Lennox SSB036H4S4, Installation Instructions Manual

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Page 23
SSB*H4 SERIES
CHECKING AIR FLOW AT INDOOR COIL
1. Determine the desired
D
T —Measure entering air temperature
using dry bulb ( A ) and wet bulb ( B ).
D
T 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
D
T (T
Drop
–
D
T) is 3º, no
adjustment is needed. See examples: Assume
D
T = 15 and A
temp. = 72º, these C temperatures would necessitate stated ac­
tions:
Cº
T
Drop
–
D
T
=
ºF ACTION
53º
19 – 15
=
4 Increase the airflow
58º
14 – 15
=
-1 (3º range) no change
62º
10 – 15
=
-5 Decrease the airflow
4. Adjust the fan speed
—See indoor unit instructions to increase/de­
crease fan speed.
Changing air flow affects all temperatures; recheck temperatures to
confirm that the temperature drop and
D
T are 3º.
D
T
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 flow air flow
All temperatures are
expressed in ºF
Figure 19. Checking Indoor Airflow over Evaporator Coil using Delta-T Chart
WHEN TO CHARGE?
Warm weather best
Can charge in colder weather
CHARGE METHOD? Determine by:
Metering device type
Outdoor ambient temperature
TXV
APPROACH OR
SUBCOOLING
65ºF (18.3ºC)
and Above
START: Determine how refrigerant is metered
WEIGH‐IN
64ºF (17.7ºC)
and Below
REQUIREMENTS:
Sufficient heat load in structure
Indoor temperature between 70‐80ºF (21-26ºC)
Manifold gauge set connected to unit
Thermometers:
-
to measure outdoor ambient temperature
- to measure liquid line temperature
- to measure suction line temperature
Figure 20. Determining Charge Method
WEIGH-IN
Liquid Line
Set Diameter
HFC-410A
(ounces per foot)
5/16”
3/8”
1/2”
0.40
0.60
1.00
NOTE - The above nameplate is for illustration purposes only. Go to
actual nameplate on outdoor unit for charge information.
CHARGING METHOD FOR LONG LINE SETS
NOTE - Insulate liquid line when it is routed through areas where the
surrounding ambient temperature could become higher than the
temperature of the liquid line or when pressure drop is equal to or
greater than 20 psig.
Amount specified
on nameplate
Adjust amount for variation in
line set length and liquid line
diameter using table below.
Total charge
+
=
64ºF (17.7ºC) and Below
Example : Units are factory­charged for 15 feet (4.6 meters) of 3/8" line set.
Factory charge for 3/8" is 0.60 oz/ft x 15 = 9.0 ounces.
Charging Formula for Liquid Line Charge Adjustments
[(Line set oz./ft. x total length) ­ (factory charge for line set)] = charge adjustment
Figure 21. Using HFC-410A Weigh-In Method