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specified range. Firmly tighten the inlet air
shutter locking nuts when finished.
NOTE:
Adjust the inlet air shutter only at 100%
firing rate. Do not adjust the differential
pressure regulator.
27. Change the firing rate to 30%. Allow time for
the combustion analyzer to settle. Check the
measured oxygen reading to insure that it is
still within the range as per Table 1.
28. Continue this procedure until all oxygen
levels are within the ranges specified in
Tables 1,2, and 3.
29. Record all readings on the AERCO start-up
sheet provided with each unit. Proceed to
Section 4.5.
4.4 PROPANE COMBUSTION
CALIBRATION
For propane units it will be necessary to install
an additional 8" W.C. manometer as described
below. This is used to measure the pressure
drop across the air/propane-mixing orifice.
1. Referring to Fig. 4.5 remove the 1/8" NPT
plug from the gas inlet pipe ahead of the
burner and install a 1/8" NPT barbed fitting.
2. Remove the 1/2" NPT plug from the tee
located after the air pressure regulator and
install a 1/2" barbed fitting (see fig. 4.5).
3. Attach the 8" W.C. manometer to the barbed
fittings installed in steps 1, and 2.
4. While following the combustion calibration
procedure in Section 4.3 measure the
pressure drop across the air/propane mixing
orifice using the 0-8" W.C. manometer.
5. This reading should remain a constant 3.8"
to 4" W.C. throughout the operating range.
6. If the pressure drop is not within this range,
remove the cap from the air pressure
regulator.
7. Using a flat blade screwdriver adjust the
regulator until 3.8"-4.0" W.C. is obtained.
Clockwise will increase the reading and
counter-clockwise will decrease the reading.
8. It adjustments are made to this regulator it
will be necessary to recheck oxygen settings
at 16%, 30%, and 100% firing rates
After an adjustment is made to the air
regulator, the cap must be put back on
securely to obtain an accurate reading
Figure 4.5
Propane Air Differential Pressure Taps
4.5 UNIT REASSEMBLY
Once combustion calibration is set properly, the
unit can be re-assembled for permanent
operation.
1. Put the green ON/OFF switch in the off
position. Disconnect the AC power supply to
the unit.
2. Shut off the gas supply to the unit.
3. Remove the regulator adjustment tool by
first pulling up the screwdriver blade to
disengage it from the regulator adjusting
screw, and then turning the tool out of the
top of the regulator.
4. Remove the gasket from the tool and place
it back onto the regulator cap.
5. Apply a drop of silicone to the regulator
adjusting screw to lock its setting.
6. Reinstall the cap and gasket back on the
regulator. Tighten the cap using a
screwdriver or wrench.
7. Remove all of the manometers and barbed
fittings and reinstall the pipe plugs using a
suitable thread compound.
8. Replace the unit's panels and hood.
22
INITIAL START-UP
NOTE:
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