Lennox XC14 Installation Instructions Manual page 20

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)
If refrigerant is added
or removed, verify
charge using the
Subcooling Method.
If value is LESS
than shown, add
refrigerant.
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 325−375 psig
(2240−2585 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.
505367M 04/08
ABOVE or
BELOW
64ºF and
BELOW
If value is MORE
than shown, remove
refrigerant.
MORE or
LESS
Figure 36. Using HFC−410A Approach TXV Charge Method
ABOVE or
BELOW
64ºF and
BELOW
If value is MORE
than shown, remove
refrigerant.
MORE or
LESS
Figure 37. Using HFC−410A Subcooling TXV Charge Method
1. Confirm proper airflow across coil using figure 33.
65ºF
2. Compare unit pressures with table 7, 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. When heat demand is satisfied, set thermostat to call
for cooling.
6. Allow temperatures and pressures to stabilize.
7. Record outdoor ambient temperature:
AMBº =_________
8. Record liquid line temperature:
LIQº = __________
9. Subtract to determine approach (APPº):
LIQº_____ − AMBº _____ = APPº_____
10. Compare results with table below.
APPº (Approach) Values(F:+/−1.0° [C: +/−0.6°])
ºF (ºC)* −018 −024
65 (18) 4 (2.2) 5 (2.8) 4 (2.2)
75 (24) 5 (2.8) 6 (3.3) 5 (2.8)
85 (29) 6 (3.3) 6 (3.3) 6 (3.3)
95 (35) 5 (2.8) 7 (3.9) 6 (3.3)
105 (41) 3 (1.7) 6 (3.3) 6 (3.3)
115 (45) 3 (1.7) 6 (3.3) 6 (3.3)
*Temperature of air entering outdoor coil
1. Confirm proper airflow across coil using figure 33.
65ºF 2. Compare unit pressures with table 7, Normal
Operating Pressures.
and
3. Set thermostat to call for heat (must have a cooling
ABOVE
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 6):
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°])
ºF (ºC)* −018 −024
65 (18) 10 (5.6) 10 (5.6) 10 (5.6) 11 (6.1) 10 (5.6)
75 (24) 6 (3.3) 8 (4.4)
85 (29) 6 (3.3) 8 (4.4)
95 (35) 6 (3.3) 8 (4.4)
105 (41) 10 (5.6) 8 (4.4)
115 (45) 10 (5.6) 8 (4.4)
*Temperature of air entering outdoor coil
Page 20
−030 −036 −042 −048
5 (2.8) 6 (3.3) 7 (3.9)
5 (2.8) 8 (4.4) 8 (4.4)
6 (3.3) 8 (4.4) 8 (4.4)
6 (3.3) 8 (4.4) 8 (4.4)
5 (2.8) 8 (4.4) 8 (4.4)
6 (3.3) 8 (4.4) 9 (5.0)
−030 −036 −042
8 (4.4)
8 (4.4) 11 (6.1) 7 (3.9) 8 (4.4)
7 (3.9) 11 (6.1) 7 (3.9) 8 (4.4)
7 (3.9) 10 (5.6) 7 (3.9) 8 (4.4)
7 (3.9) 10 (5.6) 7 (3.9) 8 (4.4)
6 (3.3) 9 (5.0) 7 (3.9) 7 (3.9)
−060
8 (4.4)
9 (5.0)
9 (5.0)
9 (5.0)
9 (5.0)
9 (5.0)
−048 −060
8 (4.4)
7 (3.9)
8 (4.4)
7 (3.9)
6 (3.3)
6 (3.3)