Page 49
Unit Start-Up
FOR YOUR SAFETY READ BEFORE OPERATING
 WARNING
Do not use this furnace if any part has been underwater. 
A  ood-damaged  furnace  is  extremely  dangerous. 
Attempts to use the furnace can result in re or explosion. 
Immediately call a qualied service technician to inspect 
the furnace and to replace all gas controls, control 
system parts, and electrical parts that have been wet or 
to replace the furnace, if deemed necessary.
 WARNING
Danger of explosion. Can cause injury or 
product or property damage. Should the gas 
supply fail to shut off or if overheating occurs, 
shut off the gas valve to the furnace before 
shutting off the electrical supply.
 CAUTION
Before attempting to perform any service or maintenance, 
turn the electrical power to unit OFF at disconnect switch.
 WARNING
During blower operation, the ECM motor emits 
energy that may interfere with pacemaker operation. 
Interference is reduced by both the sheet metal cabinet 
and distance.
Priming Condensate Trap
The condensate trap should be primed with water prior 
to start-up to ensure proper condensate drainage. Either 
pour  10  .  oz.  (300  ml)  of  water  into  the  trap,  or  follow 
these steps to prime the trap:
1 -   Follow the lighting instructions to place the unit into 
operation.
2 -  Set the thermostat to initiate a heating demand.
3 -   Allow the burners to re for approximately 3 minutes.
4 -   Adjust the thermostat to deactivate the heating 
demand.
5 -   Wait for the combustion air inducer to stop. Set the 
thermostat to initiate a heating demand and again 
allow the burners to re for approximately 3 minutes.
6 -   Adjust the thermostat to deactivate the heating 
demand and again wait for the combustion air 
inducer to stop. At this point, the trap should be 
primed  with  sufcient  water  to  ensure  proper 
condensate drain operation.
BEFORE BEFORE PLACING THE UNIT INTO OPERA-
TION, smell all around the furnace area for gas. Be sure 
to  smell  next  to  the  oor  because  some  gas  is  heavier 
than air and will settle on the oor. The gas valve on the 
SLP98DFV is equipped with a gas control switch. Use only 
your hand to move the control switch. Never use tools. If 
the switch will not move by hand, do not try to repair it. 
Force or attempted repair may result in a re or explosion.
Placing the furnace into operation:
SLP98DFV units are equipped with an automatic ignition 
system. Do not attempt to manually light burners on this 
furnace. Each time the thermostat calls for heat, the burn-
ers will automatically light. The ignitor does not get hot 
when there is no call for heat on units with this ignition 
system.
 WARNING
If you do not follow these instructions exactly, a re or 
explosion may result causing property damage, personal 
injury or death.
Gas Valve Operation (Figure 48)
1 -   STOP! Read the safety information at the beginning 
of this section.
2 -   Set the thermostat to the lowest setting.
3 -  Turn off 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 access panel.
6 -   Move the gas valve switch to the OFF position. See 
gure 48.
7 -   Wait ve minutes to clear out any gas. If you then 
smell gas, STOP! Immediately call the gas supplier 
from a neighbor’s phone. Follow the gas supplier’s 
instructions. If you do not smell gas go to next step.
8 -   Move gas valve switch to the ON position. See 
gure 48. Do not force.
GAS VALVE
NEGATIVE AIR
PRESSURE PORT
POSITIVE AIR
PRESSURE PORT
MANIFOLD
PRESSURE TAP
INLET
OUTLET
SUPPLY
PRESSURE
TAP
GAS VALVE SHOWN IN THE ON POSITION
FIGURE 48