Adjustment Procedures
6-4
750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual
6.3 — Modulating Motor
The modulating motor has a 90º shaft rotation. The motor manu-
facturer also provides a 160º stroke model for other applications.
If a replacement is obtained from someone other than a Cleaver-
Brooks Service or Parts representative, it may have an incorrect
stroke. To prevent damage, determine the 90º stroke prior to
installing a replacement.
The stroke may be determined by powering the motor and con-
necting terminal R-B to actually determine the stroke as the motor
drives to an open position.
FIGURE 6-3. Modulating Motor
6.4 — Modulating Motor Switches: Low-Fire and High-Fire
The modulating motor contains either one or two internal switches depending upon application. The micro-
switches are actuated by adjustable cams attached to the motor shaft.
Factory replacement motors have the cams preset. The low-fire start switch is set to make the red and yellow leads
at approximately 8º on motor closing. The high-fire purge air proving switch (located in the modulating motor) is
set to make red and blue tracer leads at approximately 60º on motor opening. Normally, the settings are left as is,
but job conditions may require readjustment. If the cams require adjustment or resetting, follow the instructions in
the manufacturer’s technical manual.
6.5 — Burner Operating Controls: General
The standard boiler operating control package consists of three separate controls:
• Operating Limit Control
• High Limit Control
• Modulating Control
NOTE: Adjustments to the boiler operating controls should be made by an authorized Cleaver-Brooks Service Tech-
nician. Refer to the appropriate boiler Operation and Maintenance manual for specific information on boiler startup
and operation.
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