Lennox XP14 Elite Series Installation Instructions Manual page 16

Temp. ] DT
ofair 180 24 24 24 23 23 22 22 22 20 19 18 17 16 15
entering._178 23 23 23 22 22 21 21 20 19 18 17 16 15 14
indoor _ I _
coilOF _lru 22 22 22 21 21 20 19 19 18 17 16 15 14 13
I _'174 21 21 21 20 19 19 18 17 16 16 15 14 13 12
_[72 20 20 19 18 17 17 16Z_15 14 13 12 11 10
70 19 19 18 18 17 17 16 15 15 14 13 12 11 10
Wet-bulb°F 57 58 59 60 61 62 63 64 65 66 67 68 69 70 ]
m
9o
DRY
BULB
All temperatures are INDOOR WET
expressed in °F COIL BULB
_6
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 ceil--Measure the coil's dry
bulb entering and leaving air temperatures (A and C). Temperature
Drop Formula: (TDrop) = A minus C.
Step 3. Determine if fan needs adjustment--If the difference be-
tween the measured TDrop and the desired DT (TDropiDT) is within
+3 °, no adjustment is needed. See examples: Assume DT = 15 and A
temp. = 72 °, these C temperatures would necessitate stated actions:
C ° TDrop- DT = °F ACTION
53° 19 15 = 4 Increase the airflow
58° 14 15 = -1 (within +3 ° range) no change
62 ° 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 +3 °.
Figure 23. Checking Indoor Airflow over Evaporator Coil using Delta-T Chart
SETUP FOR CHARGING
Connect the manifold gauge set to the unit's service ports
(see figure 20):
• low pressure gauge to vapor service port
• high pressure gauge to liquid service port
Close manifold gauge set valves. Connect the center
manifold 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 Adjust amt. for Additional charge
specified variation in specified per
on line set length indoor unit match-up Total
nameplate (table 6) (table 7) charge
+ + =
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505244M 04/08