27
GAS CONVERSION
This gas fi red heating appliance was shipped
from the factory for use with natural gas. How-
ever, the appliance can be converted for use
with LP gas. Use the following procedure for
gas conversion of the burner.
ATMOSPHERIC AND DIRECT IGNITION
FURNACES
a. Follow the instructions to “Turn Off Gas to the
Appliance.”
b. Disconnect the gas pipe union and the electri-
cal wires connected to the gas valve.
c. Remove the pilot tube and thermocouple from
the gas valve (M1G*).
d. To remove the gas valve assembly, remove
screw(s) from gas valve bracket. Gas valve
and spud may be removed. Orifi ce is located at
the end of the spud (M1G*,M1M*),or remove
three (3) bolts from U-shaped manifold plate
and orifi ce assembly (M1B*).
e. Replace the main orifi ce with the L.P. gas
orifi ce supplied in the envelope located by
the gas valve. Check to insure the orifi ce size
matches the nameplate.
f. It is not necessary to convert the pilot ori-
fi ce.
g. For Honeywell gas valves with the regulator
converter (Figure 33), check for the letters NAT
or LP on the pressure regulator cap. Unscrew
the cap, invert it, replace, and tighten until
snug.
h. For the Robertshaw gas valve with the regula-
tor converter (Figure 34), remove the black
cover and unscrew the converter located on
top of the gas valve. Invert the converter. (For
“LP” the red ring will be located at the bottom
and the “LP” stamping on the converter will
appear right side up.) Then screw converter
back into the regulator, hand tight plus 1/8
turn, and replace the black cover onto the
converter top to protect the threads.
i. Reassemble the burner assembly into the
furnace.
j. Reconnect the gas piping and electrical wires
to the gas valve.
k. Open the manual shut-off valve and follow the
FURNACE START-UP procedure as outlined
previously in this manual to put the furnace
into operation.
NOTE: The pilot fl ame is adjustable by turning
the adjustment screw located on the gas valve
with a small screwdriver. (See Figure 29)
TROUBLESHOOTING - STANDING PILOT
MODELS
Main Burner Does Not Come On
a. Check the electrical supply to the furnace.
b. Be sure the furnace On-Off switch is in the
“ON” position.
c. Check for proper thermostat operation.
d. Check for broken or open thermostat wires.
e. Check to make sure the insulation located on
the inside of the front panel is glued securely
around the fan switch and the limit switch.
f. Shut off the electrical supply to the furnace
and remove the electrical box cover.
g. Check for a defective transformer or blown
fuse.
h. Check electrical circuit for proper grounding,
polarity, and make sure the electrical connec-
tions are tight.
i. Check to see if limit switches may have failed
to close.
j. Replace the electrical box cover and restore
electrical power to the furnace. Turn the On-
Off switch to “ON” and raise the thermostat
setting above room temperature.
k. Check for 24 volts at the gas valve.
l. Replace the gas valve if the pilot is established
and it does not open when powered with 24
volts.
Gas Valve Powered (24 volts)– No Main
Flame
a. The manual shut-off valve must be on.
b. The pilot fl ame must be established.
c. The gas valve control lever must be in the
“ON” position.
Figure 34. Convertible Pressure
Regulator
Robertshaw
Valve
