temperature or pressure controller will now modulate the firing rate
to match the load demand of the system, while maintaining proper
fuel/air ratios. Prior to reaching the system pressure or
temperature operating control cut off point, the burner should be at
or near the low fire operating position. At the end of the firing
cycle, the normally closed Oil Valve will be de-energized and the
Modulating Motor will position the Air Dampers and Modulating
Valve to the low fire position, ready for the next start up sequence.
This depiction shows the Linkage in the low fire light off position.
See page 21, Fig. 28 for linkage adjustment information. Also see
this page, Fig. 27 for information on the VaricamTM modulating
characterized fuel metering sytsem.
*Not shown in this depiction. See page 4, Fig. 3.
Some modulating Low-High-Off and Low-
High-Low burners will be supplied with
simplex, rather than internal bypass type, oil
nozzles. The mechanical operation of the
simplex nozzle system is essentially the
same as the internal bypass system - except
that low fire oil pressures should be set at
conditions) and high fire oil pressures at
280 to 300 psig at the oil pump nozzle
pressure gauge test port. Refer to the
Burner Specification sheet shipped with the
burner and/or page 31, Table 9 for high fire
oil pressures and flow rates.
The oil pump depicted in the oil flow
schematic above is as manufactured by
Webster Electric Company Inc. If the pump
on your burner is not Webster, refer to the
oil pump bulletin shipped with the burner
for specific adjustment information. Also
see page 11, Fig. 11.
vary with the specific Flame Safeguard
Control being used. Refer to the specific
Flame Safeguard Control bulletin supplied
with the burner for complete information.
Gas or Gas/Oil Burner Fuel/Air Premix Adjustment - Oil, or Gas/Oil Burner Diffuser Adjustment
FUEL AIR PREMIX
The adjustable premix blast tube (optional) incorporates an
adjustable gas/air premix within the burner firing head. The premix
configuration is primarily used for cylindrical combustion chambers
or high heat release pressurized fireboxes. Moving the adjustment
knob back increases the premix air; moving it forward decreases
the premix air. Generally, the best (quietest/smoothest) operation
is in the full forward position with minimum premix air. The premix
adjustment is set at the factory in the full forward position. To
attain the best combustion results for specific job conditions,
change position in small increments.
Moving the blast tube diffuser assembly fore or aft on gas or oil
firing will move the flame front (point of retention) in order to attain
conditions. If the initial midway point factory setting does not
provide satisfactory results, move fore or aft in small increments to
achieve the best combustion results. If unit is oil or combination
gas/oil, the attached, flexible copper oil nozzle line will move fore
or aft with the assembly. When firing on oil, moving the assembly
forward will tend to broaden the flame pattern and moving it back
will narrow the flame pattern. Similar results are obtained on gas,
but observation of sound and combustion tests are the best
determinants of results on either gas or oil.
Gas/Oil · Detail and Adjustments on Modulating VaricamTM Characterized Fuel Metering System.
(page 3 - 972)