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9 - Replace the access panel.
10 - Turn on all electrical power to to the unit.
11 - Set the thermostat to desired setting.
NOTE - When unit is initially started, steps 1 through 11
may need to be repeated to purge air from gas line.
12 - If the appliance will not operate, follow the
instructions "Turning Off Gas to Unit" and call the
gas supplier.
Turning Off Gas to Unit
1 - Set the thermostat to the lowest setting.
2 - Turn off all electrical power to the unit if service is to
be performed.
3 - Remove the access panel.
4 - Move the gas valve switch to the OFF position.
5 - Replace the access panel.
Failure To Operate
If the unit fails to operate, check the following:
1 - Is the thermostat calling for heat?
2 - Are access panels securely in place?
3 - Is the main disconnect switch closed?
4 - Is there a blown fuse?
5 - Is the filter dirty or plugged? Dirty or plugged filters
will cause the limit control to shut the unit off.
6 - Is gas turned on at the meter?
7 - Is the manual main shut-off valve open?
8 - Is the gas valve turned on?
9 - Is the unit ignition system in lock out? If the unit
locks out again, inspect the unit for blockages.
10 - Is blower harness connected to ignition control?
Furnace will not operate unless harness is
connected.
High Altitude Information
NOTE - In Canada, certification for installations at eleva-
tions over 4500 feet (1372 m) is the jurisdiction of local
authorities.
SLP99DFV units require no manifold pressure adjust-
ments for operation at altitudes up to 10,000 feet (3048
m) above sea level. Units installed at altitude of 7,501 to
10,000 feet (2287 to 3048m) require a pressure switch
change and conversion kit. See TABLE 31.
The combustion air pressure switch is factory-set and re-
quires no adjustment.
Gas Pressure Measurement
Gas Flow (Approximate)
GAS METER CLOCKING CHART
SLP99
Unit
1 cu ft
Dial
-070
55
-090
41
-110
33
-135
27
Natural-1000 btu/cu ft LP-2500 btu/cu ft
Furnace should operate at least 5 minutes before check-
ing gas flow. Determine time in seconds for two revolu-
tions of gas through the meter. (Two revolutions assures a
more accurate time.) Divide by two and compare to time
in TABLE 28. If manifold pressure matches TABLE 28 and
rate is incorrect, check gas orifices for proper size and
restriction. Remove temporary gas meter if installed.
NOTE - To obtain accurate reading, shut off all other gas
appliances connected to meter.
Supply Pressure Measurement
A threaded plug on the inlet side of the gas valve provides
access to the supply pressure tap. Remove the thread-
ed plug, install a field-provided barbed fitting and connect
a manometer to measure supply pressure. Replace the
threaded plug after measurements have been taken.
Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking com-
bustion. Take combustion sample beyond the flue outlet
and compare to the tables below. The maximum carbon
monoxide reading should not exceed 100 ppm.
SLP99DFV Unit
070
090
110
SLP99DFV Unit
070
090
110
Page 51
TABLE 28
Seconds for One Revolution
Natural
2 cu ft
1 cu ft
Dial
Dial
110
136
82
102
66
82
54
68
TABLE 29
High Fire
6.5 - 9.0
7.7 - 10.2
TABLE 30
Low Fire
4.7 - 7.2
LP
2 cu ft
Dial
272
204
164
136
5.7 - 8.2
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