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20
Optional Modulation Linkage Adjustment
Instructions
The optional modulation linkage assembly has been
designed as an economic means to adjust the damper
and the butterfl y valve to maintain air to gas ratios. When
the optional Modulation linkage assembly is supplied
with the burner, initial adjustments will be made at the
factory. To ensure optimum operation, minor additional
adjustments must be made after the burner is fi red on a
boiler.
The following adjustment will be pre-set at the factory,
but may require minor adjustment at start-up:
The damper motor high fi re and low fi re cams will be
preset.
The linkage between the damper and the butterfl y
valve will be preset as illustrated in the manual.
The butterfl y valve shaft will be set to a nominal
position.
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Figure 11 - Modulation Assembly for Right Handed
Gas Entry (Optional Construction)
Figure 12 - Modulation Assembly for Left Handed
Gas Entry (Standard Construction)
Adjustment Procedure
Referring to the appliance
manufacturer’s literature, insure that
all preliminary adjustments and calibrations required for
the burner and appliance have been performed.
A) Prior to starting the burner
Verify that the damper motor high fi re and low fi re cam
settings match the nameplate (Figure 1) or Table 3.
Examine the linkage for signs of damage.
Referring to the illustrations in Figures 11 or 12,
verify that the linkage is installed as shown.
Prior to adjusting the burner, have available all the
necessary test equipment.
A manometer to check pressures downstream
of the gas pressure regulator; at the manifold
pressure test connection and in the furnace
A draft gauge to check breaching pressure
A fl ue gas analyzer that can measure O
2
(or
CO
2
) and CO.
Adjust the gas pressure regulator to about ½” WC
higher than the anticipated high fi re gas pressure
(see Table 3).
To prevent the burner from modulating to high fi re,
set the modulation controller to the manual control
mode. If necessary, refer to the manual supplied
with the modulation controller.
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6.
Section: Start the Burner