Lennox Dave Lennox Signature Collection XC15 User Manual

Page 17
XC15 SERIES
1. Determine the desired DTMeasure entering air temperature
using dry bulb (A) and wet bulb (B). DT is the intersecting value 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: (T
Drop
) = A minus C.
3. Determine if fan needs adjustmentIf the difference between the
measured T
Drop
and the desired DT (T
Drop
–DT) is within +3º, no ad-
justment is needed. See examples: Assume DT = 15 and A temp. =
72º, these C temperatures would necessitate stated actions:
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
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
BULB
DRY
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 31. Checking Indoor Airflow over Evaporator Coil using Delta−T Chart
WHEN TO CHARGE?
S Warm weather best
S Can charge in colder weather
CHARGE METHOD? Determine by:
S Outdoor ambient temperature
REQUIREMENTS:
S Sufficient heat load in structure
S Indoor temperature between 70-80ºF (21−26ºC)
S Manifold gauge set connected to unit
S Thermometers:
− to measure outdoor ambient temperature
− to measure liquid line temperature
− to measure suction line temperature
TXV
APPROACH OR
SUBCOOLING
65ºF
(18.3ºC) and
Above
START: Determine the correct charge method:
WEIGH-IN
64ºF
(17.7ºC) and
Below
Figure 32. Determining Charge Method
WEIGH IN
START: Measure outdoor ambient temperature
BELOW
1. Check Liquid and suction line pressures
2. Compare unit pressures with Table 5,
Normal Operating Pressures.
3. Conduct leak check; evacuate as
previously outlined.
4. Weigh in the unit nameplate charge plus
any charge required for line set differences
over feet.
Liquid Line
Set Diameter
Ounces per 5 feet (g per 1.5 m)
adjust from 15 feet (4.6 m) line set*
3/8" (9.5 mm)
3 ounce per 5’ (85 g per 1.5 m)
NOTE − *If line length is greater than 15 ft. (4.6 m), add this
amount. If line length is less than 15 ft. (4.6 m), subtract this
amount.
Refrigerant Charge per Line Set Length
ABOVE
USE EITHER APPROACH
OR SUBCOOLING
METHOD
This nameplate is for illustration purposes
only. Go to actual nameplate on outdoor
unit for charge information.
Above or
below 65ºF
(18ºC)?
Figure 33. Using Weigh In TXV Method

Lennox Dave Lennox Signature Collection XC15 Specifications

General

Brand	Lennox
Model	Dave Lennox Signature Collection XC15
Category	Air Conditioner
Language	English