Allied 11K50, Installation Instructions, Page: 4 / 4

507369-03 Issue 1737 Page 4 of 4
Placing the Unit into Operation
IMPORTANT
Follow the lighting instructions provided on the unit.
If lighting instructions are not available, refer to the
following section.
Units are equipped with a hot surface ignition system. The
ignition system automatically lights the burners each time
the thermostat calls for heat.
1. STOP ! Read the safety information at the beginning
of this section.
2. Set the thermostat to its lowest setting.
3. Turn off all electrical power to the furnace.
4. Do not try to light the burners by hand.
5. Remove the unit access panel.
6.
Move gas valve switch to OFF . See Figure 3.
7. Wait five (5) minutes for any gas to clear out. If you
then smell gas, STOP ! Immediately call your gas
supplier from a neighbor’s phone. Follow the gas
supplier’s instructions. If you do not smell gas, go to
the next step.
8. Move gas valve switch to ON . See Figure 3.
9. Replace the unit access panel.
10.
Turn on all electrical power to the unit.
11. Set the thermostat to desired setting.
12.
If the furnace will not operate, see the section “Turning
Gas Off to the Unit” and call your the gas supplier.
Gas Pressure Measurement
Gas Flow (Approximate)
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
Table 1. Gas Meter Clocking Chart
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 1. If manifold pressure matches Table 2 and rate is
incorrect, check gas orifices for proper size and restriction.
Remove temporary gas meter if installed.
Supply Pressure Measurement
When testing supply gas pressure, use the 1/8” N.P.T.
supply line tap located on the gas valve to facilitate test
gauge connection. See Figure 2. Check gas line pressure
with unit firing at maximum rate. Low pressure may result
in erratic operation or underfire. High pressure can result in
permanent damage to gas valve or overfire.
On multiple unit installations, each unit should be checked
separately, with and without units operating. Supply
pressure must fall within range listed in Table 2.
NOTE: To obtain accurate reading, shut off all other gas
appliances connected to meter.
Manifold Pressure Measurement
1. Connect test gauge to manifold pressure tap (Figure
2) on gas valve.
2. Start unit and allow 5 minutes for unit to reach steady
state.
3. After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in
Table 2.
4. If necessary, make adjustments. Figure 2 shows
location of adjustment screw.
Capacity
Manifold
Pressure in. w.g.
0 - 7500 ft.
Supply Line Pressure
in. w.g.
Min Max
All Models 10.0 11.0 13.0
Table 2.
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 Table 3.
NOTE: Shut unit off and remove manometer as soon as
the supply pressure, manifold pressure and combustion
sample have been obtained. Take care to remove barbed
fitting and replace threaded plug.
Model CO
2
% for LP
All A93, A95, 92G1, 95G1 &
96G1 Units
8.4 - 9.6
All A80 & 80G1 Units 7.5 - 9.0
The carbon monoxide reading should not exceed 100 ppm.
Table 3.
Turning Off Gas to the Unit
1. Set the thermostat to its lowest setting.
2. Turn off all the electrical power to the unit.
3. Remove the access panel.
4.
Move the switch on the gas valve to
OFF
. Do not force
the switch.