at least six
inches away from the compressor should be 8-15
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, subcooling and ambient temperature are also important
parameters. A system charged to a clear sight glass is often over-charged.

5.1.3. Fan Speed Control System Charging

The standard outdoor air cooled condenser for Data Aire equipment is a fan speed control system.
Connect the refrigerant drum to the low side of the system. Make sure all hoses are properly
purged. From a vacuum, feed liquid refrigerant into the high side of the system until the pressure
equalized, at this pint there will be about 79 to 80% of the total charge of the system. Charge with
approximately three pounds per nominal ton plus the line set. Charge circuit with about six pounds
of refrigerant to begin.
For example, a model DAMA 0212 is a nominal 2 ton unit. Charge with about six lbs. of refrigerant
to begin. It is likely that more refrigerant will be required to complete the charging procedure. Make
sure all hoses are properly purged.
Before starting a compressor, if the system has a refrigerant holding charge, 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 pre-heating 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-cool, or
low charge. It is likely that more refrigerant will be required to complete the charging procedure.
Adjust the refrigerant charge until the subcooling is between 8 and 10
o
15 F, there will be fl ashing and/or bubbles in the sight glass when the system is properly charged.
After the system is allowed to stabilize, verifi cation of a few key measurements should be noted.
The discharge pressure should be about 225 to 275 psi and the subcooling should be 8-10
depending on ambient conditions. Suction temperature should be 58 psi or greater. The superheat
at the compressor suction line at least six inches away from the compressor should be 8-15
units that are water/glycol cooled and air cooled units with air cooled condensers. Units with remote
condensing units the superheat should be 20 to 25
o
same 8 to 10 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, subcooling and ambient temperature are also important
parameters. A system charged to a clear sight glass is often over-charged.
o
F.
o
F at the compressor, the subcooling will be the
20
o
F and the super heat is 8 to
o
F,
o
F, for