508228-01Issue 2136Page 36 of 41
Adding or Removing Refrigerant
This system uses HFC-410A refrigerant which operates at much higher pressures than HCFC-22. The pre-installed liquid
line lter 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 xed orices as a refrigerant metering device.
Check airow using the Delta-T (DT) process shown below..
Cº T
Drop
– DT = ºF ACTION
53º 19 –15 = 4 Increase the airflow
58º 14 –15 = -1 (within +3º range) no change
62º 10 –15 = -5 Decrease the airflow
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
Temperature of air
entering indoor
coil ºF
INDOOR COIL
DRY BULB
DRY
BULB
WET BULB
B
T
Drop
19º
A
Dry-bulb
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). DT
is the intersecting value of A and B in the table (see triangle).
2. Find temperature drop across coil — Measure the coil's dry bulb entering and leaving air temperatures
(A and C). Te mperature Drop Formula: (T
Drop
) = A minus C.
3. Determine if fan needs adjustment — If the difference between the measured T
Drop
and the desired
DT (T
Drop
–DT) is within +3º, no adjustment is needed. See example below:
4. Adjust the fan speed — See indoor unit instructions to increase/decrease fan speed.
Assume DT = 15 and A temp. = 72º, these C temperatures would necessitate stated actions:
AIRFLOW
Use the following procedure to adjust for optimal air flow across the indoor coil:
INDOOR COIL
Changing air flow affects all temperatures; recheck
temperatures to confirm that the temperature drop
and DT are within +3º.
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