12
105735
VENT-FREE NATURAL GAS HEATERS
BLUE-FLAME MBN20LB
™
CLEANING AND
MAINTENANCE
WARNING: Turn off heater
and let cool before cleaning.
CAUTION: You must keep
control areas, burner, and circu-
lating air passageways of heater
clean. Inspect these areas of
heater before each use. Have
heater inspected yearly by a quali-
fied service person. Heater may
need more frequent cleaning due
to excessive lint from carpeting
and pet hair, sawdust, cobwebs,
etc.
CLEANING BURNER
PILOT AIR INLET HOLE
We recommend that you clean the unit ev-
ery 2,500 hours of operation or every three
months.
Figure 19 - Correct Burner Flame Pattern
Figure 20 - Incorrect Burner Flame Pattern
NOTICE: Do not mistake orange
flames with yellow tipping. Dirt
or other fine particles enter the
heater and burn causing brief
patches of orange flame.
WARNING: If yellow tipping
occurs, your heater could pro-
duce increased levels of carbon
monoxide. If burner flame pat-
tern shows yellow tipping, follow
instructions at bottom of this
page.
1/2 HEAT SHIELD
OR GLASS HEIGHT
Figure 18 - Incorrect Pilot Flame Pattern
INSPECTING
BURNER
Check pilot flame pattern and burner flame
pattern often.
PILOT FLAME PATTERN
Figure 17 shows a correct pilot flame pat-
tern. Figure 18 shows an incorrect pilot
flame pattern. The incorrect pilot flame is
not touching the thermocouple. This will
cause the thermocouple to cool. When the
thermocouple cools, the heater will shut
down.
If pilot flame pattern is incorrect, as shown
in Figure 18
• turn heater off (see To Turn Off Gas to
Appliance, page 11)
• see Troubleshooting, pages 13 through 15
Figure 17 - Correct Pilot Flame Pattern
BURNER FLAME PATTERN
Figure 19 shows a correct burner flame
pattern. Figure 20 shows an incorrect burner
flame pattern. The incorrect burner flame
pattern shows yellow tipping of the flame. It
also shows the flame higher than 1/2 the
heat shield height.
If burner flame pattern is incorrect, as shown
in Figure 20
• turn heater off (see To Turn Off Gas to
Appliance, page 11)
• see Troubleshooting, pages 13 through 15
Thermocouple
Pilot Burner
Pilot Burner
Thermocouple
1/2 HEAT SHIELD
OR GLASS HEIGHT
Yellow
Tipping
Figure 21 - Pilot Inlet Air Hole
Pilot Assembly
Pilot Air Inlet
Hole
We also recommend that you keep the burner
tube and pilot assembly clean and free of
dust and dirt. To clean these parts we recom-
mend using compressed air no greater than
30 PSI. Your local computer store, hard-
ware store, or home center may carry com-
pressed air in a can. You can use a vacuum
cleaner in the blow position. If using com-
pressed air in a can, please follow the direc-
tions on the can. If you don't follow direc-
tions on the can, you could damage the pilot
assembly.
1.
Shut off the unit, including the pilot.
Allow the unit to cool for at least thirty
minutes.
2.
Inspect burner, pilot for dust and dirt.
3.
Blow air through the ports/slots and
holes in the burner.
Clean the pilot assembly also. A yellow tip
on the pilot flame indicates dust and dirt in
the pilot assembly. There is a small pilot air
inlet hole about two inches from where the
pilot flame comes out of the pilot assembly
(see Figure 21). With the unit off, lightly
blow air through the air inlet hole. You may
blow through a drinking straw if compressed
air is not available.
CABINET
Air Passageways
• Use a vacuum cleaner or pressurized air
to clean.
Exterior
• Use a soft cloth dampened with a mild
soap and water mixture. Wipe the cabi-
net to remove dust.