Nordyne Downflow Direct Vent Forced Air Gas Oil Furnaces SERIES M1B - Manual (Page 22)

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How to Shut Off Gas - Direct Ignition
1. Set the thermostat to the lowest setting.
2. Turn off all electric power to the appliance
before servicing unit.
3. Set the furnace On-Off Switch to OFF.
• Honeywell (Figure 32): Turn gas control knob
clockwise to OFF, Robertshaw (Figure 33):
Push the gas control lever to OFF.
• For oil, shut off all valves.
4. Replace the furnace door.
Operating Instructions for Oil Gun Furnaces
If your furnace model number begins with M5S*,
the furnace is equipped with an ignition device
which automatically lights the burner.
Do not try
to light this furnace manually.
1. Open all valves in the oil line.
2. Verify the fi re door is closed.
3. Set the furnace On-Off switch to ON.
4. Set the thermostat to the desired setting.
NOTE: M5 oil gun furnaces may be converted to
gas gun in the fi eld by using the proper conversion
kit listed in the RPL.
Operating Instructions for Gas Gun Models
If your furnace model number begins with M1B,
the furnace does not have a pilot. Ignition is
accomplished by a silicon carbide hot surface
ignitor. A control module takes care of all lighting
and timing functions. There are no external
relays or timing devices.
Do not try to light this
furnace by hand. The control module is not
fi eld serviceable.
1. Before operation, smell for gas all around the
furnace, especially near the fl oor because
some gases are heavier than air and will settle
on the fl oor. If you detect gas, STOP and follow
all the safety instructions.
2. Set the thermostat to the lowest setting.
3. Turn off all electric power to the appliance.
4. Turn off the gas valve:
• Honeywell: push in the gas control knob
and turn clockwise to OFF (Figure 32).
• Robertshaw: push the gas control lever to
OFF (Figure 33).The lever cannot be placed
in the off position unless it is pushed in
slightly. DO NOT FORCE!
5. Wait ten minutes to clear out any gas. If
you smell gas, STOP! and follow the safety
information. If gas is not detected, proceed to
the next step.
6. Set the furnace On-Off switch to the ON
position.
• Honeywell: turn knob on gas control counter
clockwise to ON.
• Robertshaw: push the gas control lever to
ON.
7. Turn electric power to the appliance ON.
8. Set the thermostat to HEAT and/or the desired
temperature setting. The furnace should light
in approximately 45 seconds. If the appliance
will not operate, follow the instructions “How to
Shut Off Gas - Direct Ignition Furnace” (page
21) and call your service technician or gas
supplier.
In the event of any fl ashback or explosion,
immediately shut off the furnace and call your
service technician.
How to Shut Off Gas - Oil & Gas Gun
1. Set the thermostat to the lowest setting.
2. Turn off all electric power to the appliance at
the breaker or fuse box.
3. Set the thermostat MODE switch to OFF.
4. Turn the gas valve OFF:
• Honeywell: push in and turn the gas control
knob clockwise to the OFF position (Figure
32).
• Robertshaw - push the gas control lever to
the OFF position (Figure 33).
5. Replace the furnace door.
NOTE: M1B gas gun furnaces may be converted
to oil gun in the fi eld by using the proper
conversion kit listed in the RPL
Burner Adjustments
Burner settings are made at the factory. However,
these settings may change during shipping,
handling, and installation. The following items
should be checked and readjusted if necessary.
Gas Pressure
The gas pressure can be checked with a
manometer at the pressure tap located on the
side of the gas valve. The gas valve pressure
regulator can be adjusted by removing the
regulator selector stack and turning the slotted
insert located directly under the selector stack.
The regulator selector stack must be secured
in place before each pressure reading is taken.
Natural gas manifold pressure should be 3.5”
W.C. and L.P. gas manifold pressure should be
10” W.C. Replace the gas pressure tap plug on
the gas valve.
Pilot Flame (Standing Pilot Only)
The pilot fl ame can be adjusted by turning the
pilot adjustment screw, located on top of the
gas valve (See Figure 30, page 20). The pilot
fl ame height should be between 3/4” and 1.” The
fl ame tip should be visible just above the pilot
bracket when viewed through the observation
door. The same pilot orifi ce is used with both
natural and LP gas.