18
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 successfully 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 furnace 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 thermostat).
17. SERVICE GUIDE
BURNER ADJUSTMENTS
Burner settings and adjustments are made at the factory.
However, these settings may change during shipping,
handling, and installation. 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 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.
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 observation door. The same pilot
orifice is used with both natural and L.P. gas.
b. After this sequence, the control module tests to see if
flame is sensed. If it has, the furnace continues to heat
until the thermostat is satisfied.
c. If the burner has not lit, the ignition sequence is repeated
a maximum of two more times. If flame is not sensed after
three attempts, the control enters “Lockout” and no further
attempts to light the burner will occur. If “Lockout” occurs,
contact a qualified service technician for assistance.
d. When call for heat is satisfied, the thermostat contacts
open and the gas valve shuts off gas flow.
TO TURN OFF GAS/OIL APPLIANCE:
a. Set the thermostat to the lowest setting.
b. Turn off all electric power to the appliance before servicing
unit.
c. Set the On-Off Switch to “OFF.”
d. Honeywell - turn gas control knob clockwise to “OFF”
Robertshaw - Push the gas control lever to “OFF.”
e. For oil, shut off all valves.
f. Replace the furnace door.
THE FURNACE CONTROLS AND FUNCTIONS
1. On-Off Switch - This switch turns electrical power to the
furnace on and off. The switch must be set in the “On”
position for the furnace to operate. For M1G* models, in
warm weather there is a possibility of the blower coming
on periodically or operating continuously due to a heat
buildup within the furnace by a combination of warm
weather and heat from the pilot. This is normal operation
as long as there is power to the furnace and the On-Off
switch is at the “ON” position. If blower operation is not
desired, the On-Off switch may be set in the “OFF”
position to cut the electrical power to the furnace.
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 automatic 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
Before placing the furnace in service it must be
checked to make sure it is equipped for the type
of gas being used. The burner flame must also be
observed and adjusted if necessary. Failure to
observe this caution may result in unsafe
operation, explosion and/or fire, or asphyxiation.
See the following sections “Gas Supply” and
“Combustion Air.”
DANGER:
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