Lennox XP14 SERIES User Manual

Page 17
Step 1. Determine the desired DTMeasure entering air tempera-
ture using dry bulb (A) and wet bulb (B). DT is the intersecting value
of A and B in the table (see triangle).
Step 2. Find temperature drop across coilMeasure the coil’s dry
bulb entering and leaving air temperatures (A and C). Temperature
Drop Formula: (T
Drop
) = A minus C.
Step 3. Determine if fan needs adjustmentIf the difference be-
tween the measured T
Drop
and the desired DT (T
Drop
–DT) is within
+
3º, no adjustment is needed. See examples: Assume DT = 15 and
A temp. = 72º, these C temperatures would necessitate stated ac-
tions:
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
Step 4. Adjust the fan speedSee indoor unit instructions to in-
crease/decrease fan speed.
Changing air flow affects all temperatures; recheck temperatures to
confirm that the temperature drop and DT are within +
3º.
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
Temp.
of air
entering
indoor
coil ºF
INDOOR
COIL
DRY BULBDRY
BULB
WET
BULB
B
T
Drop
19º
A
Dry−bulb
Wet−bulb ºF
A
72º
B
64º
C
53º
air flowair flow
All temperatures are
expressed in ºF
FIGURE 20
Setup for Checking and Adding Charge
SETUP FOR CHARGING
low pressure gauge to vapor service port
high pressure gauge to liquid service port
Close manifold gauge set valves. Connect the center man-
ifold hose to an upright cylinder of HFC−410A.
CALCULATING CHARGE
If the system is void of refrigerant, first, locate and repair
any leaks and then weigh in the refrigerant charge into the
unit. To calculate the total refrigerant charge:
Amount
specified
on
nameplat
e
Adjust amt. for
variation in
line set length
(table 6)
Additional charge
specified per
indoor unit match−up
(table 7)
Tot al
charge
+ + =

Lennox XP14 SERIES Specifications

General

Brand	Lennox
Model	XP14 SERIES
Category	Heat Pump
Language	English