How To Shut Off Gas - Gas Gun; Verifying & Adjusting Temperature Rise; Burner Adjustments; Gas Pressure - Nordyne M1MB 056 Installation Instructions Manual

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 22) 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 30).
• Robertshaw: push the gas control lever to the OFF
position (Figure 31).
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 Replacement Parts List available online.
Verifying & Adjusting Temperature Rise
Confi rm the temperature rise through the furnace is
within the limits specifi ed on the furnace rating plate. Any
temperature rise outside the specifi ed limits could result
in premature failure of the heat exchanger.
1. Place thermometers in the return and supply air
stream as close to the furnace as possible. To avoid
false readings, the thermometer on the supply air side
must be shielded from direct radiation from the heat
exchanger.
2. Adjust all registers and duct dampers to the desired
position and run the furnace for 10 to 15 minutes in
high fi re before taking any temperature readings. The
temperature rise is the difference between the supply
and return air temperatures.
For typical duct systems, the temperature rise will fall
within the limits specifi ed on the rating plate with the
blower speed at the factory recommended setting. If
the measured temperature rise is outside the specifi ed
limits, it may be necessary to change the speed of the
blower. NOTE: Lowering the blower speed increases the
temperature rise and a higher blower speed will decrease
the temperature rise.
The furnace is equipped with a multi-speed motor. Refer
to the furnace wiring diagram (Figures 38 & 39, pages
33 & 34) for blower speed selection.

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 (Figure 28, page 20) located on the top
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.

Combustion Air

CAUTION:
• Combustion air adjustment must be made only
by a qualifi ed technician. Improper air adjust-
ment may cause unsafe operation, explosion
and/or fi re asphyxiation.
• If the input to the furnace is too great because
of excessive gas pressure, wrong size nozzle or
orifi ce, high altitude, etc., the burner fl ame will
be sooty and can produce carbon monoxide,
which could result in unsafe operation,
explosion and/or fi re or asphyxiation.
In order for the fl ame to burn effi ciently, it must receive
adequate combustion air. The amount of combustion air
required varies according to altitude, actual B.T.U. content
of the fuel, gas pressure, conversion to another gas and
other factors. The burner fl ame should be observed and
any necessary adjustments made before the furnace is
placed into service. See Table 7 for Factory Air settings.
Model Nat. Gas
66,000 3.5
86,000 5.3
Table 7. Factory Combustion Air Settings
LP Gas Oil
3.5 3.5
6 5
23