Lennox Merit 14ACX−018−230 Installation Instructions Manual page 24

WEIGH IN (RFC AND TXV)
CALCULATING SYSTEM CHARGE FOR OUTDOOR UNIT VOID OF CHARGE
If the system is void of refrigerant, first, locate and repair any leaks and then weigh in the refrigerant charge into the
unit. To calculate the total refrigerant charge:
Amount specified on
nameplate
NOTE Insulate liquid line when it is routed through areas where the surrounding ambient temperature could become higher than the
temperature of the liquid line or when pressure drop is equal to or greater than 20 psig.
NOTE The above nameplate is for illustration purposes only. Go to actual nameplate on outdoor unit for charge information.
USE WEIGH-IN METHOD
Weigh-in or remove refrigerant
based upon line length
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.
APPº (Approach) Values(F:+/−1.0° [C: +/−0.6°])
ºF (ºC)* −018 −024
65 (18)
4 (2.2) 2 (1.1)
75 (24)
5 (2.8) 4 (2.2)
85 (29)
6 (3.3) 4 (2.2)
95 (35)
5 (2,8) 4 (2.2)
105 (41)
3 (1.7) 4 (2.2)
115 (45)
3 (1.7) 3 (1.7)
*Temperature of air entering outdoor coil.
506645−01
Adjust amount. for variation
in line set length listed on
line set length table below.
+
Refrigerant Charge per Line Set Length
Liquid Line
Set Diameter
3/8" (9.5 mm)
*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.
Figure 21. Using HFC−410A Weigh In Method
65ºF (18.3ºC)
and Above
ABOVE or
64ºF
BELOW
(17.7ºC) and
Below
If refrigerant is added or
removed, retest to confirm
that unit is properly charged.
−030 −036
2 (1.1) 2 (1.1)
4 (2.2) 5 (2.8)
6 (3.3) 8 (4.4)
5 (2.8) 7 (3.9)
5 (2.8) 6 (3.3)
4 (2.2) 6 (3.3)
Figure 22. HFC−410A Approach TXV Charge
Total charge
=
Ounces per 5 feet (g per 1.5 m)
adjust from 15 feet (4.6 m) line set*
3 ounce per 5' (85 g per 1.5 m)
1. Confirm proper airflow across coil using figure 19.
2. Compare unit pressures with table 4, Normal Operating
Pressures.
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.
−041 −042
3 (1.7) 6 (3.3)
3 (1.7) 6 (3.3)
4 (2.2) 8 (4.4)
4 (2.2) 8 (4.4)
4 (2.2) 8 (4.4)
5 (2.8) 8 (4.4)
Page 24
−047 −048 −059/−060
9 (5.0) 7 (3.9) 8 (4.4)
9 (5.0) 8 (4.4) 9 (5.0)
8 (4.4) 8 (4.4) 9 (5.0)
8 (4.4) 8 (4.4) 9 (5.0)
8 (4.4) 8 (4.4) 9 (5.0)
8 (4.4) 9 (5.0) 9 (5.0)