Lennox EL23XCV Series Manual page 78

AIRFLOW
DRY
BULB
C
T
DROP
53º
19º
AIR
FLOW
ALL TEMPERATURES ARE
EXPRESSED IN ºF
ASSUME DT = 15 AND A TEMP. = 72º, BELOW C TEMPERATURES REQUIRE ACTION:
Cº
T –
DT
DROP
53º
19 – 15
58º
14 – 15
62º
10 – 15
FIGURE 47. Checking Indoor Airflow over Evaporator Coil using Delta-T Chart
Use the WEIGH-IN method for adding initial refrigerant charge, and then use SUBCOOLING method for for verifying refrigerant charge.
WEIGH-IN
CHARGING METHOD
64ºF (17.7ºC) and Below
Adjust amount for variation in
line set length and liquid line
Amount specified
diameter using table below.
on nameplate
+
Liquid Line
Set Diameter
5/16"
3/8"
1/2"
TEMPERATURE OF AIR
INDOOR COIL
ENTERING INDOOR COIL ºF
A
AIR
64º
FLOW
INDOOR
COIL
ºF ACTION
=
4 INCREASE THE AIRFLOW
=
-1
(WITHIN +3º RANGE) NO CHANGE
=
-5
= DECREASE THE AIRFLOW
Total charge
=
HFC-410A
(ounces per foot)
0.40
0.60
1.00
FIGURE 48. Using HFC-410A Weigh-In Method
80 24 24 24 23 23 22 22 22 20 19 18 17 16 15
78 23 23 23 22 22 21 21 20 19 18 17 16 15 14
76 22 22 22 21 21 20 19 19 18 17 16 15 14 13
74 21 21 21 20 19 19 18 17 16 16 15 14 13 12
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
A
1. DETERMINE THE DESIRED DT — MEASURE ENTERING AIR
72º
TEMPERATURE USING DRY BULB (A) AND WET BULB (B).
DT IS THE INTERSECTING VALUE OF A AND B IN THE
TABLE (SEE TRIANGLE).
B
2. FIND TEMPERATURE DROP ACROSS COIL — MEASURE
ING THE COIL (A AND C). TEMPERATURE DROP FORMULA:
(T
DROP
DRY BULB
FERENCE BETWEEN THE MEASURED T
WET
SIRED DT (T
BULB
NEEDED. SEE EXAMPLE AT LEFT:
4. ADJUST THE FAN SPEED
TIONS TO INCREASE/DECREASE FAN SPEED.
TURES; RECHECK TEMPERATURES TO CONFIRM THAT THE
TEMPERATURE DROP AND DT ARE WITHIN +3º.
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 nameplate is shown for illustration purposes only. Go to
actual nameplate on outdoor unit for charge information.
Charging Formula for Liquid Line Charge Adjustments
Example
Factory charge for 3/8" is 0.60 oz/ft x 15 = 9.0 ounces.
Page 78
DT
57 58 59 60 61 62 63 64 65 66 67 68 69 70
B
) = A MINUS C.
–DT) IS WITHIN +3º, NO ADJUSTMENT IS
DROP
DROP
.