Lennox AC13 -018 Installation Instructions Manual page 18

START: Measure outdoor ambient temperature
USE EITHER APPROACH
OR SUBCOOLING
METHOD
WEIGH IN TXV
Refrigerant Charge per Line Set Length
Ounces per 5 feet (g per 1.5 m)
Liquid Line
adjust from 15 feet (4.6 m) line set*
Set Diameter
3/8" (9.5 mm)
3 ounce per 5' (85 g per 1.5 m)
NOTE − *If line length is greater than 15 ft. (4.6 m), add this
amount. If line length is less than 15 ft. (4.6 m), subtract this
amount.
START: Measure outdoor ambient temperature
USE WEIGH-IN METHOD
DO NOT CHARGE UNIT
Weigh-in or remove refrigerant
(Results of charging at low
based upon line length
temperatures not reliable)
BLOCK OUTDOOR COIL: [sometimes necessary with lower
temperatures] Use cardboard or plastic sheet to restrict the airflow
through the outdoor coil to achieve pressures from 200−250 psig
(1379−1724 kPa) . Higher pressures are needed to check charge.
Block equal sections of air intake panels and move coverings
sideways until the liquid pressure is in the above noted ranges.
If refrigerant is added
or removed, verify
charge using the
Approach Method.
If value is LESS
than shown, add
refrigerant.
506109−01 10/08
ABOVE or
BELOW
65ºF
(18ºC) and
ABOVE
Figure 34. HCFC−22 Weigh In TXV Method
ABOVE or
BELOW
64ºF
(17.7ºC) and
BELOW
If value is MORE
than shown, remove
refrigerant.
TEMP*
MORE or
*Temperature of air entering outdoor coil is 65ºF (18ºC) or above.
LESS
Figure 35. HCFC−22 Subcooling TXV Charge
Page 18
64ºF
1. Check Liquid and suction line pressures
(17.7ºC) and
2. Compare unit pressures with Table 5,
BELOW
3. Conduct
4. Weigh in the unit nameplate charge plus
1. Confirm proper airflow across coil using figure
65ºF
32.
(18ºC)
2. Compare unit pressures with Table 5, Normal
and
Operating Pressures.
ABOVE 3. Set thermostat to call for heat (must have a
cooling load between 70-80ºF (21−26ºC)
4. Connect gauge set
5. Measure outdoor ambient temperature
6. When heat demand is satisfied, set thermostat to
call for cooling
7. Allow temperatures and pressures to stabilize.
NOTE − If necessary, block outdoor coil to
maintain 325 − 375 psig.
8. Record liquid line temperature:
LIQº = ______
9. Measure liquid line pressure and use the value to
determine saturation temperature (see table 4):
SATº = ______
10. Subtract to determine subcooling (SCº):
SATº_____ − LIQº _____ = SCº _____
11. Compare results with table below.
SCº (Subcooling) Values (F:+/−1.0° [C: +/−0.6°])
−018 −024 −030
7 (3.8) 12 (6.7) 9 (5.0)
Normal Operating Pressures.
leak check; evacuate
previously outlined.
any charge required for line set differences
over 15 feet.
This nameplate is for illustration purposes
only. Go to actual nameplate on outdoor
unit for charge information.
−036 −042 −048
10 (5.6) 14(8.0) 10 (5.6) 13 (7.2)
as
−060