Page 28
ADDING OR REMOVING REFRIGERANT
This system uses HFC-410A refrigerant which operates at much higher pressures than HCFC-22. The pre-installed liquid
line filter drier is approved for use with HFC-410A only. Do not replace it with components designed for use with HCFC-22.
This unit is NOT approved for use with coils which use capillary tubes or fixed orifices as a refrigerant metering device.
Check airflow using the Delta-T (DT) process using the illustration in figure 19.
Cº
T
DROP
–
D
T
=
ºF
ACTION
53º
19
–
15
=
4
INCREASE THE AIRFLOW
58º
14
–
15
=
-1
(3º RANGE) NO CHANGE
62º
10
–
15
=
-5
DECREASE THE AIRFLOW
D
T
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
TEMPERATURE OF AIR
ENTERING INDOOR COIL ºF
INDOOR
COIL
DRY BULB
DRY
BULB
WET
BULB
B
T
DROP
19º
A
DR
Y-BUL
B
WET-BULB ºF
A
72º
B
64º
C
53º
AIR
FLOW
AIR
FLOW
ALL TEMPERATURES ARE
EXPRESSED IN ºF
1. DETERMINE THE DESIRED DT — MEASURE ENTERING AIR
TEMPERATURE USING DRY BULB (
A
) AND WET BULB (
B
).
D
T
IS THE INTERSECTING VALUE OF
A
AND
B
IN THE
TABLE (SEE TRIANGLE).
2.
FIND TEMPERATURE DROP ACROSS COIL
— MEASURE
ING THE COIL (
A
AND
C
). TEMPERATURE DROP FORMULA:
(
T
DROP
) =
A
MINUS
C
.
FERENCE BETWEEN THE MEASURED
T
DROP
SIRED
D
T
(T
DROP
–
D
T)
IS 3º, NO ADJUSTMENT IS
NEEDED. SEE EXAMPLE AT LEFT:
4.
ADJUST THE FAN SPEED
TIONS TO INCREASE/DECREASE FAN SPEED.
ASSUME
D
T
= 15 AND
A
TEMP. = 72º, BELOW
C
TEMPERATURES REQUIRE ACTION:
AIRFLOW
INDOOR COIL
TURES; RECHECK TEMPERATURES TO CONFIRM THAT THE
TEMPERATURE DROP AND
D
T ARE 3º.
FIGURE 19
. Checking Indoor Airflow over Evaporator Coil using Delta-T Chart
.
WEIGH-IN
Liquid Line
Set Diameter
HFC-410A
(ounces per foot)
5/16”
3/8”
1/2”
0.40
0.60
1.00
NOTE - The nameplate is shown for illustration purposes only. Go to
actual nameplate on outdoor unit for charge information.
CHARGING METHOD
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.
Amount specified
on nameplate
Adjust amount for variation in
line set length and liquid line
diameter using table below.
Total charge
+
=
64ºF (17.7ºC) and Below
Example
Factory charge for 3/8" is 0.60 oz/ft x 15 = 9.0 ounces.
Charging Formula for Liquid Line Charge Adjustments
FIGURE 20. Using HFC-410A Weigh-In Method
