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5.
Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit control to shut the unit off.
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 lockout? If the unit locks
out again, inspect the unit for blockages.
Heating Sequence of Operation
1. When thermostat calls for heat, combustion air inducer
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, flame sensor proves the flame, and the
combustion process continues.
6.
If flame is not detected after first 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. To interrupt the 60 minute lockout
period, move thermostat from "Heat" to "OFF" then
back to "Heat". Heating sequence then restarts at step
1.
Gas Pressure Adjustment
Gas Flow (Approximate)
Gas Meter Clocking Chart
Seconds for One Revolution
Natural
Capacity
1 cu ft
Dial
-045
80
-070
55
-090
41
Natural - 1000 btu/cu ft
Table 15.
NOTE: To obtain accurate reading, shut off all other gas
appliances connected to meter.
Furnace should operate at least 5 minutes before checking
gas flow. 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
15. If manifold pressure matches Table 17 and rate is
incorrect, check gas orifices for proper size and restriction.
Remove temporary gas meter if installed.
Page 42 of 55
LP
2 cu ft
1 cu ft
2 cu ft
Dial
Dial
160
200
110
136
82
102
LP - 2500 btu/cu ft
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 field-provided barbed fitting and connect a
manometer to measure supply 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 field provided barbed
fitting. 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
flame. 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 17.
NOTE: Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to remove
barbed fitting and replace threaded plug.
Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking
combustion. Take combustion sample beyond the flue
outlet and compare to the tables below. The maximum
carbon monoxide reading should not exceed 100 ppm.
Unit
All
The maximum carbon monoxide reading should not exceed
100 ppm.
Dial
High Altitude Information
400
NOTE: In
272
elevations over 4500 feet (1372 m) is the jurisdiction of
local authorities.
204
Units may be installed at altitudes up to 10,000 ft. above
sea level. See Table 17 for de-rate manifold values. Units
installed at altitude of 7501 - 10,000 feet require an orifice
change. Units installed at altitudes of 4501 - 10,000 feet
(1373 to 3048 m) require a pressure switch change which
can be ordered separately. Table 18 and Table 19 list
conversion kit and pressure switch requirements at varying
altitudes.
The combustion air pressure switch is factory-set and
requires no adjustment.
Issue 2223
CO
% for Nat
2
7.2 - 8.2
Table 16.
Canada,
certification
CO
% for L.P.
2
8.6 - 9.6
for
installations
at
507769-05G / 31-5000656
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