Page 56
10 - T urn 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
13 -
“Turning Off Gas to Unit” and call your service
technician or 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 upper access panel.
4 - Move the gas valve switch to the OFF position.
5 - Replace the upper 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 - 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 integrated control?
Furnace will not operate unless harness is
connected.
C-Safety or Emergency Shutdown
Turn off unit power. Close manual and main gas valves.
D-Extended Period Shutdown
Turn off thermostat or set to “UNOCCUPIED” mode. Close
all gas valves (both internal and external to unit) to guar-
antee no gas leak into combustion chamber. Turn off pow
-
er to unit. All access panels and covers must be in place
and secured.
V-HEATING SYSTEM SERVICE CHECKS
A-CSA Certification
All units are CSA design certified without modifications.
Refer to the SLP99DFV Installation Instruction.
B-Gas Piping
WARNING
Do not over torque (800 in-lbs) or under torque (350
in-lbs) when attaching the gas piping to the gas
valve.
CAUTION
I
f a flexible gas connector is required or allowed by
the authority that has jurisdiction, black iron pipe
shall be installed at the gas valve and extend outside
the furnace cabinet. The flexible connector can then
be added between the black iron pipe and the gas
supply line.
Gas supply piping should not allow more than 0.5”W.C.
drop in pressure between gas meter and unit. Supply gas
pipe must not be smaller than unit gas connection.
Compounds used on gas piping threaded joints should be
resistant to action of liquefied petroleum gases.
C-Testing Gas Piping
IMPORTANT
In case emergency shutdown is required, turn off the
main shut-off valve and disconnect the main power
to unit. These controls should be properly labeled
by the installer.
When pressure testing gas lines, the gas valve must be
disconnected and isolated. Gas valves can be damaged if
subjected to more than 0.5psig (14” W.C.). See FIGURE
MANUAL MAIN SHUT-OFF
VALVE WILL NOT HOLD
NORMAL TEST PRESSURE
CAP
FURNACE
ISOLATE
GAS VALVE
1/8” N.P.T. PLUGGED TAP
FIGURE 48
When checking piping connections for gas leaks, use
preferred means. Kitchen detergents can cause harmful
corrosion on various metals used in gas piping. Use of a
specialty Gas Leak Detector is strongly recommended. It
is available through Lennox under part number 31B2001.
See Corp. 8411-L10, for further details.
Do not use matches, candles, flame or any other source o
ignition to check for gas leaks
D- Proper Gas Flow (Approximate)
TABLE 28
GAS METER CLOCKING CHART
SLP99
Unit
Seconds for One Revolution
Natural
LP
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
Dial
-070
55
110
136
272
-090
41
82
102
204
-110
33
66
82
164
-135
27
54
68
136
Natural-1000 btu/cu ft LP-2500 btu/cu ft
