Stulz FLAIR series, Installation, Operation And Maintanance Manual

Page: 23 / 48

FLAiR Series Installation, Operation & Maintenance Manual
(©Aug, 2007)
Air Technology Systems, Inc.
2.8 System Settings and Adjustments
Refrigerant charging procedures vary depending on the
type of refrigerant used in the unit. Before charging,
check the unit nameplate to confirm the refrigerant
type. If the unit operates with
R22 refrigerant see
section 2.8.1. If R407C is used, see section 2.8.2.
NOTE
Refrigerant charging must be performed by a jour-
neyman, refrigeration mechanic or an air condi-
tioning technician.
2.8.1 R22 Refrigerant Charging Procedures
2.8.1.1 Self-Contained Systems
All self-contained water/glycol-cooled units (units that
require no refrigerant field piping) are factory charged
with R22. No field charging is required.
2.8.1.2 Remote Air-Cooled Split Systems (AR/AHU)
Remote air-cooled units are shipped from the factory
with a dry nitrogen holding charge, which must be
removed before piping and charging the unit.
PREPARING SYSTEM FOR CHARGING
1. Once all connections have been made, pressurize
the system to 150 psig with dry nitrogen. Leaks
may be detected by checking the standing
pressure.
2. After ensuring there are no leaks, relieve pressure
and evacuate the system. Pull a vacuum of 50
microns or less using the suction and discharge
service ports and the service port of the receiver (if
applicable). Hold the vacuum for at least 2 hours.
Ensure no portion of system has been isolated
from the evacuation process (liquid, suction or
discharge lines).
CAUTION
A proper vacuum must be drawn on the refriger-
ant system prior to charging. If this is not done
the refrigerant will combine with moisture in the
pipes to form an acid that will eventually lead to
compressor failure.
2-12
FINE TUNING THE SYSTEM CHARGE
2.8.1.2.1 0ºF Fan Cycling and -20ºF Variable
Speed Control
The following instructions are for charging systems
with condenser fan cycling or variable speed control
using R22 refrigerant.
1. Bleed air from hoses and "break" the system
vacuum by supplying R22
vapor. Supply R22
vapor to the suction port until the pressure is
raised to about 50 psig. This small holding charge
allows the low pressure switch to “make” through
out the process of fine tuning the system charge.
WARNING
Do not add liquid R22 refrigerant to suction side
of system.
2. Start the system and use the system controller to
lower the temperature set-point 3-5°F below room
temperature. This will ensure the cooling mode
stays on during the charging procedure.
CAUTION
An adequate heat load must be supplied to the
unit to ensure a proper charge.
3. Supply R22 vapor to the suction port until the
liquid line sight glass is cleared of all bubbles.
4. After the unit has stabilized, the liquid line sight
glass should be clear and the discharge pressure
should be a minimum of 200 psig. A superheat
reading should be taken on the suction line near
the feeler bulb from the thermal expansion valve,
ensuring the temperature measuring device is well
insulated. The superheat should be approximately
12-15ºF. Maximum allowable superheat tempera-
ture is 20°F.
5. A sub-cooling reading should be taken on the
output side of the condenser, with the temperature
measuring device being well insulated. The sub-
cooling temperature should be approximately 10-
20ºF.