Lennox Elite XC16−024−230 Installation Instructions Manual page 23

CHECKING AIR FLOW AT INDOOR COIL
Check airflow using the Delta−T (
Temp.
80 24 24 24 23 23 22 22 22 20 19 18 17 16 15
of air
entering
78 23 23 23 22 22 21 21 20 19 18 17 16 15 14
indoor
76 22 22 22 21 21 20 19 19 18 17 16 15 14 13
coil ºF
74 21 21 21 20 19 19 18 17 16 16 15 14 13 12
A 72 20 20 19 18 17 17 16 15 15 14 13 12 11 10
70 19 19 18 18 17 17 16 15 15 14 13 12 11 10
Wet−bulb ºF
57 58 59 60 61 62 63 64 65 66 67 68 69 70
T
Drop
C
19º
53º
air flow
DRY
BULB
All temperatures are
expressed in ºF
Figure 17. Checking Indoor Airflow over Evaporator Coil using Delta−T Chart
WEIGH IN
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:
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.
DT)
process using the illustration in figure 17.
DT
B
A
72º
air flow B
64º
DRY
BULB
INDOOR WET
BULB
COIL
CHARGING METHOD
64ºF (17.7ºC) and Below
Adjust amount. for variation
in line set length listed on
Amount specified on
line set length table below.
nameplate
*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 18. Using HFC−410A Weigh In Method
1. Determine the desired DT Measure entering air temper-
ature using dry bulb (A) and wet bulb (B). DT is the intersect-
ing value of A and B in the table (see triangle).
2. Find temperature drop across coil
bulb entering and leaving air temperatures (A and C). Tem-
perature Drop Formula: (T
3. Determine if fan needs adjustment
the measured T
Drop
+3º, no adjustment is needed. See examples: Assume DT =
15 and A temp. = 72º, these C temperatures would necessi-
tate stated actions:
DT
T –
Cº
Drop
19 – 15
53º
14 – 15
58º
10 – 15
62º
4. Adjust the fan speed
crease/decrease fan speed.
Changing air flow affects all temperatures; recheck tempera-
tures to confirm that the temperature drop and DT are within
+3º.
Total charge
+
=
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)
Page 23
Measure the coil's dry
) = A minus C.
Drop
If the difference between
and the desired DT (T
–DT) is within
Drop
=
ºF ACTION
=
4 Increase the airflow
=
−1 (within +3º range) no change
=
−5 Decrease the airflow
See indoor unit instructions to in-
XC16 SERIES