Carrier 48KLA Installation, Start-Up And Service Instructions Manual page 16

CHECKING AND ADJUSTING REFRIGER¬
ANT CHARGE — Refrigerant system is fully
charged with R-22 refrigerant, tested and factory
sealed. For most applications, factory charge is the
correct amount for best performance; however, this
charge may require a slight adjustment to attain
rated performance.
NOTE: Adjustment of refrigerant charge is not re¬
quired unless unit is suspected of not having proper
R-22 charge. For all applications, correct R-22
charge for best performance is charge that results in
a suction gas superheat of 5 F at compressor inlet
when unit is operating at ARI rating conditions of
95 F db outdoor and 80 F db/ 67 F wb indoor.
A superheat charging label is attached to outside
of compressor access door. Label includes a Field
Superheat Charging Table and a Required Suction-
Tube (F) temperature chart.
Table 7 is intended for use when minor unit charge
adjustments are required. For large adjustments,
evacuate unit and weigh in charge according to unit
rating plate. Use Table 7 to approximate charge if
ARI rating conditions cannot be obtained. Refer to
required airflow rates in Table 8. Charge unit with
outdoor fan operating only at high speed.
An accurate superheat-, thermocouple-, or
thermistor-type thermometer, a sling psychrometer
and a gage manifold are required when using super¬
heat charging method for evaluating unit charge.
Do not use mercury or small dial-type thermometers
because they are not adequate for this type of
measurement.
Proceed as follows:
1. Remove caps from low- and high-pressure serv¬
ice fittings. See Fig. 4 for location of entrance
for refrigerant pressure gage hoses.
2. Using hoses with valve core depressors, attach
low- and high-pressure gage hoses to low- and
high-pressure service fittings, respectively.
3. Start unit in cooling mode and let unit run until
system pressures stabilize.
4. Measure and record the following:
a. Outdoor ambient-air temperature (F db).
b. Evaporator inlet-air temperature (F wb).
c. Suction-tube temperature (F) at low-side
service fitting.
d. Suction (low-side) pressure (psig).
5. Using Field Superheat Charging Table, compare
outdoor-air temperature (F db) with evaporator
inlet-air temperature (F wb) to determine desired
system operating superheat temperature.
6. Using Required Suction-Tube (F) table, com¬
pare desired superheat temperature with suction
(low-side) operating pressure (psig) to determine
proper suction tube temperature.
Table 7 — Refrigerant Charging Label
DESIRED SUPERHEAT TEMPERATURE (F)
{Measured @ Low-Side Service Port)
OUTDOOR
EVAPORATOR AIR INLET EWB (F>
EDB (F) 54 |
"J
58 |Q 62 64 66
68 70]
-
72 i 74 j 76
65 10 ; 13 : 16 Eg 21 24
m
30 j ESI HI HI QB
70 7
10 1
13
m
19 i 21 B 27! HI jcgj El
75
—
6
M
B 18
m
24 | 28: BSl ES SsSi
80
— —
Bj
m
KB 15
m
EB HI
El
E9
85
— — —
Bl
m
11 IH IS B B Eti
90
— — —
B
m
B
m m
ESS 31
95
— — — B
m
Mol 14 LL8J 22
m
100
— — — — —
B
B
IB KH ES IB
105 j n
— — — —
B B kq
B E£3 Hi
110
n
—
B
—-
—
—
n
B
KIq
115
-
■ —
-
B
—
B
IQ
Eg
KM
NOTES:
1 DashedAreas: Do not attemptto charge system undertheseconditionsor
refrigerant slugging may occur
2 Add charge if actual superheat temperature is higher than chart value
and remove if lower Allow ±3F for tolerance
REQUIRED SUCTION-TUBE TEMPERATURE {F) vs.
DESIRED SUPERHEAT TEMPERATURE (F)
(Measured @ Low-Side Service Port)
DESIRED
SUPERHEAT
SUCTION OR LOW-SIDE PRESSURE (Psig)
AT SERVICE PORT
TEMP (F)
61.5 64.2 67.1 70 73 76 79.2 82.4
85.7
0
35 37 39
41
43 45 47
49 51
2 37 39 41 43 45 47 49 51 53
4 39 41 43 45 47 49 51 53 55
6
41
43 45 47
49
51 53 55
57
8 43 45 47
49
51 53 55
57
59
10 45 47
49 51 53
55
57
59
61
12 47 49 51 53 55 57 59 61 63
14 49 51 53 55 57 59 61 63 65
16 51 53 55 57 59 61 63 65 67
18 53 55 57 59 61 63 65 67 69
20 55 57 59
61
63
65 67
69
71
22 57 59 61 63 65 67 69 71 73
24 59 61 63 65 67 69 71 73 75
26 61 63 65 67 69 71 73 75 77
28 63 65 67 69
71 73 75
77 79
30 65 67 69 71 73 75 77 79 81
32 67 69 71 73 75 77 79 81 83
34 69 71 73 75 77 79 81 83 85
"ni" """ .d
36 71 73 75 77 79 81 83 85 87
38 73 75 77 79 81 83 85 87 89
40 75 77 79 81
83
85 87 89 91
NOTE: Measure suction-tube temperature with an accurate superheat
thermocouple, or thermistor-type thermometer
7. Compare actual suction-tube temperature with
proper suction tube temperature. Using a toler¬
ance of ±3 F, add refrigerant if actual tempera¬
ture is more than 3 F higher than proper suction
tube temperature, or remove refrigerant if actual
temperature is more than 3 Flower than required
suction-tube temperature.
NOTE: If the problem causing inaccurate readings is
a refrigerant leak, see Unit Preparation, Refrig¬
erant Leaks section of these instructions.
L
16