Lennox HS29-012, Unit Information

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Page 12
D − Charging
If the system is completely void of refrigerant, the recom-
mended and most accurate method of charging is to weigh the
refrigerant into the unit according to the total amount shown on
the unit nameplate. Also refer to the SPECIFICATIONS tables
on pages 1 and 2.
If weighing facilities are not available or if unit is just low on
charge, the following procedure applies.
1 − Expansion Valve Systems
The following procedures are intended as a general guide for
use with expansion valve systems only. For best results, indoor
temperature should be between 70
°
F and 80
°
F (21.1
°
C and
26.7
°
C). Outdoor temperature should be 60
°
F (15.6
°
C) or
above. Slight variations in charging temperature and pressure
should be expected. Large variations may indicate need for fur-
ther servicing.
IMPORTANT
The following procedure requires accurate
readings of ambient (outdoor) temperature, liq-
uid temperature and liquid pressure for proper
charging. Use a thermometer with accuracy of
+2
°
F (+ 1.1
°
C) and a pressure gauge with accu-
racy of +5 PSIG ( +34.5 kPa).
APPROACH METHOD (TXV SYSTEMS)
(Ambient Temperature of 60 F [16 C] or Above)
1 − Connect gauge manifold. Connect an upright
HCFC−22 drum to center port of gauge manifold.
2 − Record outdoor air (ambient) temperature.
3 − Operate indoor and outdoor units in cooling mode. Al-
low outdoor unit to run until system pressures stabi-
lize.
4 − Make sure thermometer well is filled with mineral oil
before checking liquid line temperature.
5 − Place thermometer in well and read liquid line tem-
perature. Liquid line temperature should be warmer
than the outdoor air temperature. Table 4 shows how
many degrees warmer the liquid line temperature
should be.
Add refrigerant to lower the liquid line tempera-
ture.
Recover refrigerant to raise the liquid line tem-
perature.
Add refrigerant slowly as the unit approaches the
correct temperature. This will allow refrigerant
to stabilize allowing the correct temperature to
be read.
6 − When unit is properly charged, liquid line pressures
should approximate those in table 6.
TABLE 4
HS29 MODEL NO.
Approach Temperature
Liquid Line − Outdoor Ambient F ( C)
−141, −012 7 (3.6)
−211, −018 4 (2.2)
−261, −024−2 5 (2.8)
−024−3, −030 11 (6.1)
−311 10 (5.6)
−410, −460, −048 12 (6.7)
−036 14 (7.8)
−510, −650 13 (7.2)
−042 17 (9.5)
−060 12 (6.7)
IMPORTANT
Use tables 6 and 7 as a general guide for per-
forming maintenance checks. Tables 6 and 7 are
not a procedure for charging the system. Minor
variations in these pressures may be expected
due to differences in installations. Significant
deviations could mean that the system is not
properly charged or that a problem exists with
some component in the system. Used prudent-
ly, tables 6 and 7 could serve as a useful service
guide.
2 − RFCIV Systems
The following procedures are intended as a general guide for
use with RFCIV systems only. For best results, indoor tempera-
ture should be between 70
°
F and 80
°
F (21.1
°
C and 26.7
°
C).
Outdoor temperature should be 60
°
F (15.6
°
C) or above. Slight
variations in charging temperature and pressure should be ex-
pected. Large variations may indicate a need for further servic-
ing.
1 − Connect gauge manifold. Connect an upright
HCFC−22 drum to center port of gauge manifold.
2 − Operate indoor and outdoor units. Allow outdoor unit to
run until system pressures stabilize.
3 − Make sure thermometer well is filled with mineral oil
before checking liquid line temperature.
4 − Read liquid line pressure and convert to condensing
temperature using temperature/ pressure con-
version chart.
Condensing temperature (read from gauges) should
be warmer than liquid line temperature.
5 − Place thermometer in well and read liquid line temper-
ature. Table 5 and table 8 show how much warmer
the condensing temperature should be.
6 − Subtract liquid line temperature from condensing tem-
perature to determine subcooling. Compare with
table 6.
Add refrigerant to lower liquid line temperature.
Recover refrigerant to raise liquid line temp.
7 − When unit is properly charged liquid line pres-
sures should approximate table 6 .
E − Oil Charge
See compressor nameplate.