7
NAT.
GAS
CONSULT
MANUAL
BEFORE
ADJUSTING
GAS
PRESSURE
OFF
ON
GAS CONTROL SWITCH
SHOWN IN “OFF” POSITION
GAS CONTROL SWITCH
SHOWN IN “OFF” POSITION
TWO-STAGE GAS CONTROL
SINGLE-STAGE GAS CONTROL
MODULATING GAS CONTROL
A11292
Fig. 11 -- Control Switch to OFF
6. After waiting five minutes, turn control switch on the gas con-
trol to the ON position. Turn the control switch to ON. See
Fig. 12.
NAT.
GAS
CONSULT
MANUAL
BEFORE
ADJUSTING
GAS
PRESSURE
OFF
ON
GAS CONTROL SWITCH
SHOWN IN “ON” POSITION
TWO-STAGE GAS CONTROL
SINGLE-STAGE GAS CONTROL
GAS CONTROL SWITCH
SHOWN IN “ON” POSITION
MODULATING GAS CONTROL
A11291
Fig. 12 -- Control Switch to ON
7. Replace main furnace door. See Fig. 13.
A11257
Fig. 13 -- Furnace Door Replaced (Upflow Configuration)
8. Turn ON the electrical supply to the furnace and wait one
minute. See Fig. 14.
A92359
Fig. 14 -- Turn on Electrical Supply
9. Open the external manual gas valve. See Fig. 15.
OP
EN
A06189
Fig. 15 -- Open Valve
10. Set the room thermostat “MODE” to “HEAT” and adjust the
set point to a temperature slightly above the room temperat-
ure. This will automatically signal the furnace to start.
11. When the furnace receives the start signal, the combustion air
draft inducer is started. When the pressure switch senses that
there is sufficient combustion air, the hot surface igniter is en-
ergized.
After the hot surface igniter is heated for about 20 seconds, the
gas valve permits gas to flow to the main burners. After igni-
tion and a time delay of up to 60 sec, the furnace blower will
start. Variable--capacity furnaces start at low speed until the
control makes the necessary adjustments to operate the blower
at either the low-- or high--heat speed.
NOTE:
If the main burners fail to ignite after four attempts, the
furnace control system will lock out. If lockout occurs, main
burners fail to light, or blower does not come on, shut down the
furnace and call your dealer for service.
12. Set your thermostat to the temperature that satisfies your
comfort requirements. SUGGESTION: Setting the thermo-
stat back a few degrees—and compensating for the differ-
ence with warmer clothing—can make a big difference in
your fuel consumption on extremely cold days. The few de-
grees at the top of your thermostat “comfort level” are the
most costly degrees to obtain.
When the room temperature drops below the temperature selected
on the thermostat, the furnace will switch on automatically. When
the room temperature reaches the setting selected on the thermostat,
the furnace will be automatically switched off.
Continuous Fan Operation
--Some thermostats have a “FAN”
switch with two selections: AUTO and ON. When the thermostat is
set on AUTO, the furnace blower cycles on and off, controlled by
the thermostat. In ON position, the furnace blower runs
continuously. Continuous fan keeps the temperature level in your
home more evenly balanced. It also continuously filters the indoor
air.
