750-96 (revised 2010)
Model CB Packaged Boiler Manual
4-3
4.3 — Gas Pilot
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).
4.3 — 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 5.
On initial starting attempts, several efforts might be required to accomplish bleeding time of the pilot line. While
checking pilot adjustment, observe whether the pilot flame is extinguished promptly when the burner switch is
opened. Linger flame is indicative of a leaking gas pilot valve and a condition requiring correction before proceed-
ing.
4.4 — Atomizing Air
The supply and pressure of the atomizing air on an oil fired burner should be checked. Before starting, inspect the
oil pump lube oil level. Add oil if necessary to bring the level to the midpoint or slightly higher in the sight glass.
Use SAE 20 detergent oil of a grade mentioned in Chapter 7 and fill in accordance with instructions given there.
Check the oil level of the air intake strainer. The adjusting cock beneath the strainer should be fully open.
To verify air flow and pressure, place the run/test switch on the program relay to the test position. If this is a com-
bination fuel burner, make sure that the gas/oil selector switch is set to “oil.” Turn the burner switch on. The burner
will cycle to the low fire pre-purge position and stop there.
Observe the reading on the air pressure gauge. With no oil flow, the pressure should be a minimum of 7 psi.
If there is no pressure, determine the cause and correct it before proceeding. Check for obstructions in the air
inlet line, incorrect rotation (air pump rotation is clockwise), or a loose oil nozzle or other leaks. If pressure is much
higher without any oil flow, check for obstruction in the discharge line or at the oil nozzle.
The air pressure will increase when an oil flow exists. At low firing rate, the air pressure should be approximately
12 psi or slightly higher. If it is much higher, carefully adjust the cock in the intake line to limit the air pump output.
The low fire flame shape will determine the amount of any necessary throttling.
At high fire the air pressure should not exceed 24 psi. Greater air pressure causes excessive wear of the air pump,
increases lube oil usage, and can overload the motor.
After air flow has been verified, turn the burner switch off and return the run/test switch to the “run” position.
NOTE: Abnormally high pressure indicated on the nozzle air pressure gauge is an indication that the burner nozzle has
become clogged. In this event, check the nozzle and clean as necessary.
To Next Page
Loading...
