Carrier 50BA - Manual (Page 21)

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->NOTE: Water regulating valve (water-cooled
condenser) or condenser airflow (air-cooled
condenser) must he properly set before checking
system charge.
UNIT SIZE 50BA004 AND 006 - Units are
shipped with full operating charge. If recharging is
necessary:
1
.
2
.
3.
4.
6
.
Insert thermometer bulb in insulating rubber
sleeve on liquid line near filter-drier.
Add pressure gage to discharge line near
compressor.
After unit conditions have stabilized, read head
pressure on discharge line gage.
From standard Pressure-Temperature chart for
R-22, find equivalent saturated condensing
temperature.
Read liquid line temperature on thermometer;
then subtract from saturated condensing tem­
perature. The difference equals subcooling
temperature.
Compare the subcooling temperature with the
normal temperature listed in the following table.
If subcooling is low, add charge; if high, remove
charge.
UNIT
50BВ0ПП4
50BA006
^B^COOLING*
25
22 + 2 F
^Saturated condensing temperature at compressor minus
liquid line temperature
EXAMPLE;
Head pressure (from gage)
= 220 psig
Saturated cond temp (from chart) = 108 F
Liquid line temp (from thermometer) = 96 F
Subcooling (by subtraction) = 12 F
(add charge)
UNIT SIZE 50BB004 AND 006 — Units are
shipped with a holding charge only. To charge;
1. Open suction and discharge line service valves.
2. Blow holding charge, evacuate and leakiest
system.
3. Using standard refrigerant charging techniques
and the charts which follow (Fig. 33 and 34), add
refrigerant as required to maintain proper
operating conditions.
UNIT SIZE 50BA008 THRU 064 — These units,
with water-cooled condensers, are shipped with a
full operating charge. If recharging is necessary
(complete charge lost), weigh in amount of refrig­
erant indicated on unit nameplate and Table 1.
If unit has partial charge, it may be charged with
sight glass using standard charging techniques. Ad­
just the water regulating valve to maintain proper
saturated condensing temperature (168 - 226 psig).
Refrigerant can be added to 50BA008 and 012
units after sight glass is cleared to take advantage
of the condenser subcooling feature. Add refrigerant
as follows;
50BA008 — 2.6 lb
50BA0I2 — 0.5 lb
On 50BA064 units, adding liquid refrigerant to
the level of condenser test cock will provide 12 to
15 F subcooling.
UNIT SIZE 50BB008 THRU 064 — These units,
with remote air-cooled condensers, are shipped with
a holding charge only. To charge;
1. Open suction and discharge line service valves.
2. Blow holding charge, evacuate and leakiest
system.
3. Add sufficient refrigerant vapor to permit con­
tinuous operation after starting unit.
Start unit per Start-Up Section; then, using
standard charging techniques, add refrigerant as
required
to maintain normal operating
conditions.
Use charging chart supplied with condenser. If
information is not available, block off enough of
condenser coil to maintain 220 psig discharge
pressure and charge to a clear sight glass.
Return-Air Grille Removal (50BA,BB004-012) —
Loosen 2 screws visible thru grille at upper and
lower corner of one side. Slide grille side frame off
unit; then slide grille sideways and pull it away from
unit. To reassemble, reverse procedure.
4.
TEA
COMPRESSOR SUCTION PRESSURE (PSIG)
Temperature, Entering Air
COMPRESSOR SUCTION PRESSURE (PSIG)
TEA — Temperature, Entering Air
Fig. 34 — Charging Chart, 50BB006
21