750-91 (revised 2009)
Model CB-LE Packaged Boiler Manual
5-3
5.3 — Gas Pilot
• On a hot water boiler, the high limit temperature control should be 5º to 10º F above the operating limit tem-
perature control setting but within the limits of the design pressure of the pressure vessel.
5.2.3 — Modulating Control
Inspect the modulating control for proper setting. The control must be set and adjusted so that the modulating
motor returns to low fire position before the operating limit control opens. It is further desirable to have its low
point setting somewhat below the cut-in setting of the limit control so that the burner operates in low fire position
for a brief period on each start rather than immediately driving to a high fire position.
5.2.4 — Low-Water Cutoff and Pump Control
Inspect the low-water cutoff and pump control as well as the auxiliary low-water cutoff (if equipped with this
optional device). Check for freedom of float movement. Float movement can be verified by observing the level of
water in the gauge glass when the water supply has been cut off either by the stopping of the feed pump or by the
closing of a valve, and the restarting of the pump or opening of the valve when water is drained from the pressure
vessel. The importance of proper functioning of low-water controls cannot be over-emphasized. Be sure that the
control and the piping are level.
The CB Level Master is the standard low water cutoff device on CB high pressure steam boilers. See CB manual
750-281 for complete operation, maintenance, and parts information.
5.2.5 — Additional Considerations
The settings of controls relating to fuel, either oil or gas, are covered in subsequent sections.
In the event the boiler is equipped with optional control devices not listed here, be certain to ascertain that their
settings are correct. If additional information is required, see your local Cleaver-Brooks authorized representative.
On initial startup or whenever the boiler is placed into operation from a “cold” start, the manual-automatic selector
switch should be set at “manual” and the manual flame control set at “close.” After the boiler is in operation and
thoroughly warmed, the selector switch should be turned to “automatic,” so that the burner firing rate may be con-
trolled by the modulating control in accordance with load demands.
Close all power entrance switches (supplied by others).
5.3 — Gas Pilot
The gas pilot should be checked for satisfactory performance prior to initial firing. Follow the pilot flame adjust-
ment instructions given in Chapter 6.
NOTE: The settings of all the above controls may require some readjustment after the boiler is started and running
for a short period. The scale settings on the controls are relatively accurate, but are principally for use as guides. Final
adjustment should be based on and agree with the reading of the steam pressure gauge or the water temperature ther-
mometer.
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