Typical Operating Characteristics - Lennox SLP99UHV Series Unit Information

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 off when the system switch is
in OFF position.
B-Temperature Rise
Temperature rise for SLP99UHV 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 first 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 fire 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 difference 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, first check the firing rate. Provided the
firing rate is acceptable, increase blower speed to
reduce temperature.
C-External Static Pressure
1 - Tap locations shown in FIGURE 53.
2 - Punch a 1/4" diameter hole in supply and return
air plenums. Insert manometer hose flush 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.
D-Discharge Air Temperature Sensor (DATS)
Units may have a discharge air temperature sensor locat-
ed in the supply duct only. If the sensor is not in the supply
duct then it must be removed and relocated.
Two types sensor are used (FIGURE 54 or FIGURE 55).
If the sensor is suspect, check the location using FIGURE
54, FIGURE 56, FIGURE 57 and FIGURE 58 with tables
TABLE 34, TABLE 36 and TABLE 38. Or check the lo-
cation using FIGURE 55, FIGURE 56, FIGURE 57 and
FIGURE 58 with TABLE 35, TABLE 37 and TABLE 39.
FIGURE 59 shows field wiring for both types sensor to
the furnace control. If the location and wiring are correct
but the sensor is not working properly replace the sensor.
Follow the DATS instructions found in the kit.
STATIC PRESSURE TEST
Discharge Air Temperature Sensor Location
Page 69
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FIGURE 53
Type 1
FIGURE 54
Type 2
FIGURE 55
Plenum
b
a
Coil
AIR FLOW AIR FLOW
Upflow
FIGURE 56