Installation Guide

507332-01Page 26 of 35 Issue 1723
6. Is gas turned on at the meter?
7. Is the manual main shut-off valve open?
8. Is the internal manual shut-off 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 off 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.
Heating Sequence of Operation
See Figure 27
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 pre-purge, 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)
Table 11.
Gas Meter Clocking Chart
Capacity
Seconds for One Revolution
Natural LP
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
Dial
-045 80 160 200 400
-070 55 110 136 272
-090 41 82 102 204
-110 33 66 82 164
-135 27 54 68 136
Natural - 1000 btu/cu ft LP - 2500 btu/cu ft
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
11 above. If manifold pressure matches Table 13 and rate is
incorrect, check gas orices 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 13
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.
Figure 27. Heating Sequence of Operation
Demand
15
ON
OFF
CAI
35
1
Pre-Purge
Ignitor Warm-up
Blower
“On” Delay
Post
Purge
5 SEC80
Ignitor
Gas Valve
Indoor Blower
39
Trial for
Ignition
Blower on time will be 45 seconds after gas valve is energized. Blower off time will depend on “OFF TIME” Setting.