Lennox G43UF SERIES

__ ---A
DRY BULB
ADDING OR REMOVING REFRIGERANT
This system uses HFC·410A refrigerant which operates at much higher pressures than HCFC~22. The pre-Installed liquid
line filler 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 (or use with colis which use capillary tubes or flxed orifices as a refrigerant meterIng device.
Check airflow using the Delta-T (DT) process using the illustration in figure 13.
AIRFLOW
INDOOR COIL
DT
80 24 ~4 24 23 23 22 22 22 20 19 18 17 16 15
Temperature of air ~
entering indoor 09 18 2323232222 212120191817161514
coli <:IF ~
76 222222 2121201919181716151413
c
-------------+~~~~~O~9~~~;~~~:Jl~:~:~~~~~~~~
10 19 19 18 18 1117 16 15 1514 1312 11 10
Wet-bulb
OF 5158596061 62636465666768697
...... T~D~rG~
19
D
< llirnow
All temperatures are elCprelillod in OF
Use the following procedure to adjust for optimal air flow across the indoor coil:
1. Determine the desired DT - Measure entering air temperature using dry bulb (A) and wet bulb (8). DT
is the intersecting valuB 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). Temperature Drop Formula: (To
rop
)
:: A minus C.
3, Determine if fan needs adjustment -If the difference between the measured To
rop
and the desired
DT (Torop-DT) is Within ±3°. no adjustment is needed. See example below:
Assume DT :: 15 and A temp ... 72°. these C temperatures would necessitate stated actions;
C" T Drop - DT :: OF AeTlON
53" 19 - 15 4 Increase the airflow Changing air flow affecls all temperatures; recheck
58" 14 _ 15 .. -1 (within +30\ h temperatures to confirm that the temperature drop
- range, no c ange and DT are within +30.
62" 10 - 15 :: -5 Decrease the airflow
4. Adjust the fan speed - See Indoor unit instructions to Increase/decrease fan speed.
Figure 13. Checking Indoor Airflow over Evaporator Coil using
Delta-T Chart
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