Advertisement
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 51.
WEIGH-IN
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
31-5000750 Rev. 1
INDOOR COIL
AIR
FLOW
INDOOR
COIL
ºF
ACTION
=
4
INCREASE THE AIRFLOW
=
=
-1
(WITHIN +3º RANGE) NO CHANGE
=
-5
DECREASE THE AIRFLOW
CHARGING METHOD
Total charge
=
HFC-410A
(ounces per foot)
5/16"
0.40
3/8"
0.60
1/2"
1.00
Figure 52. Using HFC-410A Weigh-In Method
TEMPERATURE OF AIR
ENTERING INDOOR COIL ºF
A
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
64º
ING THE COIL (A AND C). TEMPERATURE DROP FORMULA:
(T
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.
DT
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
57 58 59 60 61 62 63 64 65 66 67 68 69 70
B
) = A MINUS C.
DROP
–DT) IS WITHIN +3º, NO ADJUSTMENT IS
DROP
DROP
.
Advertisement
