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Unitary Products Group
CAUTION:
Combustion air adjustments
must be made only by a qualified technician.
Improper air adjustment may cause unsafe op-
eration, explosion or asphyxiation.
To adjust the combustion air:
1. To light and operate furnace see label inside lower
furnace door.
2. Allow the burner to burn for about 1 MINUTE.
3. Look through the observation window and observe
the appearance of the flame.
4. On natural gas, the base of the flame should be blue
but the tips of the flame will be yellow. (See Figure
19.)
5. On Propane gas, almost all of the flame will be yellow
although some blue should still be present at the
base of the flame next to the end of the burner. (See
Figure 20.)
6. If the flame is too yellow, the combustion air should
be increased. If the flame is excessively blue (no yel-
low) the combustion air should be decreased.
7. To adjust the combustion air, loosen the lock screw
holding the combustion air rod in place. Push in on
the rod to increase the combustion air. Pull out on the
combustion air rod to decrease the combustion air.
Tighten lock screw after adjustment is made. Do not
completely close air damper at any time. Complete
closure of air damper to burner will result in improper
operation. See caution above.
View of Burner Through the Observation Window
LIGHT BLUE
WITH YELLOW TIPS
DARK BLUE
BLUE TIPS JUST STARTING
TO BECOME PRONOUNCED.
YELLOW WITH
ORANGE TIPS
LIGHT BLUE
NO BLUE TIPS
EXTENDING
FROM THE END
OF THE BURNER
DARK BLUE
DARK BLUE
LONG AND EXTREMELY
PRONOUNCED BLUE TIPS
EXTENDING FROM THE
END OF THE BURNER
WHTISH YELLOW TO
LIGHT YELLOW
LIGHT BLUE
BLUE TIPS JUST STARTING
TO BECOME PRONOUNCED
DARK YELLOW TO
ORANGISH YELLOW
MAIN FLAME IS A
WHITISH YELLOW
REFLECTIVE COLOR.
VERY LITTLE BLUE
EXTENDING FROM
THE END OF THE
BURNER.
WHITISH YELLOW
LIGHT BLUE
LONG AND EXTREMELY
PRONOUNCED BLUE TIPS
EXTENDING FROM THE
END OF THE BURNER
CORRECT AMOUNT OF
PRIMARY AIR
TOO LITTLE PRIMARY AIR
PUSH SHUTTER ROD IN
TOO MUCH PRIMARY AIR
PULL SHUTTER ROD OUT
CORRECT AMOUNT OF
PRIMARY AIR
TOO LITTLE PRIMARY AIR
PUSH SHUTTER ROD IN
TOO MUCH PRIMARY AIR
PULL SHUTTER ROD OUT
FIGURE 20 --
PROPANE GAS FLAME APPEARANCE
FIGURE 19 --
NATURAL GAS FLAME APPEARANCE
View of Burner Through the Observation Window
If Furnace Fails to Operate Properly
1. Check setting of thermostat -- and position of HEAT/
COOL switch if air conditioning is installed. If a set--
back type thermostat is employed be sure that the
thermostat is in the correct operating mode.
2. Check to see that electrical power is ON.
3. Check to see that the knob on the gas control valve
is in the full ON position.
4. Make sure filters are clean, return grilles are not ob-
structed, and supply registers are open.
5. Be sure that furnace flue piping is open and unob-
structed.
If the cause for the failure to operate is not obvious, do
not attempt to service the furnace yourself. Call a quali-
fied service agency or your gas supplier.
Summary of Contents for DLAS
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