Lennox 14HPX-018 Installation Instructions Manual page 13

80
78
76
74
I Wet-bulb °F
24 24 24 23 23 22
23 23 23 22 22 21
22 22 22 21 21 20
21 21 21 20 19 19
20 20 19 18 17 17
19 19 18 18 17 17
57 58 59 60 61 62
I)T
22 22 20 19 18 17 16 15
21 20 19 18 17 16 15 14
19 19 18 17 16 15 14 13
18 17 16 16 15 14 13 12
161L_5._15 14 13 12 11 10
16 15 15 14 13 12 11 10
I
63 64 65 66 67 68 69 70 I
DRY
I
BULB
INDOOR t WET
COIL BULB
6
Step 1. Determine the desired l)T--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: (TDrop) = A minus C.
Step 3. Determine if fan needs adjustment--If the difference be-
tween the measured TDrop and the desired I)T (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 +30
Figure 15. Checking Indoor Airflow over Evaporator Coil using Delta-T (I)T) Chart
OUTDOOR UNIT
CHECK
EXPANSION VALVE
LOW HUGH
PRESSURE PRESSURE
LIQUID
LINE I
VALVE
DISTRIBUTOR
(_ BIFLO
FILTER /
DRIER OUTDOOR
CO,L
MUFFLER
SERV
:_ COMPRESSOR
t
NOTE - ARROWS INDICATE DIRECTION
OF REFRIGERANT FLOW
REVERSING VALVE
_ APOR
LINE
VALVE
CHECK EXPANSION VALVE --
NOTE- USE GAUGE PORTS ON VAPOR LINE VALVE AND LIQUID VALVE FOR EVACUATING REFRIGERANT
LINES AND INDOOR COIL. USE VAPOR GAUGE PORT TO MEASURE VAPOR PRESSURE DURING CHARGING.
INDOOR_INI
.--'-1
--,ll_l I I
INDOOR
COIL
Figure 16. 14HPX Cooling Cycle (Showing Gauge Manifold Connections)
COOLING MODE INDOOR AIRFLOW CHECK
Check airflow using the Delta-T (DT) process (figure 15).
HEATING MODE INDOOR AIRFLOW CHECK
Blower airflow (CFM) may be calculated by energizing
electric heat and measuring:
• temperature rise between the return air and supply air
temperatures at the indoor coil blower unit,
• measuring voltage supplied to the unit,
• measuring amperage being drawn by the heat unit(s).
Then, apply the measurements taken in following formula
to determine CFM:
Amps x Volts x 3.41
CFM =
1.08 x Temperature rise (F)
SETUP FOR CHARGING
Connect the manifold gauge set to the unit's service ports
(see figure 16):
• 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 Adjust amt. for Additional charge
specified variation in specified per
on line set length indoor unit matchup Total
nameplate (table in figure 17) (tables 4 through 10) charge
+ + =
Page13
14HPX SERIES