21
Figure 6. Air Shutter Adjustments for
Power Gas Burner
The ignition control is equipped with a relight feature. If the
flame is extinguished during the run cycle, the control will
close the gas valve and repeat the ignition sequence as
previously described. Once in lockout, the control can be
reset by interrupting the 24 VAC power. This can be easily
accomplished by setting the thermostat below room tem-
perature for at least forty-five (45) seconds, and then return-
ing it to desired setting.
If adjusting the thermostat does not reset the ignition control,
turn power to the appliance off for forty-five (45) seconds,
and then turn it back on.
NOTE: If the gas control has been replaced or serviced,
lighting may not be satisfactory until air has been purged
from the gas line or the gas input and combustion air have
been adjusted.
Checking Natural Gas Input
Check the label on the burner to be sure the burner is
equipped with orifices for type of gas being used. Alternate
orifices are in bag attached to the burner. Instructions for
changing orifices are covered later herein.
To check the input, time the dial on the meter for one
revolution while the burner is operating. Be sure to isolate
all other gas consuming appliances except pilots. If the time
varies more than 5% from the times shown on the chart,
check the gas pressure according to the procedure stated in
GAS BURNER CONTROLS. If the pressure reading
matches the pressure shown on the chart; check to be sure
the proper burner orifice is being used. Further gas prob-
lems should be referred to the local gas supplier. Natural gas
varies in BTU value from 950 to 1,050 BTU per cubic foot.
The chart is based on natural gas at an average of 1,000
BTU per cubic foot, burner manifold pressure of 3.5" W.C.
and meter dial size of 1 cubic foot.
Adjusting the Burner
1. Air shutters are factory preset for installation in a given
furnace. (See Figure 15) Local conditions may require
fine tuning. Rotate the air shutter disc at the left of the
burner housing to adjust the combustion air. Rotate the
disc counterclockwise to increase combustion air. Rotate
the disc clockwise to decrease combustion air.
The combustion air for the power gas burner is taken from
the outside of the manufactured home.
Operating at high altitudes —
for operation at elevations
of more than 2,000 feet above sea level, the input should be
de-rated 4% for each 1,000 feet above sea level by reducing
orifice size, or decreasing the manifold pressure.
1. Observe combustion flame through observation door on
CMF series furnaces immediately after burner is placed
in operation. Yellow flame tips should be visible above
combustion chamber.
2. Burner should run quietly. Excessive updraft may cause
burner to rumble; rotate disc to decrease air supply.
(CAUTION: See Note below.)
3. After checking the flame pattern and for noise level, lock
disc in position by tightening slotted head screw.
NOTE: It is very important that air supply be ample without
decreasing efficiency of burner. An inadequate amount of
air can cause carbon monoxide (CO). The carbon dioxide
(CO
2
) content of the flue products should be in the range of
8.0 to 9.0 percent for natural gas and 9.0 to 10.0 percent for
LP gas.
Adjusting Heat Distribution
1. Set the room thermostat for the desired room
temperature.
2. Balance the heat distribution by adjusting the register
openings.
Checking LP Gas Input
LP gas installations are not usually supplied with meters for
determining the amount of gas used. The chart shows the
approximate time required per dial revolution if a meter is
used that is calibrated for cubic feet delivery. The chart is
based on LP gas at an average of 2,500 BTU per cubic foot,
burner manifold pressure of 10" W.C. and meter dial size of
1 cubic foot.
Burner
BTUH
Burner
Time Per
Model
Input
Orifice
Rev.
PGB-1
90,000
No. 16
40 sec.
PGB-2
75,000
No. 20
47 sec.
Table 1.
Burner
BTUH
Burner
Time Per
Model
Input
Orifice
Rev.
PGB-1
90,000
No. 36
98 sec.
PGB-2
75,000
No. 40
117 sec.
Table 2.
PGB Basic Air Shutter
Settings
To check combustion
air openings: Insert air
guage vertically into the
blower, the gauge
should stop within the
range shown in the
chart. Make sure the
shutter is securely
locked. See Installation
Manual.
Burner Model
Air Setting
PGB-1
G
PGB-2
D
PGB-3
C
LOCKING
SCREW
