Modulation Adjustment Instructions - Beckett CG15 Manual

A notch in the white spacer at the base of the cam stack
indicates the position of the damper by its alignment
with the degree marker on the damper position label
(Shown in Figure 24 ). To set a cam, turn that cam's
adjustment screw until the pointer on the cam aligns
with the desired setting on the white spacer between
cams. The burner's damper can be manually rotated by
disengaging the motor's gear train from the cam stack
(Shown in Figure 25 ).
1. Press in and towards the center of the motor on the
cam disengaging pin. It will allow the damper to
move while the cam remains stationary.
2. After adjusting the cams for high and low fire
settings it is important to set the damper position
between the adjusted limits. If the damper position
is left outside the adjusted limits the actuator may
not be engaged until the end of the first operating
cycle.
3. WARNING! Re-engage the pin by pushing it
toward the side of the motor and allowing it to
pop out to its original position, otherwise the
motor will rotate without moving the damper.
If the proportional controller signal does not fully open
or close the damper to its high or low fire setting
during modulation, or if modulation is not linear across
Figure 26 — Damper Cam Adjustment
Minimum position potentiometer
Cam disengaging pin
the control range, it may be necessary to adjust the
maximum or minimum position potentiometer in the
damper motor (Shown in Figure 26 ). See the SQM40
manual in the burner's literature package for detailed
instructions. Note: Both potentiometers require 30
turns to span their range. Don't give up too soon.
32 — Section: Start Up And Operation
Maximum position
potentiometer

Modulation Adjustment Instructions

Modulating burners are provided with manual controls that
allow set-up adjustment of the burner ( Figure 27 and
Figure 28 ).
When the Manual / Auto switch is in the Manual
position, control of the damper position is set by
the firing rate potentiometer. When the Manual /
Auto switch is in the Auto position the firing rate
potentiometer has no effect on damper position, and the
damper is controlled by the flame safeguard during start-
up and shut-down and by the boiler's modulating control
during the run interval.
For 135 OHM controls only, If the Manual/Auto switch
is in the Manual position and the boiler pressure (or
temperature) approaches the control limit set on the
boiler's modulation control (or lead / lag or building
automation system), that control will over-ride the
manual control and drive damper position back to low.
This feature can be used to limit the firing rate when
warming up a cold boiler.
Figure 27 — Firing Rate Control on Wiring Box
Firing Rate
Potentiometer
Manual/Auto
Switch
Figure 28 — Firing Rate Control on 12 x 16 Panel
CG15, CG25, CG50 Burner Manual, Form No. 6104BCG50
Burners with a panel will have
their manual controls located
on the top of the panel.