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B-Heating Start-Up
 WARNING
Shock and burn hazard.
SL280DFV units are equipped with a hot surface 
ignition system. Do not attempt to light manually.
1 -   STOP!  Read the safety information at the beginning 
of this section.
2 -   Set the thermostat to the lowest setting
3 -   Turn o all electrical power to the unit.
4 -   This  furnace  is  equipped  with  an  ignition  device 
which automatically lights the burners. Do not try to 
light the burners by hand.
5 -   Remove the upper access panel.
6 -   Turn switch on gas valve to OFF. Do not force. See 
FIGURE 17 or FIGURE 18.
7 -   Wait ve minutes to clear out any gas. If you then 
smell gas, STOP! Immediately call your gas supplier 
from a neighbor’s phone. Follow the gas supplier’s 
instructions.
8 -   If you do not smell gas go to next step.
GAS VALVE SHOWN IN ON POSITION
INLET PRESSURE POST
HIGH FIRE ADJUSTMENT
SCREW
(under cap)
MANIFOLD
PRESSURE TAP
WHITE RODGERS GAS VALVE
LOW FIRE ADJUSTMENT
SCREW
(under cap)
FIGURE 17 
GAS VALVE SHOWN IN ON POSITION
MANIFOLD
PRESSURE
TAP ON
SIDE
HIGH FIRE
ADJUSTING SCREW 
(under cap)
INLET PRESSURE TAP
ON SIDE
Resideo Two-Stage Gs Valve
FIGURE 18 
9 -   Turn switch on gas valve to ON. Do not force. See 
FIGURE 17 or FIGURE 18.
10 -  Replace the upper access panel.
11 -  Turn on all electrical power to to the unit.
12 -  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.
Turning O Gas To Unit
1 -  Set thermostat to lowest setting.
2 -   Turn o all electrical power to unit if service is to be 
performed.
3 -   Remove access panel.
4 -   Turn switch on gas valve to OFF. Do not force. See 
FIGURE 17 or FIGURE 18.
5 -  Replace 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 or tripped circuit breaker?
5 -   Is the lter dirty or plugged? Dirty or plugged lters 
will cause the limit control to shut the unit o.
6 -   Is gas turned on at the meter?
7 -   Is the manual main shut-o valve open?
8 -   Is the internal manual shut-o valve open?
9 -   Is the unit ignition system in lock out? If the unit locks 
out again, call the service technician to inspect the 
unit for blockages.
10 -  Is  pressure  switch  closed?  Obstructed  ue  will 
cause unit to shut o at pressure switch. Check ue 
and outlet for blockages.
11 -  Are  ame  rollout  switches  tripped?  If  ame  rollout 
switches are tripped, call the service technician for 
inspection.
C-Safety or Emergency Shutdown
Turn o unit power. Close manual and main gas valves.
D-Extended Period Shutdown
Turn o 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 o pow-
er to unit. All access panels and covers must be in place 
and secured.