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 12.
AIRFLOW |
|
| |
INDOOR COIL | Dry−bulb | DT | |
Temperature of air | 80 24 24 24 23 23 22 22 22 20 19 18 17 16 15 | ||
| |||
entering indoor |
| 78 23 23 23 22 22 21 21 20 19 18 17 16 15 14 | |
coil ºF |
| 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 | |
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 | |||
DRY |
| B | |
BULB |
|
| |
C
TDrop
53º | 19º |
air flow | air flow |
A
72º
B
64º
INDOOR COIL
All temperatures are expressed in ºF
DRY BULB
WET BULB
Use the following procedure to adjust for optimal air flow across the indoor coil: |
| |
1. | Determine the desired DT | 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 |
|
| (A and C). Temperature Drop Formula: (TDrop) = A minus C. |
|
3. | Determine if fan needs adjustment ference between the measured | TDrop and the desired |
| DT |
|
Assume DT = 15 and A temp. = 72º, these C temperatures would necessitate stated actions:
Cº | TDrop – | DT | = | ºF | ACTION |
| |
53º | 19 | – | 15 | = | 4 | Increase the airflow | Changing air flow affects all temperatures; recheck |
|
|
|
| = |
|
| temperatures to confirm that the temperature drop |
58º | 14 | – | 15 | −1 | (within +3º range) no change and DT are within +3º. | ||
62º | 10 | – | 15 | = | −5 | Decrease the airflow |
|
4.Adjust the fan speed
Figure 12. Checking Indoor Airflow over Evaporator Coil using Delta−T Chart
Page 27
XC17 SERIES
