Lennox Elite Series Installation Instructions Manual page 24

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)
APPROACH TXV
If refrigerant is added
or removed, retest to
confirm that unit is
properly charged.
If value is greater than shown (high approach),
add refrigerant; if less than shown (liquid
temperature too close to ambient temperature,
low approach), remove 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)
SUBCOOLING TXV
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.
Once refrigerant charge is
correct, disconnect gauge set
and replace service port caps.
If refrigerant is added or
removed, verify charge
using the Approach
Method.
If value is LESS
than shown, add
refrigerant.
506635−01 11/10
ABOVE or
BELOW
64ºF and
BELOW
Figure 21. Using HFC−410A Approach (TXV) Charge Method
ABOVE or
BELOW
64ºF and
BELOW
CARDBOARD OR
PLASTIC SHEETS
If value is MORE
than shown, remove
refrigerant.
MORE or
LESS
Figure 22. Using HFC−410A Subcooling (TXV) Charge Method
1. Connect gauge set as illustrated in figure 17.
65ºF
2. Confirm proper airflow across coil using figure 19.
and
3. Compare unit pressures with table 4, Normal
ABOVE
Operating Pressures.
4. Set thermostat to call for heat (must have a cooling
load between 70-80ºF (21−26ºC).
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
Any 4 (2.2) 8 (4.4) 8 (4.4)
*Temperature of air entering outdoor coil
1. Connect gauge set as illustrated in figure 17.
65ºF
2. Confirm proper airflow across coil using figure 19.
and
3. Compare unit pressures with table 4, Normal
ABOVE
4. Set thermostat to call for heat (must have a cooling
5. Measure outdoor ambient temperature
6. When heat demand is satisfied, set thermostat to call
7. Allow temperatures and pressures to stabilize.
8. Record liquid line temperature:
9. Measure liquid line pressure and use the value to
10. Subtract to determine subcooling (SCº):
11. Compare results with table below.
SCº (Subcooling) Values (F:+/−1.0° [C: +/−0.6°])
ºF (ºC)* −018 −024
Any 10 (5.6) 10 (5.6)
*Temperature of air entering outdoor coil
Page 24
−030 −036 −042 −048
11 (6.1) 7 (3.9) 8 (4.4)
Operating Pressures.
load between 70-80ºF (21−26ºC)
for cooling
NOTE − If necessary, block outdoor coil to maintain
325 − 375 psig.
LIQº = ______
determine saturation temperature (see table 3):
SATº = ______
SATº_____ − LIQº _____ = SCº _____
−030 −036 −042
9 (5.0) 12 (6.7) 8 (4.4)
−060
9 (5.0)
−048 −060
9 (5.0) 7 (3.9)