Page 19
TABLE 7
Adding Charge per Indoor Unit Match using Subcooling Method
Use
cooling
mode
Use
heating
mode
1 Check the airflow as illustrated in figure20 to be sure the indoor airflow is as required.
(Make any air flow adjustments before continuing with the following procedure.)
2 Measure outdoor ambient temperature; determine whether to use
cooling
mode
or
heating mode
to check charge.
3 Connect gauge set.
4 Check Liquid and Vapor line pressures. Compare pressures with Normal Operating
Pressures table 5, (
Table 5 is a general guide. Expect minor pressure variations.
Significant differences may mean improper charge or other system problem.
)
5 Set thermostat for heat/cool demand, depending on mode being used:
Using cooling mode
When the outdoor ambient temperature is 60°F (15°C) and above.
Target subcooling values in table below are based on 70 to 80°F (21−27°C) indoor return
air temperature; if necessary, operate heating to reach that temperature range; then set
thermostat to cooling mode setpoint to 68ºF (20ºC). When pressures have stabilized,
continue with step 6.
Using heating mode
When the outdoor ambient temperature is below 60°F (15°C).
Target subcooling values in table below are based on 65−75°F (18−24°C) indoor return air
temperature; if necessary, operate cooling to reach that temperature range; then set
thermostat to heating mode setpoint to 77ºF (25ºC). When pressures have stabilized,
continue with step 6.
6 Read the liquid line temperature; record in the LIQº space.
7 Read the liquid line pressure; then find its corresponding temperature in the temperature/
pressure chart listed on page 20 and record it in the SATº space.
8 Subtract LIQº temp. from SATº temp. to determine subcooling; record it in SCº space.
9 Compare SCº results with table below, being sure to note any additional charge for line
set and/or match−up.
10 If subcooling value is greater than shown in table, remove refrigerant; if less than shown,
add refrigerant.
11 If refrigerant is added or removed, repeat steps 5 through 10 to verify charge.
60ºF (15ºC)
SATº
LIQº
–
SCº
=
INDOOR
HEAT
MATCH−UP
PUMP
Subcool Target
Cooling Heating
(+5ºF)
(+1ºF)
*Add
charge
INDOOR
HEAT
MATCH−UP
PUMP
Subcool Target
Cooling Heating
(+5ºF)
(+1ºF)
*Add
charge
INDOOR
HEAT
MATCH−UP
PUMP
Subcool Target
Cooling Heating
(+5ºF)
(+1ºF)
*Add
charge
XP14
−
018
lb oz
XP14
−
030 (cont’d)
lb oz
XP14
−
042 (cont’d)
lb oz
CBX27UH−018/024
13
7
0
8
CX34−31A/B
11
6
1
6
CX34−62C, −62D
12
6
0
9
CBX32MV−018/024
15
7
0
0
CX34−38A/B
11
6
2
3
CX34−49C
12
6
0
7
XP14
−
024
lb oz
CX34−43B/C
15
11
2
14
CX34−60D
12
6
0
4
CH23−41
16
8
0
2
XP14
−
036
lb oz
XP14
−
048
lb oz
CBX26UH−024
25
7
0
0
CBX26UH−036
26
5
0
0
CH23−68
20
9
2
9
CBX27UH−018/024
15
8
1
2
CBX26UH−037
25
4
1
9
CBX26UH−048
8
7
1
9
CBX32M−018/024
16
8
0
14
CBX27UH−036
13
6
0
3
CBX27UH−048
11
8
1
2
CBX32M−030
15
8
1
3
CBX32M−036
13
6
0
2
CBX32M−048, −060
11
8
1
2
CBX32MV−018/024
16
8
0
14
CBX32M−042
13
6
0
3
CBX32MV−048, −060
11
8
1
2
CBX32MV−024/030
15
8
1
2
CBX32MV−036
13
6
0
3
CBX32MV−068
10
7
1
12
CH33−42B
14
11
1
10
CBX32MV−048
11
8
2
5
CH33−50/60C
11
8
1
1
CH33−36A
16
8
1
0
C33−44C
13
6
0
0
CH33−62D
10
7
1
14
CH33−36C
16
8
0
4
CH33−50/60C
11
8
2
5
CH33−60D
11
8
0
0
CR33−30/36A/B/C
25
7
0
2
CH33−44B
13
6
1
7
CR33−50/60C
35
5
0
0
CX34−25A/B
16
8
0
14
CH33−48B
13
6
1
8
CR33−60D
37
6
0
0
CX34−31A/B
15
8
1
3
CR33−50/60C
25
4
1
15
CBX33−048, −060
12
8
1
2
CX34−36A/B/C
16
8
1
8
CR33−48B/C
25
5
0
9
CX34−62C, −62D
10
7
1
7
CX34−38A/B
14
11
2
2
CX34−49C
13
6
2
4
CX34−49D
11
8
0
14
XP14
−
030
lb oz
CX34−43B/C, −50/60C
13
6
1
8
CX34−60D
11
8
0
0
CH23−41
11
6
0
8
CX34−38A/B, −44/48C
13
6
0
0
XP14
−
060
lb oz
CH23−51
6
6
1
12
XP14
−
042
lb oz
CH23−68
12
5
0
0
CBX26UH−024
30
8
0
6
CH23−68
20
9
0
13
CBX26UH−048
12
7
1
0
CBX26UH−030
29
8
2
3
CBX26UH−042
27
6
0
0
CBX26UH−060
14
4
0
0
CBX27UH−030
11
6
2
4
CBX27UH−042
12
6
0
8
CBX27UH−060
12
5
0
0
CBX32M−030
11
6
1
6
CBX32M−048
12
6
0
7
CBX32M−048, −060
12
5
0
0
CBX32M−036
11
6
2
4
CBX32MV−048
12
6
0
8
CBX32MV−048, −060
12
5
0
0
CBX32MV−024/030
11
6
1
6
CH33−62D
12
6
0
10
CBX32MV−068
12
7
1
0
CBX32MV−036
11
6
2
4
CH33−50/60C
12
6
0
7
CH33−50/60C
12
5
0
0
C33−44C
11
6
2
3
CH33−60D
12
6
0
4
CH33−62D
12
5
0
0
CH33−36C
11
3
0
0
CR33−50/60C,−60D
26
6
0
4
CBX33−060
12
8
0
0
CH33−42B
6
6
1
12
CBX33−042,−048
12
7
0
4
CX34−62C, −62D
12
7
1
0
CR33−30/36A/B/C
30
8
0
8
CBX33−060
12
6
0
7
*Add charge = Extra match−up amount required in addition to charge indicated on Heat Pump nameplate (remember to also add any charge required for line set differ-
ences from 15 feet).
