Nordyne M1G Service Guide, Factory Combustion Air Settings M1B* - 066 =, Burner Adjustments

2.Limit Control - This furnace is protected by two high temperature safety limit switches. The auxiliary (upper) limit switch and the high temperature (lower) limit switch are auto- matic reset types. If either limit trips, the burner will shut off. If either limit switch trips off again soon after resetting, set the furnace On-Off switch to the “OFF” position and call your authorized serviceman.

3.Gas Valve - The gas valves for the gas furnaces are a 100% shut-off type and will fail safe if for some reason the gas is turned off. The valve is a “step-open” type for M1G*- models and “slow-open” for M1M*- and M1B*- models which means it opens to a “low-fire” position, and after a few seconds, “steps- open” to “high-fire.”

4.Roll Out Switch - (M1G* - 056 & 070) The furnace is protected by a manual reset safety switch located on the bottom left hand side of the combustion pipe.

5.Oil Burner Primary Control - The primary control for oil gun furnaces starts the burner, monitors a safe operating cycle, and shuts the burner off at the end of a heating cycle. The control uses a light sensing transducer to determine if fuel ignition has been suc- cessfully attained. If ignition is not attained by the end of the safety ignition timing period, the control shuts the burner off and enters “lock- out.”

6.a. Summer Cooling - (H Series): Your fur- nace is equipped to operate the circulating fan only. Turn the Fan On-Auto switch to the “ON” position during warm weather. The blower will now operate to circulate air in your home through the duct system.

b. Summer Cooling - (A, B, C, & D Series): Your furnace is A/C ready, equipped with A/ C relay and transformer. The unit is equipped to use a 4-wire thermostat. When using a 5- wire thermostat, RC and RH should be jumped (see instructions included with ther- mostat).

17. SERVICE GUIDE

BURNER ADJUSTMENTS

Burner settings and adjustments are made at the factory. However, these settings may change during shipping, handling, and installa-

tion. Therefore the following items should be checked and readjusted if necessary.

Atmospheric Gas with Standing Pilot and Direct Ignition Furnaces, Including Gas Gun.

a. 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 re- moving 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.

b. Pilot Flame (Standing Pilot Only)

The pilot flame can be adjusted by turning the pilot adjustment screw, located on top of the gas valve (See Figure 29). The pilot flame height should be between 3/4” and 1.” The flame tip should be visible just above the pilot bracket when viewed through the observa- tion door. The same pilot orifice is used with both natural and L.P. gas.

COMBUSTION AIR

In order for the flame to burn efficiently, it must receive adequate combustion air. The amount of combustion air required will vary depending on altitude, actual B.T.U. content of the fuel being used, gas pressure, conversion to an- other gas and other factors. The burner flame should be observed and any necessary adjust- ments made before the furnace is placed into service. See Table 9 for Factory Air settings.

Gas Gun

Combustion air adjustment is made to the main burner by loosening the lock nut on the plastic air shutter, located on the side of the plastic burner air inlet box. Move the threaded rod to a smaller number (counterclockwise) for less

Factory Combustion

Air Settings

M1B* - 066 = 3.5

M1B* - 086 = 4.0

M1S* - 066 = 3.0

M1S* - 086 = 5.5

Table 9.

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