Lennox Merit Series13ACD Installation Instructions Manual page 16

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 added or
removed, verify charge using
the approach method
If value is greater than shown,
remove refrigerant; if less than
shown, add refrigerant
SCº (Subcooling) Values (F:+/−1.0° [C: +/−0.6°])
ºF (ºC)* −018 −024
Any 7 (3.8) 12 (6.7)
*Temperature of air entering outdoor coil
START: Measure outdoor ambient temperature
USE WEIGH-IN METHOD DO NOT CHARGE UNIT
Weigh-in or remove refriger- (Results of charging at low
ant based upon line length temperatures not reliable)
If value is greater than shown (high
approach), add refrigerant; if less than
shown (liquid temp too close to ambient
temp, low approach),
refrigerant.
APPº (Approach) Values(F:+/−1.0° [C: +/−0.6°])
ºF (ºC)* −018 −024
Any) 6 (3.3) 6 (3.3)
*Temperature of air entering outdoor coil
505366M 01/08
Outdoor
Ambient 65ºF
(18ºC)?
BELOW
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.
−030 −036 −042 −048
9 (5) 10 (5.6) 14 (8) 10 (5.6) 13 (7.2)
Figure 30. HCFC−22 Subcooling TXV Charge
Outdoor
Ambient 65ºF
(18ºC)?
BELOW
If refrigerant added or removed,
retest to confirm that unit is
properly charged
remove
−030 −036 −042
8 (4.4) 12 (6.7) 5 (2.8)
Figure 31. HCFC−22 Approach TXV Charge
1. Confirm proper airflow across coil using figure
2. Compare unit pressures with Table 6, Normal
ABOVE
3. Use SUBCOOLING to correctly charge unit or to
4. Set thermostat to call for heat (must have a
5. Connect gauge set
6. Measure outdoor ambient temperature
7. When heat demand is satisfied, set thermostat to
8. Allow temperatures and pressures to stabilize.
9. Record line temperature:
10. Measure liquid line pressure and use the value to
11. Subtract to determine subcooling (SCº):
12. Compare results with table to the left.
−060
ABOVE
10. Subtract to determine approach (APPº):
−048 −060 11. Compare results with table to the left.
6 (3.3) 7 (3.8)
Page 16
27.
Operating Pressures.
verify the charge is correct.
cooling load between 70-80ºF (21−26ºC)
call for cooling
NOTE − If necessary, block outdoor coil to
maintain 325 − 375 psig.
LIQº = ______
determine saturation temperature:
SATº = ______
SATº_____ − LIQº _____ = SCº _____
1. Confirm proper airflow across coil using figure
27.
2. Compare unit pressures with Table 6, Normal
Operating Pressures.
3. Use APPROACH to correctly charge unit or to
verify the charge is correct.
4. Set thermostat to call for heat (must have a
cooling load between 70-80ºF (21−26ºC).
5. Connect gauge set.
6. When heat demand is satisfied, set thermostat
to call for cooling.
7. Allow temperatures and pressures to stabilize.
8. Record outdoor ambient temperature:
AMBº =_________
9. Record line temperature:
LIQº = __________
LIQº_____ − AMBº _____ = APPº_____