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Start
Burner
and Set Combustion
Figure
6. - Nozzle LinelHeadlAir
Tube Assembly
(Low firing
rate
shown.)
Retention Head
Support Legs
Electrode Clamp
Electrode Bracket
Electrode Insulator
Nozzle Adapter
Nozzle
Stops in Retention Ring
/-Electrode
Extension Rods
/
J
SK9666A
Cup
\
Nozzle Line
Ring
Throttle Cup Hub
Retention Ring
• Set Combustion
with Test Instruments
1. Allow the burner to run for approximately
5 to 10
minutes.
2.
Set the stack or over-fire draft to the level speci-
fied by the appliance manufacturer.
,
Natural
Draft Applications;
typically
over=fire
draft is -0.01" or
-0.02" w.c.
•
Direct
Venting;
typically may not require draft
adjustment.
•
High Efficiency/Positive
Pressure Appliances;
also vary from traditional appliances (see manu-
facturer's recommendations).
.
Follow these five steps to properly
adjust the
burner:
Step 1:
Adjust the head/air until a trace of smoke
is achieved.
This can be accomplished
by turn-
ing the screw on the head/air adjustment
plate
assembly to increase air (CCW) or decrease air
(CW).
The NX burner has a reduced diameter air tube, preci-
sion-designed
air throttle cup and combustion head for
improved performance.
This design provides very accu-
rate control of the air/fuel ratio, but the light reaching the
cad cell through small holes in these components is lim-
ited. Because of this, the average cad cell resistance
may be higher than conventional
burners
with larger
openings.
Step 2:
At the trace of smoke level, measure the
CO2 (or 02).
This is the vital reference point for
further adjustments.
Example: 13.5% CO2 (2.6%
02)
Step 3:
Increase the air to reduce the CO2 by 1.5
to 2 percentage points. (02 will be increased by
approximately 2.0 to 2.7 percentage points.)
Ex-
ample: Reduce CO2 from 13.5% to 11.5% (2.6%
to 5.3% 02).
Step 4:
Recheck smoke level. It should be Zero.
This
procedure
provides
a
margin
of
reserve
air
to
accommodate
variable
conditions.
If the draft
level has changed,
recheck
the
smoke
and
CO2
levels
and
readjust
burner, if necessary.
Step 5"
Once the combustion has been set, tighten
the lower acorn nut and splined nut on the air ad-
justment assembly. See Figure 5.
.
Chimney Vent Systems:
Install the burner cover
and repeat Steps 2 and 4 above. If CO2 increas-
es (02 decreases), remove the cover and adjust
the air setting so the CO2 (02) with the cover
installed meets the requirements of Step 3.
5. Direct Vent Systems with outside air ducted to
burner:
Install the burner cover.
.
Start and stop the burner several times to ensure
satisfactory
operation. Test the primary control
and all other appliance safety controls to verify
that they function according to the manufactur-
er's specifications.
Page 10
RWB6104WMNX
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