41
CHECKING REFRIGERANT CHARGE
Servicing of the refrigeration circuit must only be performed
by agencies or individuals possessing Type II or Universal
certification as defined in Section 608 of the Clean Air Act. See
Qualifications on page 8.
This HPWH unit is factory charged with 134a refrigerant. See the
rating label on the HPWH unit and Table 9 for refrigerant charge
by weight. It should not be necessary to add or remove refrigerant
during installation or start up. Refrigerant lost during frequent
refrigerant pressure testing can cause low refrigerant conditions.
Air and water ow should always be checked rst to eliminate
other potential problems before checking the refrigerant charge.
Check Water Temperature Rise
Always check water temperature rise through the HPWH
unit’s internal heat exchanger before checking the refrigerant
charge. See Start Up on page 29 for information on how to
measure the water temperature rise.
If the measured water temperature rise during start up was
within 8°F to 12°F (4°C to 7°C) checking the charge is not
necessary unless other conditions warrant testing.
If the measured temperature rise through the HPWH unit is less
than 8°F (4°C) checking the charge is not necessary unless
other conditions warrant testing. Short water piping runs
between the HPWH and the storage tank will produce lower
temperature rises and are not problematic.
If the measured temperature rise through the HPWH unit is
more than 12°F (7°C) check for restrictions in the inlet and
outlet water piping connected between the HPWH unit and the
storage tank.
SUPERHEAT CALCULATION
1.
2.
Measure and record the suction pressure at the
suction line pressure access port inside the unit.
Convert the recorded suction pressure to
saturated temperature.
3. Measure the suction line temperature near the suction line
pressure access port inside the unit.
4. Compare the suction line temperature to the to the saturated
temperature in Table 10.
TABLE 10
R134A SATURATED TEMPERATURE CHART
SATURATED
TEMPERATURE °F
SATURATED
TEMPERATURE °C
REFRIGERANT
PRESSURE (PSI)
0 -18 7
5 -15 9
10 -12 12
15 -9 15
20 -7 18
25 -4 22
30 -1 26
35 2 30
40 4 35
45 7 40
50 10 45
55 13 51
60 16 57
65 18 64
70 21 71
75 24 79
80 27 87
85 29 95
90 32 104
95 35 114
100 38 124
105 41 135
110 43 146
115 46 158
120 49 171
125 52 185
130 54 199
135 57 214
140 60 229
145 63 246
150 66 263
155 68 281
5. The difference between saturated temperature and suction
line temperature is the superheat. Superheat normal range
should be 8°F to 12°F (4.4°C to 6.7°C).
TABLE 9
MODEL FACTORY CHARGE R134A
C25
7#
C60
C90
C125
C185
C250
14#
20#
60#
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