Use and Care Manual
507713-01Page 26 of 32 Issue 1623
Heating Sequence Of Operation
See gure 36.
1. When thermostat calls for heat, combustion air blower
starts.
2. Combustion air pressure switch proves blower operation.
Switch is factory set and requires no adjustment.
3. After a 15 second prepurge, the hot surface ignitor
energizes.
4. After a 20 second ignitor warm-up period, the gas
valve solenoid opens. A 4 second trial for ignition period
begins.
5. Gas is ignited, ame sensor proves the ame, and the
combustion process continues.
6. If ame is not detected after rst ignition trial, the ignition
control will repeat steps 3 and 4 four more times before
locking out the gas valve. The ignition control will then
automatically repeat steps 1 through 6 after 60 minutes.
7. To interrupt the 60 minute, move thermostat from “Heat”
to “OFF” then back to “Heat”. Heating sequence then
restarts at step 1.
Gas Pressure Adjustment
Gas Flow (Approximate)
Furnace should operate at least 5 minutes before checking
gas ow. Determine time in seconds for two revolutions of
gas through the meter. (Two revolutions assures a more
accurate time.) Divide by two and compare to time in Table
7 below. If manifold pressure matches Table 9 and rate is
incorrect, check gas orices for proper size and restriction.
Remove temporary gas meter if installed.
NOTE: To obtain accurate reading, shut off all other gas
appliances connected to meter.
Supply Pressure Measurement
A threaded plug on the inlet side of the gas valve provides
access to the supply pressure tap. Remove the threaded
plug, install a eld provided barbed tting and connect
a manometer to measure supply pressure. See Table 9
for proper line pressure. Replace the threaded plug after
measurements have been taken.
Manifold Pressure Measurement
1. Remove the threaded plug from the outlet side of the gas
valve and install a eld provided barbed tting. Connect
to a manometer to measure manifold pressure.
2. Start unit and allow 5 minutes for unit to reach steady
state.
3. While waiting for the unit to stabilize, observe the ame.
Flame should be stable and should not lift from burner.
Natural gas should burn blue.
4. After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in Table
12.
NOTE: Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to remove
barbed tting and replace threaded plug.
Proper Combustion
Furnace should operate a minimum 15 minutes with correct
manifold pressure and gas flow rate before checking
combustion. Take combustion sample beyond the ue out
let and compare to the tables below. The maximum carbon
monoxide reading should not exceed 100 ppm.
Table 8
INTEGRATED IGNITION CONTROL
Blower on time will be 45 seconds after gas valve is energized. Blower off time will depend on “OFF TIME” Setting.
Figure 36
Table 7