Lennox XP16 Series Unit Information page 27

CHARGING INFORMATION FOR MODEL XP16−XXX−230−03, XP16−XXX−230−04 and XP16−XXX−230−05
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.
COOLING MODE INDOOR AIRFLOW CHECK
Check airflow using the Delta−T (
illustration in Figure 17.
HEATING MODE INDOOR AIRFLOW CHECK
Blower airflow (CFM) may be calculated by energizing
electric heat and measuring:
AIRFLOW
INDOOR COIL
DRY
BULB
C
53º
All temperatures are expressed in ºF
Use the following procedure to adjust for optimal air flow across the indoor coil:
1. Determine the desired DT
secting value of A and B in the table (see triangle).
2. Find temperature drop across coil
Temperature Drop Formula: (T
3. Determine if fan needs adjustment
is within +3º, no adjustment is needed. See example below:
Assume DT = 15 and A temp. = 72º, these C temperatures would necessitate stated actions:
DT =
T –
Cº
Drop
=
19 – 15
53º
=
14 – 15
58º
=
10 – 15
62º
4. Adjust the fan speed
Figure 17. Checking Indoor Airflow over Evaporator Coil using Delta−T Chart Formula
XP16
DT)
process using the
Temperature of air
entering indoor
coil ºF
A
T
Drop
19º
air flow
Measure entering air temperature using dry bulb (A) and wet bulb (B). DT is the inter-
Measure the coil's dry bulb entering and leaving air temperatures (A and C).
) = A minus C.
Drop
If the difference between the measured T
ºF ACTION
4 Increase the airflow
−1 (within +3º range) no change
−5 Decrease the airflow
See indoor unit instructions to increase/decrease fan speed.
Temperature rise between the return air and supply air
D
temperatures at the indoor coil blower unit,
Measuring voltage supplied to the unit,
D
Measuring amperage being drawn by the heat unit(s).
D
Then, apply the measurements taken in following formula to
determine CFM:
Amps x Volts x 3.41
CFM =
1.08 x Temperature rise (F)
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
Wet−bulb ºF
57 58 59 60 61 62 63 64 65 66 67 68 69 70
INDOOR COIL
Changing air flow affects all temperatures; recheck tem-
peratures to confirm that the temperature drop and DT
are within +3º.
Page 27
DT
B
air flow
B
64º
WET BULB
and the desired DT (T
Drop
A
72º
DRY BULB
–DT)
Drop