Page 21
FIGURE 22
Upflow Furnace Shown
Supply Air
Return Air
TEMPERATURE RISE
Supply Duct Temperature
Return Duct Temperature
_
Temperature Rise =
C-External Static Pressure
1 - Tap locations shown in figure 23 .
2 - Punch a 1/4” diameter hole in supply and return air ple
nums. Insert manometer hose flush with inside edge of
hole or insulation. Seal around the hose with perma
gum. Connect the zero end of the manometer to the
discharge (supply) side of the system. On ducted sys
tems, connect the other end of manometer to the return
duct as above.
3 - With only the blower motor running and the evaporator
coil dry, observe the manometer reading. Adjust blow
er motor speed to deliver the air desired according to
the job requirements. For heating speed external static
pressure drop must not be more than 0.5” W.C. For
cooling speed external static pressure drop must not
be more than 0.8” W.C.
4 - Seal the hole when the check is complete.
D-Blower Speed Taps
Blower speed tap changes are made on the integrated con
trol. See figure NO TAG. The heating tap is connected to
the “HEAT” terminal and the cooling tap is connected to the
“COOL” terminal. The continuous blower tap is connected
to the “FAN” terminal. Unused taps must be secured on
dummy terminals labeled ”PARK. To change out existing
speed tap, turn off power and switch out speed tap with tap
connected to “PARK”. See blower speed tap table on unit
diagram for motor tap colors for each speed.
FIGURE 23
Upflow Furnace Shown
EXTERNAL STATIC PRESSURE
Supply Duct Static
Return Duct
Total Duct Static =
(dry coil)
Supply Air
Return Air
-
+
or
High
Low
VI-MAINTENANCE
Annual Furnace Maintenance
At the beginning of each heating season, and to comply
with the
Lennox Limited Warranty
, your system should be
checked by a licensed professional technician (or equiva
lent) as follows:
1- Check wiring for loose connections, voltage at indoor
unit and amperage of indoor motor
.
2- Check the condition of the belt and shaft bearings if ap
plicable.
3- Inspect all gas pipe and connections for leaks
.
4- Check the cleanliness of filters and change if necessary
(monthly).
TABLE 15
Cabinet Width
Return Air Filter Size (inches)
A (14-1/2”)
14 x 25 x 1 (1)
B (17-1/2”)
16 x 25 x 1 (1)
C (21”)
20 x 25 x 1 (1)
