Startup Procedures; Sequence Of Operation - Rheem 801S Series Installation Instructions Manual

START-UP PROCEDURES
This furnace is equipped with a direct ignition control. Each time
the room thermostat calls for heat, the ignitor lights the main
burners directly. See the lighting instructions on the furnace.
TO START THE FURNACE
1. Remove the burner compartment control access door.
2. IMPORTANT: Be sure that the manual gas control has been
in the "OFF" position for at least five minutes. Do not attempt
to manually light the main burners.
3. Turn off the furnace electrical power and set the room ther-
mostat to its lowest setting.
4. Turn the gas control to the "ON" position or move the gas
control lever to the "On" position.
5. Replace the burner compartment control access door.
6. Turn on the furnace electrical power.
7. Set the room thermostat to a point above room temperature
to light the main burners.
8. After the burners are lit, set the room thermostat to a desired
temperature.
9. Operate gas heat for a minimum period of 15 minutes and ad-
just input rate (page 42) and observe condensate system for
leaks. Correct leaks and set rate, shutdown furnace and re-
peat until no leaks in condensate system can be detected.
TO SHUT DOWN THE FURNACE
1. Set the room thermostat to its lowest setting and wait for fur-
nace to shut down.
2. Remove the burner compartment control access door.
3. Shut off the gas to the main burners by turning the gas control
to the "OFF" position.
SHOULD OVERHEATING OCCUR OR THE GAS SUPPLY
FAIL TO SHUT OFF, CLOSE THE MANUAL GAS VALVE
FOR THE APPLIANCE BEFORE SHUTTING OFF THE
ELECTRICAL SUPPLY. FAILURE TO DO SO CAN CAUSE
AN EXPLOSION OR FIRE RESULTING IN PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.
38

SEQUENCE OF OPERATION

UT ELECTRONIC CONTROLS
Integrated Controls with Direct Spark Ignition.
1. Each time the thermostat "W" (Heating) contacts close, the
furnace control checks to make sure the pressure switch is
open. Next the induced draft blower (inducer) begins a pre-
purge cycle.
2. The air proving negative pressure switch(es) closes.
3. After the 30-second pre-purge, the gas valve opens for an
8-second trial for ignition.
4. The spark igniter is energized to light the gas burners and
stays energized for the up to 7 seconds after the gas
valve opens.
5. 8 seconds after the gas valve opens the remote flame sen-
sor must prove flame ignition for one second using the
process of flame rectification. If the burners don't light, the
system goes through another ignition sequence. It does this
up to four times before entering a 1-hour lockout.
6. The main blower starts approximately 20 seconds after the
burners ignite.
7. When the thermostat "W" (Heat Call) ends, the gas valve
closes, flame is extinguished, the induced draft blower stops
after a 10-second post-purge, and the negative pressure
switch opens.
8. The main blower continues until timed off by the setting on
the integrated furnace control board.
Sequence if the system doesn't light or doesn't sense flame:
1. On a call for heat, the furnace control checks to make sure
the pressure switch is open. Next the control runs the inducer
for 30 seconds to prepurge.
2. After the 30-second pre-purge, the gas valve opens for an 8-
second trial for ignition. The inducer continues and the igniter
stays energized.
3. If flame is not sensed during the 8th second after the gas
valve opens, the gas valve closes, and the igniter de-ener-
gizes.
4. The inducer stops (may take up to 20 seconds for inducer fan
to stop rotating) and the control verifies that the pressure
switch has opened. Once the open pressure switch is con-
firmed, the control begins the next ignition cycle by energizing
the inducer for a pre-purge of 30 seconds. After a 30-second
pre-purge period, the gas valve is energized and the control
looks for a flame signal for up to 8 seconds. If no flame is
sensed, the cycle is repeated up to 4 times before entering a
1-hour lockout.