Lennox International Inc. o23v - Manual (Page 21)

FIGURE 25
STATIC PRESSURE
TEST
MANOMETER
OIL UNIT
Page 21
FIGURE 24
COMBUSTION AIR MOTOR & WHEEL
BOLT
BOLT
MOTOR AND WHEEL
NOTE−When reinstalling blower wheel use the AFII mul-
tipurpose gauge (Beckett part # T−500) to space the dis-
tance from the back of the blower wheel to the face of the
motor (1/16" [2 mm]).
B−Removing Indoor Blower
1− Turn off electric power to furnace.
2− Remove blower access door.
3− Remove two screws located in the front blower rails.
4− Pull blower forward enough to disconnect the motor
leads.
5− Pull blower assembly out and place to the side.
VI−TYPICAL OPERATING CHARACTERISTICS
A−Blower Operation and Adjustment
NOTE− The following is a generalized procedure and
does not apply to all thermostat controls.
1− Blower operation is dependent on thermostat con-
trol system.
2− Generally, blower operation is set at thermostat sub-
base fan switch. With fan switch in ON position, blower
operates continuously. With fan switch in AUTO position,
blower cycles with demand.
3− In all cases, blower and entire unit will be off when line
voltage is disconnected.
B−Temperature Rise
Temperature rise for O23V units depends on unit input
blower speed, blower horsepower and static pressure.
The blower speed must be set for unit operation within the
range of AIR TEMP. RISE
°F" listed on the unit rating plate.
To Measure Temperature Rise:
1. Place plenum thermometers in the supply and return air
plenums. Locate supply air thermometer in the first hori-
zontal run of the plenum where it will not pick up radiant
heat from the heat exchanger.
2. Set thermostat to highest setting.
3. After plenum thermometers have reached their
highest and steadiest readings, subtract the two
readings. The difference should be in the range
listed on the unit rating plate.
C−Blower Speed
Blower speed selection is accomplished by changing the
jumpers on the blower motor control board. Page 5 explains
blower speed adjustments.
D−External Static Pressure
1. Measure tap locations as shown in figure 25.
2. Punch a 1/4" (6 mm) diam-
eter hole in supply and re-
turn air plenums. Insert
manometer hose flush with
inside edge of hole or in-
sulation. Seal around the
hose with permagum. Con-
nect the zero end of the ma-
nometer to the discharge (supply) side of the sys-
tem. On ducted systems, connect the other end of
manometer to the return duct as above. For systems
with non−ducted returns, leave the other end of the
manometer open to the atmosphere.
3. With only the blower motor running and the evapo-
rator coil dry, observe the manometer reading.
4. Pressure drop must not exceed 0.5" W.C. (124.3 Pa).
5. Seal around the hole when the check is complete.