CleaverBrooks CBLE, Operation And Maintenance Manual

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Adjustment Procedures
6-2 750-91 (revised 2009)
Model CB-LE Packaged Boiler Manual
6.2 — Linkage: Modulating Motor and Air Damper
The linkage consists of various arms, connecting rods, and swivel ball joints that transmit motion form the modu-
lating motor to the metering cam(s), rotary air damper, and gas butterfly valve.
When properly adjusted, a coordinated movement of the damper and metering cams within the limits of the mod-
ulating motor travel is attained to provide proper fuel-air ratios through the firing range.
In linkage adjustments there are several important factors that must serve as guides.
•
The modulating motor must be able to complete its full travel range.
•
Initial adjustment should be made with the motor in full closed position, that is with the shaft on the power end
of the motor in its most counterclockwise position.
•
The closer the connector is to the drive shaft, the less the arm will travel - the closer the connector is to the
driven shaft, the farther that arm will travel.
•
Over-travel linkage, where used, should not be required in order to extend its spring to the fullest stretch.
With the modulating motor in the low-fire position, the arm on its shaft should be at an angle of 45º below the hor-
izontal. The driven arm on the jackshaft should also be 45º below horizontal. Secure both arms and fit the connect-
ing linkage rod in place between them.
Position the oil and/or gas modulating cams on the jackshaft so that the cam follower assembly is between the first
and second cam adjusting screws (under the first adjusting screw for High Turndown Burners). In this position,
fuel delivery is at low-fire rate. Tighten the set screws to secure the cams on the jackshaft.
FIGURE 6-1.
Rotary Air Damper
NOTE: On combination gas and oil boilers, the gas butterfly valve might not be used. Also on combination gas and
oil boilers, the oil metering valve might not be used.
Do not restrict the full travel of the modulating motor. Failure to follow these instructions could result in equipment
damage.
!
Caution