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VI-TYPICAL OPERATING CHARACTERISTICS
A-Blower Operation and Adjustment
1 - Blower operation is dependent on thermostat control
system.
2 - Generally, blower operation is set at thermostat
subbase fan switch. With fan switch in ON position,
blower operates continuously. With fan switch in
AUTO position, blower cycles with demand or runs
continuously while heating or cooling circuit cycles.
3 - Depending on the type of indoor thermostat, blower
and entire unit will be o when the system switch is
in OFF position.
B-Temperature Rise
Temperature rise for SLP99DFV units depends on unit in-
put, blower speed, blower horsepower and static pressure
as marked on the unit rating plate. The blower speed must
be set for unit operation within the range of “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 rst horizontal run of the plenum where it will
not pick up radiant heat from the heat exchanger.
2 - Set thermostat for heat call. Unit must operate
on second- stage heat. If using a single-stage
thermostat furnace must re at least 10 minutes
before switching to second-stage heat.
3 - After plenum thermometers have reached their
highest and steadiest readings, subtract the two
readings. The dierence should be in the range
listed on the unit rating plate. If the temperature
is too low, decrease blower speed. If temperature
is too high, rst check the ring rate. Provided the
ring rate is acceptable, increase blower speed to
reduce temperature.
C-External Static Pressure
1 - Tap locations shown in FIGURE 57.
2 - Punch a 1/4” diameter hole in supply and return
air plenums. Insert manometer hose ush with
inside edge of hole or insulation. Seal around the
hose with permagum. Connect the zero end of the
manometer to the discharge (supply) side of the
system. On ducted systems, 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 blower motor speed to deliver the air desired
according to the job requirements.
4 - External static pressure drop must not be more than
0.8” W.C. in the heating mode and must not exceed
1.0” W.C in the cooling mode.
5 - Seal the hole when the check is complete.
Return
Supply
TEMPERATURE RISE
Supply Duct Temperature
Return Duct Temperature
_
Temperature Rise =
FIGURE 57
VII-MAINTENANCE
WARNING
ELECTRICAL SHOCK, FIRE,
OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly could
result in dangerous operation, serious injury, death
or property damage.
Improper servicing could result in dangerous
operation, serious injury, death, or property damage.
Before servicing, disconnect all electrical power to
furnace.
When servicing controls, label all wires prior
to disconnecting. Take care to reconnect wires
correctly. Verify proper operation after servicing.
At the beginning of each heating season, system should
be checked as follows by a qualied service technician:
Blower
Check the blower wheel for debris and clean if necessary.
The blower motors are prelubricated for extended bearing
life. No further lubrication is needed.
WARNING
The blower access panel must be securely in place
when the blower and burners are operating. Gas
fumes, which could contain carbon monoxide, can
be drawn into living space resulting in personal
injury or death.
Filters
All SLP99DFV lters are installed external to the unit. Fil-
ters should be inspected monthly. Clean or replace the l-
ters when necessary to ensure proper furnace operation.
All units use a 16 x 25 x 1 lter.
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